A Comparison of Gradient Estimation Methods for Volume Rendering on Unstructured Meshes

—This paper presents a study of gradient estimation methods for rendering unstructured-mesh volume data. Gradient estimation is necessary for rendering shaded isosurfaces and specular highlights, which provide important cues for shape and depth. Gradient estimation has been widely studied and deployed for regular-grid volume data to achieve local illumination effects, but has been otherwise for unstructured-mesh data. As a result, most of the unstructured-mesh volume visualizations made so far were unlit. In this paper, we present a comprehensive study of gradient estimation methods for unstructured meshes with respect to their cost and performance. Through a number of benchmarks, we discuss the effects of mesh quality and scalar function complexity in the accuracy of the reconstruction, and their impact in lighting-enabled volume rendering. Based on our study, we also propose two heuristic improvements to the gradient reconstruction process. The first heuristic improves the renderi...

• Type: Journal
• Year: 2011
• Where: TVCG
• Authors: Carlos D. Correa, Robert Hero, Kwan-Liu Ma
• Keywords: Gradient Estimation, Gradient Estimation Methods, TVCG 2011, Volume Data