Visibility determination on projected grid surfaces

An algorithm is presented for solving the hidden-line and hidden-surface problems on grid surfaces, such as graphs of bivariate functions specified by their values on a set of grid points. The algorithm is implemented in image space, taking advantage of the raster display resolution. The procedure examines the edges of a projected grid surface in a systematic order to find all points visible to the observer from which a visible periphery for the surface is established. As the algorithm proceeds, this changing periphery floats toward the edges of the visible parts of the solid surface and determines the visibility of every point of the edges being processed. The procedure is therefore termed the floating perimeter algorithm. (FPA).<
>