Mental Ray - Random black boxes appear

[3DArchitecture]

I am using Max 7 sp1. With some large scenes I

am getting random black boxes when using Mental Ray.

Is this a bug in max? If not, what is a solution.

See image attached.

Thanks

[derijones]

It happens with Mental Ray in Maya too. Never got to the bottom of it, but it appears that several people have the problem:

http://forums.cgsociety.org/showthread.php?t=234449

http://www.cgarchitect.com/vb/showthread.php?p=80034#post80034

http://tinyurl.com/bur3r

 

Try fiddling with your lighting setup, although they do seem to appear at random (did 4 test renders at 1280x1024, no problems, rendered at 3000x2000 - spots...aaargh!)

Hope it helps

Deri

[the white witch]

try increasing the depth of your reflection and refration from 6 to something much higher....

[abicalho]

Are you rendering locally or through the network? Do those dots persist if you re-render or are they random?

 

Are you using GI, FG? If you lower (or increase) the GI/FG bounces, does that solve it? Does enabling/disabling GI/FG remove the problem too?

[3DArchitecture]

Thanks for the help. The black holes are smaller and in some cases gone,

but I still get them in some renderings. It doesn't seem to be tied to any one

setting, rather a combination of settings will help to some degree but not totally eliminate it...esp. in large renderings. What seem to help the most

was limiting the Final Gather radius with lower Sample settings.

I'm still not sure what is causing this??? I've even simply put one material

because it was really showing up with relective surfaces, but this did not elliminate it either... so I will keep testing different variable a post later.

 

Thanks,

[abicalho]

What version of MAX are you using, and have you installed the Service Pack available for it?

[3DArchitecture]

I'm using 3DS Studio Max 7 with Service Pack 1.

[abicalho]

Do a quick test. Select all your geometry and apply a UVWMap Modifier, choose Box and give it any size. I know it'll make your scene incorrect, but it's just a test. Render with the same parameters and see if it the black dots are gone.

If they are, then you found the problem. One of the objects in your scene has incorrect UV coords and that object is causing this problem. The solution takes time, and it will be to locate this object.

I'd also suggest contacting Autodesk and entering this as a defect, since it maybe something else.

[nisus]

Justy looks like everyone is having the same issues... What does discreet/autodesk/menatl say about this?

 

nisus

[abicalho]

Nisus,

 

I used to, but do not work at Media and Entertainment any longer, so I cannot help you with that problem. You'll have to use the proper channels - through your reseller, through the newsgroups, logging a bug (there's a form in the newsgroup) or by contacting product support directly.

[nisus]

Hi Alex,

 

I know you don't work there anymore. I just meant, what is being said about it on general forums... If so many people have this problems..

 

ow hell... i'm just tired... soon my first hours of sleep since monday night... ;-p

 

nisus

[abicalho]

Hi Nisus,

 

This is the 3rd time I hear about it. One other was here and the third was in a brazilian forum.

[joske]

I had similar problems using raytrace reflections (MRAY max7.5 SP1)

removing an object in my scene with raytrace reflections got rid of the black spots ... just to come back with a vengange in later renders (had to resort to photopaint removal of the spots due to dealine pressure : I had no more time fooling around to solve the prob)

so I guess that makes four

solution for this would be great...

[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

 

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

[noi-pi]

Perhaps its in the Multi-subobject material. This confirms that material

somehow is the real culprit.

 

I would like to share also some solution. I came across with this type of

problem with Mentalray. I played various settings but to no avail.

I even checkevery object if theres some mesh errors or overlapping

surfaces but none. So I suspect its in the Materials.

 

1st image below shows the Black Spots. All the cylinders in there (balusters,

and lamp supports) have a Standard Metal shader. I simply replace it with

Standard Blinn and I'm back on track (image 2).

[3DArchitecture]

Found a solution:

 

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.

 

Kenneth Loyd

[vizwhiz]

i just had This same problem

i had Turned on FG and it happened

 

black alien space ships blots in The sky

no UV no subobject materials in The scene

 

here is a link To This from Two days ago

 

http://www.cgarchitect.com/vb/showthread.php?t=14590

 

randy

[nisus]

best solution: DO NOT use architectural materials!!!

 

nisus