Recent advances in a number of technologies, including digital data acquisition and image processing, have caused a revolution in light and electron microscopy. One important result of this revolution has been that it is now possible to investigate directly the structure of cells and cell components in three dimensions. For some time our laboratory has been developing the hardware and software required for high resolution three-dimensional imaging, utilizing both light and electron microscopy. This development effort has been driven by our desire to understand the three-dimensional structure and organization of chromosomes within the cell nucleus. Due to the vast amount of information contained in the three-dimensional data sets (typically 10 - 50 Mbytes each) and the complexity of the biological samples, data visualization plays a critical role. Without powerful display and analysis tools, it would be essentially impossible to extract useful information. Toward this end, we have spent considerable effort in developing software to aid the biologist in comprehending his three-dimensional data. A key aspect of this has been the utilization of multiple display windows that readily allow the comparison of different data or simultaneous viewing of data from multiple directions (PRISM, Chen et al, 1990). With the advancement of our research project, we require a parallel evolution in the visualization methods used to examine and understand the volumetric data. Consequently, a project was begun one year ago to develop a new image visualization system which will meet the future data visualization and image analysis requirements of our research.