From a series of plastic model kits produced by Imai, called Megaro Zamac. There was never an anime show related to this series, I think Imai simply produced the kits to cash in on the giant robot model craze. This particular mecha was obviously more than slightly inspired by the Imperial AT-AT from The Empire Strikes Back, though from the scale of the kit the real thing would be considerably more than twice the size of the AT-AT.
This image is an update of the Dha Gards scene which I originally rendered in Cinema 4D XL6, back in 2002. This version was done in Cinema 4D Release 14 and takes advantage of the many new features added to the program over the last twelve years.