Ubuntu 14.04 编译 opencv

https://www.samontab.com/web/2014/06/installing-opencv-2-4-9-in-ubuntu-14-04-lts/
记录一下， 这篇是写得 比较好的，直接转过来

sudo apt-get update
sudo apt-get upgrade

sudo apt-get install build-essential libgtk2.0-dev libjpeg-dev libtiff4-dev libjasper-dev libopenexr-dev cmake python-dev python-numpy python-tk libtbb-dev libeigen3-dev yasm libfaac-dev libopencore-amrnb-dev libopencore-amrwb-dev libtheora-dev libvorbis-dev libxvidcore-dev libx264-dev libqt4-dev libqt4-opengl-dev sphinx-common texlive-latex-extra libv4l-dev libdc1394-22-dev libavcodec-dev libavformat-dev libswscale-dev default-jdk ant libvtk5-qt4-dev

cd ~
wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.9/opencv-2.4.9.zip
unzip opencv-2.4.9.zip
cd opencv-2.4.9

mkdir build
cd build
cmake -D WITH_TBB=ON -D BUILD_NEW_PYTHON_SUPPORT=ON -D WITH_V4L=ON -D INSTALL_C_EXAMPLES=ON -D INSTALL_PYTHON_EXAMPLES=ON -D BUILD_EXAMPLES=ON -D WITH_QT=ON -D WITH_OPENGL=ON -D WITH_VTK=ON ..

cmake 的时候可能出现 GL.so 不存在 的错误，但实际又存在的情况，此时 先备份已有文件，然后重新建立软连接，
也不知道为什么会这样，奇怪。。。
参考下 https://blog.youkuaiyun.com/wuguangbin1230/article/details/77816299

如果想少编译一些东西，可运行

cmake \ -DCMAKE_BUILD_TYPE=RELEASE \
-DCMAKE_INSTALL_PREFIX=~/opencv-3.4.1/build/installed \
\ -DWITH_CUDA=OFF \
\ -DBUILD_DOCS=OFF \
-DBUILD_EXAMPLES=OFF \
-DBUILD_TESTS=OFF \
-DBUILD_PERF_TESTS=OFF \ 
..

make
sudo make install

sudo gedit /etc/ld.so.conf.d/opencv.conf
加上 /usr/local/lib

sudo ldconfig

sudo gedit /etc/bash.bashrc
加上两行
PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
export PKG_CONFIG_PATH

Finally, close the console and open a new one, restart the computer or logout and then login again. OpenCV will not work correctly until you do this.

运行示例代码：

cd ~/opencv-2.4.9/samples/c
chmod +x build_all.sh
./build_all.sh

./facedetect --cascade="/usr/local/share/OpenCV/haarcascades/haarcascade_frontalface_alt.xml" --scale=1.5 lena.jpg

如果有多个 opencv 版本， 使用 cmake 时， 在FIND_PACKAGE(OpenCV REQUIRED)之前加上

set(CMAKE_PREFIX_PATH "/home/xxx/opencv-3.4.1/build/installed/")