intphys-2.0

Data generation for the Intuitive Physics Challenge - http://www.intphys.com

Developed with Unreal Engine 4.18 and the UnrealEnginePython plugin.

The 2.0 version of intphys is a reimplementation of intphys-1.0 based on UE-4.19 using the Python scripting language (intphys-1.0 was developed with UE-4.8 and Lua).

Important note

This software is used for generation of the datasets used in the Intuitive Physics Challenge, it allows users to generate more train scenes but the code for test scenes generation is kept private.

Video exemples

Train samples

Train samples are always physically possible and have high variability

Test samples

Test samples have a constrained variability and come as quadruplets: 2 possibles cases and 2 impossibles ones

Metadata

Each video comes with it's associated depth field and object masking (each object have a unique id), along with a detailed status in JSON format.

Installation details

This installation process succeeded on Debian stable (Jessie), Ubuntu 16.04 and Ubuntu 18.04. It may be fine for other Unices as well, but this have not been tested.

• Setup an Epic Games account at https://github.com/EpicGames/Signup/, needed to clone the Unreal Engine repository from github.

• Setup the compiler. You need clang-3.8 on Ubuntu 16.04 or below, or clang-3.9 on Ubuntu 18.04 (because 3.8 is no more available on that distribution). The compilation will fail if using a more recent version of clang.

  Make sure you have clang installed and that /usr/bin/clang++ effectively points to the 3.8 or 3.9 version. To check it, have a /usr/bin/clang++ --version, it should output something like:

    clang version 3.9.1-19ubuntu1 (tags/RELEASE_391/rc2)
    Target: x86_64-pc-linux-gnu
    Thread model: posix
    InstalledDir: /usr/bin
  

  If this is not the case, install it and update clang to point to the right version (here 3.9 as example, adapt it for 3.8):

    sudo apt install clang-3.9
    sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-3.9 100
    sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-3.9 100
  

• Install Unreal Engine as documented here.

  • First clone the Engine sources, version 4.19:

    git clone https://github.com/EpicGames/UnrealEngine -b 4.19
    cd UnrealEngine
    

  • If compiling with clang-3.9 you may need to modify a file in the engine sources (the next step may fail, see here for details). Edit the file Engine/Source/ThirdParty/FBX/2018.1.1/include/fbxsdk/core/fbxproperty.h and replace the line 1188 as:

      return StaticInit(pObject, pName, FbxGetDataTypeFromEnum(eFbxEnum), pValue, pForceSet, pFlags);
      // return StaticInit(pObject, pName, FbxGetDataTypeFromEnum(FbxTypeOf(*((FbxReference*)0))), pValue, pForceSet, pFlags);
    

  • Then compile the engine:

    ./Setup.sh
    ./GenerateProjectFiles.sh
    make
    

• Install dependencies required for intphys dataset generation:

    sudo apt-get install libpng++-dev
  

• Install intphys in a separate directory. Clone the repository and its UnrealEnginePython submodule from github:

    git clone git@github.com:bootphon/intphys.git
    cd intphys
    git submodule update --init Plugins/UnrealEnginePython
  

• You need Python>=3.6 installed as /usr/bin/python3.6 (else you need to tweak the UnrealEnginePython plugin here so that it can find python>=3.6 in a non-standard path, for exemple in a virtual environment). You also need the dataclasses module (in the standard library with python>=3.7). To install it on ubuntu 16.04, have a:

    sudo add-apt-repository ppa:jonathonf/python-3.6
    sudo apt-get update
    sudo apt-get install python3.6 python3.6-dev
    /usr/bin/python3.6 -m pip install dataclasses
  

• Setup your ~/.bashrc: The intphys code reads the path to UnrealEngine and the path to the Python scripts from the UE_ROOT and PYTHONPATH environment variables repectively. Add that to your ~/.bashrc:

    export UE_ROOT=/absolute/path/to/UnrealEngine
    export PYTHONPATH=$PYTHONPATH:/absolute/path/to/intphys/Content/Scripts
  

• Build intphys package: We now need to package the intphys project into a standalone binary program. Just have a:

    ./Tools/build/build_package.sh
  

  TROUBLESHOOT

  • During compilation, there may be errors in libpng++ library. Because it is a header-only library, it may seem easier to download lib from nognu.org/pngpp. However, every version from 0.2.1 to 0.2.10 has one problem -- exceptions. UnrealEngine disables exceptions during compilation and libpng++ uses exceptions. Though using libpng++ from non-standard locations should generally work, it does not in this case. It is better to use libpng++ package installed in standard /usr/include/png++ by the command above. In my case, I had libpng++ 0.2.5 installed. If the error is: Then a solution is: -- Include header #include <string> -- Change (message + ": ") to (message + std::string{": "})

  • During compilation there may be other errors in the intphys plugin. If the error is: Then a solution is: Change PyExc_Exception, TCHAR_TO_UTF8(*outErrorMsg.ToString()) to PyExc_Exception, "%s", TCHAR_TO_UTF8(*outErrorMsg.ToString()) If the error is: The a solution is: Change *u_function->GetName() to TCHAR_TO_UTF8(*u_function->GetName())

Usage

• Use the intphys.py program to run the game and generate data. To discover the arguments, have a:

    ./intphys.py --help
  

• The basic usage is calling intphys.py scenes.json -o ./output_data. This reads the scenes to be generated from the scenes.json file and write them in the folder ./output_data.

• Generate scenes using the packaged game:

    ./intphys.py Examples/train.json
  

• When developing you may want to run the project within UE4Editor (--editor option) or as a standalone game (--standalone-game option). The --verbose option is usefull for dev as well.

• Use the --headless option to disable direct rendering on screen (the game will be rendered in a frame buffer instead).

• You can also use Tools/parallel/intphys_parallel.sh to call several instances of intphys.py in parallel and speedup the dataset generation.

Additional utils

In the Tools directory are stored few utility scripts, see README there for more information.

Tweaks

Here are some tweaks and error reports usefull for intphys development.

UE4 crash: cannot open OpenGL context

Occured after an update of the nvidia graphic drivers. Just reboot and try again. sudo glxinfo helps.

Precompiled headers

After a system update you may issue an error when running ./Tools/build/build_package.sh about .gch precompiled headers. The issue is like:

fatal error: file '/usr/include/linux/version.h' has been modified since the precompiled header '.../UE4Editor/Development/Engine/SharedPCH.Engine.h.gch' was built
note: please rebuild precompiled header '.../UE4Editor/Development/Engine/SharedPCH.Engine.h.gch'

In that case remove all the .gch files and recompile the engine:

cd $UE_ROOT
find Engine/Intermediate -type f -name "*.gch" -delete
./GenerateProjectFiles.sh && make