Visualizing Flow Over Curvilinear Grid Surfaces
Using Line Integral Convolution
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
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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