Lecture 20

Munzner, Visualization Analysis and Design, Chapter 8.4.2
Display of Surfaces from Volume Data. Marc Levoy, IEEE Computer Graphics and Applications, 8(3), 29-37, 1988.
You may also want to read the errata.

A rendering algorithm for visualizing 3D scalar fields. Paolo Sabella. SIGGRAPH 1988: 51-58.
Volume rendering. Robert A. Drebin, Loren C. Carpenter, Pat Hanrahan. SIGGRAPH Computer Graphics, Vol. 22, No. 4, August, 1988, pages 51-58.
Footprint Evaluation for Volume Rendering. Lee Westover. ACM SIGGRAPH Computer Graphics, vol. 24, no. 4, pp. 367-376, 1990.
Real-Time Volume Graphics. Klaus Engel, Markus Hadwiger, Joe Kniss, Aaron Lefohn, Christof Rezk-Salama and Daniel Weiskopf. In ACM Siggraph 2004, Course 28, 2004.
While I recommend the book, you can Focus on Chapters 1, 3 and Sections III and VII in the coursenotes their SIGGRAPH 2004 course, as well as
the slides from newer coursenotes from EG 2006, specifically parts 1,3,5-7.