Mastering OpenCV 3 - Second Edition

Finding camera matrices

Now that we have obtained matches between keypoints, we can calculate the essential matrix. However, we must first align our matching points into two arrays, where an index in one array corresponds to the same index in the other. This is required by the findEssentialMat function as we've seen in the Estimating Camera Motion section. We would also need to convert the KeyPoint structure to a Point2f structure. We must pay special attention to the queryIdx and trainIdx member variables of DMatch, the OpenCV struct that holds a match between two keypoints, as they must align with the way we used the DescriptorMatcher::match() function. The following code section shows how to align a matching into two corresponding sets ...