DEM Library

Collaboration diagram for DEM Library:

Modules
	DEM Planetary bodies
	DEM library constants
	DEM library typedefs
	DEM library function calls

Detailed Description

DEM (Digital Elevation Model).

The COSMOS system integrates Digital Elevation Models (DEMs)for a variety of planetary surfaces. Full globe support at 30 arc sec resolution is available for Earth, Mars, and Moon. Additional higher resolution DEMs of select areas can be added. Additional placeholders are available for other major planetary bodies, as well as targets of opportunity, such as asteroids can be used as the data available.

DEMs are stored as floating point numbers in groups of 4; representing altitude in meters, and a Normal (NMAP) in x, y, and z. DEMs for each planetary body are stored at different resolutions, allowing for a minimum of overhead. Only the DEMs required for the desired location and resolution are loaded. Memory use is limited by recycling the oldest accessed DEMs and reclaiming their memory.

General usage involves first first opening the DEM system for a given body through map_dem_open. This This will return a handle that can be used for all subsequent DEM calls for that body. See DEM Planetary bodies for the constants for the various planets. Once a planetary body is open calls to map_dem_pixel will return the DEM value for the requested Latitude and Longitude, at the requested resolution.