| 摘要 |
PROBLEM TO BE SOLVED: To solve such problems that, in conventional prospective calculations, a calculation is performed using mesh type altitude data, so that a space calculation amount increases due to the number of mesh lines and a large-capacity memory is required and that, when determining propriety of a prospect of a target point, it takes a long time in calculation when extracting all intersections between a great-circle course that connects an observation point to a target point and the meshes, and evaluating the altitude.SOLUTION: The prospective calculation device uses a plurality of functions approximating to mesh type altitude data so as to restrict a memory usage. When determining propriety of a prospect of a target point, an algebraically-derived equation can be solved by a numerical analysis algorithm so as to enhance speed of the calculation. |
