FLOATING LINES AND CONES FOR USE AS A GPS MISSION PLANNING AID

This paper presents a new method for generating obstruction diagrams a s a function of site obstacles for GPS observations. The proposed meth od takes advantage of the human ability for stereoscopic vision. Inste ad of going on the site and measuring the azimuth and elevation angle of every obstacle in the vicinity of a prospective GPS point, the phot ogrammetric approach proposes using a visibility cone injected into a stereoscopic model. In this way, the time consuming and costly phase o f site reconnaissance is eliminated. In the presence of obstructions, the cone rays that are lower than the obstacles are raised like floati ng lines. Afterwards, by recording the azimuth and elevation angles of these rays, obstruction contours can be generated. With this diagram, superimposed on the satellite track plot, the mission planner can eva luate the best GPS observation window based, for example, on Geometric Dilution of Precision (GDOP). A practical test shows the applicabilit y and feasibility of the method.