Patent ID: 7876319

Claim:
A stereoscopic image generator comprising: a memory with stored altitude-inclusive 3D digital data of a ground surface in a prescribed terrain area; a DEM data generator configured to read 3D digital data in the memory to restore a latticed plane representing the ground surface, to generate a set of DEM data representing lattice points thereon each defined by a combination of height and ordinates thereof; an aboveground opening image generator configured to work on the latticed plane, operating at a respective one of focused points thereon to calculate in a plurality of azimuths thereabout respective angular vectors of lattice points giving maximal see-through angles within a distance range, determining an average thereof as an aboveground opening of this focused point, allotting thereto a brighter color as the aboveground opening is greater in value, to generate an aboveground opening image; a belowground opening image generator configured to work on a reversed plane of the latticed plane, operating at a respective one of the focused points thereon to calculate in a plurality of azimuths thereabout respective angular vectors of lattice points giving maximal see-through angles within the distance range, determining an average thereof as a belowground opening of this focused point, allotting thereto a darker color as the belowground opening is greater in value, to generate a belowground opening image; and a first synthesizer configured to work on the latticed plane, operating at a respective one of the focused points thereon to synthesize the aboveground opening image and the belowground opening image in a weighting manner to determine a synthesized value representing an openness about this focused point, giving thereto a tone commensurate with the synthesized value, to provide a first synthesized image, wherein the aboveground opening image generator is adapted to operate at a respective focused point having a value of aboveground opening thereof determined within a range of 40 degrees to 120 degrees, allotting thereto a tone according to a first gray scale set to be brightest at a scale of 110 degrees and darkest at a scale of 50 degrees, to provide the aboveground opening image with a tendency to get brighter as the value of aboveground opening increases.