6.2 Terrain Gap Identification and Analysis for Assured Mobility

Assured land mobility of military forces may be adversely impacted by unexpected discontinuities in terrain that fall within the relative vertical error limits of standard terrain elevation models. We define terrain gaps as consisting of such anomalies, within the context of military maneuver, having characteristic dimensions on the order of ten meters or less and minimum slope of approximately 40 degrees, which may impede or constrain the movement of manned or unmanned ground vehicles. Gaps may be natural or man-made, wet or dry, permanent or transient. They may include irrigation ditches, stream banks, short but steep escarpments, canals, walls, berms, excavation overburden, and other microterrain features with a positive or negative elevation difference from immediately surrounding terrain. We examined LIDAR (LIght Detection and Ranging) data over southwestern Montana to capture detailed elevation profiles over suspected terrain gaps, and derived geometric attributes from profile subsets to characterize gap morphology from the perspective of critical military parameters. These data were captured as geospatial information in a GIS environment containing gap linear feature classes with associated attribute data. The profile subsets for each gap feature lend themselves to automatic extraction of elevation breaklines in defining the spatial limits of the gap in the direction of maximum slope change. The distribution of gap features with attribution within the study area demonstrates the critical role that micro-terrain gaps can play in tactical military routing and maneuver models, by obviating bridging, crossing, and avoidance decisions on the ground with advance knowledge of gaps from tactical remote sensors.
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