Lighting transfer functions using gradient aligned sampling

Eric B. Lum, Kwan-Liu Ma

Research output: Chapter in Book/Report/Conference proceedingConference contribution

63 Scopus citations


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 voxel's 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.

Original languageEnglish (US)
Title of host publicationIEEE Visualization 2004 - Proceedings, VIS 2004
EditorsH. Rushmeier, G. Turk, J.J. Wijk
Number of pages8
StatePublished - Dec 1 2004
EventIEEE Visualization 2004 - Proceedings, VIS 2004 - Austin, TX, United States
Duration: Oct 10 2004Oct 15 2004


OtherIEEE Visualization 2004 - Proceedings, VIS 2004
Country/TerritoryUnited States
CityAustin, TX


  • Direct volume rendering
  • Multi-dimensional transfer functions
  • Shading
  • Transfer functions
  • Volume visualization

ASJC Scopus subject areas

  • Engineering(all)


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