Topographic/F) hotometric Model of Small Bodies

Developing image accluisition requirements is a major part of the Autmiolnous Feature and Star ‘lkacking (AI+’AST) projec~’s work in advancing sensor technologies for planetary exp]oratio~l. Sensing and detecting desired planetary features also i]lvolve topographic and photometric characterization of celestial bodies. The photometric study can provide felicitous designs of optics, focal plane array, and processing pertaining to feature extraction and tracking. II] this paper, we present the results b~<ed on our preliminary study and i~nplementation of photolnctric moclcling on the A1’AS’l”S SGIbased 31) graphics testbed. Specifically, a computer-generated topographical model of Phobos is used since the photometry of Phobos have been studied in great details, ‘lhc photometric function derived is mapped onto the computer-generated topographic model. Using the phc)tometric model and specific camera parameters, a)) accurate CC]) pixel response to target irradiancc can then be calculated. This pixel informatio~l can be used by the feature tracking algorithm, and sensitivity to signal-to-noise ratio can then be determined.