tx2 opencv ubuntu16.04 问题总结

 1.交叉编译opencv3.2.0后连接出现：

libopencv_imgcodecs.so: undefined reference to `png_init_filter_functions_neon'

进入到3rdparty/libpng，在CMakeLists.txt最顶端增加：

set(ENABLE_NEON ON)

2.error: ‘NppiGraphcutState’ does not name a type

         NppiGraphcutState* pState;

解决方案：需要修改一处源码：
在graphcuts.cpp中将
#if !defined (HAVE_CUDA) || defined (CUDA_DISABLER) 
改为
#if !defined (HAVE_CUDA) || defined (CUDA_DISABLER) || (CUDART_VERSION >= 8000)

3.VIDEOIOERROR: V4L/V4L2: 

缺少依赖，安装一下依赖，重装opencv，重装时只需cmake后续步骤，不用卸载。
apt-getinstall libv4l-0 libv4l-dev
参考链接:
http://blog.sina.com.cn/s/blog_96b836170102was7.html

4.file not recognized: File truncated

sample.o: file not recognized: File truncated
collect2: error: ld returned 1 exit status
make[5]: *** [libsample.so] Error 1
make[4]: *** [toolkit/library/target] Error 2

解决方法: make clean
然后执行: make

5.ccache 编译加速，参考一下链接

http://blog.csdn.net/snailjava/article/details/1647813

https://www.cnblogs.com/jason2013/articles/4675468.html

6.opencv安装前一定先安装好各种需要的依赖包，然后安装opencv.

如果后安了依赖库，需重新安装opencv,只需cmake make make install等。

用ccache貌似可以加速make等编译。