voxel

A 3D pixel. Contraction of Volume Element. Imagine aproximating a 3D object to a 3D mesh, and you'll get the idea. If pixels are squares, then voxels are cubes; though people tend to draw them as rectangles to save memory and time. Used in demos and video / computer games (eg, Commanche Maximum Overkill) to display nice landscapes, and more recently (in Tiberian Sun and Blade Runner) for characters and objects. Some people have said that voxels are the future, since they could represent a truely changable environment, but due to the massive memory requirements, and the fact that they cannot be accelerated adequitely, this is a long way off. Voxels are used in the scientific community to represent samples taken in a 3D space in the same way 2D data can be represented as an image.

Addendum: Err... I've just been told that pixels are not squares, and voxels are not cubes... But you get the idea. They are samples taken at a periodic distance. The sample is used to represent a volume with the dimension of that sample distance around the point sampled. Also, there was a story on /. recently (Aug 2000) about a company making high end voxel accelerators, so maybe the time of voxels is closer than we think.

The memory and speed limitations of voxels have been mostly overcome (at least from a game programming perspective) by advances in modern computing hardware. The problem now is that voxel objects look "chunky", especially when used as a first-person 3D engine. Imagine a scene rendered in 320x200 and displayed in 640x480 and you'll have a rough approximation of what current voxel first-person engines look like.

Or, you can go to http://www.advsys.net/ken/voxlap.htm and see some screenshots of Ken Silverman's in-progress voxel engine. They adequately demonstrate both the strengths and weaknesses of voxels.

This is the greatest challenge to overcome with voxels. There have been many suggestions, such as storing data in a voxel structure but then using polygons to represent the data on the screen; this would still allow marvelously deformable levels (imagine every rocket impact taking a chunk out of a level wall and eventually breaching it) while still looking acceptable, but would also require rendering many more polygons than a traditional polygonal engine would.