User Manual

Table Of Contents
Fit Method
The Fit Method determines how the projection is fitted within the projection cone.
The first thing to know is that although this documentation may call it a “cone,” the Projector 3D
and Camera 3D nodes do not project an actual cone; it’s more of a pyramid of light with its apex
at the camera/projector. The Projector 3D node always projects a square pyramid of lighti.e.,
its X and Y angles of view are the same. The pyramid of light projected by the Camera 3D node
can be non-square depending on what the Film Back is set to in the camera. The aspect of the
image connected into the Projector 3D/Camera 3D does not affect the X/Y angles of the
pyramid, but rather the image is scaled to fit into the pyramid based upon the fit options.
When both the aspect of the pyramid (AovY/AovX) and the aspect of the image (height *
pixelAspectY)/(width * pixelAspectX) are the same, there is no need for the fit options, and in
this case the fit options all do the same thing. However, when the aspect of the image and the
pyramid (as determined by the Film Back settings in Camera 3D) are different, the fit options
become important.
For example, Fit by Width fits the width of the image across the width of the Camera 3D
pyramid. In this case, if the image has a greater aspect ratio than the aspect of the pyramid,
some of the projection extends vertically outside of the pyramid.
There are five options:
Inside: The image is uniformly scaled so that its largest dimension fits inside the cone.
Another way to think about this is that it scales the image as big as possible subject
to the restriction that the image is fully contained within the pyramid of the light.
This means, for example, that nothing outside the pyramid of light ever receives any
projected light.
Width: The image is uniformly scaled so that its width fits inside the cone. Note that the
image could still extend outside the cone in its height direction.
Height: The image is uniformly scaled so that its height fits inside the cone. Note that
the image could still extend outside the cone in its width direction.
Outside: The image is uniformly scaled so that its smallest dimension fits inside the
cone. Another way to think about this is that it scales the image as small as possible
subject to the restriction that the image covers the entire pyramid (i.e., the pyramid is
fully contained within the image). This means that any pixel of any object inside the
pyramid of light always gets illuminated.
Stretch: The image is non-uniformly scaled, so it exactly covers the cone of the
projector.
Projection Mode
Light: Projects the texture as a diffuse/specular light.
Ambient Light: Uses an ambient light for the projection.
Texture: When used in conjunction with the Catcher node, this mode allows re-lightable
texture projections. The projection strikes only objects that use the catcher material as
part of their material shaders.
One useful trick is to connect a Catcher node to the Specular Texture input on a 3D
Material node (such as a Blinn). This causes any object using the Blinn material to
receive the projection as part of the specular highlight. This technique can be used in
any material input that uses texture maps, such as the Specular and Reflection maps.
Chapter – 80 3D Nodes 1688