Maintaining code compatibility between OpenCV 2 and OpenCV 3

Question

My library currently uses OpenCV 2. Now, I am trying to compile the library to use OpenCV 3. It seems that some header files were moved and some constants were renamed. For exam

Answer 1

The OpenCV guys have put up a transition guide online : http://docs.opencv.org/master/db/dfa/tutorial_transition_guide.html

In essence I think the following have changed:-

• ml module-> The existence of StatModel in OpenCV 3 and that being the root for all classifiers.
• features2d and xfeatures2d -> SIFT and a couple of others have moved from being in the core repository to the opencv_contrib repo
• And many others I am not aware of

As for code working with Opencv3 and opencv2, I usually introduce a prepocessor directive which holds a flag:-

#define HAS_OPENCV3 1
#ifdef HAS_OPENCV3
#include  //Any OPENCV3 code
#else
#include  //Any Opencv2 code
#endif

Since the relative portions are eliminated before compilation, it will also compile with only the OpenCV2 or OpenCV3 libraries. But, introduces a lot of redundancy (which can be avoided by some clever coding).