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Work with Final Gather
Work with Final Gather
Retune the final gather settings for pre-Maya 6.5 scenes
Final gather sample workflow
Final gather is a simple and efficient method
of producing indirect illumination. You can add lighting effects
to your scene without using lights or photons (as in other types
of illumination: global illumination, caustics and so on). Instead,
final gather allows you to illuminate your scene from surface to surface
by using the irradiance color of a surface shader as the source
of bounce color.
Final gather is the last step that occurs in
rendering. It occurs after photon tracing, and after the lighting
and shadow calculations are complete. Therefore, final gather allows
the irradiance color to spill and bleed into shadows.
The sample workflow below illustrates how to
illuminate a scene using only final gather without the use of any
additional lighting. First, you create a surface shader and assign
it to a piece of geometry such as a plane. Adjust the Out Color
attribute of the surface shader; this is the irradiance color of
the plane. You can now light the objects in your scene by placing
this plane above the scene like a studio soft light.
Lighting your scene using surfaces
The following workflow uses the irradiance of
a surface shader as the only source of light for the scene. No other
lights are added to the scene, and the default lights are disabled.
- Select
File > New Scene to
create a new scene.
- Select
the Rendering Menu set.
- Select
Create > Polygon Primitives > Torus to
create a torus. Select
Create > Polygon Primitives > Planeto
create a ground plane to catch soft shadows. Move the torus so that
it lies above the ground plane.
- Assign
a Blinn material to the Torus. Select the Torus and then select
Lighting/shading > Assign New Material > Blinn.
- Select
Render > Render Using > mental ray. Final
Gather is a mental ray for Maya feature and is only supported
if the mental ray renderer is selected.
- Select
Window > Rendering Editors > Render Settings to
open the Render Settings window.
- Click
on the Common tab. Under the Render
Options section, uncheck Enable Default Light.
- Click
on the
Quality tab of
the mental ray tabs. Under Quality
Presets, select Production: Fine Trace.
- Adjust
the following settings under the
Quality tab:
- Change
the Min Sample Level and Max
Sample Level from 1 and 2 to 0 and 2 (respectively).
This will speed up the rendering process.
- The Raytracing options
are optimally set (for the purpose of this exercise) at 1 for Reflections and
1 for Refractions.
- Expand
the Final Gathering section and
check Final Gathering to enable the
algorithm.
- Lights
are not needed in this scene. Open the Hypershade window
by selecting
Window > Rendering Editors > Hypershade.
Click on the Lights tab and delete any lights
present.
- In
the Hypershade window, select Create
> Materials > Surface Shader to create the Surface
Shader.
- Click
the Surface Shader. In the Attribute
Editor, set the Out Color parameter
by choosing white as your Out Color.
This is the irradiance color of the surface shader.
- Select
Create > Polygon Primitives > Planeto
create a plane. This is your light source.
- Move
and scale the plane above the midpoint of your scene. A larger plane will
create a softer lighting.
- Assign
the surface shader to the plane. Select the plane, then
the
surface shader swatch to select Assign Material to Selection.
- Render
the frame.
TipTo brighten the illumination in your scene,
increase the V value of the Out Color to
a value between 3 and 5. This increases the irradiance of your light
card.
