Approximating the Visible Region of a Point on a Terrain

Given a terrain T and a point p on or above it, we wish to compute the region Rp that is visible from p. We present a generic radar-like algorithm for computing an approximation of Rp. The algorithm extrapolates the visible region between two consecutive rays (emanating from p) whenever the rays are close enough; that is, whenever the difference between the sets of visible segments along the cross sections in the directions specified by the rays is below some threshold. Thus the density of the sampling by rays is sensitive to the shape of the visible region. We suggest a specific way to measure the resemblance (difference) and to extrapolate the visible region between two consecutive rays. We also present an alternative algorithm, which uses circles of increasing radii centered at p instead of rays emanating from p. Both algorithms compute a representation of the (approximated) visible region that is especially suitable for visibility from p queries. Finally, we report on the experime...

• Type: Conference
• Year: 2004
• Where: ALENEX
• Authors: Boaz Ben-Moshe, Paz Carmi, Matthew J. Katz
• Keywords: ALENEX 2004, ALENEX 2007, Algorithm, Consecutive Rays, Visible Region