Repository: Artoria2e5/PRCoords Branch: master Commit: a853b1fc19ee Files: 51 Total size: 138.8 KB Directory structure: gitextract_j7s_ktue/ ├── .gitignore ├── .npmignore ├── .vscode/ │ └── settings.json ├── LICENSE.gplv3 ├── README.md ├── approx/ │ └── approx.ipynb ├── cpp/ │ ├── Makefile │ ├── badmath.hh │ ├── bench.cc │ ├── bench4.sh │ ├── bench_out/ │ │ ├── README.md │ │ ├── native_nick.md │ │ ├── native_stdsin.md │ │ ├── nick.md │ │ └── stdsin.md │ ├── demo.cc │ ├── libprcoords.cc │ └── prcoords.h ├── docs/ │ ├── demo.html │ ├── index.md │ └── proj4_plugin.js ├── haskell/ │ ├── PRCoords.cabal │ ├── PRCoords.hs │ └── Setup.hs ├── js/ │ ├── .npmignore │ ├── PRCoords.d.ts │ ├── PRCoords.js │ ├── misc/ │ │ ├── insane_is_in_china.js │ │ └── package.json │ └── package.json ├── julia/ │ ├── Project.toml │ └── src/ │ └── PRCoords.jl ├── lua/ │ └── PRCoords.lua ├── matlab/ │ ├── PRCoords.m │ ├── bd_gcj.m │ ├── bd_gcj_precise.m │ ├── bd_wgs.m │ ├── bd_wgs_precise.m │ ├── caijun_precise.m │ ├── gcj_bd.m │ ├── gcj_wgs.m │ ├── gcj_wgs_precise.m │ ├── wgs_bd.m │ └── wgs_gcj.m ├── package.json ├── pgsql/ │ ├── distance_agg.sql │ ├── prcoords.sql │ └── prcoords_postgis.sql ├── py/ │ ├── prcoords.py │ └── setup.py └── racket/ └── prcoords.rkt ================================================ FILE CONTENTS ================================================ ================================================ FILE: .gitignore ================================================ py/*/ cpp/*.exe cpp/*.a cpp/*.dll cpp/*.so cpp/*.o cpp/*.obj cpp/*.def cpp/*.lib cpp/*.exp node_modules julia/.vscode/settings.json cpp/nanobench.h cpp/bench cpp/demo ================================================ FILE: .npmignore ================================================ # npm sucks and i can only put things under git root /* !/js js/misc !/doc ================================================ FILE: .vscode/settings.json ================================================ { "files.associations": { "*.embeddedhtml": "html", "iostream": "cpp" } } ================================================ FILE: LICENSE.gplv3 ================================================ GNU GENERAL PUBLIC LICENSE Version 3, 29 June 2007 Copyright (C) 2007 Free Software Foundation, Inc. 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If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. But first, please read . ================================================ FILE: README.md ================================================ PRCoords ======== People's Rectified Coordinates (PRCoords) is a cross-language implementation of "public secret" Chinese coordinate obfuscation methods including GCJ-02 and BD-09, along with general deobfuscation methods previously established in [ChinaMapShift][], [eviltransform][], and [geoChina][]. (Referring to the process of replacing straight lines with wavy ones as a "transform" is euphemism overdone.) For a background on China's geographic obfuscation, see [Restrictions on geographic data in China](https://en.wikipedia.org/wiki/Restrictions_on_geographic_data_in_China#Coordinate_systems) and [中华人民共和国测绘限制](https://zh.wikipedia.org/wiki/中华人民共和国测绘限制) on Wikipedia. [ChinaMapShift]: https://gist.github.com/anonymous/e7c6f67555099180ce1ae8da4ba2c513 [geoChina]: https://github.com/caijun/geoChina/blob/master/R/cst.R [eviltransform]: https://github.com/googollee/eviltransform Languages --------- - [x] JavaScript ([`npm install prcoords`](https://www.npmjs.com/package/prcoords)) [![](https://data.jsdelivr.com/v1/package/npm/prcoords/badge)](https://www.jsdelivr.com/package/npm/prcoords) * Web demo: https://artoria2e5.github.io/PRCoords/demo * Now with AMD support and faux `__esModule` interop for Babel and TypeScript! - [x] Python ([`pip install prcoords`](https://pypi.org/project/prcoords/)) - [x] \(Obj-\)C/C++ (C ABI) * [x] Makefile with `install` - [ ] Ruby - [ ] Swift - [ ] C# - [x] Haskell (GCJ only; data structure incomplete) * need to move googollee/eviltransform#54 here sometime. - [ ] Java - [x] Matlab/Octave - [x] PGSQL - [ ] Typed Racket * is it done? (should I split them into submodules?) For languages not yet supported, we recommend you to check for [eviltransform][] (MIT) or [geoChina][] (GPLv3, R) instead. API --- PRCoord's APIs operate on, and returns, dedicated structures for coordinates. In API names, we generally refer to WGS-84 as `wgs`, GCJ-02 as `gcj`, and BD-09 (lat-lon) as `bd`. ### Inverse functions The obfuscations generally have these properties to maintain basic usefulness: 1. `obfs(coord)` is sort of close to `coord`. 2. `obfs(a) - obfs(b)` is usually close to `a - b`. (The closer `a` and `b` are to each other, the better it works.) In general two approaches of inverting the "forward" obfuscations, or working from `obfs(coord)` to `coord`, are implemented: * _Run it backwards_: `obfs(coord)` is never too far from `coord`, so just use  `obfs(obfs(coord)) - obfs(coord)` to estimate `obfs(coord) - coord`. * _Iterate a bit_: Get a rough `guess` somehow, and just use property 2 to estimate the remaining error as `obfs(guess) - obfs(coord)` and correct the `guess`. You can read on the demo page about how well these methods work from the `ΔRoundtrip` entry. Unless you are doing archival work, you generally don't have to iterate. ### The "in China" sanity check Typically PRCoords is only supposed to be ran on obfuscated input data, which are primarily Chinese coordinates. For this reason, initial implementations include this [very very rough](https://news.ycombinator.com/item?id=10965506) sanity check that spans a rectangular region on a mercator-projected map. This check can be overridden by passing a boolean value, or may be not at all implemented in certain languages if I am not in the right mood for doing silly things. There is an "insane" sanity check intended to approximate the range of Google and Baidu's distortion, intended for use by [IITC](https://iitc.me): [`js/insane_is_in_china.js`](https://github.com/Artoria2e5/PRCoords/blob/master/js/insane_is_in_china.js). It is basically a ray-casting polygon check with 70 vertices. You, as the caller, should still be responsible for telling whether a point is part of the gov-screwed Chinese data. FAQ --- ### Why another wheel? * Correctness * Public Domain * Clean API based on pairs of coordinates * Need to find a place for this sarcastic name ### Can the systems be described as WKT or proj-strings? Not directly as a datum, because in both representations a datum is either "sane" (no non-linearity in 3D, Helmert possible) or a big table of grids. It should be possible to describe the two CS with a `PROJECTION` entry as a `PROJCS`. Since a `PROJCS` cannot be nested in another, the BD transformation must be described using WGS84 and a fuzed GCJ-BD projection. The situation is similar with [Baidu "Meractor"](https://github.com/gumblex/cntms/commit/bbde4006adeb92f48da1ff7d1f88da393d382f8a).
Speculative WKT/PROJ4 ```js PROJCS["Baidu 2009, Pseudo-Mercator", GEOGCS["WGS 84", DATUM["WGS_1984", SPHEROID["WGS 84",6378137,298.257223563, AUTHORITY["EPSG","7030"]], AUTHORITY["EPSG","6326"]], PRIMEM["Greenwich",0, AUTHORITY["EPSG","8901"]], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9122"]], AUTHORITY["EPSG","4326"]], PROJECTION["CN_Obfs_Baidu_2009_Mercator"], AXIS["x",east], AXIS["y",north], UNIT["metre",1, AUTHORITY["EPSG","9001"]], EXTENSION["PROJ4","+proj=baidumerc +units=m +nadgrids=@null +wktext +no_defs"], AUTHORITY["EPSG","888002"]] PROJCS["Chinese BSM 2002, Pseudo-Ellipsoidal", GEOGCS["WGS 84", AUTHORITY["EPSG","4326"]], PROJECTION["CN_Obfs_GCJ_2002_Ellipsoidal"], AXIS["longitude",east], AXIS["latitude",north], UNIT["degree",0.0174532925199433, AUTHORITY["EPSG","9122"]], EXTENSION["PROJ4","+proj=gcjlonglat +units=deg +nadgrids=@null +wktext +no_defs"], AUTHORITY["EPSG","888000"]] ```
The good people at proj4js has made their stuff [very easy to extend](https://github.com/proj4js/proj4js/issues/358). Here is [an example](https://runkit.com/artoria2e5/proj4-plugin-prcoords) (backed up in [`docs/proj4_plugin.js`](https://github.com/Artoria2e5/PRCoords/blob/master/docs/proj4_plugin.js) in case RunKit goes down) of how to add PRCoords support to proj4js. ### Should I use fast fp math? Yes. Nobody knows what the original looks like anyways, so what's wrong with letting the compiler recombine a bit more? You can't be more off than the one-meter random error (in "EMQ") anyways. Or tinker with 32-bit floats and fixed-point numbers. Or try approximation tools like [Sollya](http://sollya.gforge.inria.fr/) or [MC++](https://omega-icl.github.io/mcpp/). Really, just search on the Internet for "\ Taylor Chebyshev Model". You only need less than 1e-6 error on a [not-very-large slice](https://github.com/Artoria2e5/PRCoords/blob/a3a8bb8/js/PRCoords.js#L91) of the Earth anyways. I threw TaylorModels.jl at GCJ-02, and got ~~decent~~ results out of it. Still too lazy to put it in code though. Check out [approx/approx.ipynb](https://github.com/Artoria2e5/PRCoords/blob/master/approx/approx.ipynb). (Nope, not decent. Gotta do it properly some day, just don't use the notebook and expect it to work!) I tried another route with the C++ version using a devmaster user Nick's `sinpi()` approximation. It seems to be good enough for 1e-6: check out [cpp/bench_out](https://github.com/Artoria2e5/PRCoords/tree/master/cpp/bench_out) and [cpp/badmath.hh](https://github.com/Artoria2e5/PRCoords/blob/master/cpp/badmath.hh). Physical PRCoords ----------------- You can print out a minimal copy of PRCoords with [this PDF file](https://commons.wikimedia.org/wiki/File:PRcoords_Cheatsheet.pdf). I am working on some better options [in issue #2](https://github.com/Artoria2e5/PRCoords/issues/2). A fairly simple tote bag with an older version of the PDF is [available from Teespring](https://teespring.com/miniprcoords-tote-v1). Feel free to print and sell t-shirts with the PDF file! It is put in the Public Domain, so you don't have to pay me for that. You can always fund my subversive activities on [Patreon](https://www.patreon.com/artoria2e5) though. License ------- Unless otherwise mentioned, all files in this package, including this README file, are dual-licensed under: * [CC0 1.0 Public Domain Dedication](https://creativecommons.org/publicdomain/zero/1.0/) * [GNU General Public License (version 3 or up)](https://gnu.org/licenses/gpl.html) GPL is only included for fun here. Sources ------- * [Algorithm.Coords.Converter](https://archive.is/20130815104734/emq.googlecode.com/svn/emq/src/Algorithm/Coords/Converter.java) from [EMQ](https://code.google.com/archive/p/emq/) ([GitHub mirror](https://github.com/richardyu-au/emq)) is probably *the* GCJ leak. It is a JSP project "for demonstrating GIS systems", probably done by some government contractor. * There is some randomness in the GCJ deltas on both axes: one `sin` invocation and one LCG. Each add a maximum of 1 meter of error. * [on4wp7](https://archive.is/20150702191259/https://on4wp7.codeplex.com/SourceControl/changeset/view/21483%23353936) (2013) is the earliest rationalized GCJ (forward) implementation. No randomness is attempted. * [ChinaMapShift][] (2014) figured out the quick iterative inverse for GCJ. I learned about it via geoChina first and generalized it here. * BD-09 is not very well sourced, but [pycoordtrans](https://github.com/zxteloiv/pycoordtrans) (2014) seems to have it. See also -------- * [eviltransform][] is among the most popular cross-language soltions to the problem. It borrows its name directly from [EvilTransform.cs](https://github.com/Leask/EvilTransform/blob/master/EvilTransform.cs), an early refactored version of a raw-flesh Java implementation found in "[emq](https://code.google.com/archive/p/emq/)", some sort of government contractor GIS demo project. * Since June 2016, eviltransform contains numerous parameter errors that compromise its output, especially for BD-09. See googollee/eviltransform[#43](https://github.com/googollee/eviltransform/issues/43), [#53](https://github.com/googollee/eviltransform/pull/53) and [#44](https://github.com/googollee/eviltransform/issues/44) for corrections. As of June 2019 these problems are not fixed. * [geoChina][] by caijun is a clear, concise implementation written in R. It features the iterative method from ChinaMapShift. * I am planning on moving some of the comments on the algorithm found in [my initial JavaScript implementation](https://zh.wikipedia.org/wiki/User:Artoria2e5/PRCoords.js) to the [GitHub Wiki](https://github.com/Artoria2e5/PRCoords/wiki). I don't think anyone is going to be interested in copying comments on these idiocy when translating my implementation to other languages. * If you are doing a translation, consider only using the comments from the PDF. * [Ishisashi's writeup](https://chaoli.club/index.php/4777/0) on this subject. They wrote a super enhanced version of the demo too. Oh, and finally, here is an official [news report](https://archive.fo/20110804185923/http://cxzy.people.com.cn/GB/196034/14908095.html) on that particular *\[bleep\]* who came up with GCJ-02. ================================================ FILE: approx/approx.ipynb ================================================ { "cells": [ { "cell_type": "markdown", "metadata": {}, "source": [ "Approximation\n", "=============\n", "\n", "Scroll down and you should find some approximations of the obfuscation code.\n", "I have no idea what evil forces compelled me to do this, but eh let's roll with it." ] }, { "cell_type": "code", "execution_count": 3, "metadata": {}, "outputs": [], "source": [ "using TaylorModels" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "GCJ-02\n", "------\n", "\n", "The `abs()` makes it impossible to feed into taylor, so I think I will just feed the trigs in. Splitting the x and y too, so we don't get a lot of zero in the coeffs.