MR Rendering an exterior scene (using FG)

From TOI-Pedia


This tutorial covers rendering an exterior scene using Mental Ray Final Gather.

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We assume you have a scene with your geometry. Please make sure you remove all lights before you start to make your light setup. It's recommended to start with the default Render Settings.

When using Mental Ray Final Gather don't use additional lights to simulate extra diffuse/ambient light as you would do with Software or Vector rendering!


Load your scene and open the Render Settings. Set Render using to Mental Ray.

If the Mental Ray option is not shown in the pull-down menu of the Render Settings, go to: Window » Settings/Preferences » Plug-in Manager and make sure the check-boxes for Mayatomr.mll (Mayatomr.bundle on Mac) are checked.
Since Maya 2016 a major overhaul has been made to the user interface. This also affects the standard tabs in the Render Settings of mental ray. It is possible to change it to legacy tabs similar to Maya 2015 and earlier.

Make sure the mental ray plug-in is already loaded! Open Windows » Settings/Preference » Preferences and choose Rendering in the Categories panel. Check the boxes Show Maya Legacy Passes and Use Legacy Render Settings and click Save.

Reload the mental ray plug-in or restart Maya to see the changes.

In the Common tab, set the Image size to 320x240 or 640x480 for fast preview rendering.

MR RenderSettings AntiAliasing Sampling.jpg

In the Mental Ray tab, go to Anti-Aliasing Quality. Make sure Sampling mode is set to Adaptive Sampling and set the Max Sample Level to 1 for medium image quality. You may choose to set Multi-Pixel Filter to triangle.

In the Final Gathering section, enable Final Gathering. The settings will be covered later.

There is a shortcut to enable Final Gather, located at the top of the Mental Ray tab in the Render Settings, in the section Rendering features.

Choosing a setup for your environment and sunlight

There are two main options: Image Based Lighting (IBL) and the Physical Sun and Sky. Please refer to the corresponding tutorial to learn how to make your setup. Afterwards you can return to this tutorial to continue.

Image Based Lighting

This would involve creating and IBL sky-dome and directional light for the sunlight. This is covered in detail in MR Basic Final Gather using Image Based Lighting (IBL).

more control to create your own style
more work to set up, a little more complex to control

Physical Sun and Sky

Mental Ray has a built-in Physical Sun ans Sky system which is physically accurate, provided you are using MIA materials. Using the Physical Sky is covered in MR Using the Physical Sun and Sky environment.

easy to set up and control. Physically accurate
harder to get your own style

Initial Final Gather Settings

Make sure Final Gathering is enabled.

Go to the Final Gathering section.

set the accuracy to 20 for initial renderings
Point Density
set the Point Density to 0.6
Point Interpolation
set the Point Interpolation to 40

MR FG exterior initial settings.jpg

Refer to the Final Gather page for details on these settings. Note that these settings are for preview renderings. The quality will probably be mediocre, but that is something to solve later on. Preview settings should be sufficient to assess the light setup.

Tuning the image

If your image is too bright or too dark, you need to tune your settings. It depends on the type of environment you're using. Refer to the corresponding tutorials for details.

Image Based Lighting

If your image is too bright or dark, you should change the IBL parameters and/or the Final Gather scale. This is explained in the IBL tutorial.

Physical Sun and Sky

If your image is too bright or dark, you should change the exposure settings of your camera. Don't change the Sun or Sky intensity or Final Gather scale!. The exposure of the camera is controlled by the mia_exposure_control node, also known as Tone Mapper. Refer to the Physical Sun and Sky tutorial.

Tuning the Render Settings for better quality

Increase the image resolution to your final resolution or a resolution one step smaller.

In the Anti-Aliasing Quality section:

Anti-aliasing Contrast
set the Anti-aliasing Contrast to 0.05
Max Sample Level
try to leave it at 1; only set the Max Sample Level to 2 for really high quality or when you have very fine details in textures, causing a moire effect.

In the Multi-Pixel Filtering sub-section:

set the Filter to either Gauss (smooth), Mitchell (sharp) or Lanczos (sharper)

For detail on Anti-Aliasing settings, refer to Anti Aliasing Settings.

In the Final Gathering section.

increase the accuracy when needed. Increase in steps of 10. Values higher than 80 should generally not be needed.
Point Density
set the Point Density between 0.8 and 1.0
Point Interpolation
increase the Point Interpolation for smoother results (it compromises accuracy of the image in favor of speed, but for exteriors this is generally negligible).

If you have reflective materials in your scene, you may need to set Filter in the Final Gather Options to 1. Only if you see some strange bright spots in your rendering, set Filter to 1. otherwise leave it at 0.

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