Imaging modalities such as computerized tomography, emission tomography, and ultrasound have facilitated the acquisition of objective numerical data describing internal organs or structures. The algorithm presented utilizes the tomographic data of those imaging modalities. The surface of an object is approximated by means of a polyhedron with triangular faces and minimal surface area. The volume and surface area of the approximating polyhedron are used to approximate the volume and surface area of the organ. This model provides an analytic description of the object from which other properties may be calculated. Incidentally, it also allows the object to be visualized from any vantage point using the methods of computer graphics.