\n", "\n", "Let's start with... typing the formulae:" ] }, { "cell_type": "code", "execution_count": 4, "metadata": {}, "outputs": [ { "data": { "text/plain": "e1 (generic function with 1 method)" }, "execution_count": 4, "metadata": {}, "output_type": "execute_result" } ], "source": [ "# Not gonna type these pi.\n", "spi(x) = sin(x * pi)\n", "\n", "# Just the core meter-level shite. 1 and 2 are to be fed to taylor.\n", "n0(x, y) = -100 + 0.1x*y + 0.2 * sqrt(abs(x))\n", "n1(x) = 2x + 20 / 3 * (2 * spi(6x) + 2 * spi(2x))\n", "n2(y) = 3y + 0.2y^2 + 20 / 3 * (2 * spi(y) + 4 * spi(y/3) + 16 * spi(y/12) + 32 * spi(y/30))\n", "\n", "e0(x, y) = 300 + 0.1x*y + 0.1 * sqrt(abs(x)) + 2y\n", "e1(x) = x + 0.1x^2 + 20 / 3 * (2 * spi(6x) + 2 * spi(2x) + 2 * spi(x) + 4 * spi(x/3) + 15 * spi(x/12) + 30 * spi(x/30))" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "Set up for TaylorModels:" ] }, { "cell_type": "code", "execution_count": 5, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "n1tm = [337.103, 337.104] t + [-15434.3, -15434.2] t³ + [265489, 265490] t⁵ + [-4.894e+16, 4.894e+16]\n", "n2tm = [123.078, 123.079] t + [0.2, 0.200001] t² + [-74.3666, -74.3665] t³ + [34.2831, 34.2832] t⁵ + [-1.74906e+11, 1.74906e+11]\n", "e1tm = [453.04, 453.041] t + [0.1, 0.100001] t² + [-15508.6, -15508.5] t³ + [265523, 265524] t⁵ + [-4.89402e+16, 4.89402e+16]\n" ] } ], "source": [ "x_dom = -30..30\r\n", "y_dom = -30..20\r\n", "\r\n", "# 35,105 as the center of China. What can go wrong?\r\n", "x0 = 0\r\n", "y0 = 0\r\n", "\r\n", "ORDER = 6\r\n", "\r\n", "tmx = TaylorModel1(ORDER, interval(x0), x_dom)\r\n", "tmy = TaylorModel1(ORDER, interval(y0), y_dom)\r\n", "\r\n", "n1tm = n1(tmx)\r\n", "n2tm = n2(tmy)\r\n", "e1tm = e1(tmx)\r\n", "\r\n", "println(\"n1tm = \", n1tm)\r\n", "println(\"n2tm = \", n2tm)\r\n", "println(\"e1tm = \", e1tm)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "Oh well, the last term is way better than what I expected. Let's export them as usual polynomials then." ] }, { "cell_type": "code", "execution_count": 6, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "n1t = 337.10321638291134 t - 15434.235503082582 t³ + 265489.0776448309 t⁵ + 𝒪(t⁷)\n", "n2t = 123.07865253720988 t + 0.2 t² - 74.36657685107961 t³ + 34.28315615652991 t⁵ + 𝒪(t⁷)\n", "e1t = 453.0402762665314 t + 0.1 t² - 15508.57959081323 t³ + 265523.36073126463 t⁵ + 𝒪(t⁷)\n" ] } ], "source": [ "function mid_tm(t::TaylorModel1)\r\n", " coeffs = map(x -> mid(x), t.pol.coeffs)\r\n", " order = t.pol.order\r\n", " return Taylor1(coeffs, order)\r\n", "end\r\n", "n1t = mid_tm(n1tm)\r\n", "n2t = mid_tm(n2tm)\r\n", "e1t = mid_tm(e1tm)\r\n", "println(\"n1t = \", n1t)\r\n", "println(\"n2t = \", n2t)\r\n", "println(\"e1t = \", e1t)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "These should be good enough to just translate into code. If you are allowing the compiler to reassoc, there should be no need of manually writing Horner and thinking about pipelines. The reduced number of operations might even make `f32` acceptable. I will eventually put it in the cpp thing and check it.\r\n", "\r\n", "The arclen stuff have the same `sqrt` issue, so it's not getting changed here.\r\n", "\r\n", "Okay, actually, **no**. The range of numbers means that `t^7` is ridiculously large. I should really throw this at MetaLibm-Lutetia\r\n", "and ask it to do the argument reduction for me...\r\n", "\r\n", "BD-09\r\n", "----\r\n", "We have a `sqrt` in `hypot`, so no. We can't fuze any operations here anyways.\r\n", "\r\n", "\r\n", "Plotting session\r\n", "----------------\r\n", "Oops UI can't install `Plots`. And I just realized the resulting numbers are\r\n", "unreasonably large. Oops." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] } ], "metadata": { "kernelspec": { "display_name": "Julia 1.5.0-rc1", "language": "julia", "name": "julia-1.5" }, "language_info": { "file_extension": ".jl", "mimetype": "application/julia", "name": "julia", "version": "1.5.0" }, "orig_nbformat": 2 }, "nbformat": 4, "nbformat_minor": 2 } ================================================ FILE: cpp/Makefile ================================================ CXXFLAGS = -O3 -funsafe-math-optimizations -fno-math-errno -std=c++0x -Wall -Wextra -fvisibility=hidden -fvisibility-inlines-hidden -DNDEBUG $(XCXXFLAGS) # "Cross compile" shite. In other words MinGW. # TARGET is Triplet PLUS THE HYPHEN! CC = $(TARGET)gcc CXX = $(TARGET)g++ AR ?= $(TARGET)ar DLLTOOL ?= $(TARGET)dlltool # for clang's llvm bitcode: CCAR=llvm-ar CCAR ?= gcc-ar # Override when using CYGWIN: make [target] LIB=cyg SO=dll # Override when using MinGW: make [target] LIB='' SO=dll TARGET=x86_64-w64-mingw32- LIB ?= lib SO ?= so # Installation DESTDIR ?= PREFIX ?= /usr/local # Path to the Microsoft Library Manager (LIB.exe) # Available from https://aka.ms/buildtools # Tends to be buried deep, e.g. C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.22.27905\bin\Hostx64\x64 # I recommend putting a shell script called lib.exe in /usr/local/bin to call it with "$@" # # Mingw-W64 has a genlib.exe for those who dare to try. It generates MSVC-style # __IMPORT_DESCRIPTOR_%s. Or maybe the ld -Wl,--out-implib will work with MSVC # too with __imp symbols only, who knows. # # Note that this is only meaningful for MinGW output: Cygwin/MSYS builds have # dependency for cygwin1.dll, which triggers address-clashes with MSVC's libs. # # cl /Fe:demo-cl.exe demo.cc prcoords.lib LIBEXE ?= LIB.exe # Or /machine:x86. LIBFLAGS ?= /machine:x64 all: libprcoords.a $(LIB)prcoords.$(SO) demoso prec_sample: demo demof demold windows: all $(LIB)prcoords.lib # We assume that your copy of "ar" supports the "s" option, # which does some ranlib work itself. libprcoords.a: libprcoords.o $(AR) rcs libprcoords.a libprcoords.o libprcoords-lto.a: libprcoords-lto.o $(CCAR) rcs libprcoords-lto.a libprcoords-lto.o $(LIB)prcoords.$(SO): libprcoords.o $(CC) -shared -o $(LIB)prcoords.$(SO) libprcoords.o libprcoords.o: libprcoords.cc badmath.hh $(CC) $(CXXFLAGS) -fPIC -c -DPRCOORDS_DLL -DPRCOORDS_DLL_EXPORTS libprcoords.cc libprcoords-lto.o: libprcoords.cc $(CC) $(CXXFLAGS) -flto -ffat-lto-objects -c libprcoords.cc -o libprcoords-lto.o # Import library generation for MSVC users (optional) $(LIB)prcoords.def: libprcoords.o $(DLLTOOL) --dllname $(LIB)prcoords.$(SO) -z $(LIB)prcoords.def --export-all-symbols libprcoords.o # Also spits out an .exp $(LIB)prcoords.lib: $(LIB)prcoords.def $(LIBEXE) $(LIBFLAGS) /nologo /def:$(LIB)prcoords.def /out:$(LIB)prcoords.lib demo: demo.cc libprcoords.cc $(CXX) $(CXXFLAGS) -DPRCOORDS_DEMO_FORCE_STANDALONE=1 -o demo demo.cc demof: demo.cc libprcoords.cc $(CXX) $(CXXFLAGS) -DPRCOORDS_DEMO_FORCE_STANDALONE=1 -DPRCOORDS_NUM=float -DPRCOORDS_STON=stof -o demof demo.cc demold: demo.cc libprcoords.cc $(CXX) $(CXXFLAGS) -DPRCOORDS_DEMO_FORCE_STANDALONE=1 -DPRCOORDS_NUM='long double' -DPRCOORDS_STON=stold -o demold demo.cc # Horray! We do not need import libraries. # FIXME: COMMAND NOT BUILDING ON MY NIXOS demoso: demo.cc $(LIB)prcoords.$(SO) $(CXX) $(CXXFLAGS) -L. -l:$(LIB)prcoords.$(SO) -o demoso -DPRCOORDS_DLL demo.cc nanobench.h: wget -O nanobench.h https://github.com/martinus/nanobench/raw/master/src/include/nanobench.h bench: libprcoords.o prcoords.h nanobench.h bench.cc $(CXX) $(CXXFLAGS) -DPRCOORDS_BENCH $(DEFS) -o bench libprcoords.o bench.cc .PHONY: clean help install uninstall install: all mkdir -p $(DESTDIR)$(PREFIX)/bin/prcoords-demo install -s demoso -- $(DESTDIR)$(PREFIX)/bin/prcoords-demo mkdir -p $(DESTDIR)$(PREFIX)/lib install -m 644 -- libprcoords.a $(LIB)prcoords.$(SO) $(DESTDIR)$(PREFIX)/lib uninstall: rm -f -- $(DESTDIR)$(PREFIX)/bin/prcoords-demo $(DESTDIR)$(PREFIX)/lib/libprcoords.a $(DESTDIR)$(PREFIX)/lib/$(LIB)prcoords.$(SO) clean: $(RM) demo demof demold *.exe *.a *.o *.def *.dll *.obj *.lib *.exp *.obj bench ================================================ FILE: cpp/badmath.hh ================================================ /** * Internal header for implementing "fast" sin(x*pi). */ #include namespace badmath { // what are you gonna do about it? x can't be too big! // this is supposed to turn into FMA where fast, and not invoke the fma() libc function otherwise. // like how Julia's muladd() works, but at the mercy of the compiler. template inline T red4(T x) { return -4 * std::nearbyint(x * 0.25) + x; } // devmaster user "Nick"'s approximation formula // https://web.archive.org/web/20171228230531/http://forum.devmaster.net/t/fast-and-accurate-sine-cosine/9648 template inline T sinpi_nick(T x) { x = red4(x * 2); // = 0 to 2pi; nick-magic works on units of 0.5pi T y = x * (2 - std::abs(x)); return y * (0.775 + 0.225 * std::abs(y)); } template inline T sinpi_std(T x) { return std::sin(x * M_PI); } template inline T sinpi(T x) { #ifndef PRCOORDS_NO_BADMATH return sinpi_nick(x); #else return sinpi_std(x); #endif } template inline T cospi(T x) { return sinpi(x + 0.5); } } ================================================ FILE: cpp/bench.cc ================================================ #include #include "badmath.hh" #include "prcoords.h" #define ANKERL_NANOBENCH_IMPLEMENT #include "nanobench.h" double uniform(ankerl::nanobench::Rng& rng, double a, double b){ return rng.uniform01() * (b - a) + a; } PRCoords rand_coord(ankerl::nanobench::Rng& rng){ return PRCoords{.lat = uniform(rng, -90, 90), .lon = uniform(rng, -180, 180)}; } int main(){ using namespace badmath; auto rng = ankerl::nanobench::Rng(); ankerl::nanobench::Bench().minEpochIterations(10000).run( "nop", [&]() { auto coord = rand_coord(rng); ankerl::nanobench::doNotOptimizeAway(coord); } ); ankerl::nanobench::Bench().minEpochIterations(10000).run( "wgs_gcj", [&]() { auto coord = rand_coord(rng); auto res = prcoords_wgs_gcj(coord); ankerl::nanobench::doNotOptimizeAway(res); } ); ankerl::nanobench::Bench().minEpochIterations(10000).run( "gcj_wgs", [&]() { auto coord = rand_coord(rng); auto res = prcoords_gcj_wgs(coord); ankerl::nanobench::doNotOptimizeAway(res); } ); ankerl::nanobench::Bench().minEpochIterations(10000).run( "gcj_wgs_bored", [&]() { auto coord = rand_coord(rng); auto res = prcoords_gcj_wgs_bored(coord); ankerl::nanobench::doNotOptimizeAway(res); } ); ankerl::nanobench::Bench().minEpochIterations(10000).run( "bd_wgs_bored", [&]() { auto coord = rand_coord(rng); auto res = prcoords_gcj_wgs_bored(coord); ankerl::nanobench::doNotOptimizeAway(res); } ); ankerl::nanobench::Bench().minEpochIterations(10000).run( "gcj_bd", [&]() { auto coord = rand_coord(rng); auto res = prcoords_gcj_bd(coord); ankerl::nanobench::doNotOptimizeAway(res); } ); return 0; } ================================================ FILE: cpp/bench4.sh ================================================ #!/bin/sh bench_to_file() { make clean make bench XCXXFLAGS="$1" ./bench > bench_out/$2.md } native='-march=native' stdsin='-DPRCOORDS_NO_BADMATH' if (( ! KEEP_GOVNOR )); then OL_GOVNOR=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor) echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor fi bench_to_file "$native" 'native_nick' bench_to_file "$native $stdsin" 'native_stdsin' bench_to_file "" 'nick' bench_to_file "$stdsin" 'stdsin' if [[ -n $OL_GOVNOR ]]; then echo $OL_GOVNOR | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor fi ================================================ FILE: cpp/bench_out/README.md ================================================ # bench_out All four files are made by nanobench; just do `./bench4.sh`. * `nick` is the version with Nick's fast sinpi. * `std` is the version with sinpi implemented by `std::sin(M_PI * x)`. * The ones with `native_` in front are built with `-march=native`. All the other flags are per Makefile: unsafe math optimizations, no math errno, you know the drill. The native versions are just 10% faster. The real win comes from using Nick's approximation, which quarters the runtime. There seems to be no real damage to the output. I mean, nick is at most 1e-3 off. That's appropriate when we are working in how many meters to shift a point. * Compiler: GCC 13.2.0 * CPU: Ryzen 5 3600 * OS: NixOS 24.05pre, Linux 6.6.28 ## Update: more agressive nicking I also applied Nick's approximation to the `arclen` calculation in GCJ. As expected of a more important divisor, some visible damage to the output is seen, but the magnitude remians in the 1e-6 range. I consider that acceptable given the performance gain (see the files!); it's now the default. \[That does make the `bored` conversion a bit pointless. Hmm, idk.