Open CV Assertion Failed error

Question

I am currently getting this error:

Error

OpenCV Error: Assertion failed (0 <= i && i < (int)vv.size()) in getMat_, file 

/tmp/binarydeb         


        

Answer 1

The error happens because the output array for the circles doesn't have the correct format. The cv::HoughCircles function takes a cv::vector, not a vector of vectors as type for the circle array. Also the values are float, not integer.

Compare the tutorial at http://docs.opencv.org/3.1.0/d4/d70/tutorial_hough_circle.html

(What happens is that when cv::HoughCircles finds a circle, it attempts to access the vec3f matrix - however in your case this is an (empty) cv::vector of integers and hence the size-assertion fails.)