Empowering iso-surfaces with volume data

Surface rendering algorithms are fast, but not suited to applications that demand exploration of internal volume structures, as such information is lost in conventional surface rendering. In this article we introduce an enhanced surface rendering algorithm named VoS, Volume on Surface that supports visualization of internal volume structures. VoS integrates surface and volume rendering approaches into an efficient framework for interactive visualization of volume information. A ray casting is performed to map volume information onto a boundary surface extracted from the volume grid, enabling the display of structures internal to the surface using conventional surface rendering. As such, the technique exploits the advantages of surface rendering while keeping the volumetric information. VoS thus offers a low-cost alternative to volume rendering in some practical situations, as its resulting surfaces can be rendered on commodity graphics hardware at interactive rates. Moreover, a user can easily fine tune the color and opacity transfer function definitions, because changes in the transfer functions are handled at the rendering step, rather than at the costly ray-casting operation.