@TechReport{SCI:Cal2006d, author = "S.P. Callahan and L. Bavoil and V. Pascucci and C.T. Silva", title = "Progressive Volume Rendering of Large Unstructured Grids", number = "UUSCI-2006-019", year = "2006", institution = "University of Utah", type = "{SCI} Institute Technical Report", keywords = "volume rendering, rtrt real-time ray tracing, scientific visualization", url = "http://www.sci.utah.edu/publications/SCITechReports/UUSCI-2006-019.pdf", }