TY - GEN

T1 - Approximating the visible region of a point on a terrain

AU - Ben-Moshe, Boaz

AU - Carmi, Paz

AU - Katz, Matthew J.

PY - 2004

Y1 - 2004

N2 - 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 experiments that we performed with these algorithms and with their corresponding fixed versions, using a natural error measure. Our main conclusion is that the radar-like algorithm is significantly better than the others.

AB - 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 experiments that we performed with these algorithms and with their corresponding fixed versions, using a natural error measure. Our main conclusion is that the radar-like algorithm is significantly better than the others.

UR - http://www.scopus.com/inward/record.url?scp=8344248729&partnerID=8YFLogxK

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AN - SCOPUS:8344248729

SN - 0898715644

T3 - Proceedings of the Sixth Workshop on Algorithm Engineering and Experiments and the First Workshop on Analytic Algorithms and Combinatorics

SP - 120

EP - 128

BT - Proceedings of the Sixth Workshop on Algorithm Engineering and Experiments and the First Workshop on Analytic Algoritms and Combinatorics

A2 - Arge, L.

A2 - Italiano, G.F.

A2 - Sedgewick, R.

T2 - Proceedings of the Sixth Workshop on Algorithm Engineering and Experiments and the First Workshop on Analytic Algorithms and Combinatorics

Y2 - 10 January 2004 through 10 January 2004

ER -