Alain wrote:

> The window pane have a frame that cast a shadow near the base of the 
> glass. The caustics in that area are still there without, but are less 
> visible on a brighter surface. Try removing the glass itself, but leave 
> it's frame.

Tried rendering with frame but without glass but the result on
the floor seems no different than without both. I wasn't worried
about the caustics near the glass itself.

> Even with your settings, the window can still affect the photons coming 
> from another object. At least, that's what the documentation seems to 
> imply.

Which part of the documentation? I must say I didn't quite understand
how the amount of photons is determined. From the algorithm I thought it
should mostly depend on the target object. As far as I understand, an
object with pass_through should not affect photons before they hit the
target object. And those photons which get refracted on the glass so
much they actually return to the window shouldn't affect caustics
on the floor either way.

> Without the pane, the bright line that you mention is very hard to see 
> here, even with the brightness pushed to the max. I also need to sellect 
> the two images and unsellect the window to be able to see it. Tested on 
> two different monitors.

Hmm ... I have a 5 year old TFT screen which did come with a color
calibration tool but I couldn't actually get that to *do* anything,
it goes through the calibration procedure and afterwards everything
looks exactly as before. So maybe my gamma is off the scale as I
see it distinctly (I certainly don't have correct gamma as far
as all the recent eye squinting is concerned).

The actual difference in intensity seems to be about 5 levels of 255.
The attached render has radiosity disabled so the contrast is better.
You can also see the line is actually composed of a very few splotchy
photons. Probably some off photons coming exactly off the rounded
edge of the glass or something like that.

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