Patent ID: 7403856

Claim:
Method for determining in real time whether an air or a land vehicle is exposed to at least one selective source point of interest within a terrain, comprising the steps of: pre-defining a compact size Digital Terrain Model (DTMO) by: a) providing a Digital Terrain Elevation Data (DTED); b) defining at least one selective source point of interest within said DTED; c) for each source point of interest within the DTED, defining a directional fan, said directional fan definition comprises a fan opening angle, a fan azimuth, a maximal range for terrain analysis, and a fan data set having an origin at a corresponding one of said source points; d) evenly dividing each fan opening angle into plurality of angular directions according to a fan angular resolution; e) for each of said fan angular directions, determining all DTED points along said angular direction which have a line of sight with the corresponding fan source point, and discarding all other DTED points in said angular direction which do not have a line of sight with said fan source point; f) for each of said determined DTED points along a same fan angular direction, defining a line of sight starting at the fan source point and: if the point is not a peak point, ending at said point; if the point is a peak point, ending at a terrain point beyond said point, if exists, or at a point of space at said maximal range for the terrain analysis; wherein the collection of all said lines of sight along a same direction form a corresponding directional data set of exposable heights; g) associating all the data sets of exposable heights of a same fan to a corresponding fan data set, all the separate fan data sets form the said DTMO; and in real time performing the following steps: A. determining from a known x;y;z location of the vehicle the angular direction from the vehicle to said selective source point of interest, and selecting from the DTMO the fan data set which corresponds to that source point, and from said selected fan data set selecting the directional data set of exposable heights which corresponds to said determined angular direction; B. determining from the known x,y,z location of the vehicle the range from the vehicle to said selective source point of interest; C. from said selected directional data set of exposable heights and said range from the vehicle to the source point, determining whether the vehicle is above a respective line of sight at that range, and in the affirmative case, concluding that the vehicle is exposed to said source point, otherwise, concluding that the vehicle is not exposed.