問題：
CMake Error at CMakeLists.txt:3 (find_package):
By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "OpenCV", but
CMake did not find one.
Could not find a package configuration file provided by "OpenCV" with any
of the following names:
OpenCVConfig.cmake
opencv-config.cmake
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set
"OpenCV_DIR" to a directory containing one of the above files. If "OpenCV"
provides a separate development package or SDK, be sure it has been
installed.
解決方法一（源自https://www.cnblogs.com/LiuSY/p/5808210.html）：
打開你的CMakeLists.txt，添加set(OpenCV_DIR D:/Opencv2.4/opencv/build) 注意這是你的OpenCVConfig.cmake的路徑（注意路徑中的斜槓方向）
再編譯就可以啦
解決方法二：
樓主用了方法一併未實現該有的效果，可能哪裏操作出錯了，但是發現更簡單的方法。
點擊下圖的紅圈OpenCV_DIR處，或出現後方的...按鈕，點擊該按鈕，選擇文件夾路徑，該文件夾路徑就是你的OpenCVConfig.cmake的路徑，例如：D:/socure/OpenCV/opencv-3.3.1-mybuild。
然後點擊configure，gererate，出現
好的，恭喜你解決問題了