Representation of 3D objects, reconstructed from series of parallel 2D slices

Our main interest is the visualization of three-dimensional (biological) objects that have been reconstructed from series of parallel two-dimensional slices. Several representation models for such objects are inventoried, paying special attention to issues regarding display complexity (hidden-feature removal, shading). The choice of a representation is influenced by factors such as application area, input procedures, display characteristics and parameter extraction facilities. A range of representations and conversions between them should be available. A particularly simple representation is the binary voxel model. Problems related to the display of this representation are discussed. In order to promote interaction, we emphasize display speed rather than realistic rendering. We therefore keep both the binary voxel representation and a fixed number of surface normal views in the frame buffer, simultaneously displaying these views. By manipulating the colour look-up table, interactive change is possible of the direction of illumination, surface reflection function and range shading component This results in a very convincing depth-illusion, facilitating the interpretation of the spatial structure of the object.