better understand the differences in a rendering performed using
direct lighting methods vs. global illumination, you begin by rendering
the scene using the mental ray for Maya renderer without using Global
You start by performing
some preparatory setup and then render the scene. In this section
Using the mental ray for
To use the Global
Illumination feature in Maya you must render using the mental
ray for Maya renderer.
You initially render
the scene without using Global Illumination.
To change the renderer to mental ray
- In the main menu, select
Window > Rendering Editors > Render Settings (or
click the Render Settings icon on the Status
Line) to display the Render Settings window.
- In the Render Settings window,
set the Render Using setting to mental ray.
When you render an image
it will use the mental ray for Maya renderer.
NoteWhen you switch between
renderers in Maya (for example, Maya Software, Maya Hardware, and
mental ray for Maya), the common Render Settings do
not require re-setting.
When you perform repeated
test renderings for a particular scene, consider the time it takes
for each render to complete. If you reduce the time it takes to
render each test image, the testing process proceeds much faster.
Setting render settings
the first rendering test, you render the scene to see how the scene
appears without Global Illumination. The testing
process proceeds faster if the quality level for the image is initially
To set presets for rendering
- At the top of the Render
Settings window, click on the Quality tab
and set the Quality Presets setting to Draft.
The Draft setting
ensures low anti-aliasing settings are used and reduces the rendering
time compared to other preset settings. This is a good practice
when evaluating the lighting and basic material properties in your
Setting the image size
You set the size that
an image is rendered in the Render Settings window.
For this lesson, you render the image at a size that allows you
to evaluate the Global Illumination effect.
set the image size for rendering
- At the top of the Render
Settings window, select the Common tab
and open the Image Size settings.
- Set the Preset to
320 X 240.
This sets a small image
size for your rendering tests. The smaller image size renders in
less time when compared to a larger image size.
- Close the Render Settings window.
Turning on shadows
add realism to a scene, and in this lesson, help to demonstrate
how a scene rendered using Global Illumination differs
from a scene rendered using direct illumination.
To turn on shadows for the spotlight
- Open the Hypershade window
Window > Rendering Editors > Hypershade)
and click on the Lights tab to display the lights
in the scene.
scene is lit with one spotlight named spotLightShape1.
- In the Hypershade window,
double-click the icon for spotLightShape1 to display the attributes
for the spotlight.
- In the Attribute Editor,
click the spotLightShape1 tab to display the lighting attributes
for the spotlight. (You may need to minimize the Hypershade window
to see all of the Attribute Editor.)
- In the Shadows section,
open the Raytrace Shadow Attributes turn
on Use Ray Trace Shadows. This
turns on shadows for the spotlight.
- Close the Attribute Editor and Hypershade window.
Rendering the image
When you render an image,
all of the objects, lighting, shading materials, and image quality
settings are used to calculate the image, based on the particular
camera view that is set.
To render an image using mental ray for
- Click in the perspective window. This
indicates which camera view you want Maya to render.
- On the Status Line,
click the Render Current Frame icon to
launch the renderer to produce an image.
View window appears and the fruit bowl scene renders
using the mental ray for Maya renderer.
- Once the render is complete, click the Keep
Image icon in the Render View window
to save this image.
Keeping the image allows
you to compare it to any subsequent test renders you produce. In
this lesson you compare each rendered image to the previous ones
to understand how the changes you make in various settings affect
the rendered image.
The rendered image shows
the fruit bowl lit from the right of the frame. The upper and lower
portions of the image are in shadow where the edges of the wall
prevented the spotlight from lighting those portions of the scene.
The shadow areas appear dark and do not show any detail of the floor
or walls. This illumination effect is typical of an image produced with
a single light source and direct illumination.