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Pre-Integrated Volume Rendering with Non-Linear Gradient Interpolation

2010; Institute of Electrical and Electronics Engineers; Volume: 16; Issue: 6 Linguagem: Inglês

10.1109/tvcg.2010.187

2160-9306

Amel Guetat, André Ancel, Stéphane Marchesin, Jean‐Michel Dischler,

3D Shape Modeling and Analysis

Shading is an important feature for the comprehension of volume datasets, but is difficult to implement accurately. Current techniques based on pre-integrated direct volume rendering approximate the volume rendering integral by ignoring non-linear gradient variations between front and back samples, which might result in cumulated shading errors when gradient variations are important and / or when the illumination function features high frequencies. In this paper, we explore a simple approach for pre-integrated volume rendering with non-linear gradient interpolation between front and back samples. We consider that the gradient smoothly varies along a quadratic curve instead of a segment in-between consecutive samples. This not only allows us to compute more accurate shaded pre-integrated look-up tables, but also allows us to more efficiently process shading amplifying effects, based on gradient filtering. An interesting property is that the pre-integration tables we use remain two-dimensional as for usual pre-integrated classification. We conduct experiments using a full hardware approach with the Blinn-Phong illumination model as well as with a non-photorealistic illumination model.