The definitive VRay spots 'n' blotches topic

[Metin_7]

F.y.i. the above info will continue to be accessible at http://www.metinseven.com/article_vray_splotches.htm and soon at http://www.vray.info.

Cheers,

M7

[vlado]

In the first case, you can also do two other things:

1. Increase the hemispheric subdivisons

and/or

2. Adjust the QMC sampler parameters (lower noise threshold, lower early termnation amount, higher min. samples).

Best regards,
Vlado

[Metin_7]

Thanks for your additions Vlado. I'll process them into the growing story. I actually meant Hemispheric subdivions by "GI samples". I'll change that.

Cheers,

/\/\etin

P.S.: If you've got the time, could you please turn this into a sticky topic? I guess it's a useful topic to easily find here. Thanks in advance.

[onodiandras]

Metin_7. You Just saved my ass!
Whenever you came to Hungary just drop me a mail and I'll pay you a beer.

Red splotches definately belong in the 3rd category.

Thanks:

Andras

[Metin_7]

Glad to be of any help. Oh, and here's my bank account number ...

Cheerio,

M7

P.S.: Any further updates of the above text will be processed into http://www.metinseven.com/article_vray_splotches.htm. If any of you have got additional tips/tricks/info/solutions concerning this subject matter, please drop me an e-mail: metin [at] sevensheaven [dot] nl.

[TutanMark]

Hmmm... i have strange splotches too on a render i'm working on.

here's a pic, someone can help me to identify the problem? ... i have several view of the same project, and i've got same splotches on different places (more similar to the red one.. in the picture)




Thanks,
Marco

[Metin_7]

Wow, those are beautiful! I guess this is category 2 or 3. Try the checklist. I hope it works out for you.

Cheers,

Metin

[TutanMark]

Thanks metin,

I... was thinking, and this maybe can help to identify better the problem, that i'm using HDRI map in the environment/reflection slot (not in env.override).... and i saw the same problem , in the past... when hdri maps were present in the scene.

I'll make some test ... and post the results.


Your "guide" is very usefull, thanks again.

Marco

[Metin_7]

You're welcome Marco. In my experience HDRI can be a dangerous risk to cause splotches, probably because it's a high-energy, bright light source?

Cheers,

Metin

[TutanMark]

I think u are right, i used the greyscale version of the "Campus_probe.hdr" (multiplier = 2) , got from devebec site. i tried only with the greyscaled version but i can try also with the original file, to see what happens.

I used also hdri environment on some materials to improve reflections... that added to the general environment can (maybe) cause that problem ... (another test to do .. i guess)...

Hmm.. is good .. now i have any idea on what to do... i'll post results soon.

Thanks again,
Marco

[Metin_7]

I know what you mean. I had a lot of splotch problems while using the high energy kitchen bitmap by Paul Devebec.

Good luck and cheers,

/\/\7

[TutanMark]

These are tests i did:

1) Turned off Environmental HDRI .. same problem
2) Eliminated HDRI maps on material .. same problem
3) Cropped all maps (.. using that script..) .. same problem
3) Eliminated 2 objects containing standard materials .. same...


All time i got Warnings on the Vraylog... "material Overbright..." so...

4) Tried Photon Mapping method .. (different... but same problem)


5) Returned completely to Irradiance map, and turned OFF "Reflective GI Caustics" , started to turn off "GI Receive" from some Object.. and... something.. is starting to change...


6) Another pass... turned off GI on object
- all glasses objects (generate and receive)
- silver plate objects(only generate)
- reflective objects like plates and panels on chair (only generate GI)

The result is this!!!... ... nothing has changed...




Tried also to insert higher value in the Imap... the splotches disappears on the tables... and so on.. but.. appeared on walls... ehehehehe... look:



are nice... isn't it? (the splotches..)..

What else can i do?

I still have a lot of overbright warnings, on that object (less than before)

And....I have other reflective object in the scene, not on tables... so i don't think are connected to the "problem"....

regards,
Marco

[vince_1972]

humm, i had 2 week ago the seem problem with my atrium.

you must to find the problem objets.

for me, i have frozzen the half on my objet, see the result. if it's good, the problem is in the frozzen objets and so on...

for me it's was the overbrith color, but now all is ok

hope it's help you

good evening

Vince

[RErender]

One more "cause" that I don't believe is in the list, is bad or missing UVW coordinates.

1. Check that any object with a material using explicit mapping, does have mapping coordinates.

2. If any meshes are imported from another program with mapping coordinates, apply max UVW.

[TutanMark]

Thanks Vince,

I have several... overbright objects.... in the scene

I think ... it could be a mix of trouble... between irradiance map and some kind of reflection/refraction... (maybe glossy) that is causing the problem.

i'll try your trick... to see what happens

Rerender:
ok... understood... i'll check that also....

Good evening to you!
Marco