A View-Dependent and Inter-Frame Coherent Visualization of Integral Lines using Screen Contribution

Abstract

In vector field visualization, integral lines like stream, path, or streak lines are often used to examine the behavior of steady and unsteady flows. In 3D, however, visualizing integral lines is problematic since the resulting geometric structures cause occlusions, often hiding relevant features in the data. For this reason one important goal is to find a minimum number of lines which can represent all relevant features in the vector field. In this paper we propose a novel approach that reduces the number of displayed lines, and occlusions thereof, by smoothly fading out lines based on their contribution to the viewport. In order to reduce visual clutter that is introduced by rendering multiple line contribution into one pixel, the blending equation is slightly modified. In addition, an interactive brushing is applied to further support exploration. Our approach attains a view-dependent visualization of integral lines that is inter-frame coherent and achieves real-time frame rates. To demonstrate the effectiveness and efficiency of our approach, we pursued a number of tests using real-world steady and unsteady vector fields.