Integrity Monitoring of Digital Elevation Models using Corner Edge Detection of Accumulated X-Band Radials

Synthetic vision systems (SVS) provides pilots with displays of stored geo-spatial data representing terrain, obstacles and cultural features. This system has the potential to improve flight safety by providing situational awareness and reducing the likelihood of controlled flight into terrain (CFIT). In order to enable the safe use of SVS at low altitudes, real-time range-to-terrain measurements may be necessary to ensure integrity of terrain data for civil aviation applications. This paper describes an integrity monitor which uses a novel approach to check the consistency between a terrain elevation profile synthesized from an X-band weather radar (WxR) sensor and the profile given in a digital elevation model (DEM). Features, in the form of edge locations and associated curvature strengths, are extracted and placed in a graph representation. A comparison is performed on the relationships that are drawn from the node attributes using the approximate graph matching technique in order to confirm the integrity of the terrain dataset. Terrain scans from NASA's integrated intelligent flight deck (IIFD) program are used to validate the proposed integrity monitoring approach