advanced rendering for AutoCAD
One image does seem to be a bit brighter. Maybe it opens up the shadows a bit.
Or raises the ambient light.
If you flick between the two images full screen, there is actually no difference at all.
Seeing one above the other makes them look slightly different, but it's just an optical illusion.
I'm very good at optical mis-conclusions.
I'll have to look to see which engines respect that switch, I can't remember off-hand. It controls whether glossy reflections get a contribution from the direct sun component. The easiest way to see it would be to create a sphere with glossy (blurry reflections) and the default sun and sky. Try the different engines. It's off by default because reflections from the solar disk can create some very high values.
I'll take a look at the code in a bit.
Looks like there's some code to handle this in both the path tracer and hybrid engines. A little unclear in the packet tracer.
In this case, yes, it's subtle. It's only readily apparent in the reflection of the window in the upper right quadrant of the sphere (as expected) where a small, bright, reflection of the solar disk can be seen. I'm guessing that actually measuring the luminance at that point would yield a very different result, although the tone mapping is mitigating this.
Reflections of the solar disk are very bright so I would expect to see cases that are not so subtle.