Lighting Transfer Functions Using Gradient Aligned Sampling

• Published in: 2004 IEEE Visualization Conference pp. 289 - 296
• Main Authors: Lum, Eric B., Ma, Kwan-Liu
• Format: Conference Proceeding
• Language: English
• Published: Washington, DC, USA IEEE Computer Society 01.01.2004; IEEE
• Series: ACM Conferences
• Subjects: Applied sciences; Artificial intelligence; Chromium; Computer graphics; Computer science; control theory; systems; Computing methodologies; Computing methodologies > Computer graphics; Computing methodologies > Computer graphics > Image manipulation; Computing methodologies > Computer graphics > Rendering; Data visualization; direct volume rendering; Electromagnetic wave absorption; Exact sciences and technology; Lighting; multi-dimensional transfer functions; Multidimensional systems; Optical reflection; Pattern recognition. Digital image processing. Computational geometry; Rendering (computer graphics); Sampling methods; shading; Transfer functions; volume visualization; shading; direct volume rendering; transfer functions; volume visualization; multi-dimensional transfer functions; Visualization; Boundary value problem; Lighting; Voxel; Shadow; Image rendering; Tridimensional image; Opacity; Sampling; Transfer function
• ISBN: 0780387880; 9780780387881
• DOI: 10.1109/VISUAL.2004.64

An important task in volume rendering is the visualization of boundaries between materials. This is typically accomplished using transfer functions that increase opacity based on a voxelýs value and gradient. Lighting also plays a crucial role in illustrating surfaces. In this paper we present a multi-dimensional transfer function method for enhancing surfaces, not through the variation of opacity, but through the modification of surface shading. The technique uses a lighting transfer function that takes into account the distribution of values along a material boundary and features a novel interface for visualizing and specifying these transfer functions. With our method, the user is given a means of visualizing boundaries without modifying opacity, allowing opacity to be used for illustrating the thickness of homogeneous materials through the absorption of light.