Speaking of Orion...

"Computer graphics experts at the San Diego Supercomputer Center (SDSC), astrophysicists and artists at the American Museum of Natural History's Hayden Planetarium, and C. R. O'Dell of Rice University, worked together to produce a 3D model of the Orion Nebula. This model enables us to fly in and around the nebula, seeing it from the vantage point of a virtual spacecraft.

"Visualization of the nebula uses a volume modeling technique to define the cloudy structure of the nebula. Space in the region of the nebula is divided up into little cubes of space. Each cube is called a voxel, which is short for volume element. Each voxel is given a color and an opacity. The higher the opacity, the denser the gas in the voxel's region of space."