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Render raytraced shadows
Cast shadows
Remove shadows
Catch shadows for an alpha channel
For more information about shadows, see
Shadow in Maya.
The following is a simple example of how to
use the Use Background material to catch shadows.
To
capture only shadows in an alpha channel
- In Hypershade,
create a Use Background material and assign it to the shadow catching
object(s).
- Select
the objects(s) in the scene casting shadows. In the Render
Stats section of the objects’ Attribute Editor,
turn Primary Visibility off.
- Render
the scene.
Shadow information is captured in the alpha
channel.
To
assign Use Background to stand-in geometry
- Use
this workflow to make a 3D object look like it’s in a real environment. The
real environment usually comes from a snapshot or live action shot that
is assigned to an image plane. The object can cast shadows onto
the seemingly invisible plane, which acts as the shadow catcher.
- Create
an image plane using the scene in which you want to place the stand-in
geometry by doing the following.
- Select View > Image Plane
> Import Image from the current view.
- Browse
to the file you want and click Import.
A placement icon appears in either the current
view or all views, depending on the Display mode you set, and the Image
Plane Attribute Editor opens.
- Select
an Image File or Texture from
the Type drop-down list, then
click the folder icon next to Image Name to
load an image plane into the view.
NoteMake sure you select the
Image
Plane Attached to Camera option to position the plane
where you want it before you create a stand-in object. For more
information about image planes, see
Image plane in
the
Shading guide.
- Set
the following attributes in the Image Plane Attributes section:
- Display–looking
through camera
- Image
Plane–attached to Camera
- Adjust
the perspective camera so that the construction grid plane aligns approximately
where you want to place the object.
- Create
and position a NURBS or polygonal plane on which to cast shadows
and reflections.
- Position
the object you want to cast shadows onto the stand-in geometry on
the grid plane.
- In Hypershade,
create a Use Background material and
assign it to the plane.
- Create
and position lights in the scene. Turn on the Use
Depth Map Shadows attribute in the Shadows section
of the light’s Attribute Editor to see the
shadows in the rendered result.
- Render
the scene in Render View (for best results,
do not IPR render).
- Adjust
the location of the geometry, the lights, and the Use
Background attributes if necessary and then re-render
the scene at any time.