Virtual Sign Demo

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2013Mar 16

This is a demo of my work from several years ago. It shows a sample virtual sign placed in a televised rodeo broadcast. The sign appears to be painted on the dirt, but is actually just a product of computer video processing. The sign in the demo is a simple white box, but conceivably could contain any advertising message. I developed the algorithms and software that detected the occluding animals and rider (so that the virtual sign would not cover the action) and that blended the sign with the shadows and lighting. The software operates in real-time at standard-definition broadcast speeds and throughput. Traditionally, virtual sign insertion requires the use of a green screen (aka, "chroma keying") physically placed in the venue. The color of the screen is so different from any colors in the action that it is easy for computers to detect and locate every pixel of occluding objects. In the rodeo example, we can't very well paint the dirt bright lime green (I hear rodeo fans hate that). The occlusion detection algorithms I developed distinguish the various shades of brown of the animals and rider from those of the dirt. Commonly, virtual signs look unnatural because they don't adjust to ambient lighting and shadows. In the rodeo example, I detected shadows (as opposed to just darker dirt) and adjusted the brightness of the sign in the shadowed locations.