EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Campbell & Shepard 1997
Campbell, B.A. and Shepard, M.K. (1997). Effect of Venus surface illumination on photographic image texture. Geophysical Research Letters 24: doi: 10.1029/97GL00598. issn: 0094-8276.

Radar images from Magellan have provided tremendous opportunities to study the geology and bulk dielectric properties of Venus, but many questions can only be addressed through direct photography or imaging spectroscopy of the surface. The thick atmosphere creates a situation of nearly isotropic illumination, so true shadows cannot exist for even very rough terrain. We carried out ray-tracing simulations for synthetic surfaces under both isotropic and directional illumination conditions. Relative to similar surfaces viewed under directional illumination, venusian terrain will exhibit an equal or greater range of mean brightness with changing roughness, but a concurrent reduction in the maximum possible standard deviation of brightness across any region of given roughness. The local variability of an image is often referred to as texture, and these results indicate that Venus geologic units will appear more homogeneous in brightness than the same surfaces viewed under favorable directional illumination. In addition, the lack of a preferred lighting direction makes identification of surface structural patterns difficult. A similar situation may occur on Titan.¿ 1997 American Geophysical Union

BACKGROUND DATA FILES

Abstract

Keywords
Planetology, Solid Surface Planets, Surface materials and properties, Planetology, Solid Surface Planets, Instruments and techniques
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit