Rotoscoping is the process of bringing video frames into a scene to use as the background for matching objects.

The boat is a 3ds Max object composited over a video of a breaking wave.

The way to use rotoscoping is to specify a digital disk recorder or movie file and read the frames into the viewport using the Animation Synchronization controls in the Viewport Background dialog . Once you've specified your source device or file in the Viewport Background dialog, one frame of the video displays for each scene frame by default. Remember to tun on Animate Background as well as Show Background to have your video frames appear in sequence in the viewport.

To produce the composited, rendered image, use Video Post or a compositing application to composite the background image and the rendered scene together.