Build error: OpenMP_libomp_LIBRARY on MacOs

Not sure, if this dependency is optional? If so, how to force Cmake to ignore the error?

-- Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES) 
-- Could NOT find OpenMP_CXX (missing: OpenMP_CXX_FLAGS OpenMP_CXX_LIB_NAMES) 
-- Could NOT find OpenMP (missing: OpenMP_C_FOUND OpenMP_CXX_FOUND) 
-- Found AMD library: /opt/local/lib/libamd.dylib
-- Found AMD header in: /opt/local/include
-- Found CAMD library: /opt/local/lib/libcamd.dylib
-- Found CAMD header in: /opt/local/include
-- Found COLAMD library: /opt/local/lib/libcolamd.dylib
-- Found COLAMD header in: /opt/local/include
-- Found CCOLAMD library: /opt/local/lib/libccolamd.dylib
-- Found CCOLAMD header in: /opt/local/include
-- Found CHOLMOD library: /opt/local/lib/libcholmod.dylib
-- Found CHOLMOD header in: /opt/local/include
-- Found CXSPARSE library: /opt/local/lib/libcxsparse.dylib
-- Found SuiteSparseQR library: /opt/local/lib/libspqr.dylib
-- Found SuiteSparseQR header in: /opt/local/include
-- Did not find Intel TBB library, assuming SuiteSparseQR was not compiled with TBB.
-- Found SuiteSparse_config library: /opt/local/lib/libsuitesparseconfig.dylib
-- Found SuiteSparse_config header in: /opt/local/include
-- Found METIS library: /opt/local/lib/libmetis.dylib.
CMake Warning (dev) at /opt/local/share/cmake-3.19/Modules/FindPackageHandleStandardArgs.cmake:424 (message):
  The package name passed to `find_package_handle_standard_args` (ceres) does
  not match the name of the calling package (Ceres).  This can lead to
  problems in calling code that expects `find_package` result variables
  (e.g., `_FOUND`) to follow a certain pattern.
Call Stack (most recent call first):
  cmake/FindCeres.cmake:49 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  CMakeLists.txt:38 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- No preference for use of exported gflags CMake configuration set, and no hints for include/library directories provided. Defaulting to preferring an installed/exported gflags CMake configuration if available.
-- Found installed version of gflags: /opt/local/lib/cmake/gflags
-- Detected gflags version: 2.2.2
-- Found OpenCV: /opt/local (found version "3.4.12") 
-- Found OpenCV: /opt/local (found version "3.4.12") found components: core imgproc calib3d imgcodecs 
-- pybind11 v2.2.4
-- Configuring done
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
OpenMP_libomp_LIBRARY (ADVANCED)
    linked by target "foundation" in directory .../Source/OpenSfM/opensfm/src/foundation

-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.
Traceback (most recent call last):
  File "setup.py", line 36, in <module>
    configure_c_extension()
  File "setup.py", line 27, in configure_c_extension
    subprocess.check_call(cmake_command, cwd='cmake_build')
  File "/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/subprocess.py", line 364, in check_call
    raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['cmake', '../opensfm/src', '-DPYTHON_EXECUTABLE=.../.virtualenvs/proto-sfm/bin/python']' returned non-zero exit status 1.

[zhengminxu]

I faced the same problem, and after I installed libomp via homebrew, the CMake error was gone and the build went successfully.

[fabianschenk]

In OpenSfM/opensfm/src/CMakeLists.txt, I commented:

# find_package(OpenMP)

Then I deleted the cmake_build folder and rebuilt. You can also install cmake tool on Mac and check if any of the OpenMP variables for libraries and includes are set.