\] `bd` calculation also now uses nick. It also gets benched. Going native seems to cause a 15% regression on `bd`, std or nick. Might be a good idea to look into that, or at least see what clang does. Anyone wishing to turn off nick can use the `-DPRCOORDS_NO_BADMATH` define. There *might* be a point in turning off nick for specific parts of the calculation, but I don't want to spend time on that. ================================================ FILE: cpp/bench_out/native_nick.md ================================================ Warning, results might be unstable: * CPU frequency scaling enabled: CPU 0 between 550.0 and 4,208.0 MHz Recommendations * Use 'pyperf system tune' before benchmarking. See https://github.com/psf/pyperf | ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark |--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:---------- | 4.12 | 242,648,826.64 | 0.4% | 22.00 | 16.60 | 1.325 | 0.00 | 0.0% | 0.01 | `nop` | 30.80 | 32,472,208.69 | 3.6% | 223.00 | 121.17 | 1.840 | 2.00 | 0.0% | 0.01 | `wgs_gcj` | 37.95 | 26,349,634.73 | 0.2% | 238.00 | 149.56 | 1.591 | 4.00 | 0.0% | 0.01 | `gcj_wgs` | 157.44 | 6,351,722.84 | 2.1% | 683.36 | 622.28 | 1.098 | 13.03 | 2.3% | 0.02 | `gcj_wgs_bored` | 154.01 | 6,493,059.75 | 1.3% | 683.44 | 613.84 | 1.113 | 13.03 | 2.3% | 0.02 | `bd_wgs_bored` | 70.30 | 14,224,263.54 | 3.0% | 360.39 | 274.90 | 1.311 | 49.20 | 3.0% | 0.01 | `gcj_bd` ================================================ FILE: cpp/bench_out/native_stdsin.md ================================================ Warning, results might be unstable: * CPU frequency scaling enabled: CPU 0 between 550.0 and 4,208.0 MHz Recommendations * Use 'pyperf system tune' before benchmarking. See https://github.com/psf/pyperf | ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark |--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:---------- | 4.09 | 244,330,932.16 | 0.5% | 22.00 | 16.60 | 1.325 | 0.00 | 0.0% | 0.01 | `nop` | 196.22 | 5,096,191.73 | 0.3% | 1,279.11 | 780.29 | 1.639 | 160.01 | 7.2% | 0.02 | `wgs_gcj` | 197.34 | 5,067,445.81 | 0.3% | 1,294.41 | 782.36 | 1.655 | 162.02 | 7.0% | 0.02 | `gcj_wgs` | 623.01 | 1,605,113.03 | 0.6% | 3,861.91 | 2,462.12 | 1.569 | 489.22 | 5.6% | 0.07 | `gcj_wgs_bored` | 622.11 | 1,607,439.62 | 0.4% | 3,856.47 | 2,461.61 | 1.567 | 488.46 | 5.6% | 0.08 | `bd_wgs_bored` | 89.76 | 11,141,416.00 | 0.3% | 540.45 | 356.74 | 1.515 | 77.21 | 5.5% | 0.01 | `gcj_bd` ================================================ FILE: cpp/bench_out/nick.md ================================================ Warning, results might be unstable: * CPU frequency scaling enabled: CPU 0 between 550.0 and 4,208.0 MHz Recommendations * Use 'pyperf system tune' before benchmarking. See https://github.com/psf/pyperf | ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark |--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:---------- | 3.25 | 307,628,660.33 | 0.4% | 22.00 | 12.97 | 1.696 | 0.00 | 0.0% | 0.01 | `nop` | 45.60 | 21,931,100.65 | 0.8% | 448.00 | 179.13 | 2.501 | 38.00 | 0.0% | 0.01 | `wgs_gcj` | 59.09 | 16,922,136.13 | 2.1% | 465.00 | 231.72 | 2.007 | 40.00 | 0.0% | 0.01 | `gcj_wgs` | 198.70 | 5,032,812.17 | 0.6% | 1,365.35 | 779.44 | 1.752 | 121.13 | 0.3% | 0.02 | `gcj_wgs_bored` | 197.66 | 5,059,121.12 | 0.5% | 1,364.69 | 774.35 | 1.762 | 121.07 | 0.2% | 0.02 | `bd_wgs_bored` | 58.40 | 17,123,351.22 | 0.4% | 391.40 | 227.11 | 1.723 | 55.21 | 2.7% | 0.01 | `gcj_bd` ================================================ FILE: cpp/bench_out/stdsin.md ================================================ Warning, results might be unstable: * CPU frequency scaling enabled: CPU 0 between 550.0 and 4,208.0 MHz Recommendations * Use 'pyperf system tune' before benchmarking. See https://github.com/psf/pyperf | ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark |--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:---------- | 3.24 | 308,253,800.28 | 0.2% | 22.00 | 12.97 | 1.696 | 0.00 | 0.0% | 0.01 | `nop` | 216.41 | 4,620,855.79 | 6.9% | 1,315.38 | 853.91 | 1.540 | 160.04 | 7.2% | 0.03 | :wavy_dash: `wgs_gcj` (Unstable with ~10,854.4 iters. Increase `minEpochIterations` to e.g. 108544) | 206.03 | 4,853,603.19 | 1.4% | 1,332.00 | 811.94 | 1.641 | 162.03 | 7.0% | 0.03 | `gcj_wgs` | 653.44 | 1,530,359.50 | 1.0% | 3,973.24 | 2,546.70 | 1.560 | 488.60 | 5.6% | 0.08 | `gcj_wgs_bored` | 653.92 | 1,529,245.44 | 0.6% | 3,976.15 | 2,533.60 | 1.569 | 488.87 | 5.6% | 0.08 | `bd_wgs_bored` | 93.34 | 10,713,089.73 | 0.4% | 543.42 | 361.83 | 1.502 | 77.21 | 5.5% | 0.01 | `gcj_bd` ================================================ FILE: cpp/demo.cc ================================================ /** * People's Rectified Coordinates, C++ demo. */ #if PRCOORDS_DEMO_FORCE_STANDALONE #include "libprcoords.cc" #else #include "prcoords.h" #endif #include #include #include #include using namespace std; #ifndef PRCOORDS_STON #define PRCOORDS_STON stod #endif std::string show_coord(PRCoords v) { std::stringstream stream; stream << std::fixed << std::setprecision(8) << v.lat << ", " << v.lon; return stream.str(); } PRCoords parse_coord(const string& s) { int cut = s.find(", "); return PRCoords{ PRCOORDS_STON(s.substr(0, cut)), PRCOORDS_STON(s.substr(cut + 1)) }; } int main(void) { string input; while (getline(cin, input)) { PRCoords v = std::move(parse_coord(input)); cout << "w2g\t" << show_coord(prcoords_wgs_gcj(v)) << endl << "w2b\t" << show_coord(prcoords_wgs_bd(v)) << endl << "g2b\t" << show_coord(prcoords_gcj_bd(v)) << endl << "g2wQ\t" << show_coord(prcoords_gcj_wgs(v)) << endl << "b2wQ\t" << show_coord(prcoords_bd_wgs(v)) << endl << "b2gQ\t" << show_coord(prcoords_bd_gcj(v)) << endl << "g2wP\t" << show_coord(prcoords_gcj_wgs_bored(v)) << endl << "b2wP\t" << show_coord(prcoords_bd_wgs_bored(v)) << endl << "b2gP\t" << show_coord(prcoords_bd_gcj_bored(v)) << endl << endl; } } ================================================ FILE: cpp/libprcoords.cc ================================================ /** * People's Rectified Coordinates, C++11 implementation * Should yield a C-compatible ABI. */ #include "prcoords.h" #include #include #include #include "badmath.hh" #ifndef M_PI #define M_PI ((PRCOORDS_NUM) (3.14159265358979323846L)) #endif // Assume #ifndef __has_builtin # define __has_builtin(x) 0 #endif #ifndef NDEBUG #define assume(R) assert(R) #elif __has_builtin(__builtin_assume) #define assume(R) __builtin_assume(R) #elif __has_builtin(__builtin_unreachable) #define assume(R) ((R) ? (void) 0 : __builtin_unreachable ()) #elif 1200 <= _MSC_VER #define assume(R) __assume(R) #else #define assume(R) ((void) 0) #endif #define assume_angle(x, a) assume(x >= -a && x <= a) #define assume_coord(c) do { \ assume_angle(c.lat, 90); \ assume_angle(c.lon, 180);\ } while(0) // enforces PRCOORDS_NUM using std::sin; using std::cos; using std::sqrt; using std::atan2; using std::pow; using std::fabs; using badmath::sinpi; using badmath::cospi; /// Krasovsky 1940 ellipsoid /// @const const static PRCOORDS_NUM GCJ_A = 6378245; const static PRCOORDS_NUM GCJ_EE = 0.00669342162296594323; // f = 1/298.3; e^2 = 2*f - f**2 const static PRCOORDS_NUM BD_DLAT = 0.0060; const static PRCOORDS_NUM BD_DLON = 0.0065; /// Epsilon to use for "exact" iterations. /// Wanna troll? Use Number.EPSILON. 1e-13 in 15 calls for gcj. /// @const const static PRCOORDS_NUM PRCOORDS_EPS = 1e-5; typedef PRCoords (*PRCOp)(PRCoords); /// These conversions are for bored people: too accurate to be useful /// given pseudo-random noises added to GCJ. /// /// Should we implement a 2-iter version? /// Just "wgs = wgs - (fwd(wgs) - bad);", repeated twice. template PRCOORDS_LOCAL static PRCoords bored_reverse_conversion(PRCoords bad) { assume_coord(bad); PRCoords wgs = rev(bad); PRCoords diff{INFINITY, INFINITY}; int i = 0; while ((fabs(diff.lat) + fabs(diff.lon)) > PRCOORDS_EPS && i++ < 10) { diff = fwd(wgs) - bad; wgs = wgs - diff; } return wgs; } extern "C" { PRCoords prcoords_wgs_gcj(PRCoords wgs) { assume_coord(wgs); PRCOORDS_NUM x = wgs.lon - 105, y = wgs.lat - 35; // These distortion functions accept (x = lon - 105, y = lat - 35). // They return distortions in terms of arc lengths, in meters. // // In other words, you can pretty much figure out how much you will be off // from WGS-84 just through evaulating them... // // For example, at the (mapped) center of China (105E, 35N), you get a // default deviation of <300, -100> meters. #ifndef APPROX PRCOORDS_NUM dLat_m = -100 + 2 * x + 3 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * sqrt(fabs(x)) + ( 2 * sinpi(x * 6) + 2 * sinpi(x * 2) + 2 * sinpi(y) + 4 * sinpi(y / 3) + 16 * sinpi(y / 12) + 32 * sinpi(y / 30) ) * 20 / 3; PRCOORDS_NUM dLon_m = 300 + x + 2 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(fabs(x)) + ( 2 * sinpi(x * 6) + 2 * sinpi(x * 2) + 2 * sinpi(x) + 4 * sinpi(x / 3) + 15 * sinpi(x / 12) + 30 * sinpi(x / 30) ) * 20 / 3; #else // Approximation code from julia side. I should probably // extract the xy-to-ne thing, but that would mean making the whole // program templates. Not today. // FIXME: The coefficients are giving me ridiculously large numbers! PRCOORDS_NUM dLat_m = 0; PRCOORDS_NUM dLon_m = 0; #endif // NOTE: Using sinpi_nick causes the results to be off by 1e-6. // That's acceptable casualty. // Don't like it? Use PRCOORDS_NO_BADMATH. PRCOORDS_NUM radLat = wgs.lat / 180; PRCOORDS_NUM magic = 1 - GCJ_EE * pow(sinpi(radLat), 2); // just a common expr // [[:en:Latitude#Length_of_a_degree_of_latitude]] PRCOORDS_NUM lat_deg_arclen = (M_PI / 180) * (GCJ_A * (1 - GCJ_EE)) / pow(magic, 1.5); // [[:en:Longitude#Length_of_a_degree_of_longitude]] PRCOORDS_NUM lon_deg_arclen = (M_PI / 180) * (GCJ_A * cospi(radLat) / sqrt(magic)); // The screwers pack their deviations into degrees and disappear. // Note how they are mixing WGS-84 and Krasovsky 1940 ellipsoids here... return PRCoords{ wgs.lat + (dLat_m / lat_deg_arclen), wgs.lon + (dLon_m / lon_deg_arclen), }; } PRCoords prcoords_gcj_wgs(PRCoords gcj) { assume_coord(gcj); return gcj - (prcoords_wgs_gcj(gcj) - gcj); } PRCoords prcoords_gcj_bd(PRCoords gcj) { assume_coord(gcj); PRCOORDS_NUM x = gcj.lon; PRCOORDS_NUM y = gcj.lat; // trivia: pycoordtrans actually describes how these values are calculated PRCOORDS_NUM r = sqrt(x * x + y * y) + 0.00002 * sinpi(y * 3000 / 180); PRCOORDS_NUM t = atan2(y, x) + 0.000003 * cospi(x * 3000 / 180); // Hard-coded default deviations again! return PRCoords{ r * sin(t) + BD_DLAT, r * cos(t) + BD_DLON, }; } PRCoords prcoords_bd_gcj(PRCoords bd) { assume_coord(bd); PRCOORDS_NUM x = bd.lon - BD_DLON; PRCOORDS_NUM y = bd.lat - BD_DLAT; PRCOORDS_NUM r = sqrt(x * x + y * y) - 0.00002 * sinpi(y * 3000 / 180); PRCOORDS_NUM t = atan2(y, x) - 0.000003 * cospi(x * 3000 / 180); return PRCoords{ r * sin(t), r * cos(t), }; } PRCoords prcoords_wgs_bd(PRCoords wgs) { return prcoords_gcj_bd(prcoords_wgs_gcj(wgs)); } PRCoords prcoords_bd_wgs(PRCoords bd) { return prcoords_gcj_wgs(prcoords_bd_gcj(bd)); } PRCoords prcoords_gcj_wgs_bored(PRCoords gcj) { return bored_reverse_conversion(gcj); } PRCoords prcoords_bd_gcj_bored(PRCoords bd) { return bored_reverse_conversion(bd); } PRCoords prcoords_bd_wgs_bored(PRCoords bd) { return bored_reverse_conversion(bd); } } #if PRCOORDS_TEST #include #include std::string show_coord(PRCoords v) { return std::to_string(v.lat) + ", " + std::to_string(v.lon); } int main(void) { std::cout << std::is_pod::value << std::endl << show_coord(prcoords_wgs_gcj(PRCoords{35, 105})) << std::endl << show_coord(prcoords_wgs_bd(PRCoords{35, 105})) << std::endl << show_coord(prcoords_wgs_gcj(PRCoords{34, 106})) << std::endl << show_coord(prcoords_wgs_bd(PRCoords{34, 106})) << std::endl; } #endif ================================================ FILE: cpp/prcoords.h ================================================ /** * People's Rectified Coordinates, C/C++ Header. */ #ifndef PRCOORDS_H #define PRCOORDS_H /** May be changed to "long double" for bored folks * (need an "L" suffix on literals for the seriously bored) * "float" is not recommended */ #ifndef PRCOORDS_NUM #define PRCOORDS_NUM double #endif // Generic helper definitions for shared library support #if defined _WIN32 || defined __CYGWIN__ #define PRCOORDS_HELPER_DLL_IMPORT __declspec(dllimport) #define PRCOORDS_HELPER_DLL_EXPORT __declspec(dllexport) #define PRCOORDS_HELPER_DLL_LOCAL #else #if __GNUC__ >= 4 // works on clang lmao #define PRCOORDS_HELPER_DLL_IMPORT __attribute__ ((visibility ("default"))) #define PRCOORDS_HELPER_DLL_EXPORT __attribute__ ((visibility ("default"))) #define PRCOORDS_HELPER_DLL_LOCAL __attribute__ ((visibility ("hidden"))) #else #define PRCOORDS_HELPER_DLL_IMPORT #define PRCOORDS_HELPER_DLL_EXPORT #define PRCOORDS_HELPER_DLL_LOCAL #endif #endif #ifdef PRCOORDS_DLL // defined if PRCOORDS is compiled as a DLL #ifdef PRCOORDS_DLL_EXPORTS // defined if we are building the PRCOORDS DLL (instead of using it) #define PRCOORDS_API PRCOORDS_HELPER_DLL_EXPORT #else #define PRCOORDS_API PRCOORDS_HELPER_DLL_IMPORT #endif // PRCOORDS_DLL_EXPORTS #define PRCOORDS_LOCAL PRCOORDS_HELPER_DLL_LOCAL #else // PRCOORDS_DLL is not defined: this means PRCOORDS is a static lib. #define PRCOORDS_API #define PRCOORDS_LOCAL #endif // PRCOORDS_DLL #ifdef __cplusplus #define PRCOORDS_CONSTEXPR constexpr #if __cplusplus >= 201300L #define PRCOORDS_CONSTEXPR14 constexpr #else #define PRCOORDS_CONSTEXPR14 inline #endif // c++14, including 1y extern "C" { #else #include #define PRCOORDS_CONSTEXPR inline #endif typedef struct PRCoords { PRCOORDS_NUM lat, lon; } PRCoords; // make them pure /// GCJ APIs should all probably turn on china-checks. /// But we should allow some override.... Damn C. PRCOORDS_API PRCoords prcoords_wgs_gcj(PRCoords); PRCOORDS_API PRCoords prcoords_gcj_wgs(PRCoords); PRCOORDS_API PRCoords prcoords_gcj_bd(PRCoords); PRCOORDS_API PRCoords prcoords_bd_gcj(PRCoords); PRCOORDS_API PRCoords prcoords_wgs_bd(PRCoords); PRCOORDS_API PRCoords prcoords_bd_wgs(PRCoords); PRCOORDS_API PRCoords prcoords_gcj_wgs_bored(PRCoords); PRCOORDS_API PRCoords prcoords_bd_gcj_bored(PRCoords); PRCOORDS_API PRCoords prcoords_bd_wgs_bored(PRCoords); PRCOORDS_LOCAL static PRCOORDS_CONSTEXPR bool prcoords_in_china(const PRCoords& a) { // cut out some return a.lat >= 16.7414 && a.lon >= 72.004 && a.lat <= 55.8271 && a.lon <= 137.8347; } #ifdef __cplusplus } PRCOORDS_LOCAL inline PRCoords operator- (const PRCoords& a, const PRCoords& b) { return PRCoords { a.lat - b.lat, a.lon - b.lon }; } // for sorting // lat // | // -<-o---lon (quadrants III, IV and x < 0) // < | < PRCOORDS_LOCAL inline bool operator< (const PRCoords& a, const PRCoords& b) { return a.lat < b.lat || (a.lat == b.lat && a.lon < b.lon); } PRCOORDS_LOCAL inline bool operator> (const PRCoords& a, const PRCoords& b) { return b < a; } PRCOORDS_LOCAL inline bool operator<=(const PRCoords& a, const PRCoords& b) { return !(a > b); } PRCOORDS_LOCAL inline bool operator>=(const PRCoords& a, const PRCoords& b) { return !(a < b); } PRCOORDS_LOCAL inline bool operator==(const PRCoords& a, const PRCoords& b) { return a.lat == b.lat && a.lon == b.lon; } PRCOORDS_LOCAL inline bool operator!=(const PRCoords& a, const PRCoords& b) { return !(a == b); } #endif // __cplusplus #endif // header ================================================ FILE: docs/demo.html ================================================ People Rectify Coordinates

