Inter-comparison of the various methods of estimating the view factors for a 1000 facet segment dominated by a large pit. In each of the four panels the color scale represents absolute value percent differences in total view factor of a facet with respect to the M₄ method. The limits on the color scale are 0–5%, and facets above this limit are shown in yellow. This includes a couple of facets at the edges of the extracted surface that do not have the visibility of any other facets. The labels in each panel indicate a particular method to which the results belong. The numbers in parentheses indicate the number of sub-facets for the M₃ methods, for example, M₃-Lin(64) means that M₃-Linear with each facet split into 64 sub-facets. A comparison of the “combined” method aimed to optimize speed and accuracy is presented in the bottom right panel, which is detailed in Appendix B.