RadianceIES scene size? - 'ab' ERROR?

[thp44]

Hey IES-support

I like to know if I need to change any RadianceIES settings if I'm working with a large scene size with a lot of geometry.
I would say that a larger scene size would increase inaccuracy in the simulations?

E.g. a scene 350000 x 350000 mm with lot of buildings. If i like to simulate a room ~6000 x 6000 mm what would my settings be?

I might also have detected an error in the settings if i change the ambient bounces from 3 to e.g. 8 (max) the render time decreases and the result is less precise. Isn't it an error?

http://imageshack.us/photo/my-images/833/iesq.jpg/

[thp44]

Anyone?

[ZapBran]

wouldn't expect the accuracy to reduce - might want to go on vacation while you are awaiting the thing finishing though.
IES uses the lbl radiance engine (old one I think):
http://radsite.lbl.gov/radiance/refer/ray.html#Scene

[PCully]

I spoke with one of our Radiance users in the Support Team here and the resounding advice was never to go to 8 ambient bounces. 4 seems to be the standard upper limit, I don't really know if 8 isn't allowed (I mean Radiance allows it) but it does seem to be the point where things become unpredictable at least.

Having such a large model it not advisable in one image if you are looking for average Daylight Factors or average lux levels. I would run a room at a time or perhaps a section of the model in one image – using either Illuminance – WP or Illuminance – WP View.

The quality settings for an illuminance image would usually be "High"

If you are an experienced user then you could edit the Customise parameters however I recommend you never use this unless you understand the parameters.

Phil