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We present a very efficient algorithm, named <i>EMFlow</i>, and its implementation to compute the drainage network, that is, the flow direction and flow accumulation on huge terrains stored in external memory. It is about 20 times faster than the two most recent and most efficient published methods: <i>TerraFlow</i> and <i>r.watershed.seg</i>. Since(More)
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)
Microsatellite markers (SSR) have broad utility in genetic studies due to a high rate of polymorphisms, a codominant nature and multiallelism. EST–SSRs are markers derived from the expressed sequences of a genome and represent transcribed genes. Despite the importance of the genus Coffea, only a small number of EST–SSR markers are currently available. Thus,(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)
Viewshed (or visibility map) computation is an important component in many GIScience applications and, as nowadays there are huge volume of terrain data available at high resolutions, it is important to develop efficient algorithms to process these data. Since the main improvements on modern processors come from multi-core architectures, parallel(More)
We present EMFlow , a very efficient algorithm and its implementation , to compute the drainage network (i.e. the flow direction and flow accumulation) on huge terrains stored in external memory. Its utility lies in processing the large volume of high resolution terrestrial data newly available, which internal memory algorithms cannot handle efficiently.(More)
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