To make use of the three-dimensional information contained in a series of computed tomography (CT) or magnetic resonance (MR) slices, one must either mentally reconstruct the data or generate a model using a computer display. Computer-aided rendering of a three- dimensional surface allows inspection of the model from different angles. Creation of a three- dimensional model in wireframe or shaded surface format from tomographic slices requires identification of points along the surface of interest in each slice. This task can be accomplished (1) by manually outlining the surface in the images, or (2) by a computer algorithm designed to produce points along the surface of interest. In dealing with image sets of the head, objects outside the head (e.g., support structures, stereotactic frames, and noise) complicate the automatic detection of the perimeter of the head. This paper examines three methods of automatic wireframe generation from CT or MR slices of the head. The three approaches are based on the following techniques: traditional edge detection filters, neural networks, and thresholding combined with region connectivity analysis and region elimination. Results of the three approaches are presented along with a comparison of the relative advantages and disadvantages of each.