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White dots in reflections (mental ray material)


nudawa
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When I use Mental Ray to render with A&D or Pro Materials. When there are mats with blurry reflection (the sample box in reflection can be adjusted, glossiness and reflection is lower than 1.0) the rendered images will have many white dots on the highlight parts of the reflections.

 

I've tried to turn on/off the FG and GI, increase the reflection sample to xtremely high like 1024 but that doesn't seem to solve the problem.

Without these dots, MR seem perfect for me. Can someone help me ?

 

67447612.jpg

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The IES is freelight with IES web distribution, light emits from point

I tried to turn off all the IES and place a freelight point emitting near by the chair to render, the dots still there...

 

I've uploaded the files, if possible, please download it and check it for me. I'd be very grateful for that. The file is in 3ds Max 2010 format.

 

http://rapidshare.com/files/288438390/x.max.html

Edited by nudawa
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OK had a look at your scene.

 

There are a few fundimental setup things that need to be fixed first.

 

1)Set Gamme ON (with 2.2)

2)Rather use mrPhotographic exposure, It works better than log

 

Now the problem

 

I think I have narrowed it down to the self-illumintaing material on the light fittings. The contrast between the really dark area of the room and the really bright material is too much. The speckles are refections of these bright fixings.

 

Pro-materials dont give enough control to fix this so rather use A&D.

There is an option to make the self-illuminated material NOT be visible to reflections, Use this (its in the options for self illumination)

 

Overall you need to take another look at you lighting setup, simplify it and spread the light around more. ie try not to have so many lights together in one area, and other areas totally unlit.

 

jhv

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Hi Guys,

 

the most problem with FG-Splochtes, Grainy ... comes from the Sample. I have wrote a Scene Optimizer, because i have most over 200 Materials in my Scene and i must have a tool with a one click solution. I can´t look in all the material to find the error, because a day have only 24 hours. This tool have the new Sample Curve Technology to optimize the hole Scene: AO, Reflection & Refractions. For example: it´s scan the Glossy Value for all Materials and set the Sample Value new. Than have you no Problems with: to many Sample or not enough samples.

 

look here: http://www.infinity-vision.de/ShaderUtilities/de/index.html

 

screen_A&D_utilities_2010_plus.JPG

 

ps: the english version comes in one week. :rolleyes:

 

mfg

hot chip

Edited by thorsten hartmann
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Hi

 

Thanks for the comment. What for Problems with Pro-Materials do you mean and second it give the TH-Materials with a lot of more Parameters as the normal Pro-Materials. The Shader Utilities can scan all Materials: A&D, TH-Materials, SSS-Shader and and....

 

TH-Materials Tread: http://www.cgarchitect.com/vb/37445-new-advanced-pro-materials.html

 

mfg

hot chip

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Your pro-material script adresses alot of the problems with pro-materials, ie the lack of control.

 

Just by seeing this same speckly issue in two different threads, where alot of the materials are pro and photons are being used, I was wondering if there was a link.

 

jhv

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I also wonder if this might be a Max 2010 issue??

Most of the fixes that 'fix' splotches aren't working.

I'm not on 2010 but I'm not getting this problem.

I was wondering the same thing...I think there is a 2010 issue.

I have not seen this with prior releases, but just ran into it myself late last week.

Certainly it seems turning on Self-Illum makes this happen in 2010.

I have several scenes I did in 2009 where it was never an issue, and this is regardless to what the samples are set at.

That seems to excasberate the issue.

However, even turning it off, I was still getting these artifacts to some degree, regardless of how far up I cranked the samples.

Last week I (after reading this very thread) I turned up the blur on the mrSky. That seemed to help, but did not get rid of the artifacts entirely.

 

In the end, I found setting the material picking up the splotchies to use "Fast(Interpolate)" did eliminate the problem. HOWEVER...this is a *cheap* fix for working under the deadline that I was, and the image did not have the reflections the way I planned on them to be.

 

In the next couple of days, when I have free time, I am going to open up a 2009 scene with Self-Illum and nice blurry reflections with 2010 and see what the results are.

 

Further, I would suspect it was the mrSky entirely, but I also tried my scene from last week where I switched over to a standard skylight, but the splotchies still appeared.

Of course, in making that switch, I set the mrPhotoExposure control to "unitless" and cranked it up.

 

Hmmm...as I write this, I wonder if it is related to using the exposure control?

I'll test some of these things out over the next few days. For now...bedtime.

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This was an issue with 2009, There is a thread on Vizdepot that explors this issue in great depth. I'll try dig it out.

 

Why do you say that fast interpolate is a "Cheap" Fix?

 

Not an exposure control thing, This scene was using Logarithmic and when I switched it to mrPhotographic it was still there.

 

nudawa: No problem glad to help

 

jhv

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Why do you say that fast interpolate is a "Cheap" Fix?

I certainly didn't intend to make it sound like fast interpolate itself is a cheap fix.

I meant that for what I was making, it was just a quick fix to get the job out the door, rather than look for the cause of the specks.

This was a very short project and setting the fast interpolate got it done, albiet without the result I wanted to see (tho the client was very happy)

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excessive use of Fast interpolate can and does look very odd. However properly used it does help a heap in rendering time.

 

At the end of the day, if you have a scene that has been correctly put together you wont run into these issues.

 

luckymutt - Thats what I thought you meant, I just wanted to be sure.

 

jhv

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