编译错误：error: ‘type’ is not a member of ‘cv::DataType＜cv::Vec＜unsigned char, 3＞

github上有人提过相似问题：

https://github.com/opencv/opencv/issues/10115

https://github.com/ros-perception/image_pipeline/issues/308

解决方法：在引用opecv相关的头文件之前加上：

#define OPENCV_TRAITS_ENABLE_DEPRECATED

重新编译。