What do the values of the mask parameter returned by findHomography represent?

Question

I am using the function findHomography of OpenCV with the RANSAC method in order to find the homography that relates two images linked with a set of keypoints.

Answer 1

The mask returned by findHomography is an 8-bit, single-channel cv::Mat (or std::vector, if you prefer) containing either 0 or 1 indicating the outlier status.

EDIT: You access each element of the mask by calling .at, which is leading to the confusing output. You should be using .at, which will interpret the matrix value correctly.