Using line integral convolution for flow visualization: curvilinear grids, variable-speed animation, and unsteady flows

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 technique in three ways: 1. The existing algorithm is limited to vector fields over a regular Cartesian grid. We extend the algorithm and the animation techniques possible with it to vector fields over curvilinear surfaces, such as those found in computational fluid dynamics simulations. 2. We introduce a technique to visualize vector magnitude as well as vector direction, i.e., variable-speed flow animation. 3. We show how to modify LIC to visualize unsteady (time dependent) flows. Our implementation utilizes texture-mapping hardware to run in real time, which allows our algorithms to be included in interactive applications.