How to correct CMAKE error: package 'opencv' not found

Question

OK，我知道opencv linking之前有讨论过，但是看不出报错，不明白改正。我正在尝试 link DBoW2 库，它需要 opencv。我收到未定义的引用错误。

$ mingw32-make
Linking CXX shared library ..\lib\libDBoW2.dll
CMakeFiles\DBoW2.dir/objects.a(FORB.cpp.obj):FORB.cpp:(.text+0x124): undefined reference to `cv::Mat::zeros(int, int, int)'
CMakeFiles\DBoW2.dir/objects.a(FORB.cpp.obj):FORB.cpp:(.text+0x1db): undefined reference to `cv::fastFree(void*)'
CMakeFiles\DBoW2.dir/objects.a(FORB.cpp.obj):FORB.cpp:(.text+0x394): undefined reference to `cv::Mat::deallocate()'
CMakeFiles\DBoW2.dir/objects.a(FORB.cpp.obj):FORB.cpp:(.text+0x46a): undefined reference to `cv::Mat::copyTo(cv::_OutputArray const&) const'
CMakeFiles\DBoW2.dir/objects.a(FORB.cpp.obj):FORB.cpp:(.text+0x503): undefined reference to `cv::Mat::copySize(cv::Mat const&)'
CMakeFiles\DBoW2.dir/objects.a(FORB.cpp.obj):FORB.cpp:(.text+0x93f): undefined reference to `cv::Mat::create(int, int const*, int)'
collect2.exe: error: ld returned 1 exit status

这是 CMakeLists.txt 文件

cmake_minimum_required(VERSION 2.8)
project(DBoW2)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}  -Wall  -O3 -march=native ")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall  -O3 -march=native")

set(HDRS_DBOW2
  DBoW2/BowVector.h
  DBoW2/FORB.h 
  DBoW2/FClass.h       
  DBoW2/FeatureVector.h
  DBoW2/ScoringObject.h   
  DBoW2/TemplatedVocabulary.h)
set(SRCS_DBOW2
  DBoW2/BowVector.cpp
  DBoW2/FORB.cpp      
  DBoW2/FeatureVector.cpp
  DBoW2/ScoringObject.cpp)

set(HDRS_DUTILS
  DUtils/Random.h
  DUtils/Timestamp.h)
set(SRCS_DUTILS
  DUtils/Random.cpp
  DUtils/Timestamp.cpp)

find_package(OpenCV REQUIRED)

set(LIBRARY_OUTPUT_PATH ${PROJECT_SOURCE_DIR}/lib)

include_directories(${OpenCV_INCLUDE_DIRS})
add_library(DBoW2 SHARED ${SRCS_DBOW2} ${SRCS_DUTILS})
target_link_libraries(DBoW2 ${OpenCV_LIBS})

我用的是gui界面，参数OpenCV_DIR自动设置为C:/OpenCV/minwg_64。在该目录下有一个目录 lib 包含库文件，如 "libopencv_videostab300.dll.a"

CMakeCache.txt 文件包含行

//Dependencies for the target
DBoW2_LIB_DEPENDS:STATIC=general;opencv_videostab;general;opencv_videoio;general;opencv_video;general;opencv_superres;general;opencv_stitching;general;opencv_shape;general;opencv_photo;general;opencv_objdetect;general;opencv_ml;general;opencv_imgproc;general;opencv_imgcodecs;general;opencv_highgui;general;opencv_hal;general;opencv_flann;general;opencv_features2d;general;opencv_core;general;opencv_calib3d;

根据我的阅读，以下几行应该足够了，但我遇到了 linker 错误。

find_package(OpenCV REQUIRED)
include_directories(${OpenCV_INCLUDE_DIRS})
target_link_libraries(DBoW2 ${OpenCV_LIBS})

编辑 1：

回应克里斯梅斯

添加了 pkg 检查

pkg_check_modules (OPENCV REQUIRED opencv)

现在configure报错了，算是进步了，但还是很茫然。我在 opencv 安装/构建中一定有错误。我在外部驱动器上有第二个副本，它是最近（并且很容易）使用 cmake 之类的东西构建的。但是将 OpenCV_DIR 设置为外部构建会产生相同的错误。

Found PkgConfig: C:/msys64/usr/bin/pkg-config.exe (found version "0.28") 
checking for module 'opencv'
  package 'opencv' not found

编辑 2：

这是当我启动一个新缓存并按两次生成（第一次它只生成 make，sh）时 CMake 自动生成的设置。

CMAKE_BUILD_TYPE (BLANK)
CMAKE_GNUtoMS (UNCHECKED)
CMAKE_INSTALL_PREFIX C:/Program Files (x86)/DBoW2
CMAKE_MAKE_PROGRAM C:/msys64/mingw64/bin/mingw32-make.exe
CMAKE_SH C:/msys64/usr/bin/sh.exe
OpenCV_DIR C:/OpenCV/minwg_64

C:/OpenCV/minwg_64 目录包含从 mingw gcc 64 构建的 opencv 库，以及包含 OpenCVConfig.cmake 和目录 bin 和 lib 的 cmake 文件。我想知道我是否需要目录 staticlib？

对于windows环境，我有

OPENCV_DIR = C:\OpenCV\minwg_64  (where built bin and lib are located)
OPENCV_VER = 300
PATH includes C:\OpenCV\minwg_64\bin

Answer 1

在 linux 我使用 pkg_check_modules cmake 插件：

find_package( OpenCV REQUIRED )
find_package( PkgConfig REQUIRED )
pkg_check_modules (OPENCV REQUIRED opencv)
include_directories(/usr/include/opencv2)

target_link_libraries(DBoW2 ${OPENCV_LDFLAGS})

注意： 我不记得我为什么使用硬编码 /usr/include/opencv2，但我想 OPENCV_INCLUDE_DIRS 在我尝试时没有任何用处。可能有更干净的方法:)

How to correct CMAKE error: package 'opencv' not found