Rotoscoping

Boat is an object composited over video of breaking wave.

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

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 check the Animate background box as well as the Show Background box to have your video frames appear in sequence in the viewport.

To produce the composited, rendered image, use 3ds max Video Post to composite the background image and the rendered scene together.