一种非结构矢量场的线卷积积分方法

A LIC Method for Visualization of Unstructured Vector Field

传统的结构化LIC方法不适用于非结构矢量场数据处理的主要原因有两个,一是矢量幅度的表现力不强,二是因分辨率等因素无法有效地应用于采样点位置随机的矢量场.为解决上述问题,可以采用如下方法:在DDA曲线的生成过程中,采用基于数值的计算方法替代结构化LIC中基于网格的计算方法,从而有效地保证了处理结果的分辨率;在DDA曲线的卷积积分(LIC)处理过程中,采用区域标记的策略替代快速LIC方法中的线标记策略,一方面,因为被标记的采样点不再作为以后各轮DAA曲线生成的起始点,从而可以有效地减少计算量;另一方面,区域标记方法能够使LIC处理的结果稀疏化,表现为矢量场中幅度大的区域矢量线密集,而幅度小的区域矢量线稀疏,从而有效地提高矢量场幅度、结构的表现力.

There are two drawbacks for the traditional LIC （line integral convolution） methods to visualize data of unstructured vector field： one is its restriction to a fixed resolution and the other is its poor ability of revealing vector magnitude. In this paper, a new method is presented for computing LIC images with unstructured vector data. In this method, numerical integrators are utilized to allow computation at arbitrary resolution, and a mask method is employed for masking vector data by the region of DDA curve. This method can reduce computational cost by minimizing the total number of DDA lines. Because the size and shape of a DDA region are decided by the vectors＇ magnitude on the DDA line, as a result, in LIC images the vectors with big magnitude are surrounded with dense DDA lines while the vectors with small size are surrounded with sparse DDA lines. The inner structure of the field as well as the magnitude of vectors can be depicted more clearly compared with the traditional LIC.