People Rectify Coordinates

With restrictions from the People’s Republic of China

Input

    • ;
    • .
    • ° ′ ″ ;
    • ° ′ ″ .

Results

Operation Result ΔObfs/m ΔRoundtrip/m
WGS → GCJ
WGS → BD
GCJ → WGS
BD → WGS
GCJ →cai WGS
BD →cai WGS
GCJ → BD
BD → GCJ
BD →cai GCJ

. Toggle sections: Notes, FAQ, footer. And print.

Notes

  1. Caijun’s iterative method is included for precise decoding. It's most useful for bored folks whose GPS data is pretty accurate and GCJ-02 obfuscation not tainted by the original LCPRNG.

    If you are doing Wikipedia or any kind of archival work, use it to avoid introducing extra error.

  2. BD is defined in terms of GCJ, hence the last three functions.
  3. This demo omits the “in China” sanity check. Data regarding Baidu’s behavior with overseas maps is needed for further decisions. Observations:
    • Unlike Google Maps, Baidu's map in Hong Kong is fully subject to BD-09 ∘ GCJ-02 chained distortions.
    • Coordinates in Russia, outside of the sanity check rectangle, uses WGS-84 or and/or friends.
    • TODO: check along the boundary.

FAQ

What is this all about?
The PRC government requires all local map services to use an obfuscated, deviation-orienated coordinate system. Click on the “restriction” link to read the full Wikipedia article.
Why should I care?
With half a kilometer of deviation, GCJ-02 and friends fucks up your Ingress games, causes crazy errors in elevation profiles along cycle routes, and cheerfully leads you into roadside ditches plus a bone fracture.
Why doesn’t Google/Bing correct its Chinese data served to global users?
I don’t know. Perhaps they are afraid of getting fined or further kicked out of China. Maybe try OpenStreetMap next time?
Why are you writing another implementation?
Because I got bored.
How does Caijun’s iterative method work?
Cai has explained the method in full in his R implementation. Go read it, or read Wikipedia.
Powered by PRCoords. Try playing with window.PRCoords in your console!

CC0
To the extent possible under law, Mingye Wang has waived all copyright and related or neighboring rights to People Rectify Coordinates. This work is published from: United States.

