Maya Ambient Occlusion Render - Tutorial
The tutorial may also be used for versions of Maya other than Maya 2014.
This tutorial will require a basic understanding of modeling and rendering using Maya 2014.
Before doing anything, be sure to delete any lights you may have in your scene as they can affect the render.
Once you have opened your scene, you will have to make a "Render Layer".
-  Channel Box / Layer Editor  >  Render (Found in the bottom right hand corner of the screen)
From here, you will have to select all of the objects that you want to render. With your objects selected, create a "New Layer and Assign Selected Object" using the button in the bottom right. Rename the Layer to AmbientOcclusion or something similar so you do not get confused later on in the pipeline.
Now, to enable Ambient Occlusion, you have to click on the "Attribute Editor" and then go to the Tab titled AmbientOcclusion (or what you named your Render Layer").
On the right, you should see a "Presets" button. Left-click it and select "Occlusion".
Your selected objects will now become completely black but don't freak out, that's supposed to happen.
Now, staying in the current Tab, click on the arrow to the right of "Out Color".
You wouldn't see much if you rendered the scene now, so there are a few things you'll need to change.
First, change the "Max Distance" to 20. This will allow the light to spread further from the camera, allowing you to render objects further away.
Now change the "Samples" to 64. This will greatly improve the overall quality of the final render and make it less grainy.
Finally, change the "Spread" to 0.9. This will basically make the shadows spread out a little more and have more of a gradient.
Be sure to alter any of these settings to get the render you want.
Remember, the more polygons you are rendering, the longer and more RAM intensive it will be.
Now, render your scene.
(While doing this, remember that any lights in your scene will interfere with the render. Mentalray's "Physical Sun and Sky" will just render using that, totally neglecting Ambient Occlusion)
