James, A.Day, A.M.2015-11-112015-11-1119981017-4656https://doi.org/10.2312/egs.19981006Hidden surface removal can be achieved using the Priority Face Determination (PFD) tree to create a priority ordering of n polygons in log4=3 n time. In this paper, we describe the Hidden Face Determi- nation (HFD) tree which is based upon the PFD tree. The HFD tree is constructed in a similar way as the PFD tree, but an addition means that polygons completely hidden by others in the scene can be determined at each node. Thus, not only does the HFD tree calculate the priority order of polygons in log4=3 n time, but determines which polygons are invisible from a given location.