================================================ FILE: docs/index.md ================================================ Just go to the GitHub repo. ================================================ FILE: docs/proj4_plugin.js ================================================ // mirror of https://runkit.com/artoria2e5/proj4-plugin-prcoords const proj4 = require("proj4") const prcoords = require("prcoords") const noop = Function.prototype const DEG = Math.PI / 180 function xy_to_ll(p) { return { lon: p.x / DEG, lat: p.y / DEG } } function ll_to_xy(p) { return { x: p.lon * DEG, y: p.lat * DEG } } function xy_rename_ll(p) { return { lon: p.x, lat: p.y } } function ll_rename_xy(p) { return { x: p.lon, y: p.lat } } function wrap(f, ...args) { return (p) => ll_to_xy(f(xy_to_ll(p), ...args)) } // We lie our way to Baidu "Mercator". proj4.defs([ [ "_CLARK_MC", "+proj=merc +a=6378206.4 +b=6356583.8 +lat_ts=0.0 +lon_0=0.0 +x_0=0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs", ], ["_CLARK_LL", "+proj=longlat +a=6378206.4 +b=6356583.8"], ]) proj4.Proj.projections.add({ init: noop, forward: wrap(prcoords.wgs_gcj), inverse: wrap(prcoords.gcj_wgs_bored), names: ["gcj", "gcj02", "CN_Obfs_GCJ_2002_Ellipsoidal"], }) proj4.Proj.projections.add({ init: noop, forward: wrap(prcoords.wgs_bd), inverse: wrap(prcoords.bd_wgs_bored), names: ["baidu", "bd09", "CN_Obfs_Baidu_2009_Ellipsoidal"], }) proj4.Proj.projections.add({ init: noop, forward: (p) => proj4("_CLARK_LL", "_CLARK_MC", ll_rename_xy(prcoords.wgs_bd(xy_to_ll(p)))), inverse: (p) => ll_to_xy( prcoords.bd_wgs_bored(xy_rename_ll(proj4("_CLARK_MC", "_CLARK_LL", p))), ), names: ["baidu", "bd09mc", "CN_Obfs_Baidu_2009_Mercator"], }) proj4.defs([ // Why isn't units=degrees working... work around with wrap() now. ["GCJ02", "+title=GCJ 02 (long/lat) +proj=gcj02 +units=degrees"], ["BD09", "+title=Baidu 2009 (long/lat) +proj=bd09 +units=degrees"], ["BD09MC", "+title=Baidu 2009 (Mercator) +proj=bd09mc +units=m"], ]) console.log([ // should be the same as https://artoria2e5.github.io/PRCoords/demo xy_to_ll(proj4("WGS84", "BD09", { x: 105, y: 35 })), xy_to_ll(proj4("WGS84", "GCJ02", { x: 105, y: 35 })), ]) console.log([ // should be very close to the original proj4( "BD09", "WGS84", ll_to_xy({ lat: 35.005403668456964, lon: 105.00966682831948 }), ), proj4( "GCJ02", "WGS84", ll_to_xy({ lat: 34.99909863223526, lon: 105.00328624145706 }), ), ]) console.log([ proj4("WGS84", "BD09MC", { x: 105, y: 35 }), proj4("BD09MC", "WGS84", { x: 11689750, y: 4139877 }), ]) ================================================ FILE: haskell/PRCoords.cabal ================================================ -- Initial prcoords.cabal generated by cabal init. For further -- documentation, see http://haskell.org/cabal/users-guide/ -- The name of the package. name: PRCoords -- The package version. See the Haskell package versioning policy (PVP) -- for standards guiding when and how versions should be incremented. -- http://www.haskell.org/haskellwiki/Package_versioning_policy -- PVP summary: +-+------- breaking API changes -- | | +----- non-breaking API additions -- | | | +--- code changes with no API change version: 0.1.0.0 -- A short (one-line) description of the package. synopsis: Library for GCJ-02 and BD-09 (de)obfuscation from/to WGS-84. May trigger mental episodes. description: People's Rectified Coordinates (PRCoords) is a cross-language implementation of "public secret" Chinese coordinate obfuscation methods including GCJ-02 and BD-09, along with general deobfuscation methods previously established in pycoordtrans, eviltransform, and geoChina. -- URL for the project homepage or repository. homepage: https://github.com/Artoria2e5/PRCoords -- The license under which the package is released. license: PublicDomain -- The file containing the license text. -- license-file: LICENSE -- The package author(s). author: Mingye Wang -- An email address to which users can send suggestions, bug reports, and -- patches. maintainer: arthur200126@gmail.com -- A copyright notice. -- copyright: category: Geography build-type: Simple -- Extra files to be distributed with the package, such as examples or a -- README. -- extra-source-files: -- Constraint on the version of Cabal needed to build this package. cabal-version: >=1.10 library -- Modules exported by the library. exposed-modules: PRCoords -- Modules included in this library but not exported. -- other-modules: -- LANGUAGE extensions used by modules in this package. other-extensions: BangPatterns -- Other library packages from which modules are imported. build-depends: base -- >=4.8 && <4.9 -- AC-Angle -- Directories containing source files. -- hs-source-dirs: -- Base language which the package is written in. default-language: Haskell2010 ================================================ FILE: haskell/PRCoords.hs ================================================ {-# LANGUAGE BangPatterns #-} {-# OPTIONS_GHC -fexcess-precision #-} {-# OPTIONS_GHC -optc-ffast-math -optllc--enable-unsafe-fp-math -optllc--enable-no-nans-fp-math -optllc--enable-no-infs-fp-math #-} --- | This module contains functions for generating People's Rectified Coordinates. --- Jeez, my naming is awful. module PRCoords where -- (wgsGcj, gcjBd, wgsBd, gcjWgs, bdGcj, bdWgsC, gcjWgsC, bdGcjC, bdWgsC, caijun) -- import Data.Angle -- import Numeric.FastMath data PCoords = PCoords { !lat :: Double , !lon :: Double } deriving (Eq, Ord, Show) subtractPCoords :: PCoords -> PCoords -> PCoords subtractPCoords a b = PCoords (lat a - lat b) (lon a - lon b) wgsGcj :: PCoords -> PCoords wgsGcj (PCoords lat lon) = PCoords (lat + dLat / arclenLat) (lon + dLon / arclenLon) where gcj_a = 6378245.0 -- <_ Krasovsky 1940 gcj_ee = 0.00669342162296594323 -- f = 1/2983; e^2 = 2*f - f**2 magic = 1 - gcj_ee * ((sin (pi * lat / 180)) ** 2) -- common expr arclenLat = (pi / 180) * (gcj_a * (1 - gcj_ee)) / (magic ** 1.5) arclenLon = (pi / 180) * (gcj_a * (cos (pi * lat / 180)) / (sqrt magic)) x = lon - 105 -- Here goes the deviation y = lat - 35 gcjTerm !v !f !n = n * (sin f * v * pi) -- check operator stuff later dLat = -100 + 2 * x + 3 * y + 0.2 * y ** 2 + 0.1 * x * y + 0.2 * (sqrt (abs x)) + (*) (20/3) ( gcjTerm x 6 2 + gcjTerm x 2 2 + gcjTerm y 1 2 + gcjTerm y (1/3) 4 + gcjTerm y (1/12) 16 + gcjTerm y (1/30) 32) dLon = 300 + 1 * x + 2 * y + 0.1 * x ** 2 + 0.1 * x * y + 0.1 * (sqrt (abs x)) + (*) (20/3) ( gcjTerm x 6 2 + gcjTerm x 2 2 + gcjTerm x 1 2 + gcjTerm x (1/3) 4 + gcjTerm x (1/12) 15 + gcjTerm y (1/30) 30) gcjWgs :: PCoords -> PCoords gcjWgs a = subtractPCoords a (subtractPCoords ga a) where ga = wgsGcj a caiFix :: (PCoords -> PCoords) -> PCoords -> PCoords -> Int -> PCoords caiFix fwd guess fwd_result iter | iter > 5 = better | (abs $ lon diff) + (abs $ lat diff) < 1E-5 = better | otherwise = caiFix fwd better fwd_result (iter+1) where fwd_guess = fwd guess diff = subtractPCoords fwd_guess fwd_result better = subtractPCoords guess diff caijun :: (PCoords -> PCoords) -> (PCoords -> PCoords) -> (PCoords -> PCoords) caijun fwd rev = (\x -> caiFix fwd (rev x) x 0) gcjWgsC :: PCoords -> PCoords gcjWgsC = caijun wgsGcj gcjWgs -- next: baidu ================================================ FILE: haskell/Setup.hs ================================================ import Distribution.Simple main = defaultMain ================================================ FILE: js/.npmignore ================================================ misc ================================================ FILE: js/PRCoords.d.ts ================================================ // Type definitions for PRCoords // Project: PRCoords export as namespace PRCoords export interface PRCoord { lat: number lon: number } export type PRCoordOp = (c: PRCoord, checkChina?: boolean) => PRCoord export function distance(a: PRCoord, b: PRCoord): number // We do not use the PRCO type to make it a bit more transparent on the IDE export function gcj_wgs(c: PRCoord, checkChina?: boolean): PRCoord export function wgs_gcj(c: PRCoord, checkChina?: boolean): PRCoord export function wgs_gcj_bored(c: PRCoord, checkChina?: boolean): PRCoord export function gcj_bd(c: PRCoord, __dummy__?: boolean): PRCoord export function bd_gcj(c: PRCoord, __dummy__?: boolean): PRCoord export function bd_gcj_bored(c: PRCoord, __dummy__?: boolean): PRCoord export function wgs_bd(c: PRCoord, checkChina?: boolean): PRCoord export function bd_wgs(c: PRCoord, checkChina?: boolean): PRCoord export function bd_wgs_bored(c: PRCoord, checkChina?: boolean): PRCoord export function __bored__(fwd: PRCoordOp, rev: PRCoordOp): PRCoordOp ================================================ FILE: js/PRCoords.js ================================================ ;(function (factory, scope) { "use strict" var res = factory() if (typeof module === 'object') { module.exports = res } else { if (typeof define === 'function' && define.amd) define('prcoords', function() { return res }) try { // Global can be undefined scope.PRCoords = res } catch(e) {} } })((function (){ "use strict" // /** * People's Rectified Coordinates * @file Utils for inserting valid WGS-84 coords from GCJ-02/BD-09 input * @author User:Artoria2e5 * @url https://github.com/Artoria2e5/PRCoords * * @see [[:en:GCJ-02]] * @see https://en.wikipedia.org/wiki/User:Artoria2e5/coord-notice * @see https://github.com/caijun/geoChina (GPLv3) * @see https://github.com/googollee/eviltransform (MIT) * @see https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936 (Anonymous) * @see https://github.com/zxteloiv/pycoordtrans (BSD-3) * * @license CC0 * To the greatest extent possible, this implementation of obfuscations designed * in hope that they will screw y'all up is dedicated into the public domain * under CC0 1.0 . * * Happy geotagging/ingressing/whatever. * * To make my FSF membership shine brighter, this conversion implementation is * additionally licensed under GPLv3+: * @license GPLv3+ * @copyright 2016 Mingye Wang (User:Artoria2e5) * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ /// Krasovsky 1940 ellipsoid /// @const var GCJ_A = 6378245 var GCJ_EE = 0.00669342162296594323 // f = 1/298.3; e^2 = 2*f - f**2 /// Epsilon to use for "exact" iterations. /// Wanna troll? Use Number.EPSILON. 