Device executing intervisibility calculation

Abstract

A device executing intervisibility calculation includes a mechanism executing a radial spoke scan pattern where individual radials are traversed beginning at a threat installation and extending outward along a radial to a distance corresponding to threat range capability. Intervisibility calculation is simplified to allow implementation in a simple, dedicated hardware engine to provide rapid execution time while ensuring accurate intervisibility results. The intervisibility engine includes lookup tables to provide precalculated data and advantageously avoids divide operations whereby the intervisibility calculation may be executed by use of a series of adds, subtracts, and multiplies relative to intervisibility data developed while traversing a given radial. The engine calculates a slope for each data post visited in traversing a radial, and identifies a data post as being visible when its associated slope is greater than a previously encountered greatest magnitude slope. The engine stores in a digital terrain elevation database an intervisibility ground reference value representing a magnitude of vertical clearance between a given data post elevation and a threat detection envelope thereabove. The execution time provided by the intervisibility engine of the present invention is sufficiently fast to allow dynamic, in-flight calculation to aid in intervisibility calculation relative to a just discovered or just moved threat installation. The digital terrain elevation data may be referenced to display or select routes relative to known or detected threat installations.