Line Integral Convolution for Real‐Time Illustration of Molecular Surface Shape and Salient Regions

Abstract

We present a novel line drawing algorithm that illustrates surfaces in real‐time to convey their shape. We use line integral convolution (LIC) and employ ambient occlusion for illustrative surface rendering. Furthermore, our method depicts salient regions based on the illumination gradient. Our method works on animated surfaces in a frame‐coherent manner. Therefore, it yields an illustrative representation of time‐dependent surfaces as no preprocessing step is needed. In this paper, the method is used to highlight the structure of molecular surfaces and to illustrate important surface features like cavities, channels, and pockets. The benefit of our method was evaluated with domain experts. We also demonstrate the applicability of our method to medical visualization.

A Survey of Surface‐Based Illustrative Rendering for Visualization

“…Different noise fields can be used, for example based on shading, colour or features [KYM12]. This method is also not reduced to using the PCDs as the primary directions for the strokes but can also use other directions such as tangents of isocurves of view‐dependent features, tangents of isophote curves [Min13, Min15] or light gradients [LKEP14]. While the LIC approach produces generally hatching‐like images that can convey shape, the resulting images only exist in form of pixels and are not as similar to the traditional illustration style as the results from the streamline‐based approach.…”

“…In the context of molecular sciences, illustrative visualization techniques can be applied to molecules to explain the continuous character of the different abstraction schemes [vdZLBI11], make additional visual variables available to visualize surface information [CG07, CPJG09, LKEP14] or illustrate complex temporal aspects and reactions [BPJG12, MPSV14, MWPV15]. The abstraction introduced by many illustrative techniques cannot only make it possible to portray complex assemblies like the contents of a cell [KAK*18, LMAPV15] (Figure c) but also facilitate the rendering of such scenes at interactive rates.…”

Visualization of Biomolecular Structures: State of the Art Revisited

“…Lawonn et al . [LKEP14] combined feature lines and hatching to emphasize important features on molecular surfaces. The method is based on line integral convolution (LIC) on the vector field of the illumination gradient, which emphasizes salient surface regions.…”

Physics-Based Visual Characterization of Molecular Interaction Forces

“…To realize a more intuitive communication, also modified shading algorithms are applied when visualizing complex molecular models. One of the most popular techniques used in this context is ambient occlusion [51,28,15,25,14,20], but also contour lines [47,29] or hatching [7,31] have been applied. 3D molecular interaction visualization.…”