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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 8 (1992), S. 321-342 
    ISSN: 1432-0541
    Keywords: Computational geometry ; Geometric probing ; Polyhedral scenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We show, in this paper, how the exact shapes of a class of polyhedral scenes can be computed by means of a simple sensory device issuing probes. A scene in this class consists of disjoint polyhedra with no collinear edges, no coplanar faces, and such that no edge is contained in the supporting plane of a nonincident face. The basic step of our method is a strategy for probing a single simple polygon with no collinear edges. When each probe outcome consists of a contact point and the normal to the object at the point, we present a strategy that allows us to compute the exact shape of a simple polygon with no collinear edges by means of at most3n — 3 probes, wheren is the number of edges of the polygon. This is optimal in the worst case. This strategy can be extended to probe a family of disjoint polygons. It can also be applied in planar sections of a scene of polyhedra of the class above to find out, in turn, each edge of the scene. If the scene consists ofk polyhedra with altogethern faces andm edges, we show that $$\tfrac{{10}}{3}n\left( {m + k} \right) - 2m - 3k$$ probes are sufficient to compute the exact shapes of the polyhedra.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Discrete & computational geometry 19 (1998), S. 485-519 
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. The paper bounds the combinatorial complexity of the Voronoi diagram of a set of points under certain polyhedral distance functions. Specifically, if S is a set of n points in general position in R d , the maximum complexity of its Voronoi diagram under the L ∞ metric, and also under a simplicial distance function, are both shown to be $\Theta(n^{\lceil d/2 \rceil})$ . The upper bound for the case of the L ∞ metric follows from a new upper bound, also proved in this paper, on the maximum complexity of the union of n axis-parallel hypercubes in R d . This complexity is $\Theta(n^{\left\lceil d/2 \right\rceil})$ , for d ≥ 1 , and it improves to $\Theta(n^{\left\lfloor d/2 \right\rfloor})$ , for d ≥ 2 , if all the hypercubes have the same size. Under the L 1 metric, the maximum complexity of the Voronoi diagram of a set of n points in general position in R 3 is shown to be $\Theta(n^2)$ . We also show that the general position assumption is essential, and give examples where the complexity of the diagram increases significantly when the points are in degenerate configurations. (This increase does not occur with an appropriate modification of the diagram definition.) Finally, on-line algorithms are proposed for computing the Voronoi diagram of n points in R d under a simplicial or L ∞ distance function. Their expected randomized complexities are $O(n \log n + n ^{\left\lceil d/2 \right\rceil})$ for simplicial diagrams and $O(n ^{\left\lceil d/2 \right\rceil} \log ^{d-1} n)$ for L ∞ -diagrams.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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