Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
It looks like you have provided a non-zero ambient value with the -av setting. This setting is used to specify background "ambient" illumination, which can be a useful shortcut if you need to run a fast simulation with few ambient bounces, but you have a good idea what the diffuse contribution to the scene should be. When a diffuse ray path reaches the number of bounces specified by -ab, it is assigned the value of -av rather than spawn new ambient rays into the scene.
Note: If your goal is physically based rendering, you should avoid the use of -av and instead use high -ab and -lr values (and a corresponding low -lw) in order to trace diffuse lighting paths farther into the scene.