1e-13 in 15 calls for gcj. /// @const var PRC_EPS = 1e-5 /// Baidu's artificial deviations /// @const var BD_DLAT = 0.0060 var BD_DLON = 0.0065 /// Mean Earth Radius /// @const var EARTH_R = 6371000 /// Distance for haversine method; suitable over short distances like /// conversion deviation checking function distance(a, b) { function hav(θ) { return Math.pow(Math.sin(θ/2), 2) } var Δ = _coord_diff(a, b) return 2 * EARTH_R * Math.asin(Math.sqrt( hav(Δ.lat * Math.PI / 180) + Math.cos(a.lat * Math.PI / 180) * Math.cos(b.lat * Math.PI / 180) * hav(Δ.lon * Math.PI / 180) )) } function sanity_in_china_p(coords) { return coords.lat >= 0.8293 && coords.lat <= 55.8271 && coords.lon >= 72.004 && coords.lon <= 137.8347 } function _coord_diff(a, b) { return { lat: a.lat - b.lat, lon: a.lon - b.lon, } } function _stringify(c) { return "(" + c.lat + ", " + c.lon + ")" } function wgs_gcj(wgs, checkChina) { if ((checkChina === undefined || checkChina) && !sanity_in_china_p(wgs)) { console.warn("Non-Chinese coords found, returning as-is: " + _stringify(wgs)) return wgs } var x = wgs.lon - 105, y = wgs.lat - 35 // These distortion functions accept (x = lon - 105, y = lat - 35). // They return distortions in terms of arc lengths, in meters. // // In other words, you can pretty much figure out how much you will be off // from WGS-84 just through evaulating them... // // For example, at the (mapped) center of China (105E, 35N), you get a // default deviation of <300, -100> meters. var dLat_m = -100 + 2 * x + 3 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x)) + ( 2 * Math.sin(x * 6 * Math.PI) + 2 * Math.sin(x * 2 * Math.PI) + 2 * Math.sin(y * Math.PI) + 4 * Math.sin(y / 3 * Math.PI) + 16 * Math.sin(y / 12 * Math.PI) + 32 * Math.sin(y / 30 * Math.PI) ) * 20 / 3 var dLon_m = 300 + x + 2 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x)) + ( 2 * Math.sin(x * 6 * Math.PI) + 2 * Math.sin(x * 2 * Math.PI) + 2 * Math.sin(x * Math.PI) + 4 * Math.sin(x / 3 * Math.PI) + 15 * Math.sin(x / 12 * Math.PI) + 30 * Math.sin(x / 30 * Math.PI) ) * 20 / 3 var radLat = wgs.lat / 180 * Math.PI var magic = 1 - GCJ_EE * Math.pow(Math.sin(radLat), 2) // just a common expr // [[:en:Latitude#Length_of_a_degree_of_latitude]] var lat_deg_arclen = (Math.PI / 180) * (GCJ_A * (1 - GCJ_EE)) / Math.pow(magic, 1.5) // [[:en:Longitude#Length_of_a_degree_of_longitude]] var lon_deg_arclen = (Math.PI / 180) * (GCJ_A * Math.cos(radLat) / Math.sqrt(magic)) // The screwers pack their deviations into degrees and disappear. // Note how they are mixing WGS-84 and Krasovsky 1940 ellipsoids here... return { lat: wgs.lat + (dLat_m / lat_deg_arclen), lon: wgs.lon + (dLon_m / lon_deg_arclen), } } // rev_transform_rough; accuracy ~2e-6 deg (meter-level) function gcj_wgs(gcj, checkChina) { return _coord_diff(gcj, _coord_diff(wgs_gcj(gcj, checkChina), gcj)) } function gcj_bd(gcj, __dummy__) { var x = gcj.lon var y = gcj.lat // trivia: pycoordtrans actually describes how these values are calculated var r = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * Math.PI * 3000 / 180) var θ = Math.atan2(y, x) + 0.000003 * Math.cos(x * Math.PI * 3000 / 180) // Hard-coded default deviations again! return { lat: r * Math.sin(θ) + BD_DLAT, lon: r * Math.cos(θ) + BD_DLON, } } // Yes, we can implement a "precise" one too. // accuracy ~1e-7 deg (decimeter-level; exceeds usual data accuracy) function bd_gcj(bd, __dummy__) { var x = bd.lon - BD_DLON var y = bd.lat - BD_DLAT // trivia: pycoordtrans actually describes how these values are calculated var r = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * Math.PI * 3000 / 180) var θ = Math.atan2(y, x) - 0.000003 * Math.cos(x * Math.PI * 3000 / 180) return { lat: r * Math.sin(θ), lon: r * Math.cos(θ), } } function bd_wgs(bd, checkChina) { return gcj_wgs(bd_gcj(bd), checkChina) } function wgs_bd(bd, checkChina) { return gcj_bd(wgs_gcj(bd, checkChina)) } // generic "bored function" factory, Caijun 2014 // gcj: 4 calls to wgs_gcj; ~0.1mm acc function __bored__(fwd, rev) { return function rev_bored(heck, checkChina) { if (checkChina === undefined) checkChina = true var curr = rev(heck, checkChina) var diff = {lat: Infinity, lon: Infinity} // Wait till we hit fixed point or get bored var i = 0 while (Math.max(Math.abs(diff.lat), Math.abs(diff.lon)) > PRC_EPS && i++ < 10) { diff = _coord_diff(fwd(curr, checkChina), heck) curr = _coord_diff(curr, diff) } return curr } } var exports = { distance: distance, wgs_gcj: wgs_gcj, gcj_wgs: gcj_wgs, gcj_bd: gcj_bd, bd_gcj: bd_gcj, wgs_bd: wgs_bd, bd_wgs: bd_wgs, // Precise functions using caijun 2014 method // // Why "bored"? Because they usually exceed source data accuracy -- the // original GCJ implementation contains noise from a linear-modulo PRNG, // and Baidu seems to do similar things with their API too. __bored__: __bored__, gcj_wgs_bored: __bored__(wgs_gcj, gcj_wgs), bd_gcj_bored: __bored__(gcj_bd, bd_gcj), bd_wgs_bored: __bored__(wgs_bd, bd_wgs), } // We can stub this out too if we are aiming for ES3, but then there are no // trailing commas Object.defineProperty(exports, '__esModule', { value: true }) return exports }), typeof self !== 'undefined' ? self : typeof this !== undefined ? this : globalThis) ================================================ FILE: js/misc/insane_is_in_china.js ================================================ (function(){ "use strict" // Insane version of the "is in China" check (70 points. I tried.) // // Dedicated to the Public Domain under CC0, except for pnpoly by // Wm. Randolph Franklin (BSD3) // // Incorrect use of this polygon can lead to adverse geopolitical issues. // This set of points is only intended to approximate the scope of a type of distortion, // and has nothing to do with any political entities. // // Also, screw geodetics. The Earth is flat according to this approximation. /// *** pnpoly *** /// // Copyright (c) 1970-2003, Wm. Randolph Franklin // // Permission is hereby granted, free of charge, to any person obtaining // a copy of this software and associated documentation files (the // "Software"), to deal in the Software without restriction, including // without limitation the rights to use, copy, modify, merge, publish, // distribute, sublicense, and/or sell copies of the Software, and to // permit persons to whom the Software is furnished to do so, subject to // the following conditions: // // 1. Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimers. // 2. Redistributions in binary form must reproduce the above // copyright notice in the documentation and/or other materials // provided with the distribution. // 3. The name of W. Randolph Franklin may not be used to endorse or // promote products derived from this Software without specific // prior written permission. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. function pnpoly(xs, ys, x, y) { if (! (xs.length === ys.length)) throw new Error("pnpoly: assert(xs.length === ys.length)") var inside = 0 // j records previous value. Also handles wrapping around. for (let i = 0, j = xs.length - 1; i < xs.length; j = i++) inside ^= (((ys[i] > y) !== (ys[j] > y)) && (x < (xs[j] - xs[i]) * (y - ys[i]) / (ys[j] - ys[i]) + xs[i])) // Let's make js as magical as C. Yay. return !!inside } /// ^^^ pnpoly ^^^ /// // We will need to filter out these points for Baidu. // (We will need South China Sea too.) var is_near_hkmo = function (lat, lon) { return 22 <= lat && lat <= 22.7 && 113.5 <= lon && lon <= 114.5 } // Well we now have indices for HK/MO. var HK_LENGTH = 12 // lon, lat var POINTS = [ // start hkmo 114.433722, 22.064310, 114.009458, 22.182105, 113.599275, 22.121763, 113.583463, 22.176002, 113.530900, 22.175318, 113.529542, 22.210608, 113.613377, 22.227435, 113.938514, 22.483714, 114.043449, 22.500274, 114.138506, 22.550640, 114.222984, 22.550960, 114.366803, 22.524255, // end hkmo 115.254019, 20.235733, 121.456316, 26.504442, 123.417261, 30.355685, 124.289197, 39.761103, 126.880509, 41.774504, 127.887261, 41.370015, 128.214602, 41.965359, 129.698745, 42.452788, 130.766139, 42.668534, 131.282487, 45.037051, 133.142361, 44.842986, 134.882453, 48.370596, 132.235531, 47.785403, 130.980075, 47.804860, 130.659026, 48.968383, 127.860252, 50.043973, 125.284310, 53.667091, 120.619316, 53.100485, 119.403751, 50.105903, 117.070862, 49.690388, 115.586019, 47.995542, 118.599613, 47.927785, 118.260771, 46.707335, 113.534759, 44.735134, 112.093739, 45.001999, 111.431259, 43.489381, 105.206324, 41.809510, 96.485703, 42.778692, 94.167961, 44.991668, 91.130430, 45.192938, 90.694601, 47.754437, 87.356293, 49.232005, 85.375791, 48.263928, 85.876055, 47.109272, 82.935423, 47.285727, 81.929808, 45.506317, 79.919457, 45.108122, 79.841455, 42.178752, 73.334917, 40.076332, 73.241805, 39.062331, 79.031902, 34.206413, 78.738395, 31.578004, 80.715812, 30.453822, 81.821692, 30.585965, 85.501663, 28.208463, 92.096061, 27.754241, 94.699781, 29.357171, 96.079442, 29.429559, 98.910308, 27.140660, 97.404057, 24.494701, 99.400021, 23.168966, 100.697449, 21.475914, 102.976870, 22.616482, 105.476997, 23.244292, 108.565621, 20.907735, 107.730505, 18.193406, 110.669856, 17.754550, ] var lats = POINTS.filter((ditch, i) => i % 2 == 1) var lons = POINTS.filter((ditch, i) => i % 2 == 0) POINTS = null // no need var bdlats = lats.slice(HK_LENGTH) var bdlons = lons.slice(HK_LENGTH) function isInGoogle(lat, lon) { // Yank out South China Sea if (lat <= 17.75455) return false; return pnpoly(lats, lons, lat, lon) } function isInBaidu(lat, lon) { // Yank out South China Sea, as: // 1. Nobody wants Baidu's crap Sansha data // 2. I am too lazy to add like four points if (lat <= 17.75455) return false; return pnpoly(bdlats, bdlons, lat, lon) } exports = {isInBaidu: isInBaidu, isInGoogle: isInGoogle} if (typeof module === "object" && module.exports) { module.exports = exports } else if (typeof window !== "undefined") { window.PRCoords = exports } })() ================================================ FILE: js/misc/package.json ================================================ { "name": "insane-in-china", "version": "0.0.1", "description": "Routine for deciding whether one coordiate might be affected by Chinese obfuscation.", "main": "insane_is_in_china.js", "repository": { "type": "git", "url": "https://github.com/Artoria2e5/PRCoords.git", "directory": "js/misc" }, "keywords": [ "gcj", "wgs", "bd", "baidu", "coordinates", "pnpoly" ], "author": "Mingye Wang (Artoria2e5) ", "license": "BSD-3-Clause", "bugs": { "url": "https://github.com/Artoria2e5/PRCoords/issues" } } ================================================ FILE: js/package.json ================================================ { "name": "prcoords", "version": "1.0.3-rc1", "description": "Chinese coordinate obfuscation methods (GCJ-02, BD-09) and inverses.", "main": "PRCoords.js", "repository": { "type": "git", "url": "https://github.com/Artoria2e5/PRCoords.git", "directory": "js", "//note": "Unused before I figure out what to do with docs and readme." }, "keywords": [ "gcj", "wgs", "bd", "baidu", "coordinates" ], "author": "Mingye Wang (Artoria2e5) ", "license": "CC0-1.0", "bugs": { "url": "https://github.com/Artoria2e5/PRCoords/issues" }, "dependencies": {} } ================================================ FILE: julia/Project.toml ================================================ name = "PRCoords" uuid = "0c59880a-3f55-4b0d-8a02-bd83932d11da" authors = ["Mingye Wang "] version = "0.1.0" ================================================ FILE: julia/src/PRCoords.jl ================================================ module PRCoords struct Coords lat::Float64 lon::Float64 end end # module ================================================ FILE: lua/PRCoords.lua ================================================ -- People's Rectified Coordinates -- https://github.com/Artoria2e5/PRCoords -- -- Dedicated to the Public Domain under CC0 -- Artoria2e5, 2017. PRCoords = { ["EARTH_R"] = 6371000 } -- Ray-casting polygon function PRCoords._in_poly(xs, ys, x, y) assert(#xs == #ys, "poly length don't match") local inside = false for i=1,#xs do if (ys[i] > y) ~= (ys[j] > y) and (x < (xs[j] - xs[i]) * (y - ys[i]) / (ys[j] - ys[i]) + xs[i]) then inside = (not inside) end end return inside end local function bind_poly(xs, ys) return function(x, y) return PRCoords._in_poly(xs, ys, x, y) end end function PRCoords.cdiff(a_lat, a_lon, b_lat, b_lon) return a_lat - b_lat, a_lon - b_lon end local function cerr(lat, lon) return abs(lat) + abs(lon) end function PRCoords.cdist(a_lat, a_lon, b_lat, b_lon) local function hav(theta) return math.sin(theta/2) ^ 2 end local delta_lat = a_lat - b_lat local delta_lon = a_lon - b_lon return 2 * PRCoords.EARTH_R * math.asin(math.sqrt( hav(delta_lat * math.pi / 180) + math.cos(a.lat * math.pi / 180) * math.cos(b.lat * math.pi / 180) * hav(delta_lon * math.pi / 180))) end function PRCoords.caijun(forward, reverse) return function(bad_lat, bad_lon) local guess_lat, guess_lon = reverse(bad_lat, bad_lon) local iter = 0 local diff_lat, diff_lon, tlat, tlon repeat tlat, tlon = forward(guess_lat, guess_lon) diff_lat, diff_lon = PRCoords.cdiff(tlat, tlon, bad_lat, bad_lon) guess_lat -= diff_lat guess_lon -= diff_lon iter += 1 until cerr(diff_lat, diff_lon) <= 1e-5 or iter >= 10 end end function PRCoords.wgs_gcj(wlat, wlon) local y, x = wlon - 105, wlat - 35 end ================================================ FILE: matlab/PRCoords.m ================================================ function v = PRCoords() %% People's Rectified Coordinates: Chinese geographic obfuscations %% Dedicated to the Public Domain under CC0. %% Mingye Wang (Artoria2e5), 2017, 2025. %% @url https://github.com/Artoria2e5/PRCoords v = "1.2.0"; end ================================================ FILE: matlab/bd_gcj.m ================================================ function g = bd_gcj (b) % Reverse the BD-09 distortion to GCJ-02 coordinates. x = b (2) - 0.0065; y = b (1) - 0.006; r = sqrt (x .