Guilherme C. Pena

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We present a new and faster internal memory method to compute the drainage network, that is, the flow direction and accumulation on terrains represented by raster elevation matrix. The main idea is to surround the terrain by water (as an island) and then to raise the outside water level step by step, with depressions filled when the water reaches their(More)
This paper proposes an efficient parallel heuristic for siting observers on raster terrains. More specifically, the goal is to choose the smallest set of points on a terrain such that observers located in these points are able to visualize at least a given percentage of the terrain. This problem is NP-Hard and has several applications such as determining(More)
This paper presents an efficient method to determine a set of observers (that is, where to site them) such that a given percentage of a terrain is visually covered. Our method extends the method proposed in (Franklin, 2002) including a local search heuristic efficiently implemented using dynamic programming and GPU parallel programming. This local search(More)
This paper describes a new parallel raster terrain visibility (or view-shed) algorithm, based on the sweep-line model of [Van Kreveld 1996]. Computing the terrain visible from a given observer is required for many GIS applications , with applications ranging from radio tower siting to aesthetics. Processing the newly available higher resolution terrain data(More)
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