Efficient hidden surface removal for objects with small union size

Matthew J. Katz, Mark H. Overmars, Micha Sharir

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Let 5 be a set of n non-intersecting objects in space for which we want to determine the portions visible from some viewing point. We assume that the objects are ordered by depth from the viewing point (e.g., they are all horizontal and are viewed from infinity from above). In this paper we give two algorithms that compute the visible portions in time O((U(n) + k)log2n), where U(n') is a super-additive bound on the maximal complexity of the union of (the projections on a viewing plane of) any n' objects from the family under consideration, and k is the complexity of the resulting visibility map. Both algorithms use O(U(n) log n) working storage. The algorithms are useful when the objects are "fat" in the sense that the union of the projection of any subset of them has small (i.e., subquadratic) complexity. We present three applications of these general techniques: (i) For disks (or balls in space) we have U(n) - O(n), thus the visibility map can be computed in time O((n + k) log2 n). (ii) For 'fat' triangles (where each internal angle is at least some fixed 6 degrees) we have U(n) = O(n log log n) and the algorithms run in time O((n log log n + k)log2 n). (iii) The methods also apply to computing the visibility map for a polyhedral terrain viewed from a fixed point, and yield O((nα(n) + k) log n) algorithms.

Original languageEnglish
Title of host publicationProceedings of the Annual Symposium on Computational Geometry
PublisherAssociation for Computing Machinery
Number of pages10
ISBN (Print)0897914260
StatePublished - 1 Jun 1991
Event7th Annual Symposium on Computational Geometry, SCG 1991 - North Conway, United States
Duration: 10 Jun 199112 Jun 1991

Publication series

NameProceedings of the Annual Symposium on Computational Geometry


Conference7th Annual Symposium on Computational Geometry, SCG 1991
Country/TerritoryUnited States
CityNorth Conway


FundersFunder number
ESPRIT Basic Research Action
Israeli Academy of Sciences
Israeli Binationaf Science Foundation
National Science FoundationCCR-8%01484
Office of Naval ResearchNooo14-90-J-1284
Nederlandse Organisatie voor Wetenschappelijk Onderzoek


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