* x + y .* y) - 0.00002 * sin (y * pi * 3000 / 180); theta = atan2 (y, x) - 0.000003 * cos (x * pi * 3000 / 180); gcj_lon = r .* cos (theta); gcj_lat = r .* sin (theta); g = [gcj_lat, gcj_lon]; endfunction ================================================ FILE: matlab/bd_gcj_precise.m ================================================ function g = bd_gcj_precise (b, tol, maxn) % Reverse the BD-09 distortion to GCJ-02 coordinates in a precise way. if nargin < 2 tol = 1e-13; end if nargin < 3 maxn = 10; end fun = caijun_precise (@gcj_bd, @bd_gcj); g = fun (b, tol, maxn); endfunction ================================================ FILE: matlab/bd_wgs.m ================================================ function w = bd_wgs (b) % Reverse the BD-09 distortion to WGS-84 coordinates. g = bd_gcj (b); w = gcj_wgs (g); endfunction ================================================ FILE: matlab/bd_wgs_precise.m ================================================ function w = bd_wgs_precise (b, tol, maxn) % Reverse the BD-09 distortion to WGS-84 coordinates in a precise way. if nargin < 2 tol = 1e-13; end if nargin < 3 maxn = 10; end fun = caijun_precise (@wgs_bd, @bd_wgs); w = fun (b, tol, maxn); endfunction ================================================ FILE: matlab/caijun_precise.m ================================================ function fun = caijun_precise (fwd, rev, o, tol, maxn) % usage: fun = caijun_precise (@fwd, @rev) % % With a precise forward obfuscation and a rough deobfuscation % function, construct a precise iterative deobfuscation function. % % A custom tolilon for "fixed point" detection can be specified % with the "tol" operand. The default value is 1e-4 degrees. % % A custon max iteration limit can be specified with the "maxn" % operand. The default value is 10 iterations. % % (caijun/geoChina; 2014) function c = rectify (o, tol, maxn) % Given obfuscated coords, % return something that appears much less wrong to us. c = rev (o); d = c - o; for i = 1:maxn if (max(abs(d (1))) + max(abs(d (2))) <= tol) break; end d = fwd(c) - o; c -= d; end endfunction fun = @rectify; endfunction ================================================ FILE: matlab/gcj_bd.m ================================================ function b = gcj_bd (g) % Apply the BD-09 distortion to GCJ-02 coordinates. x = g (2); y = g (1); r = sqrt (x .* x + y .* y) + 0.00002 * sin (y * pi * 3000 / 180); theta = atan2 (y, x) + 0.000003 * cos (x * pi * 3000 / 180); bd_lon = r .* cos (theta) + 0.0065; bd_lat = r .* sin (theta) + 0.006; b = [bd_lat, bd_lon]; endfunction ================================================ FILE: matlab/gcj_wgs.m ================================================ function w = gcj_wgs (g) % Reverse the GCJ-02 distortion in a rough way. gg = wgs_gcj (g); w = g * 2 - gg; endfunction ================================================ FILE: matlab/gcj_wgs_precise.m ================================================ function w = gcj_wgs_precise (g, tol, maxn) if nargin < 2 tol = 1e-13; end if nargin < 3 maxn = 10; end fun = caijun_precise (@wgs_gcj, @gcj_wgs); w = fun (g, tol, maxn); endfunction ================================================ FILE: matlab/wgs_bd.m ================================================ function b = wgs_bd (w) % Apply the BD-09 distortion to WGS-84 coordinates. g = wgs_gcj (w); b = gcj_bd (g); endfunction ================================================ FILE: matlab/wgs_gcj.m ================================================ function r = wgs_gcj (w) % Apply the GCJ-02 distortion to WGS-84 coordinates. wlat = w (1); wlon = w (2); % Krasovsky 1940 ellipsoid GCJ_A = 6378245; GCJ_EE = 0.00669342162296594323; % f = 1./298.3; e^2 = 2.*f - f.*.*2 % Deviation computation in meters, inlined. % [x, y] are relative coords from a common mapped "center" of China. x = wlat - 35; y = wlon - 105; dlat = -100 + 2 .* x + 3 .* y + 0.2 .* y .* y + 0.1 .* x .* y + ... 0.2 .* sqrt(abs(x)) + (2 .* sin(x .* 6 .* pi) + ... 2 .* sin(x .* 2 .* pi) + 2 .* sin(y .* pi) + 4 .* sin(y ./ 3 .* pi) + ... 16 .* sin(y ./ 12 .* pi) + 32 .* sin(y ./ 30 .* pi)) .* 20 ./ 3; dlon = 300 + x + 2 .* y + 0.1 .* x .* x + 0.1 .* x .* y + ... 0.1 .* sqrt(abs(x)) + (2 .* sin(x .* 6 .* pi) + ... 2 .* sin(x .* 2 .* pi) + 2 .* sin(x .* pi) + 4 .* sin(x ./ 3 .* pi) + ... 15 .* sin(x ./ 12 .* pi) + 30 .* sin(x ./ 30 .* pi)) .* 20 ./ 3; % Arc lengths for one degree on the wrong ellipsoid magic = 1 - GCJ_EE .* (sind(wlat) .^ 2); % A common expression arclen_1lat = pi / 180 .* (GCJ_A .* (1 - GCJ_EE)) ./ magic .^ 1.5; arclen_1lon = pi / 180 .* GCJ_A .* cosd(wlat) ./ magic .^ 0.5; % Pack deviations into degrees glat = wlat + dlat ./ arclen_1lat; glon = wlon + dlon ./ arclen_1lon; r = [glat, glon]; endfunction ================================================ FILE: package.json ================================================ { "name": "prcoords", "version": "1.0.5", "description": "Chinese coordinate obfuscation methods (GCJ-02, BD-09) and inverses.", "main": "js/PRCoords.js", "//": "Will this work with the repo? https://github.com/npm/npm/issues/2974", "repository": "github:Artoria2e5/PRCoords", "keywords": [ "gcj", "wgs", "bd", "baidu", "coordinates" ], "author": "Mingye Wang (Artoria2e5) ", "license": "CC0-1.0", "bugs": { "url": "https://github.com/Artoria2e5/PRCoords/issues" }, "dependencies": {} } ================================================ FILE: pgsql/distance_agg.sql ================================================ CREATE TYPE _geodistance_agg_state AS (distance double precision, lat double precision, lon double precision); CREATE FUNCTION public._geodistance_agg_sfunc (state _geodistance_agg_state, lat double precision, lon double precision) RETURNS _geodistance_agg_state AS $$ SELECT (CASE WHEN $1 IS NULL THEN 0 ELSE $1.distance+geodistance($1.lat, $1.lon, $2, $3) END), $2, $3 AS nextstate; $$ LANGUAGE SQL IMMUTABLE; CREATE FUNCTION public._geodistance_agg_ffunc (state _geodistance_agg_state) RETURNS double precision AS $$ SELECT $1.distance AS result; $$ LANGUAGE SQL IMMUTABLE; CREATE AGGREGATE geodistance_agg (double precision, double precision) ( SFUNC = _geodistance_agg_sfunc, STYPE = _geodistance_agg_state, FINALFUNC = _geodistance_agg_ffunc ); ================================================ FILE: pgsql/prcoords.sql ================================================ CREATE OR REPLACE FUNCTION public.geodistance (alat double precision, alng double precision, blat double precision, blng double precision) RETURNS double precision AS $$ SELECT 2 * 6371000 * asin( sqrt( sin(radians($3-$1)/2)^2 + sin(radians($4-$2)/2)^2 * cos(radians($1)) * cos(radians($3)) ) ) AS distance; $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE COST 100; CREATE OR REPLACE FUNCTION public.geodistance (a point, b point) RETURNS double precision AS $$ SELECT 2 * 6371000 * asin( sqrt( sin(radians($2[0]-$1[0])/2)^2 + sin(radians($2[1]-$1[1])/2)^2 * cos(radians($1[0])) * cos(radians($2[0])) ) ) AS distance; $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE COST 100; CREATE OR REPLACE FUNCTION public.wgs_gcj (wgs point) RETURNS point AS $$ DECLARE GCJ_A CONSTANT double precision := 6378245; GCJ_EE CONSTANT double precision := 0.00669342162296594323; x double precision; y double precision; dLat_m double precision; dLon_m double precision; radLat double precision; magic double precision; lat_deg_arclen double precision; lon_deg_arclen double precision; BEGIN x := wgs[1] - 105; y := wgs[0] - 35; dLat_m := (-100 + 2 * x + 3 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * sqrt(abs(x)) + ( 2 * sin(x * 6 * pi()) + 2 * sin(x * 2 * pi()) + 2 * sin(y * pi()) + 4 * sin(y / 3 * pi()) + 16 * sin(y / 12 * pi()) + 32 * sin(y / 30 * pi()) ) * 20 / 3); dLon_m := (300 + x + 2 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(abs(x)) + ( 2 * sin(x * 6 * pi()) + 2 * sin(x * 2 * pi()) + 2 * sin(x * pi()) + 4 * sin(x / 3 * pi()) + 15 * sin(x / 12 * pi()) + 30 * sin(x / 30 * pi()) ) * 20 / 3); radLat := radians(wgs[0]); magic := 1 - GCJ_EE * power(sin(radLat), 2); lat_deg_arclen := radians((GCJ_A * (1 - GCJ_EE)) / power(magic, 1.5)); lon_deg_arclen = radians(GCJ_A * cos(radLat) / sqrt(magic)); RETURN (wgs[0] + (dLat_m / lat_deg_arclen), wgs[1] + (dLon_m / lon_deg_arclen)); END; $$ LANGUAGE plpgsql IMMUTABLE STRICT PARALLEL SAFE COST 150; CREATE OR REPLACE FUNCTION public.gcj_wgs (gcj point) RETURNS point AS $$ SELECT $1 - (wgs_gcj($1) - $1) AS wgs $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE COST 150; CREATE OR REPLACE FUNCTION public.gcj_wgs_bored (gcj point) RETURNS point AS $$ DECLARE MAXITER CONSTANT double precision := 10; PRC_EPS CONSTANT double precision := 1e-5; wgs point; old point; diff point; i smallint; BEGIN wgs = gcj_wgs(gcj); LOOP diff := (wgs - old); IF i < MAXITER AND (abs(diff[0]) > PRC_EPS OR abs(diff[1]) > PRC_EPS) THEN old := wgs; wgs := wgs - (wgs_gcj(wgs) - gcj); i := i + 1; ELSE RETURN wgs; END IF; END LOOP; END; $$ LANGUAGE plpgsql IMMUTABLE STRICT PARALLEL SAFE COST 450; CREATE OR REPLACE FUNCTION public.gcj_bd (gcj point) RETURNS point AS $$ DECLARE r double precision; t double precision; BEGIN r := sqrt(gcj[0] * gcj[0] + gcj[1] * gcj[1]) + 2e-5 * sin(3000 * radians(gcj[0])); t := atan2(gcj[0], gcj[1]) + 3e-6 * cos(3000 * radians(gcj[1])); RETURN point(r * sin(t) + 0.0060, r * cos(t) + 0.0065); END; $$ LANGUAGE plpgsql IMMUTABLE STRICT PARALLEL SAFE COST 100; ================================================ FILE: pgsql/prcoords_postgis.sql ================================================ -- Depends on PostGIS and prcoords.sql CREATE OR REPLACE FUNCTION public._latlng2geometry (p point) RETURNS geometry AS $$ SELECT ST_SetSRID(ST_MakePoint(p[1], p[0]), 4326); $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE; CREATE OR REPLACE FUNCTION public._geometry2latlng (p geometry) RETURNS point AS $$ BEGIN IF GeometryType(p) != 'POINT' THEN RAISE EXCEPTION 'Input geom must be a point. Currently is: %', GeometryType(p); ELSIF ST_SRID(p) != 4326 THEN RAISE EXCEPTION 'SRID of the input geom must be 4326. Currently is: %', ST_SRID(p); END IF; RETURN point(ST_Y($1), ST_X($1)); END; $$ LANGUAGE plpgsql IMMUTABLE STRICT PARALLEL SAFE; CREATE OR REPLACE FUNCTION public.wgs_gcj (wgs geometry) RETURNS geometry AS $$ SELECT _latlng2geometry(wgs_gcj(_geometry2latlng($1))) $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE; CREATE OR REPLACE FUNCTION public.gcj_wgs (gcj geometry) RETURNS geometry AS $$ SELECT _latlng2geometry(gcj_wgs(_geometry2latlng($1))) $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE; CREATE OR REPLACE FUNCTION public.gcj_bd (gcj geometry) RETURNS geometry AS $$ SELECT _latlng2geometry(gcj_bd(_geometry2latlng($1))) $$ LANGUAGE SQL IMMUTABLE STRICT PARALLEL SAFE; ================================================ FILE: py/prcoords.py ================================================ ''' People's Rectified [[T:Coord|Coordinates]] @file Utils for inserting valid WGS-84 coords from GCJ-02/BD-09 input @author User:Artoria2e5 @url https://github.com/Artoria2e5/PRCoords @see [[:en:GCJ-02]] @see https://github.com/caijun/geoChina (GPLv3) @see https://github.com/googollee/eviltransform (MIT) @see https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936 (Anonymous) @see https://github.com/zxteloiv/pycoordtrans (BSD-3) @license CC0 To the greatest extent possible, this implementation of obfuscations designed in hope that they will screw y'all up is dedicated into the public domain under CC0 1.0 . Happy geotagging/ingressing/whatever. To make my FSF membership shine brighter, this conversion implementation is additionally licensed under GPLv3+: @license GPLv3+ @copyright 2016 Mingye Wang (User:Artoria2e5) This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . ''' import math import warnings import collections # Krasovsky 1940 ellipsoid # @const GCJ_A = 6378245 GCJ_EE = 0.00669342162296594323 # f = 1/298.3; e^2 = 2*f - f**2 # Epsilon to use for "exact" iterations. # Wanna troll? Use Number.EPSILON. 