Abstract: Terrain unaided factor and terrain information entropy are defined for the terrain contour matching (TERCOM) elevation-aided navigation system.Statistical characteristics of terrain information entropy are described, and the entropy relation between terrains of different sizes introduced.Mathematical models of various terrain parameters are presented, including SNR, roughness, slope, correlative length and terrain information entropy, etc.Based on a digital elevation model (DEM), qualitative and quantitative analyses are given with graphs of terrain navigation performance and suitability.By means of statistical analyses and threshold value settings, a suitable terrain is selected with better navigation performance.From the results a terrain database can be established for navigation, terrain suitability evaluation and flight course planning.

Key words: terrain parameter, information entropy, TERCOM, correlation suitability