Strange bug in Terragen 3

[icarus51]

Hello,

From some days i found strange artifacts in rendering by Terragen 3, last version.
When i render landscape with sunlight between clouds (sunset o sunrise, godrays etc.) i get strange frames, like squares or poligons or straight lines.
I tried everything but no results.

I tried to reinstall TG, to resize windows, to update my graphic card, to change parameters (AA, GI, Quality, Atmo etc.)
but this bug don't disappears. It seems like Buckets borders and related to sunlight and clouds. I changed Bucket size but nothing.
More strange, Terragen don't get warning - errors or likes . the rendering go on and finally i see this strange issue.
I'm desperate... can anyone help me? 
See the pictures enclosed.


Update: I tried another landscape, other clouds and other position of sun. Stranger and stranger this time NO bugs.
Sincerely, i don't understand this mystery. Is it possible that a particular view is difficult to render?




Note: I use Terragen 64bit on a PC 64bit.
Thanks in advance for your reply.
Claudio

[WAS]

Did you by chance alter settings while the render was running?

[icarus51]

Hi,

No. It's not my habit.
However, in various tests done, without touching anything, there was always the bug. I tried perhaps 12 times or about, and always i got this bug.
Strangely the program does not give warnings of error or others
.
Another strange thing is that if i make the preview this bug don't appears in the preview window and if i make the crop (a small window) in this crop render the bug does not occur.
Like i say, this is a real mystery.
Claudio

[WAS]

I wonder if the hard cloud light settings coupled with the low atmospheric quality is causing light to literally shine pass polygons, capturing their shapes?

[icarus51]

I don't know, could be, but i tried atmo setting to 40 - 50 - 60 and the bugs were always present. Seems to me that these shapes are poligonal and related with buckets render. The strange thing is that these bugs happen at random and not always, like you see in my last picture (Tg Landscape - Good).
The landscape seems to be a part of the problem.
I would like to understand the reason for this in order to fix this boring problem... i'm very tired to make tests.

Claudio

[Oshyan]

Most likely it is related to the Cloud Acceleration Cache. How many cloud layers are you using here? Try setting the lowest/least dense one(s) to "None" for Acceleration Cache.

- Oshyan

[icarus51]

Hi Oshyan,

I used a single Cloud Layer - Low Cumulus. I'll try your suggestion and i will report.

Claudio

[icarus51]

Hi,

Wow, finally i've got a picture without bugs. I've made 2 pictures at different  cloud settings but with No Acceleration Cache.
Many thanks to Oshyan for his precious suggestion. I've learned something that i did not know.
Here the pictures.

Thanks to WASasquatch too.

Claudio