The center of the face was being reported as the center in the internally-cropped image, not the center
in the original mask. When the code that detects which face corresponds to which mask ran, it samples
the mask at the center of each face, but since the center was wrong, it would use the default index 0.
The OpenCV path includes code to handle if FaceMesh finds 2+ faces when trying to get
the FaceMesh corresponding to an OpenCV face, by selecting the face that best matches the
OpenCV face. Normally FaceMesh only returns 1 face, but in the case where it found 2+ faces,
the previous version would break. (I think, I don't have any examples that trigger this path.)
Robert Barron
kex0
Sean Barrett