How to get rid of noise when rendering - Mental Ray

#1

Please see the attached screenshot. I am trying to create something like solidangle.com (Left), but mine image (Right) looks like it has noise, especially the shadow area. Generally speaking, it does not look as “crispy" as the image on the left.

Click to see hi-res images.

Mine settings can be found below. Please have a look and advise me how to improve it:

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Maya 2015 (Mac)

Sampling Mode: Unified Sampling
Quality: 2.0

Min Samples:1
Max Samples: 250

Sample Options
Filter: Mitchell
Filter Size: 4.0 4.0

Global Illumination & Final Gathering On at default settings.

IBL

Shader was created from Anisotropic

3 Area Lights (No Decay), Use Light Shape (Rectangle).
High Samples: 64
High Sample Limit: 1
Low Samples: 1

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PS: When using Unified Sampling, apart from the options under the Quality tab, what other factors can help to reduce noise. e.g. Samples parameter for mib_amb_occlusion.

I am still very new to Maya, please help me to understand more about getting the best render results.

Thank you guys.

#2

Have a look here:

https://www.youtube.com/watch?v=wVHzry2wCJQ

Watch the whole thing you might not want to mess with the legacy way.

Also I am not sure what is happening with the technical side but I thought that this new 2015 solution enabled us to use this:

https://elementalray.wordpress.com/2013/01/18/the-native-builtin-ibl/

But if not, this is a tad more complex to get going but very simple to use and gets great results.

Also (in your scene) noise will come from area lights as well as the quality settings in FG and GI.

For FG it is Accuracy and point density and for a still image Point Interpolation can help

But IBL might be a better way to get a cleaner render.

But if you want you can also simply turn off global illumination and simply click Create next to Physical Sun and Sky.

This will give you a good starting point with Final Gather enabled. GI and enter a whole other set of parameters to worry about. So for a beginner maybe just leave that off.

IBL is also a very slick solution.

#3

Please post rendering topics in the rendering subforum. Moved it for you.

#4

@ cineartist.

Thank you very much for your reply.

I checked out the links you provided, although the content is a bit deep for me, I will definitely check them out again when I have better basic knowledge of lighting. I am following a book to learn the basics of Maya, I’ve just finished Poly modeling chapter, so I think the links would make more sense to me when I finished the lighting chapter (hopefully).

My current goal is to get a good studio setup to demo my final models (apart from ambientOcclusion_mat). No fancy setups, something like a basic 3 point light setup or having 2 area lights on both sides (Not sure about the setup name).

Based on your comment, you mentioned that the noise in my scene come from area lights as well as the quality settings in FG and GI. Please have a look at the following questions:

FG settings:

You mentioned Accuracy, Point Density & Point Interpolation helps to reduce the noise. The default settings are 100, 1.000 & 10. I am wondering what these value should be if I am look for production quality render (A rough range will help).

GI setting:

I am guessing Accuracy helps to reduce the noise. The default setting is 500, how much should I increase the value for production render? (I want to get a rough idea before I blindly move the slider to max).

Area Lights setting:

Does Area Light > High Samples help to reduce noise? I am currently setup to 64. Is this high enough?

Thank you.

#5

@ ThE_JacO.

Thank you. Sorry I did not see the Render section when I posted it.

#6

In MR Scene Size also plays an important part so no one can provide you an out of the box of value which will work for you.
I don’t know if the noise is due to GI or FG ,please check by turning off one, to me it appears that it is from FG but not sure.
Please check http://userpages.umbc.edu/~bailey/Courses/Tutorials/RenderingDemo/FinalGatherDemo.html for better understanding .

#7

@ yogeshsherman.

Thank you for your reply.

I tried to turn off GI and FG, I found the noise does come from FG, so I increase the values in FG and it turned out to be more smooth image.

Thank you for your advise, the link you sent me also gave me a better understanding.

Cheers.

#8

Final gathering is tricky sometimes I was scared to death to use it in a 3 second animation of a car speeding down a back road, but there was an optimize for animations tab and all the sampling points on the animation were locked down so I wouldn’t get any flicker so keep that in mind if you render an animation.

#9

@ Crezz.

Thanks for you tip.

Where you find the "an optimize for animations tab "? I am using Maya 2015 and was looking for it in the Render Settings window but did not find it. Am I looking at the wrong place?

#10

In the render settings go to the indirect lighting tab. Go down to the final gathering tracing drop down menu and in final gather mode click on automatic to Optimize for animation. :wink:

#11

@ Crezz.

Found it! Thanks for the tip. :beer:

#12

I think artists expect too much from FG.
Its basically an optimizing shortcut for global illumination(GI) which adds great shading complexity even when the light sources are few and simple. Through a camera based preprocess, the technique stores scene lighting information on a 3d point cloud. At render time the point cloud is sampled to provide the GI component.
Rather than struggle to get detail from FG, I have always used it as a soft source for light bouncing from surface to surface. This approach has helped to created pristine flicker free animation. I suggest you increase point interpolation from the default of 10 to a much higher value like 100 or 300. This in essence blurs the lighting samples derived from the FG point cloud, so yes this can result in loss of detail but shading complexity is still there.
Through the use of an ambient occlusion(AO) component you can get the edge detail back. The mia_material has an AO parameter which will bring back the detail of the FG.