'3D Studio MAX'

'Compositing For Production Using 3DSMax and Mental Ray'
Lee Johnson

Step 9:

Do a Save As, and name the file “Blackberry_AO.max”.  You can generate the Ambient Occlusion with the mr Shader Element, but I find it’s better to create this pass in a separate render file.  If your scene contains anything transparent (like a window) that has detail behind it that you want to show up in the AO pass, you’ll have to hide that object.  Also if you have something in your scene that has displacement on it, a blanket override with the AO shader will lose the displacement.  You’d have to load the AO map in the diffuse slot of the material with the displacement, and apply the AO material to everything else.

Step 10:

In an empty Material Slot rename the material to “AO”.  Set the Self Illumination to 100 and load the Ambient Occlusion Map in the Diffuse Slot.  Drag an instance of this material to the Material Override.  You’ll need to experiment with the Max distance values to get what you want.  This value is scene dependent.  If you have two boxes that are 5 units apart, and you set the max distance to 4, you will get a solid white image. Increasing the max distance to 6 of more you will start to get detail.  Spread affects how far the effect reaches, and Samples reduces the amount of noise (Fig.08 & Fig.09).  Set the render output to “Blackberry_AO_.png”.  Now we are ready to start compositing.



Step 11:

Open Combustion, and go to File > New.  Create a composite workspace with the settings shown in Fig.10.


Step 12:

Load the Render elements in the following order (Fig.11). Please note: I have shortened the names in the workspace for easier viewing:
*mr AD Output Diffuse Direct Illumination
*mr AD Output Diffuse Indirect Illumination
*mr AD Output Reflections
*mr AD Output Self Illumination
*mr AD Output Specular
*mr AD Output Transparency
*Ambient Occlusion


Step 13:

Turn off all the layers except for the two Diffuse.  Click on Diffuse Indirect > Layer and then change the Blending mode from Normal to Add (Fig.12)


Step 14:

Do the same for Reflections, Self Illumination, Specular and Transparency.  For Shadow leave the blending mode set to Normal, but adjust the Opacity to 25%. For Ambient Occlusion, use Multiply instead of Add (Fig.13).


Step 15:

Right click on Self Illumination and choose Operators >Stylize > Glow.  Set Strength: 2.5 and Radiu : 6.  Add a Glow to the Transparency Layer with Strength: 0.65 and Radius: 10.  On the Shadow Layer go to Operators > Blur > Gaussian Blur and set the radius to 2 (Fig.14).


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