I have created artwork in Photoshop CS6 that includes an alpha channel (isolating the artwork shape from the background). I have imported the PSD file into AE CS6 and as a layer assigned it to be 3D. Under the Geometry Options for that Layer, only Curvature and Segments appear. There is no choice for Extrusion Depth. I would appreciate any advice as to what I am doing wrong. The software has all the lateste updates, using OS X 10.8.2. Note: I have saved the PSD both as flattened as well as with all the layers, which still produces the same result.
You can only extrude text layers and shape layers with the ray-traced 3D renderer.
Use Layer --> Auto Trace to produce a mask, copy&paste it to a shape layer and extrude that.
Thanks Mylenium. I performed the process you described and successfully created the mask, pasting it into a new Shape Layer. In that layer is a control for Extrusion Depth, however nothing happenes when adjusted. Is there something else I need to do? A related question; is it even possible to place artwork created in Photoshop into a Shape Layer? Thank you again.