Mental Ray Missing

 Q: Where did my Mental Ray renderer go?

A: It's probably not loaded, go to Window>Settings/Preferences> Plug-in Manager and look for "Mayatomr.mll".

Note: As of Maya 2017, the renderer Mental Ray is no longer included and was replaced with Arnold.  The Mental Ray Standalone version is still available.

What is Three Point Lighting

Q: What's "Three point lighting"?

A: It's a lighting setup that uses a light as a key light or your main source of light. Another for a fill light, you know, the light that illuminates the spots where the key light doesn't hit, to eliminate pitch black areas and simulate ambient or indirect illumination. And a rim light that is placed more in the back of the subject to create an outline that accents the subject's contours. Some artists approach creating the rim light effect using materials instead of lights! Three point lighting doesn't necessarily describe the number of lights involved but rather the aspects of the scene the lights illuminate.

Glass not Transparent

Q: Why is my glass black/white/ some other solid color?

A: Could be one or a combination of reasons. 

• Raytracing isn't turned on in the render settings 
• Even if its turned on, the refraction traces may be too low to pass through the surfaces [also, max trace settings must be high enough to cover both reflection and refraction traces].
• If Final Gathering is enabled the tracing should be checked as well, its very much like the raytrace settings.
• Last but not least, the material's refraction tracing. Refraction Limit on standard Maya shaders and Max Trace Depth on mia_materials.

Grainy Shadows

Q: Why are my raytraced shadows so grainy?

A: The sampling is too low. Increase the shadows rays on the light[s], same goes for its "Area Light" high samples of the Mental Ray section if you checked it on, when this is on, the shadow rays attribute doesn't have an effect. These attributes in addition to the anti-aliasing in the render settings can eliminate grain at the cost of render speed so being careless with sampling can make you want to drop kick your machine.

Note: This assumes that Mental Ray is your renderer but the light or shadow sampling settings are pretty universal when it concerns grainy shadows.

Jagged Edges

Q: My models have jagged edges in the rendered image, why?

A: The anti-aliasing samples are too low, check the render settings but just don't go crazy since these will increase render times.  I think anything over 2 max samples is overkill in most instances.  Higher anti-aliasing also decreases noise and "graininess".

Jagged Edges in Render View

Q: Why does my image within the Maya render view have jagged edges no matter what renderer and render settings I use?

A: If you've already cranked up your anti-aliasing settings then chances are its something really simple like the rendered image is being scaled down to fit inside the render window, so all you need to do is hit the "1:1" icon to display the actual size.