This paper presents a three dimensional method of isovist analysis implemented in the MaxScript programming language. The script accepts as its input a standard three dimensional model of the buildings and terrain being analyzed, upon which a N×N grid is projected. Each square of this grid is assigned a height value, thereby producing a simplified surface description which is amenable to mathematical analysis. A three dimensional isovist is then generated for each grid square, by placing an observation point 1.5 meters above its center and finding the intersection of a series of rays from this point to the input model. The distance from the observation point to the intersection is summed over for all the angles studied giving a compound isovist measurement for the grid square under consideration.