A scan line algorithm for displaying curved surfaces

An algorithm for displaying curved surfaces was deve loped and implemented to facilitate computer-aided design and solid modeling. Due to the complexities in finding intersections of projection rays and surfaces, most display algorithms are either unreliable or too slow. The complexities are resolved by subdivisions and a fast test for monotonicity. Surfaces are subdivided until they become either monotonic or smaller than a picture element. Monotonic surfaces are processed by scan line order to minimize the time for removing hidden surfaces and to enhance the ray-tracing process. The resulting algorithm renders real istic pictures with very high speed.