Mental Ray - Shaders


edit : nevermind… I found the files I was looking for.


Have you used the SSS Skin+ material that Zap has available on his blog? It has built in AO.


I found this video about Mental Ray and Vray anti aliasing comparison, according to it the basic settings of of mental ray tend to loose small details in the rendering .

But if the minimum sample is increased to 4 then it shows the details. But then it seems to ‘render’ the empty areas too! resulting much longer render time compared to Vray.

Is this normal? or is there any other way to fix the issue?

You could check out the video here.

Screenshots from the comparison video:

** This might not be a directly shader related issue, but I couldn’t think of any other place which has such experienced MR users like Jeff and others!


Yes I also saw this video yesterday… and the vray speed is quite fast, for that scene…


Just off the top of my head - you can use the ctrl.object shader ( to do object-based antialiasing.


… absolutely correct :thumbsup:

that cuts down the rendertime from 10 seconds - 4/64 for all
2 seconds for 1/16 for all but the object which is stil 4/64 on object based antialiasing

so same result but with a fifth of time


I searched to find the shader but i couldn’t… can you send some link that is official for the shader



Did you search under mental ray shaders?



Yes i did search it but i dont know why i didnt see it :). Thanks for the link, i find it. Any other good shaders for MR ?



The ctrl.color is very cool too :slight_smile: Esp if you are on a max version before 2009, like me.


Hello musashidan!

I did some testing with skiplus, I had already used it sometimes, but the result is not the same that of the AO composition.
Doing more tests, I saw that the ideal result, is to use of AO only in the channels unscattered and overall.
Use in the epidermal makes a small difference, in the other channels do not make a difference.
With this already reduces of render time.

In this test i use the skinplus shader:

[left]For this profile of character is perfect. But if the character is visually more aggressive, such as an Orc, it is cool leave the lines well defined and marked, these occasions the composition of the sss with shader of AO works very well.[/left]
[left]I do a test and show the result.[/left]


Can someone explain to me how to use the ctrl_object in max 2009? I must be missing something…

I create the MR Geometry Shader, then add the ctrl_shader to the slot and drag an instance to the material editor. I add the objects, but then adjusting the min and max samples has no effect on the scene.

I’d love to get this to work!


You need to set the AA settings in the Render panel higher than ctrl_object AA settings.
So render panel AA 1/16 and ctrl object would be -1/4.
Its not the smartest way but it works. I would have prefer to apply High AA settings to the select objects and the low AA Globably.


I set the range to 1/16 in the render settings. Then I make 2 ctl_objects. One for the low settings, and one for the Higher settings. I have not use more than 2, but it should work.



Is there any point to using 2 ? In essences wouldn’t that make it a total of 3 AA settings ?


with the scene that was used for that test … the block with the holes - it is the other way around

the overall aa is set to absolut minimum and the object is controlled by the geo shader !!!

the object has high AA to show the holes and the Background renders fast with minimum AA

that´s the trick

if you have much background and only a couple of objects that is where to use it and save a lot of time as i mentioned earlier :slight_smile:


Seriously that doesn’t work, well I cannot get it to work.
If my render settings AA is lower than the Geoshader that kind or overrides geoshader settings.
As far as I remember the Geoshader AA settings have to be within the range of the Render settings AA.
I’d like to see your test scene ?


I didn’t manage to get 2009 version shader working with 2010, so I’m wondering if there’s a 2010 shader I can use for rendering? I am way past using simply final gather for renders and was disappointed not to see it as an option in 2010.


… it works perfect :thumbsup:

here is the scene:



The new geoshader for 2010 is at


The way that I understood it, the aa settings in the render settings is the range for all objects that are not included in the shader. I use two because I did not want anything to render 1/16.
I wanted some objects to render at 1/4 and the rest to render at 4/16. If any objects were not added to a shader, they would render at 1/16. Isnt this correct ?