cv_exports in blobtracking for video surveillance

Question

I am doing a project on video surveillance where the vehicle has to be tracked from the video and have to also identify which vehicle is it. i am using opencv. i am using blob tracking in it. is there any other method to detec vehicles using opencv. i am new to opencv. i was going through blob tracking header file where i found one statement like:

class CV_EXPORTS CVVsModule

what does this mean. and what does CV_EXPORTS is used for. it is written with many classes. what is its significance. also tell me how to approach with my project. its really important for me.

Answer 1

here's the definition:

#if (defined WIN32 || defined _WIN32 || defined WINCE) && defined CVAPI_EXPORTS
#  define CV_EXPORTS __declspec(dllexport)
#else
#  define CV_EXPORTS
#endif

tl;dr: it's needed for functions or classes to get exported to the dll-symbol table on WIN os.