Hi,

Unfortunately, I don't have enough bandwidth to work on this Linux port. But if you are able to do it, and would like to share, it will be appreciated.

The plugin relies on PROJ library. As it is not provided with binaries, I had to build it manually for windows. using the website instructions, and I did not have any issues with MD5. I guess this is related to the way you built PROJ.

If it can help you, I build it using the vcpkg path (it gather automatically all dependencies such as sqlite3 and tiff libs for x64), then I build PROJ for VS2019 using
cmake -DCMAKE_TOOLCHAIN_FILE=%CURRENTDIR%\ProjBuild\vcpkg\scripts\buildsystems\vcpkg.cmake -DBUILD_PROJSYNC=OFF -DENABLE_CURL=OFF ..
cmake --build . --config Release -j 8

But this is probably quite different for Linux,

I would be very much interested in a Linux port as well :)

I add here my notes concerning the steps performed in order to compile the c++ dependencies of this plugin (all my Unreal stuff is obviously in /home/jeff/Projets/Unreal directory, you need to adapt this path if you wish to re-compile the libs).

• The CMake compilation step is because I am using a very old Debian release, so it should not be needed for most users.
• The LibTiff compilation is a very minimal build, without any external codec.

Build steps:

• We need to re-compile the plugin for Linux. To work with Unreal, we NEED to use a Unreal specific compilation Toolchain (at least when building for Linux):
  • Use the clang / clang++ compilers available inside UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu
  • DO NOT use the default libstdc++ but the libc++ provided by Epic (see https://adamrehn.com/articles/cross-platform-library-integration-in-unreal-engine-4/#stl-and-libc-issues-under-linux for VERY important information about c++ linkage inside Unreal under Linux environment)
  • Dependencies required:
    • CMake >= 3.9 needed. v3.6 max available on Jessie, so we need to compile it ourself.
      • build from sources (install in /usr/bin):
        • sudo apt-get remove cmake
        • https://github.com/Kitware/CMake/releases/download/v3.19.6/cmake-3.19.6.tar.gz.
        • cd cmake-3.19.6
        • ./bootstrap
          • ./bootstrap --qt-gui --qt-qmake=/home/jeff/Qt/5.9.1/gcc_64/bin/qmake do not work on my computer, not searched exactly why, I don't care about the GUI.
        • make && sudo make install
        • cmake --version > cmake version 3.19.6
    • sqlite3 needed:
      • git clone https://github.com/sqlite/sqlite.git
      • cd sqlite
      • git checkout version-3.34.1 (latest version)
      • ./configure --enable-static --disable-shared CC=/home/jeff/Projets/Unreal/UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu/bin/clang CFLAGS=-fPIC
      • make + copy generated static lib in GeoCoordinates plugin
    • Libtiff:
      • https://download.osgeo.org/libtiff/tiff-4.2.0.zip (latest version)
      • cd tiff-4.2.0
      • cmake ./ -DCMAKE_C_COMPILER=/home/jeff/Projets/Unreal/UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu/bin/clang -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DBUILD_SHARED_LIBS=OFF -Dzlib=OFF -Dlibdeflate=OFF -Dpixarlog=OFF -Djpeg=OFF -Dold-jpeg=OFF -Djbig=OFF -Dlzma=OFF -Dzstd=OFF -Dwebp=OFF -Djpeg12=OFF -Dcxx=OFF
      • make + copy generated static lib in GeoCoordinates plugin (exes do not compiles, but static lib does, so we don't care)
    • LibProj:
      • https://download.osgeo.org/proj/proj-8.0.0.tar.gz
      • cd proj-8.0.0
      • mkdir build
      • cd build
      • cmake ../ -DCMAKE_CXX_COMPILER=/home/jeff/Projets/Unreal/UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu/bin/clang++ -DCMAKE_CXX_LINK_EXECUTABLE=/home/jeff/Projets/Unreal/UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu/bin/ld.lld -DCMAKE_CXX_FLAGS="-nostdinc++ -std=c++11 -I/home/jeff/Projets/Unreal/UnrealEngine/Engine/Source/ThirdParty/Linux/LibCxx/include -I/home/jeff/Projets/Unreal/UnrealEngine/Engine/Source/ThirdParty/Linux/LibCxx/include/c++/v1" -DBUILD_SHARED_LIBS=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DBUILD_CCT=OFF -DBUILD_CS2CS=OFF -DBUILD_GEOD=OFF -DBUILD_GIE=OFF -DBUILD_PROJ=OFF -DBUILD_PROJINFO=OFF -DBUILD_PROJSYNC=OFF -DBUILD_TESTING=OFF -DENABLE_CURL=OFF -DEXE_SQLITE3=/home/jeff/Projets/Unreal/Libraries/sqlite/sqlite3 -DSQLITE3_INCLUDE_DIR=/home/jeff/Projets/Unreal/Libraries/sqlite -DTIFF_INCLUDE_DIR=/home/jeff/Projets/Unreal/Libraries/tiff-4.2.0/libtiff
      • make + copy generated static lib in GeoCoordinates plugin