To the uninitiated, three-dimensional microscopy makes the pretty pictures of fluorescently labeled cells that grace the covers of scientific journals. But to today's microscopists, the capacity to render images from 3-D and 4-D datasets is critical for studying the distances between objects in a sample and for tracking how complex samples change over time. "It's hard to look at 2-D slices one at a time and then put that together in your mind in order to see the relationships among objects," says Dean Sequera, vice president of product development for Media Cybernetics, a Silver Spring, Md.-based imaging-software company.