NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2015 Feb 10, 16:00 -0800
Lu, you wrote:
"NASA has produced a video (from moon probe photos/videos) from the "back" side of the Moon looking towards Earth. Neat!"
It's a nice animation, but just nitpicking a bit, it's not from "photos/videos" per se. In some respects, this is an intricate cartoon. The Earth is a digital animation. The Moon images are generated from a 3D model of the Moon. That's what has become available in the past few years from various missions including LRO, which this animation is intended to publicize: a highly detailed DEM or "digital elevation model" of the Moon which is a simple database detailing how high the peak of every crater and mountain is relative to a reference spheroid. This 3D model is "illuminated" with a virtual sunlight source digitally, and voilà, the mountains and crater peaks cast virtual shadows. An albedo model, which is more like a photo of the Moon, is also used to get the right grey levels.
Frank Reed
