无法使用cmake与OpenCV和LibTorch链接项目

Question

几天前，我问了一个关于将项目与OpenCV链接的类似问题。我让它工作了，但现在我遇到了一个非常奇怪的问题，使用CMake并将LibTorch添加到项目中。

如果我只在项目中使用OpenCV，那么一切都可以很好地编译、链接和运行。

但是如果我将Torch添加到CMakeLists.txt，我会得到一个链接器错误：

cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
set(CMAKE_VERBOSE_MAKEFILE ON)
project(torchscriptie)

find_package( OpenCV REQUIRED )
include_directories( ${OpenCV_INCLUDE_DIRS} )

find_package(Torch HINTS "/usr/local/libtorch")
message(STATUS "TORCH_LIBRARIES = ${TORCH_LIBRARIES}")

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${TORCH_CXX_FLAGS}")

add_executable(torchscriptie main.cpp)
target_link_libraries( torchscriptie ${OpenCV_LIBS} )
target_link_libraries(torchscriptie "${TORCH_LIBRARIES}")
set_property(TARGET torchscriptie PROPERTY CXX_STANDARD 14)

此CMakeLists.txt文件会导致以下错误：

CMakeFiles/torchscriptie.dir/main.cpp.o: In function `main':
/code/cpp/torchscriptie/main.cpp:18: undefined reference to `cv::imread(std::string const&, int)'
/code/cpp/torchscriptie/main.cpp:24: undefined reference to `cv::namedWindow(std::string const&, int)'
/code/cpp/torchscriptie/main.cpp:25: undefined reference to `cv::imshow(std::string const&, cv::_InputArray const&)'
collect2: error: ld returned 1 exit status

下面是命令：

/usr/bin/c++  -g  -rdynamic CMakeFiles/torchscriptie.dir/main.cpp.o  -o torchscriptie  -Wl,-rpath,/usr/local/lib:/usr/local/libtorch/lib /usr/local/lib/libopencv_gapi.so.4.3.0 /usr/local/lib/libopencv_stitching.so.4.3.0 /usr/local/lib/libopencv_alphamat.so.4.3.0 /usr/local/lib/libopencv_aruco.so.4.3.0 /usr/local/lib/libopencv_bgsegm.so.4.3.0 /usr/local/lib/libopencv_bioinspired.so.4.3.0 /usr/local/lib/libopencv_ccalib.so.4.3.0 /usr/local/lib/libopencv_dnn_objdetect.so.4.3.0 /usr/local/lib/libopencv_dnn_superres.so.4.3.0 /usr/local/lib/libopencv_dpm.so.4.3.0 /usr/local/lib/libopencv_face.so.4.3.0 /usr/local/lib/libopencv_freetype.so.4.3.0 /usr/local/lib/libopencv_fuzzy.so.4.3.0 /usr/local/lib/libopencv_hdf.so.4.3.0 /usr/local/lib/libopencv_hfs.so.4.3.0 /usr/local/lib/libopencv_img_hash.so.4.3.0 /usr/local/lib/libopencv_intensity_transform.so.4.3.0 /usr/local/lib/libopencv_line_descriptor.so.4.3.0 /usr/local/lib/libopencv_quality.so.4.3.0 /usr/local/lib/libopencv_rapid.so.4.3.0 /usr/local/lib/libopencv_reg.so.4.3.0 /usr/local/lib/libopencv_rgbd.so.4.3.0 /usr/local/lib/libopencv_saliency.so.4.3.0 /usr/local/lib/libopencv_stereo.so.4.3.0 /usr/local/lib/libopencv_structured_light.so.4.3.0 /usr/local/lib/libopencv_superres.so.4.3.0 /usr/local/lib/libopencv_surface_matching.so.4.3.0 /usr/local/lib/libopencv_tracking.so.4.3.0 /usr/local/lib/libopencv_videostab.so.4.3.0 /usr/local/lib/libopencv_viz.so.4.3.0 /usr/local/lib/libopencv_xfeatures2d.so.4.3.0 /usr/local/lib/libopencv_xobjdetect.so.4.3.0 /usr/local/lib/libopencv_xphoto.so.4.3.0 /usr/local/libtorch/lib/libtorch.so /usr/local/libtorch/lib/libc10.so /usr/local/lib/libopencv_shape.so.4.3.0 /usr/local/lib/libopencv_highgui.so.4.3.0 /usr/local/lib/libopencv_datasets.so.4.3.0 /usr/local/lib/libopencv_plot.so.4.3.0 /usr/local/lib/libopencv_text.so.4.3.0 /usr/local/lib/libopencv_dnn.so.4.3.0 /usr/local/lib/libopencv_ml.so.4.3.0 /usr/local/lib/libopencv_phase_unwrapping.so.4.3.0 /usr/local/lib/libopencv_optflow.so.4.3.0 /usr/local/lib/libopencv_ximgproc.so.4.3.0 /usr/local/lib/libopencv_video.so.4.3.0 /usr/local/lib/libopencv_videoio.so.4.3.0 /usr/local/lib/libopencv_imgcodecs.so.4.3.0 /usr/local/lib/libopencv_objdetect.so.4.3.0 /usr/local/lib/libopencv_calib3d.so.4.3.0 /usr/local/lib/libopencv_features2d.so.4.3.0 /usr/local/lib/libopencv_flann.so.4.3.0 /usr/local/lib/libopencv_photo.so.4.3.0 /usr/local/lib/libopencv_imgproc.so.4.3.0 /usr/local/lib/libopencv_core.so.4.3.0 -Wl,--no-as-needed,/usr/local/libtorch/lib/libtorch_cpu.so -Wl,--as-needed /usr/local/libtorch/lib/libc10.so -lpthread -Wl,--no-as-needed,/usr/local/libtorch/lib/libtorch.so -Wl,--as-needed 

我已经尝试了许多不同的命令组合，但我不知道我们的问题出在哪里。当我回显TORCH_LIBRARIES变量时，它返回：

torch;torch_library;/usr/local/libtorch/lib/libc10.so

如果我将库更改为torch_cpu，我就能够链接OpenCV库。

set(TORCH_LIBRARIES torch_cpu)

我不知道为什么Torch库在同一项目中会导致与OpenCV的链接错误。任何建议都是很棒的。

Answer 1

不知道这是否解决了你的问题，但我也有一些类似你的问题。它适用于我的cmake文件，包括以下内容：

cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
project(MyProject)
set(CMAKE_CXX_STANDARD 14)
list(APPEND CMAKE_PREFIX_PATH "folderToLibtorch/libtorch/share/cmake")
find_package(Torch REQUIRED)  
find_package(OpenCV REQUIRED)
SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -lm -ldl")
add_executable(MyProject ...some project files...)
target_link_libraries(MyProject ${TORCH_LIBRARIES} ${OpenCV_LIBS})
set_property(TARGET MyProject PROPERTY CXX_STANDARD 14)

所以确保list(APPEND CMAKE_PREFIX_PATH "folderToLibtorch/libtorch/share/cmake")包含在内，这对我来说很有用。还要注意从pytorch获得正确的libtorch版本，也许你应该使用下面的链接，而不是"pre-...“版本。祝好运

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