安装opencv ：face_landmark_model.dat
– data: Download: face_landmark_model.dat

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Couldn’t connect to server from the Internet.
Perhaps direct connections are not allowed in the current network.
To use proxy please check/specify these environment variables:

• http_proxy/https_proxy
• and/or HTTP_PROXY/HTTPS_PROXY
  

如上修改为本地地址
本地下载：

https://raw.githubusercontent.com/opencv/opencv_3rdparty/8afa57abc8229d611c4937165d20e2a2d9fc5a12/face_landmark_model.dat

vim ~/opencv-4.x/opencv_contrib-4.x/modules/face/CMakeLists.txt

具体需要根据自己的路径进行修改

"file:///home/test/download/"