Instructor Contour Extraction and Overlay for Near-real Presence in e-Learning Systems

E-Learning technologies focus on methods to replicate entities such as white board, presentation screen and other teaching aids in remote classrooms. Often, a high detail video stream of the whiteboard or presentation screen (board-stream) is streamed to the remote classroom along with the instructor’s video stream. However, remote participants find it difficult to correlate between the two displayed streams to find out the area focused by the instructor‘s gestures such as finger pointing over the board. This paper deals with a method to overlay the instructor's contour-extracted frames from the instructor-stream over the board-stream for remote participants. Since the board-stream and instructor-stream have different camera perspectives, a transformation from the instructor’s video perspective to the board-stream perspective has to be made before overlay. The process includes finding the Homography-matrix, warping and overlay. Our performance results indicate that remote participants are able to discern the area focused by the instructor on the board with much greater accuracy and speed.