Mental Ray "black holes" artifacts

[titopte]

Here´s another example of the same
http://www.patagoniaotra.com.ar/mato/cochina4.jpg
pixelation is due to compression

[ToddD]

I think you need to adjust the number of photons per sample, and the average gi photons per light.

this thread is very informative:
http://www.vizdepot.com/forums/show...tal+ray+samples (http://www.vizdepot.com/forums/showthread.php?t=1422&highlight=mental+ray+samples)

[Arkon11]

hmm...... agreed. This happened to me before, when I was using a MRshadow map, I changed it to a Ray Traced Shadows, and the problem was fixed.

[titopte]

thanks to both, for your answers.
I´m do using Raytraced shadows, and tryed fixing things with the photons per sample and FG settings.
I´ll give it a try with the GI photons in the light properties and let you know.
Thanks for the link too.
Cheers

[pcbyers]

This brings me back to my "shot full of holes" problem, which I brought up in this thread:
http://www.cgtalk.com/showthread.php?t=217279&highlight=mentally+challenged
I never figured that one out, no matter how many different settings I tried. I was just able to shift the holes around. The problem seemed to be with Final Gather - it went away when I turned it off. What I ended up doing was, rendering out a lighting pass with a grey material override, to get a black-and-white light map. Then I layered it up with diffuse and reflection passes, and it came out pretty good.

[ToddD]

pcbyers (http://member.php?u=142102), I was having problems with interior renders, I went to that thread I posted- take a look at the values they use, much much higher than you are using. I also found in the end that my latest interior(not posted yet) rendered about 40% faster when I upped those values, and reduced the FG samples--with better results. Anyway, it is worth a look IMO :)

Here is the image I found very helpful:

http://www.vizdepot.com/forums/attachment.php?attachmentid=1016

Todd

[titopte]

Thanks for your answers ToddD and pcbyers.
i´m running some tests on the weekend cause i´m at work right now. and let you know if i get some improvements. I found useful that image too.
cheers

[emonimo]

I had the same problem as you, and I fixed it just changing the value of the filter in the FG .... I don't really know the reason but it works.... in my case ..... hope it helps....

[titopte]

thanks for the tip emonimo (http://www.cgtalk.com/member.php?u=71170).
i´ll try it and let you know.
cheers

[mangolight]

Hola tio que tal?, yo tuve el mismo problema de las manchas negras, y no sabia como resolverlo. Cambie los parametros del FG pues porq es cuando activo el FG q da los problemas de las manchas negras. Pero igual nada...no sabia que esta sucediendo. Hice como uno de esos tios encima te dijo, aplique material por material renderizando uno por uno para ver cual dava problema, y sorpresa, no dio ni un problema?!, porque? nose, estoy usando los mismos parametros y los mismos materiales y ahora nada de manchas negras, te recomiendo q hagas lo mismo para ver que pasa, derrepente las manchas negras desaparecen como paso conmigo.

Abrazos desde Peru tio!
Salud!!

[titopte]

well hello,
thanks emonimo and mangolight for your answers.
i´ve been running several tests on the FG settings and here are the results: deep annoyance.
as i am doing this for fun and learn, and in the little spare time i progress slowly, when i have time to render.
you can see the results tweaking the filter and radius settings. i can hardly find a pattern, except from the radious size and (sometimes) the size of the spots.
also very strange behaviour when appling the shellac (i think it happens if there´s raytrace anywhere) material. i tryed applying the materials one by one and nothing.
i wonder if there´s nothing related to my computer´s performance (?)
next i´ll try replacing any raytrace in the scene (by now i ´ve eliminated architectural mats also).
i don´´t guess what makes the photons behave in that way (look the simetrical bounces of the black spots).
also no changes varying bounces in depth from 2 to 10
if anyone could give a hand, i´ll be greatful.
thanks.
http://www.patagoniaotra.com.ar/mato/pruebas.jpg

[SoLiTuDe]

why don't u post the scene file so some of us can actually play with it rather than speculate? or at least the people that know what they're doing can play with it hehe

[titopte]

thanks SoLiTuDe for your proposal.
i´m at work right now, and i brought here just the renders.
tomorrow i´ll upload the max file.
thank for helping.
cheers

[digtlpete]

try bumping up your trace depth under RENDER/RENDERING ALGORITHMS. If you notice it is happening more around areas which have reflections. I have also noticed that max's architectural materials will cause these artifacts, so I would check that also. Hope that helps

-Brian

[3DArchitecture]

Problem: Black spots appear in Mental Ray renderings.

