Illustrative Volume Visualization with Style Transfer Functions

for Hewlett-Packard Scalabe Visualization Array

(October, 2008)

This is an illustrative volume visualization application designed for Hewlett-Packard Scalabe Visualization Array.
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Introduction

Illustrative volume visualization frequently employs non-photorealistic rendering techniques to enhance important features or to suppress unwanted details. Classical approaches use transfer functions to just assign colors and opacities values to density values, while style transfer functions allow us to combine a multitude of different shading styles in a single rendering. In this method an image-based lighting model uses lit sphere maps to represent non-photorealistic rendering styles. An arbitrari redering style can be stored using an image of a sphere shaded in the desired style. The basic idea is to capture color variations of an object as a function of normal direction. As a sphere provides coverage of the complete set of unit normals, an image of a sphere under orthographic projection will capture all such variations on one hemisphere. This image is then used as a sphere map indexed by the eye-space normals to shade an object. The style transfer function lookup table contains references to these styles instead of colors.

From a user's point of view, the transfer function now not only specifies the color over the range of data values, but also the shading as a function of eye-space normal direction. The complexity of specifying a transfer function, however, is not increased. Instead of assigning a single color to a certain value range, a pre-defined shading style represented by a lit sphere map is chosen. In this context, one advantage of sphere maps as opposed to other mappings is that they can be directly presented to the user as an intuitive preview image for the style. Style transfer functions allow for a flexible combination of different shading styles in a single transfer function.

Reference: Stefan Bruckner, Meister Eduard Gr.ller : "Style Transfer Functions for Illustrative Volume Rendering". Computer Graphics Forum, 26(3):715-724, September 2007.v

Documentation

File	Description
styletransfer-0.1.pdf	Manual of the renderer

Downloads

File	Description
styletransfer-0.1-1.x86_64.rpm	Compiled version of the illustrative renderer for AMD64 HP-XC
styletransfer-0.1-1.src.rpm	Source version of the illustrative renderer for AMD64 HP-XC
Cg-1.5.x86_64.rpm	NVIDIA Cg library (RPM package for AMD64 HP-XC)
glew-1.3.4-1.x86_64.rpm	OpenGL Extension Wrangler (RPM package for AMD64 HP-XC)
glew-devel-1.3.4-1.x86_64.rpm	OpenGL Extension Wrangler headers (RPM package for AMD64 HP-XC)

Other downloads

File	Description
kopf.tar.gz	Sample dataset for the renderer