重新安装opencv3.4.0
参考安装博客：
opencv 安装版本测试：pkg-config --modversion opencv
https://blog.csdn.net/cocoaqin/article/details/78163171
卸载opencv的方式：进入opencv源码build目录
make uninstall
cd ..
sudo rm -r build
sudo rm -r /usr/local/include/opencv2 /usr/local/include/opencv /usr/include/opencv /usr/include/opencv2 /usr/local/share/opencv /usr/local/share/OpenCV /usr/share/opencv /usr/share/OpenCV /usr/local/bin/opencv* /usr/local/lib/libopencv*
安装过程中出现以下问题：
问题（１）
/usr/bin/ld: /usr/local/lib/libavformat.a(allformats.o): relocation R_X86_64_32 against `ff_a64_muxer' can not be used when making a shared object; recompile with -fPIC
/usr/local/lib/libavformat.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
modules/videoio/CMakeFiles/opencv_videoio.dir/build.make:256: recipe for target 'lib/libopencv_videoio.so.3.4.0' failed
make[2]: *** [lib/libopencv_videoio.so.3.4.0] Error 1
CMakeFiles/Makefile2:7097: recipe for target 'modules/videoio/CMakeFiles/opencv_videoio.dir/all' failed
make[1]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/all] Error 2
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2
解决方式：网上大部分网友说是FFMPEG未安装好的原因，因此需要把依赖库按要求安装好，参考：
https://blog.csdn.net/jasonzzj/article/details/53587889
https://www.cnblogs.com/arkenstone/p/6490017.html
https://github.com/DeaDBeeF-Player/deadbeef/issues/1691
https://blog.csdn.net/zwlq1314521/article/details/44981547
问题（２）opencv3.4.0在编译ocl_test.hpp文件过程中INTER_LINEAR_EXATC找不到声明
解决方式：将该文件中用到INTER_LINEAR_EXATC的地方 换成５这个值，参考网址：
https://blog.csdn.net/insanegtp/article/details/78893088
问题（３）
CUDA cudnn这一块出现错误了‘’/sbin/ldconfig.real: /usr/local/cuda-8.0/targets/x86_64-linux/lib/libcudnn.so.4 不是符号连接‘’
解决办法：参考博客https://blog.csdn.net/langb2014/article/details/54376716
问题（４）
collect2: error: ld returned 1 exit status
modules/viz/CMakeFiles/opencv_test_viz.dir/build.make:236: recipe for target 'bin/opencv_test_viz' failed
make[2]: *** [bin/opencv_test_viz] Error 1
CMakeFiles/Makefile2:3306: recipe for target 'modules/viz/CMakeFiles/opencv_test_viz.dir/all' failed
make[1]: *** [modules/viz/CMakeFiles/opencv_test_viz.dir/all] Error 2
Makefile:160: recipe for target 'all' failed
make: *** [all] Error 2
解决方式：
sudo apt-get autoremove libtiff5-dev
sudo apt-get install libtiff5-dev
https://*.com/questions/38729954/error-installing-opencv-on-ubuntu-16-04
问题（５）期间安装过opencv3.4.1 安装完成后无法编译darknet出现一些Ｃ Ｃ++兼容性的问题,因此卸载了重新安装opencv3.4.0