Reason: Final Gather does not work with Multi/sub materials with Raytrace reflections that are "FACETED".

Solution: Turn "FACETED" OFF.

See 3DS MAX files attached.

http://www.3darchitecture.net/samples/Mental_Ray_BLACK_SPOTS_SOLUTION.zip

Kenneth Loyd

http://www.3darchitecture.net/samples/Mental_Ray_Simple_Test_(BLACK_SPOTS).jpg

http://www.3darchitecture.net/samples/Mental_Ray_Simple_Test_(NO_BLACK_SPOTS).jpg

Kenneth Loyd
3DArchitecture

[Racrevel]

this may be a bit late and you may have fixed the problem already but if not i had this problem with an assignment earlier last year.

change the size of the photons, and mabey the amout to compensate, i forget wether to make them smaller or bigger but id go with making them smaller.

i hope this helps you

[Maneswar]

I believe Jeff Patton found that a Falloff Map in the Raytrace Reflection slot can cause Black Spots... remove the Falloff Map and it shouldn't show spots.

As for Arch Materials... make sure to adjust the advanced properties like transmittance, reflection, etc, so they are more in line with the type of material you are creating.

Maneswar

[DukeOfDesmo]

I had this problem too, I found it was my decals in multi/sub materials. For some reason filtering decides to mic the edge pixels with non existing pixels, giving the raytracer a hard time. The solution: turn filtering off in the bitmap texture.

Hope this helps!

[pcbyers]

Hey, here's what I discovered when I had the "rabbit holes" issue pop up again in a recent project. I had to do about 50 test renders to isolate the problem, but finally I discovered it was a bump map issue. I had a standard Max material, and in the bump channel I put the "bump(3dsmax)" shader instead of just a plain bitmap. Final Gather was choking on it.

It wasn't a multi/sub material, but I have had issues with multi/sub mats and Mental Ray before. So far, Arch&Design mats in a multi/sub seem to work fine.

[BrianHarbauer]

Howdy, It seems your pictures aren't up anymore but I was having the problem of black small squares randomly here and there in my renders. I found out it was the raytrace acceleration settings. In the render dialog under the renderer tab, goto Rendering Algorithms and change your bsp to large BSP. if that doesnt fix it, make sure you're using a camera instead of the perspective viewport. Cheers.

[kevjon]

Rendering with Mental Ray and FG in Max 7 and now 9, I was getting white, cyan or black splotches on some of my renders which was driving me nuts. I ended up giving MR away and using the scanline renderer with e-light for GI due to the frustration of it.
Just came across this thread and Followed Maneswar (Jeff Pattons) advice. I had falloff maps in the reflection slot of a raytrace material. Turning that off I thought had fixed it but I also found I had to set the reflection slot to RGB 0,0,0 (essentially no reflections) for it to render splotch free. Any other setting other than no reflections caused the splotches to reappear.

Other option is disable FG but can't get good renders without it.

Tried avkid85's advice about increasing the BSP but without success.

[Brian-Bradley]

Hi Kevin,


If you have Max 9 i would def recomend re-textring the scene
using the A&D shader, you can still get the problem,but it occurs
very rarely and if you texture one object at a time it shouldn't
be to difficult to deal with.

Regards
Bri

[kevjon]

Thanks Brian

Yep, I'm tyring to do that at the moment in an attempt to resolve some of my issues.

I'm now having problems with the A&D material where I can select matt, pearl and gloss templates only. All the other templates incl glass don't seem to work (as in load into the material slot), ever experience that ?

[Brian-Bradley]

Hey Kevin,

Strangely enough just last week. :thumbsup:
Quite a few on CGTalk and other forums have
run into this problem, seems to stem from
saving materials to Libraries. The base
file from whivh the templates are drawn
gets overwritten. If you have Max on another
machine as a render slave, go to your install
directory (Presumeably)
C:\Program Files\Autodesk\3ds Max 9\materiallibraries
and from that folder copy the file named
mrArch_DesignTemplates.mat and replace this
on your work machine. Other than that a replair
install of Max should sort it out.

Regards
Bri

[kevjon]

Thanks Brian

I have been adding materials to other libraries so it could be the reason it got upset.

I'll have to try the repair option as we only have one copy of the software at work.

[thorsten hartmann]

look here, i hope it can help.

german: http://forum.german-mentalray-wiki.info/viewtopic.php?t=425

english: http://mymentalray.com/forum/showthread.php?t=455

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