由于要用c++,迫不得已要安装opencv了，之前的Python都是直接pip install 就好了，c++的话还是麻烦一些。不过这样自己编译的话，是c++和Python两个语言都装了。
这里用了两种安装方式：1.本机安装 2.docker安装。中途踩了一些坑，特此记录。
一.本机安装
参考https://www.learnopencv.com/install-opencv3-on-ubuntu/
#更新包
sudo apt-get update
sudo apt-get upgrade
#安装os库
sudo apt-get remove x264 libx264-dev #先移除，自己命令执行后发现并没有这个
sudo apt-get install build-essential checkinstall cmake pkg-config yasm
sudo apt-get install git gfortran
sudo apt-get install libjpeg8-dev libjasper-dev libpng12-dev
sudo apt-get install libtiff5-dev #ubuntu16.04
sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev
sudo apt-get install libxine2-dev libv4l-dev
sudo apt-get install libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev
sudo apt-get install qt5-default libgtk2.0-dev libtbb-dev
sudo apt-get install libatlas-base-dev
sudo apt-get install libfaac-dev libmp3lame-dev libtheora-dev
sudo apt-get install libvorbis-dev libxvidcore-dev
sudo apt-get install libopencore-amrnb-dev libopencore-amrwb-dev
sudo apt-get install x264 v4l-utils
#自己这里可选的依赖没有装
git clone https://github.com/opencv/opencv.git
cd opencv
git checkout 3.3.1
cd ..
git clone https://github.com/opencv/opencv_contrib.git
cd opencv_contrib
git checkout 3.3.1
cd ..
#编译安装
cd opencv
mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D CMAKE_INSTALL_PREFIX=/usr/local \
-D INSTALL_C_EXAMPLES=ON \
-D INSTALL_PYTHON_EXAMPLES=ON \
-D WITH_TBB=ON \
-D WITH_V4L=ON \
-D WITH_QT=ON \
-D WITH_OPENGL=ON \
-D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
-D BUILD_EXAMPLES=ON ..
#查看cpu核数
nproc
make -j4 #j后面的数字代表用几个核
sudo make install
sudo sh -c 'echo "/usr/local/lib" >> /etc/ld.so.conf.d/opencv.conf'
sudo ldconfig
使用过程中发现报错fatal error: opencv2/viz.hpp: No such file or directory
是由于自己没有安装vtk所导致的，所以要安装vtk然后重新cmake重新编译一下
sudo apt-get install libvtk5-dev
#重新cmake
cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D CMAKE_INSTALL_PREFIX=/usr/local \
-D INSTALL_C_EXAMPLES=ON \
-D INSTALL_PYTHON_EXAMPLES=ON \
-D WITH_TBB=ON \
-D WITH_V4L=ON \
-D WITH_QT=ON \
-D WITH_OPENGL=ON \
-D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
-D WITH_VTK=ON \ #添加这一句
-D BUILD_EXAMPLES=ON ..
二、通过docker安装
参考：https://www.learnopencv.com/install-opencv-docker-image-ubuntu-macos-windows/
1.安装docker
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo apt-get update
apt-cache policy docker-ce
sudo apt-get install -y docker-ce
2.在docker里安装opencv3镜像
docker pull spmallick/opencv-docker:opencv-3.4.1
3.启动docker镜像
docker run --device=/dev/video0:/dev/video0 -v /tmp/.X11-unix:/tmp/.X11-unix -e DISPLAY=$DISPLAY -p 5000:5000 -p 8888:8888 -it spmallick/opencv-docker:opencv-3.4.1 /bin/bash
报错如下
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post http://%2Fvar%2Frun%2Fdocker.sock/v1.38/images/create?fromImage=spmallick%2Fopencv-docker&tag=opencv-3.4.1: dial unix /var/run/docker.sock: connect: permission denied
这是由于自己用了sudo 安装docker ,在用docker的时候就没有权限了。解决方法有二，1直接用sudo run 因为 /var/run/docker.sock 所属 docker 组具有 setuid 权限，所以将自己加入到docker group 里面
sudo gpasswd -a chunyan docker
sudo service docker restart #重启docker服务
newgrp - docker #切换当前会话到新group
之后执行
docker run --device=/dev/video0:/dev/video0 -v /tmp/.X11-unix:/tmp/.X11-unix -e DISPLAY=$DISPLAY -p 5000:5000 -p 8888:8888 -it spmallick/opencv-docker:opencv-3.4.1 /bin/bash
其中各个指令含义：
–device=/dev/video0:/dev/video0 allows use of webcam
-v /tmp/.X11-unix:/tmp/.X11-unix helps in X11 forwarding so that we can use functions like cv::imshow.
-e is used to pass an environment variable.
-it starts an interactive session
-p sets up a port forward. This flag maps the container’s port to a port on the host system.
/bin/bash runs .bashrc file on startup
