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The central contributions of the paper were threefold. First, the NID module generator was driven by pattern matching rules used by a standard software system, specifically the opensource SNORT system. This showed how an FPGA-neutral, domain-specific language could automatically be mapped to an efficient FPGA implementation and set a trend for future(More)
We present two new methods for approximating elevation data from contours to a grid. The first repeatedly interpolates new contour lines between the original ones. The second starts with any interpolated or approximated surface, determines its gradient lines, and does a Catmull-Rom spline interpolation along them to improve the elevations. We compare the(More)
We present two new pre-processing techniques that improve thin plate Digital Elevation Model (DEM) approximations from grid-based contour data. One method computes gradients from an initial interpolated or approximated surface. The aspects are used to create gradient lines that are interpolated using Catmull-Rom splines. The computed elevations are added to(More)
We describe a surface compression technique to lossily compress elevation datasets. Our approach first approximates the uncompressed terrain using an over-determined system of linear equations based on the Laplacian partial differential equation. Then the approximation is refined with respect to the uncompressed terrain using an error metric. These two(More)
Several applications of analytical cartography are presented. They include terrain visibility (including visibility indices, viewsheds, and intervisibility), map overlay (including solving roundoff errors with C++ class libraries and computing polygon areas from incomplete information), mobility, and interpolation and approximation of curves and of terrain(More)
We present a computer simulation of hydraulic erosion on levees, dams, and earth embankments, with emphasis on rill and gully initiation and propagation. We focus on erosion features that occur after an earthen structure is overtopped. We have developed a 3D fluid and hydraulic erosion simulation engine using Smoothed Particle Hydrodynamics (SPH). We(More)
This paper presents an heuristic method to give an approximated solution to the observer siting problem on high resolution terrains that are too large to be processed in the internal memory. Informally, the problem is to determine an optimal positioning of as few as possible observers for being able to observe as many target points as possible. Tests have(More)
This paper studies rill and gully initiation and propagation on levees, dams, and general earth embankments. It specifically studies where these erosion features occur, and how long a particular embankment can sustain overtopping before breaching and catastrophic failure. This contrasts to previous levee erosion analysis, which has primarily concerned the(More)
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The overall intent of this research is to develop numerical models of erosion of levees, dams and embankments, validated by physical models. The physical models are performed at 1-g and at high g’s using a geotechnical centrifuge. The erosion is modeled in detail, from beginning to end, that is from the time the levee is overtopped until the levee is(More)