1e-13 in 15 calls for gcj. # @const PRC_EPS = 1e-5 # Baidu's artificial deviations # @const BD_DLAT = 0.0060 BD_DLON = 0.0065 # Mean Earth Radius # @const EARTH_R = 6371000 class Coords(collections.namedtuple('Coords', 'lat lon')): def __add__(self, other): return Coords(self.lat + other.lat, self.lon + other.lon) def __sub__(self, other): return Coords(self.lat - other.lat, self.lon - other.lon) def __abs__(self): return math.hypot(*self) def distance(self, other): ''' Distance for haversine method; suitable over short distances like conversion deviation checking ''' hav = lambda theta: math.sin(theta / 2) ** 2 delta = self - other return 2 * EARTH_R * math.asin(math.sqrt( hav(math.radians(delta.lat)) + math.cos(math.radians(self.lat)) * math.cos(math.radians(other.lat)) * hav(math.radians(delta.lon)) )) def sanity_in_china_p(coords): return (0.8293 <= coords.lat <= 55.8271 and 72.004 <= coords.lon <= 137.8347) def wgs_gcj(wgs, check_china=True): wgs = Coords(*wgs) if check_china and not sanity_in_china_p(wgs): warnings.warn('Non-Chinese coords found, returning as-is: %r' % (wgs,)) return wgs x, y = wgs.lon - 105, wgs.lat - 35 # These distortion functions accept (x = lon - 105, y = lat - 35). # They return distortions in terms of arc lengths, in meters. # In other words, you can pretty much figure out how much you will be off # from WGS-84 just through evaulating them... # # For example, at the (mapped) center of China (105E, 35N), you get a # default deviation of <300, -100> meters. dLat_m = (-100 + 2 * x + 3 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * math.sqrt(abs(x)) + ( 2 * math.sin(x * 6 * math.pi) + 2 * math.sin(x * 2 * math.pi) + 2 * math.sin(y * math.pi) + 4 * math.sin(y / 3 * math.pi) + 16 * math.sin(y / 12 * math.pi) + 32 * math.sin(y / 30 * math.pi) ) * 20 / 3) dLon_m = (300 + x + 2 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * math.sqrt(abs(x)) + ( 2 * math.sin(x * 6 * math.pi) + 2 * math.sin(x * 2 * math.pi) + 2 * math.sin(x * math.pi) + 4 * math.sin(x / 3 * math.pi) + 15 * math.sin(x / 12 * math.pi) + 30 * math.sin(x / 30 * math.pi) ) * 20 / 3) radLat = math.radians(wgs.lat) magic = 1 - GCJ_EE * math.pow(math.sin(radLat), 2) # just a common expr # [[:en:Latitude#Length_of_a_degree_of_latitude]] lat_deg_arclen = math.radians((GCJ_A * (1 - GCJ_EE)) / math.pow(magic, 1.5)) # [[:en:Longitude#Length_of_a_degree_of_longitude]] lon_deg_arclen = math.radians(GCJ_A * math.cos(radLat) / math.sqrt(magic)) # The screwers pack their deviations into degrees and disappear. # Note how they are mixing WGS-84 and Krasovsky 1940 ellipsoids here... return Coords(wgs.lat + (dLat_m / lat_deg_arclen), wgs.lon + (dLon_m / lon_deg_arclen)) def gcj_wgs(gcj, check_china=True): '''rev_transform_rough; accuracy ~2e-6 deg (meter-level)''' gcj = Coords(*gcj) return gcj - (wgs_gcj(gcj, check_china) - gcj) def gcj_bd(gcj, _dummy=False): y, x = gcj # trivia: pycoordtrans actually describes how these values are calculated r = math.sqrt(x * x + y * y) + 0.00002 * math.sin(math.radians(y) * 3000) theta = math.atan2(y, x) + 0.000003 * math.cos(math.radians(x) * 3000) # Hard-coded default deviations again! return Coords(r * math.sin(theta) + BD_DLAT, r * math.cos(theta) + BD_DLON) # Yes, we can implement a "precise" one too. def bd_gcj(bd, _dummy=False): '''accuracy ~1e-7 deg (decimeter-level; exceeds usual data accuracy)''' bd = Coords(*bd) x = bd.lon - BD_DLON y = bd.lat - BD_DLAT # trivia: pycoordtrans actually describes how these values are calculated r = math.sqrt(x * x + y * y) - 0.00002 * math.sin(math.radians(y) * 3000) theta = math.atan2(y, x) - 0.000003 * math.cos(math.radians(x) * 3000) return Coords(r * math.sin(theta), r * math.cos(theta)) def bd_wgs(bd, check_china=True): return gcj_wgs(bd_gcj(bd), check_china) def wgs_bd(bd, check_china=True): return gcj_bd(wgs_gcj(bd, check_china)) def _bored(fwd, rev): ''' generic "bored function" factory, Caijun 2014 gcj: 4 calls to wgs_gcj; ~0.1mm acc ''' def rev_bored(bad, check_china=True): wgs = rev(bad) bad = Coords(*bad) diff = Coords(99, 99) # canary # Wait till we hit fixed point or get bored i = 0 while i < 10 and abs(diff) > PRC_EPS: diff = fwd(wgs, False) - bad wgs = wgs - diff i += 1 return wgs return rev_bored # Precise functions using caijun 2014 method # # Why "bored"? Because they usually exceed source data accuracy -- the # original GCJ implementation contains noise from a linear-modulo PRNG, # and Baidu seems to do similar things with their API too. gcj_wgs_bored = _bored(wgs_gcj, gcj_wgs) bd_gcj_bored = _bored(gcj_bd, bd_gcj) bd_wgs_bored = _bored(wgs_bd, bd_wgs) ================================================ FILE: py/setup.py ================================================ # This file is a part of PRCoords, a public-domain library from __future__ import with_statement from setuptools import setup description="Public Domain library for rectifying Chinese coordinates (gcj-02/bd-09)" try: with open("../README.md", "r") as f: long_description = f.read() except: # Will only happen with non-wheel archives and never on pypi long_description = description setup( name="prcoords", version="1.0.2", author="Mingye Wang", author_email="arthur200126@gmail.com", description=description, long_description=long_description, long_description_content_type="text/markdown", url="https://github.com/Artoria2e5/PRCoords", py_modules=["prcoords"], classifiers=[ "Programming Language :: Python :: 2", "Programming Language :: Python :: 3", "Development Status :: 5 - Production/Stable", "License :: CC0 1.0 Universal (CC0 1.0) Public Domain Dedication", "Operating System :: OS Independent", "Topic :: Scientific/Engineering :: GIS", ], ) ================================================ FILE: racket/prcoords.rkt ================================================ ;; People's Rectified Coordinates ;; Dedicated to the Public Domain under CC0 ;; No idea about the module stuff. ;; Will it handle my awful, collision-prone naming? ;;(module prcoords typed/racket ;; (provide latlon latlon-lat latlon-lon latlon? ;; Do I have to say these all? ;; I figured that before writing one for F#/Haskell/OCaml, ;; Writing one in parentheses first might be a good idea. ;; This sounds fun. #lang typed/racket ;; I could have added some more restrictions, but whatever. (struct latlon ([lat : Float] [lon : Float])) ;; I hear that those people in Haskell land use types to encode ;; more information. Should I do that? ;; These creepy x/y people... (define (latlon-from-complex [c : Float-Complex]) : latlon (latlon (imag-part c) (real-part c))) (define (latlon-to-complex [a : latlon]) : Float-Complex (make-rectangular (latlon-lon a) (latlon-lat a))) ;; This one is a little sloppy... (: dcoord (-> latlon latlon latlon)) (define (dcoord a b) (latlon (- (latlon-lat a) (latlon-lat b)) (- (latlon-lon a) (latlon-lon b)))) ;; For looking into errors (: dcoord-abs (-> latlon latlon Float)) (define (dcoord-abs a b) (max (abs (latlon-lat (dcoord a b))) (abs (latlon-lon (dcoord a b))))) ;; For estimating deviations (define (dist [a : latlon] [b : latlon]) : Float (let ([a-lat (degrees->radians (latlon-lat a))] [a-lon (degrees->radians (latlon-lon a))] [b-lat (degrees->radians (latlon-lat b))] [b-lon (degrees->radians (latlon-lon b))] [d-lat (degrees->radians (latlon-lat (dcoord a b)))] [d-lon (degrees->radians (latlon-lon (dcoord a b)))] [R 6371000.] [hav : (-> Float Float) (λ (theta) (* (sin (/ 2 theta)) (sin (/ 2 theta))))]) (* 2. R (cast (asin (sqrt (+ (hav d-lat) (* (hav d-lon) (cos a-lat) (cos b-lat))))) Float)))) ;; What, you want a polygon check? Not now. (: probably-bad (-> latlon Boolean)) (define (probably-bad a) (and #t ;; TODO #t #t #t)) ;; For your sanity, no functions will be defined with the ;; rough "sanity" check on by default. (: sanity-wrap (-> (-> latlon latlon) (-> latlon Boolean) (-> latlon latlon))) (define (sanity-wrap conv check) (λ ([a : latlon]) (if (check a) (conv a) a))) ;; Sometimes people are like... (: sanity-wrap-backward (-> (-> latlon latlon) (-> latlon Boolean) (-> latlon latlon))) (define (sanity-wrap-backward conv check) (λ ([a : latlon]) (let ([c (conv a)]) (if (check c) c a)))) ;; Finally a conversion. I understand that you have been ;; cursing for all these poorly-written BS. (: wgs-gcj (-> latlon latlon)) (define (wgs-gcj wgs) ; For (human) laziness (let* ([gcj-ee 0.00669342162296594323] ;; Krasovsky 1940, Not What You Use With WGS-84(TM) [gcj-a 6378245.] [x (- (latlon-lon wgs) 105.)] ;; Deviation params [y (- (latlon-lat wgs) 35.)] [dlat 0.] ;; Yay, huge expressions, not today [dlon 0.] [rlat (degrees->radians (latlon-lat wgs))] ;; This type checker is unhappy with... [mm (cast (- 1 (* gcj-ee (sin rlat) (sin rlat))) Positive-Flonum)] [arclat (exact->inexact (* (/ pi 180.) gcj-a (- 1 gcj-ee) (expt mm -1.5)))] [arclon (exact->inexact (* (/ pi 180.) gcj-a (cos rlat) (sqrt mm)))]) (latlon (+ (latlon-lat wgs) (/ dlat arclat)) (+ (latlon-lon wgs) (/ dlon arclon))))) ;; Do you really think I am gonna finish this? ;; A rough reverse function. (: gcj-wgs-rough (-> latlon latlon)) (define (gcj-wgs-rough gcj) (dcoord gcj (dcoord (wgs-gcj gcj) gcj))) ;; Cai's iteration. ;; Not now. Chill, it's just carrying four accumulators around and stuff. (define (caijun-iterate [fwd : (-> latlon latlon)] [rough-rev : (-> latlon latlon)] #:eps [eps : Float 1e-4] #:maxn [maxn : Integer 10]) (λ ([bad : latlon]) : latlon (letrec ([improve : (-> latlon latlon Integer latlon) (λ (curr prev i) ;; Fixing a sloppy part in js, etc.: ;; what happens if rough-rev is just an `id`? (if (or (and (< i maxn) (< (dcoord-abs curr prev) eps)) (= i 0)) (improve (dcoord curr (dcoord (fwd curr) bad)) curr (+ 1 i)) curr))]) (improve bad (rough-rev bad) 0)))) (define gcj-wgs : (-> latlon latlon) (caijun-iterate wgs-gcj gcj-wgs-rough)) ;; Baudu's Obfuscation. (define (gcj-bd [a : latlon]) : latlon (let ([bd-delta 0.0060+0.0065i] [c1 (latlon-to-complex a)] [lat (latlon-lat a)] [lon (latlon-lon a)]) (latlon-from-complex (+ (make-polar (+ (magnitude c1) (* 0.00002 (sin (* 3000. (degrees->radians lat))))) (+ (angle c1) (* 0.000003 (cos (* 3000. (degrees->radians lon)))))) bd-delta)))) (define (bd-gcj-rough [a : latlon]) : latlon (let* ([bd-delta 0.0060+0.0065i] [c1 (- (latlon-to-complex a) bd-delta)] [lat (imag-part c1)] [lon (real-part c1)]) (latlon-from-complex (make-polar (- (magnitude c1) (* 0.00002 (sin (* 3000. (degrees->radians lat))))) (- (angle c1) (* 0.000003 (cos (* 3000. (degrees->radians lon))))))))) (define bd-gcj : (-> latlon latlon) (caijun-iterate gcj-bd bd-gcj-rough)) (define (wgs-bd [a : latlon]) : latlon (gcj-bd (wgs-gcj a))) (define (bd-wgs-rough [a : latlon]) : latlon (gcj-wgs-rough (bd-gcj-rough a))) (define bd-wgs : (-> latlon latlon) (caijun-iterate wgs-bd bd-wgs-rough)) ;; Yay!