Ph.D. Showcase: Slope Preserving Lossy Terrain Compression
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چکیده
Accurate terrain representation with appropriate preservation of important terrain characteristics, especially slope steepness is becoming more crucial and fundamental as the geographical models are getting more complex and commonly used. Based on our earlier success in Overdetermined Laplacian Partial Differential Equation (ODETLAP), which allows for compact yet accurate compression of the Digital Elevation Model (DEM), we propose a new terrain compression technique which focuses on improving slope accuracy in compression of high resolution terrain data. With high slope accuracy and a high compression ratio, this technique will help all sorts of geographical applications that require a high precision in slope yet also have strict constraints on data size. Our proposed technique has the following contribution: we modify the ODETLAP system by adding slope equations for some key points picked automatically so that we can compress the elevation without explicitly storing slope values. By adding these slope equations, we can perturb the elevation in such a way that when slope is computed from the reconstructed surface, they are accurate. Note we are not storing the slope explicitly, instead we only store the elevation difference at a few locations. Since the ultimate goal is to have a compact terrain representation, encoding is also an integral part of this research. We have used Run Length Encoding (RLE) and linear prediction in the past, which gave us substantial file size reduction. In addition to that, we also propose a Minimum Spanning Tree based encoding scheme that takes advantage of the spatial correlation between selected points. Our technique is able to achieve a 1:10 compression at the cost of 4.23 degree of RMS slope error and 3.30 meters of RMS elevation error.
منابع مشابه
Slope Accuracy and Path Planning on Compressed Terrain
We report on variants of the ODETLAP lossy terrain compression method where the reconstructed terrain has accurate slope as well as elevation. Slope is important for applications such as mobility, visibility and hydrology. One variant involves selecting a regular grid of points instead of selecting the most important points, requiring more points but which take less space. Another variant adds ...
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تاریخ انتشار 2010