Volume vs Surface
- Use Alpha (transparency) level
- Does not allow visualization of specific structure easily unless there are huge constrast differences
- Superficial surface only
- Does not use alpha (transparency) level
- Allow visualization of pretty much anything as long as they can be highlighted in segmentation process
The short explanation:m trace the path of light. Show the final image based on that result.
Final product: a VOLUME mainly in Amira. Does not give specific region of interest.
The long and technically correct version: http://en.wikipedia.org/wiki/Volume_ray_casting
Whatever you visualize, is a VOLUME location. That means, no matter how you limit viewing area, your visualization is to any voxels with the same volume that possess the same gray scale value.
This is a good example of volumetric renderings: http://www.cg.tuwien.ac.at/research/publications/2005/bruckner-2005-ICV/
Allow highlight of individual structures. Does not visualize internal structures like volume renderings. Only render out the most outer exterior surface and this does not have thickness. Think of a paper 3D model. No matter how hard you try, you can make up the superficial surfaces, you cannot produce concrete materials.
This page has some good example of surface rendering results. http://math.lbl.gov/~deschamp/html/gallery.html