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Friday, January 28, 2011

Creating a nice brushed metal (anisotropic) shader with Mental Ray tutorial


ANISOTROPIC SHADER RECIPE

Here is a mix for creating an Anisotropic shader in Maya and Mental Ray. How good metal looks is very dependant on your lighting so keep that in mind.

CLICK HERE FOR THE DETAILED VERSION OF THIS TUTORIAL

Create a new Anisotropic Maya node and apply it to your object.

Now create a quick area light to hit up our object with. Menus: Create>Lights>Area Light. Position the light above your object.

I'm also just going to put a simple wood texture on the floor just to give us more
reflections to play with in the scene. Do a render to see what you are getting.

In your hypershade select your anisotrpic1 node. In the Attribute Editor under the drop
down Specular Shading DISABLE the Anisotrpic Reflectivity Checkbox. This will let you
control the level of reflectivity yourself.

Then make these settings to the anisotrpic

Reflectivity 0.736

Diffuse setting to 0.132

Spread X to 7.532 and Spread Y to 5.882

Roughness to .7

Fresnel Index to 2.0

Go to render options menu: Window>Rendering Editors>Render Settings. Then to the
Indirect Lighting Tab at the top of this you will see Image Based Lighting. Click the
CREATE button next to it. Immediately an IBL node system will be set up in your scene,
though it may look like nothing happened.

In the attribute editor it should open your IBL atributes. click the small folder to
load an HDR file. These can be downloaded from many free sites online.




Now we have nice anisotropic highlights but perfectly crisp reflections.

In the hypershade create a 2D as projection NOISE node. Make the following settings

Threshold 0.1
Amplitude 0.140
Ratio 1.0
Requency Ratio 1.744

Next in hypershade select the place2Dtexture node attached to your noise1 node. In the
attribute editor increase the "RepeatUV" fields to these values. U is first V second.

U 0.05
V 100

Basically, this just makes streaks. Now attach it to your Anisotropic shader's
reflections. First in the hypershade select the anisotropic_noise1 node. In your
attribute editor expand the Mental Ray drop down. You will see a Mi Reflection blur
attribute.

Now in your hypershade MIDDLE house click and hold down on the projection1 node. Drag it
over to the attribute editor and connect it to the Mi Reflection blur attribute.

The connection editor will appears. Connect OUTALPHA on the left to miReflectionBlur on
the right

Now let's render and see what we are getting.




To smooth grain of the reflection select your anisotropic1 node in the hypershade then
in the Attribute Editor expand the Mental Ray drop down and set the Reflection Rays
setting to 50.  





In your Hypershade under Create Maya Nodes, scroll down to the 3D textures drop down
and create a new Cloud node.

Connect the cloud node to the color aatribute on your anisotrpic node.

That's it you should have a very good starting place for anisotropic metals with this
shader.




If you want to pick up the exact shader that I am using in my Espresso scene at the top you can Subscribe to Maya Zest and I'll email it to you as a thank you.