Open3D/Open3D-ML's configuration Error-"Failed to clone repository"

This Error occurs when compiling Open3D with Open3D-ML according the official document with command:

# In the build directory
cmake -DBUILD_CUDA_MODULE=ON \
      -DGLIBCXX_USE_CXX11_ABI=OFF \
      -DBUILD_PYTORCH_OPS=ON \
      -DBUILD_TENSORFLOW_OPS=ON \
      -DBUNDLE_OPEN3D_ML=ON \
      -DOPEN3D_ML_ROOT=https://github.com/isl-org/Open3D-ML.git \
      ..

Error message: Failed to clone repository: ‘https:/github.com/isl-org/Open3D-ML.git’

This is due to cmake find_path function locates at Open3D/cpp/pybind/CMakeLists.txt, code as follows:

if (BUNDLE_OPEN3D_ML)
    find_path(
        OPEN3D_ML_ROOT
        NAMES set_open3d_ml_root.sh
        HINTS $ENV{OPEN3D_ML_ROOT}
        DOC "Path to the Open3D-ML repo. This should be set if BUNDLE_OPEN3D_ML is enabled. Alternatively set an env var with the same name to populate this var."
        REQUIRED
        NO_DEFAULT_PATH
    )

    ExternalProject_Add(
        open3d_ml
        PREFIX "${CMAKE_BINARY_DIR}/open3d_ml"
        GIT_REPOSITORY "${OPEN3D_ML_ROOT}"
        GIT_TAG origin/main
        GIT_SHALLOW
        BUILD_IN_SOURCE ON
        # do not configure
        CONFIGURE_COMMAND ""
        # do not build
        BUILD_COMMAND ""
        # do not install
        INSTALL_COMMAND ""
        )
    list(APPEND GENERATED_OUTPUTS open3d_ml)
endif()

CMake find_path performs path normalization that compress http:// into http:/, resulting in corrupted git url in build/open3d_ml/tmp/open3d_ml-gitclone.cmake.

$ less build/open3d_ml/tmp/open3d_ml-gitclone.cmake
if(error_code)
  message(FATAL_ERROR "Failed to clone repository: 'https:/github.com/isl-org/Open3D-ML.git'")
endif()

even that the CMake doc says that “find_path checks if variable is defined. ... If the variable contains any other value the search is not performed.", yet the path normalization still affect the input url.

How to fix (two solutions)

Option 1: use local Open3D-ML repo

# Pick whereever path for the Open3D-ML repo
$ git clone --depth 1 --branch v0.19.0 https://github.com/isl-org/Open3D-ML.git

You don’t have to execute source Open3D-ML/set_open3d_ml_root.sh in this point because cmake will do that for you later.

Setting the OPEN3D_ML_ROOT=<PATH_TO_Open3D-ML> as:

cmake -DBUILD_CUDA_MODULE=ON -DGLIBCXX_USE_CXX11_ABI=OFF -DBUILD_PYTORCH_OPS=ON -DBUILD_TENSORFLOW_OPS=OFF -DBUNDLE_OPEN3D_ML=ON -DOPEN3D_ML_ROOT=/home/belay/Documents/github_others/Open3D/build/Open3D-ML -DBUILD_GUI=ON -DBUILD_WEBRTC=ON -DBUILD_JUPYTER_EXTENSION=ON ..

Option 2: use local Open3D-ML repo

Fix the broken code at Open3D/cpp/pybind/CMakeLists.txt, add if(NOT OPEN3D_ML_ROOT) before find_path function, don’t forget the endif() in the ending of this block.

if (BUNDLE_OPEN3D_ML)
    if(NOT OPEN3D_ML_ROOT)
    find_path(
        OPEN3D_ML_ROOT
        NAMES set_open3d_ml_root.sh
        HINTS $ENV{OPEN3D_ML_ROOT}
        DOC "Path to the Open3D-ML repo. This should be set if BUNDLE_OPEN3D_ML is enabled. Alternatively set an env var with the same name to populate this var."
        REQUIRED
        NO_DEFAULT_PATH
    )
    endif()

Now you can execute the configuration with OPEN3D_ML_ROOT point to the Open3D-ML.git!

cmake -DBUILD_CUDA_MODULE=ON -DGLIBCXX_USE_CXX11_ABI=OFF -DBUILD_PYTORCH_OPS=ON -DBUILD_TENSORFLOW_OPS=OFF -DBUNDLE_OPEN3D_ML=ON -DOPEN3D_ML_ROOT=https://github.com/isl-org/Open3D-ML.git -DBUILD_GUI=ON -DBUILD_WEBRTC=ON -DBUILD_JUPYTER_EXTENSION=ON -DPYTHON_EXECUTABLE=/home/belay/miniconda3/envs/projectc/bin/python ..

Now you can configure open3D together with Open3D-ML, building process goes well for these two command:

make -j$(nproc)
sudo make install
sudo chmod belay:belay -R .

BUT..

Error at creating pip wheel

# Create pip wheel in build/lib
# This creates a .whl file that you can install manually.
make pip-package

Error msg that obveiously related to OPEN3D_ML_ROOT=https://github.com/isl-org/Open3D-ML.git.

Traceback (most recent call last):
  File "/home/belay/Documents/github_others/Open3D/build/lib/python_package/setup.py", line 103, in <module>
    with open("https://github.com/isl-org/Open3D-ML.git/requirements.txt", "r") as f:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: 'https://github.com/isl-org/Open3D-ML.git/requirements.txt'

This piece of code lies in Open3D/python/setup.py, just do a quick fix:

# Read requirements for ML.
if "@BUNDLE_OPEN3D_ML@" == "ON":
    if "@OPEN3D_ML_ROOT@".startswith("http") and "@OPEN3D_ML_ROOT@".endswith(".git"):
        with open("<hard-coded path to local Open3D-ML repo's requirements.txt>", "r") as f:
            install_requires += [line.strip() for line in f.readlines() if line]
    else:
        with open("@OPEN3D_ML_ROOT@/requirements.txt", "r") as f:
            install_requires += [line.strip() for line in f.readlines() if line]