I'm running into a bit of a frustrating issue, and I am not sure what the cause might be. I am creating a sky model using gendaylit with a high amount of direct solar component as seen below,
> gendaylit 05 18 8.667 -W 881 63 -a 1 -o -104 -m -120
The issue is that when I render my scene using -ab 1, I can see the solar disc. When I render it with a higher number of ambient bounces, such as 4, the solar disc is absent from the final visualization. You can see the results here: 1 ambient bounce <https://dl.dropboxusercontent.com/u/3175325/ab1.png>, 4 ambient bounces <https://dl.dropboxusercontent.com/u/3175325/ab4.png>. You will notice that in the rendering with 4 ambient bounces, the shadows are still cast properly as if the sun is present.
I am using a slightly older version of Radiance right now (RADIANCE 4.2a lastmod by on w015t-001), but I suspect that isn't the root of the problem. This issue also occurs when I use gensky <https://dl.dropboxusercontent.com/u/3175325/ab4_clsky.png>. I have never seen this kind of behavior before from Radiance. Does anyone have thoughts as to what might cause this?