Patent ID: 8374391

Claim:
A method for identifying visibility of targets, the method comprising: selecting, by a computer system, a first function that is configured to indicate whether locations in an environment are at a surface for a number of objects in the environment, in a first number of areas that are outside the surface for the number of objects in the environment, or in a second number of areas that are inside the surface for the number of objects in the environment; forming, by the computer system, a first number of volumes for the environment, wherein each volume in the first number of volumes has a size selected such that a difference between a first number of interpolated values for the each volume in the first number of volumes and a first number of values generated using the first function for the each volume in the first number of volumes is within a first threshold; and forming, by the computer system, a second number of volumes for the environment in which each volume in the second number of volumes has a size selected such that a difference between a second number of interpolated values for the each volume in the second number of volumes and a second number of values generated using a second function for the each volume in the second number of volumes is within a second threshold, wherein the second number of values generated using the second function is a number of minimum values along a number of lines from the each volume in the second number of volumes to a target in the environment.