[Radiance-general] Three-Phase Method - subdivision of window with sensor located close to the window

[Andy McNeil]

On Apr 30, 2011, at 6:11 AM, Anne Iversen wrote:

> Why do you believe that using glow probably won't make much difference - unless my sensor has a tight and/or peaky sensitivity distribution?


Low resolution sampling of the outgoing window directions will only affect calculations on surfaces near the window.  And they should just cause noise that is a fraction of the values from the direct sampling of the window by rsensor.  So the only way I can think that glow vs. light would make a sizable difference is if your sensor is somewhat shielded from the window (by sensitivity or by placement) and/or most of the rsensor samples a sent to surfaces near the window ( ie focused sensitivity).  Neither of these seem to be the cause though using -I+ would have had the effect of masking the direct contribution from the window in a similar way because rsensor rays that hit the window don't return a direct value but instead start an iluminance calculation on the window. 

I'd suggest that while you are running everything again without -I that you also simulate using classic Radiance techniques (ie not the three-phase method). 

Andy