How can I make an object invisible when I render in Cycles?

Question

Using the Cycles Render Engine How can I make an object invisible when I render?

Answer 1

These are some of the options to make an object not render in Cycles.

To make the object invisible/unrenderable

• Disable the object for rendering (turn off the camera icon)

  

• Move the object you don't want to a layer that is not renderable

  

• Give it a transparent shader:

  

To make the object invisible to camera but keep the shadows and interaction with other objects (reflections, etc)

• Restrict the visibility for camera:

  

• Using Nodes: use a light path so the object is invisible to the camera only:

  

To make the object transparent as alpha channel:

• use a holdout shader so it renders as transparent

  

• Place the object on a different layer and use that layer as mask:

  

• Use a Pass index for the object and use that on the compositor to subtract the object from the final render:

  (click on the image to enlarge)

• Similarly, you can assign a pass index to the material and use that as alpha on the compositor:

  (click on the image to enlarge)

For the last three options the Transparent Background option has to be enabled: