PDA

View Full Version : final gather colored noise artifact problem


sysameca
05-24-2012, 06:41 AM
Hello again guys. This time i have some serious problem which i cannot seem to fix.I looked everywhere in internet including this forum but i didn't found anything useful. As you can see on the attachments in the shadow areas i recieve colored noise.
Scene is lit up with mental ray Physical Sun/Sky and final gather is dropping color from a background plate of blue sky.Everything in the scene is set up with mia_material_x_passes material.
I am using Maya software.Thanks in advance

gauravnag
05-24-2012, 01:28 PM
_O)(..
It will better to understand if you attach here your mental ray settings or shader also which you applied over geometry.

sysameca
05-29-2012, 09:20 AM
Ok guys i figured it out what is happening.I tested, searched and wondered one week what is this problem.I made also a night scene without final gather and almost my whole scene was with this colored grainy noise artifact.I attached a picture with the scene..The scene is scaled in real size.So..Accidentally i found trough IPR Render that is some kind of a post effect because when it rendered the square, immediately after that it added this grain.After i saw that i remembered that i have one mini circular object with a shader emmiting "glow of 0.04". I removed the glow and this problem disappeared...My question is this - Why is it doing this? Now i need my objects to glow and cannot manage to do this..Does someone experienced this kind of problem before?

Bitter
05-30-2012, 02:37 PM
Glow in post is best. You can achieve this pretty easy in something like Nuke or Photoshop. You'll have better control and realism.

The quick n' dirty version is using a spec pass or a beauty where you reduce the exposure where only the highlights are visible. Blur this and reapply as a screen or add. Adjust as necessary.

RafaelMancini
05-31-2012, 04:55 PM
Hello again guys. This time i have some serious problem which i cannot seem to fix.I looked everywhere in internet including this forum but i didn't found anything useful. As you can see on the attachments in the shadow areas i recieve colored noise.
Scene is lit up with mental ray Physical Sun/Sky and final gather is dropping color from a background plate of blue sky.Everything in the scene is set up with mia_material_x_passes material.
I am using Maya software.Thanks in advance

How is it that you are using a mia_material and Final Gather in Maya Software?? Thats not possible.

Glow is a totally post production process. Forget you ever knew that Maya has some glow shaders, and never use them again!

sysameca
06-01-2012, 07:10 AM
hehe.Sorry i referred that i used Autodesk Maya software not the Maya Software renderer.Anyway in mental ray there is no way to make things glow at all is that it??

yogeshsherman
06-01-2012, 08:24 AM
You can still get glow like effect using mia_light_surface utility along with final gather without any issues.
Also check your light intensities they should not be too high and try out mentalray light shader for better control and effect.

InfernalDarkness
06-08-2012, 05:40 PM
Seconding Yogeshsherman' suggestion of the mia_light_surface. This is a rendertime-based "glow" and also contributes to Final Gather and reflections if you like. This is not a post-render effect like Maya's native Glow, and is used for light bulbs, fluorescent tubes, candles, anything you need to actually glow. The glow is not like Maya's at all, or Photoshop's, so you still may want to use Bitter's suggestion and do your glows in postwork anyway.

Here's a quick example of the surface_light shader in action, a bit dirty but it was just a test. You can control the light emission with a texture or file as well; there are no other lights in this scene:

http://img256.imageshack.us/img256/3581/lightsphamr2.jpg

Look in the Maya sections and do a search for "light_surface" perhaps? A wealth of testing and information exists there on the topic.

CGTalk Moderation
06-08-2012, 05:40 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.