Visualizing Flow Over Curvilinear Grid Surfaces Using Line Integral Convolution

Lisa Forssell, Proc. IEEE Visualization '94 (Washington, D.C. October 17-22, 1994)


Line Integral Convolution (LIC), introduced by Cabral and Leedom in Siggraph '93, is a powerful technique for imaging and animating vector fields. We extend the LIC paradigm in three ways: 1. The existing technique is limited to vector fields over a regular Cartesian grid. We extend it to vector fields over parametric surfaces, specifically those found in curvilinear grids, used in computational fluid dynamics simulations. 2. Periodic motion filters can be used to animate the flow visualization. When the flow lies on a parametric surface, however, the motion appears misleading. We explain why this problem arises and show how to adjust the LIC algorithm to handle it. 3. We introduce a technique to visualize vector magnitudes as well as vector direction. Cabral and Leedom have suggested a method for variable- speed animation, which is based on varying the frequency of the filter function. We develop a different technique based on kernel phase shifts which we have found to show substantially better results. Our implementation of these algorithms utilizes texture-mapping hardware to run in real time, which allows them to be included in interactive applications.

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