The best way to get information such as that for a radiosity problem is to use the SURF251 and SURF252 (for 3D) elements. They overlay the radiosity surfaces. These elements have two primary functions: 1) Provide more output for the user through the use of ETABLE. 2) Allow the user to coarsen the mesh used for the radiosity surfaces. This is referred to in the documentation as decimation. You can create these elements merely by issuing RSURF just before SOLVE. You need not define the element type before hand.