For more information
on image file backgrounds, see
Image file backgrounds.
To
create a 3D image file background
- Create an image file background for the
perspective camera you plan to render from (see
Create a static image file background or
Create an animated image file background).
- Use the background as a reference to
create a relatively simple surface or group of surfaces to act as
stand-ins for the objects in the background image that you want
to interact with the objects in the scene.
For example, if you want
an object in the scene to cast a shadow onto the floor in the background
image, create a plane as a stand-in for the floor.
- Scale and, or position the stand-in surfaces
so that they are directly over the correct areas of the background
image.
- In Hypershade,
select Create > Materials > Use Background,
and assign the new material to the stand-in surfaces. The stand-in
surfaces have the same color as the objects in the background image
that they represent.
- You can now make objects in the scene
appear to move behind objects in the background image by moving
them behind the stand-in surfaces.
The objects in the scene
also appear to cast shadows onto the objects in the background image
by casting shadows onto the stand-in surfaces. Consider the following:
- To make objects in the background image
appear to cast shadows onto objects in the scene, in the Render
Stats section of the stand-in surfaces’ Attribute
Editor, turn on Cast Shadows.
- To make the objects in the scene appear
to accurately reflect objects in the background image, in the Render
Stats section of the stand-in surface’s Attribute
Editor, turn on Visible in Reflections. Visible
in Reflections is on by default.
To make objects in the scene accurately
reflect the objects in the background image
- Assign a Blinn or Phong material
(for example) to the stand-in surfaces. Do not use a Use
Background material.
- Map a File projection
texture to Color—right-click
the File texture to select Create
as projection when applying the texture in the Create
Render Node window, or if importing a file, select As
Projection from
File > Import.
- Map the background image to the Image attribute,
set Proj Type to Perspective,
and set Link To Camera to the camera
with the background image.
The stand-in surfaces
now have the same color as the objects in the background image they
represent and the objects in the scene accurately reflect the objects
in the background image. However, it also means you have to illuminate
the stand-in surfaces properly to make them look identical to the
objects in the background image that they represent.