[Gdeaver]

You want to look up. A cruise missile looks down. Your thinking of terrain following systems. The US terrain following cruise missile is an interesting system and could have some civilian applications in machine vision. To bad the critical parts are tied up under national security. I believe Scientific American had a article on it a few years ago. Current machine vision has gone down the path of capturing more and more digital information from an image and throwing more and more computer horse power at it. The cruise missile is different. It takes an optical image and through optical and analog processing - filtering reduces the images information to just what is important. The edges and boundaries of objects which at the last stage are digitized and and compared to a processed image data base.