Strange error

[Ironshirt]

Hello everybody!

I experienced a strange problem while working on my current project. I rendered a picture overnight - see picture "project_noerror.jpg"  and saved the tgd. After that, I saved it again under a new filename and worked with the newer version.

I did some modifications to the cloud layer and the fake stones surface shader (distribution shader). After that I changed the render options and got a strange render result which I can't explain - see "project_error.jpg"

Even undoing my modifications did not solve the issue. I also tried to delete the cloud layer without any success! The errors then appeared in the atmosphere...
Restarting or resaving did not make it better.

This error does only affect the newer file I resaved from the old one.
The old one with the original cloud settings still works correctly...   so I compared both files and saved the differences to a txt file (see differences.txt). I've also attached both .tgds

This is nothing time critical (only a hobby project)  - I just wanted to have you informed about this issue... 
I will continue with my old project - this work fine for me, but perhaps you may find out something useful for bugfixing (if you have time to look at it) ...

(I'm using TG version 1.9.99.1 on a Core2Duo E6600 machine with 3GB of Ram)



regards, Michael

[rcallicotte]

It looks like you have some extreme displacement values.  Try changing all of your displacements that are 3 digit behind the decimal (example .001) to .01.

[Tangled-Universe]

It looks like you have some extreme displacement values.  Try changing all of your displacements that are 3 digit behind the decimal (example .001) to .01.

This could indeed be the problem since I see scales @ 0,0051m...can't tell whether or not they are in the fake stone shader but this could indeed be the problem.

Another thing I mentioned is that the file differs for both render-nodes. The full render, I presume, is @ detail 1 , AA 15 and GI 2/2. The quick render is @ quality 0.7, AA 8 and GI 0/0.
I presume you've rendered the second image with the quick render since the shadows are very dark, if not, lacking?
I'm not sure whether or not it is related to your problem.

I first would go for Calico's solution.

[Ironshirt]

Hi again!

Thanks for your quick answers! Calico's solution works indeed    - I disabled all displacements of the fake stones' surface shaders which I modified before and did a test render after that. There are no more errors to see!  Very good           I think I hooked the displacement by accident       can't remember when I did this   


Once again, thank you very much!

Regards,
Michael

@Tangled-Universe - just for information

I changed the clouds edge sharpness from 16 to 2.22 and increased the clouds' density from 0.00085 to 0.085
I also made the surface shader of the stones a little bit darker -  think thats why the whole scene appears that dark.

[rcallicotte]

Play with your displacements.  I have found that in some circumstances that the digits in the thousandths do not always cause this problem.  But, I'm not really sure how necessary these are and displacements this size definitely increase render time.

[Tangled-Universe]

@Tangled-Universe - just for information

I changed the clouds edge sharpness from 16 to 2.22 and increased the clouds' density from 0.00085 to 0.085
I also made the surface shader of the stones a little bit darker -  think thats why the whole scene appears that dark.

I'm really not so sure about that...but ok, doesn't matter, it works now!
Calico is right that it isn't always the reason for this to happen.