Digital Terrain Correlation for DIS

Experience with Distributed Interactive Simulation (DIS) has revealed significant problems with terrain correlation between participants, particularly between virtual and constructive simulation. Some effects from terrain miscorrelation are tanks that appear to be floating above ground, helicopters and ground vehicles that appear to dive below the terrain and ground vehicles that are oriented contrary to the way the terrain is sloping. A quick fix to the problem has been to "ground clamp" vehicles to the terrain. However, this fix doesn’t work for low- flying helicopters, and it doesn’t correct erroneous line-of- sight determinations that are used for target acquisition and weapon engagements between simulated entities. Although digital terrain may be derived from the same data source, there are many reasons for miscorrelation. This paper will reveal some of the more common reasons for miscorrelation and explain some recently developed techniques to eliminate the problem.