>Photon map accuracy changes. This may account for most of the render speed increases,
The “Photon Map accuracy” in Carrara change’s the photon search radius (and maybe the search count?). The higher the percentage, the smaller the search radius. That does then mean more photons would be needed for good coverage.
The “Lighting quality” and “Accuracy” settings (below the photon settings), I am not completely sure, but those may control the final gather .
The Photon Map accuracy, as I understand it, is a type of global map resolution. Smaller percentages, the photons are sent out in a wider range, and with higher percentages, smaller/narrow ranges. So the higher the map accuracy, the more photons that are needed to better match the range. Is this similar?
I’m still researching the Lighting Quality setting. It seems to be linked to some kind of blending of the photon or overall GI lighting calculations. The Accuracy, I’m guessing is similar to the object and shadow accuracy settings. So 16=one sample for every 16 pixels…(8,4,2,1)etc.
The photon map accuracy changes alot when scaling down scenes. The scaled down version will show quite a bit lower photon map accuarcy/resolution than the slider value allows with the default scene render settings. This seems to confirm what PhilW said about going beyond the sliders value limits.