OpenCV - undefined reference to 'cv::CascadeClassifier::detectMultiScale() after NDK update

Question

Yesterday I updated my Android Studio included NDK to version 17.0.4754217and since then I can\'t run my app anymore. When I tried to rerun the code after the u

Answer 1

When linkin opencv with your project executables, you always have to link with the general library -lopencv_core. But some packages require additional link flags. For example, if you use highgui as in

#include 

you must add opencv_highgui link flag for : -lopencv_highgui.

In you case, CascadeClassifiers are defined in

#include "opencv2/objdetect.hpp"

and thus requires a link with opencv_objdetect -lopencv_objdetect.

The solution is to add the link flag -lopencv_objdetect when compiling.