From the help menu:

"3D files in Photoshop (Photoshop Extended)
The three-dimensional (3D) file support in Photoshop allows you to open and work with 3D files (.u3d, .3ds, .obj, .kmz, and Collada file formats) created by programs like Adobe® Acrobat® 3D Version 8, 3D Studio Max, Alias, Maya, and Google Earth.

Photoshop places 3D models on a separate 3D layer. You can use the 3D tools to move or scale a 3D model, change the lighting, or change render modes—for example, from solid to wireframe mode.

Note: To edit the 3D model itself, you must use a 3D authoring program.
You can add multiple 3D layers to an image, combine a 3D layer with two-dimensional (2D) layers to create a backdrop for your 3D content, or convert a 3D layer into a 2D layer or a Smart Object.

If the 3D file contains textures, they are opened with the file and appear as separate layers in the Layers palette. You can edit the textures using any of the Photoshop painting or adjustment tools, and then reapply the textures to the model and view the results.

Note: You cannot create new textures in Photoshop, or change how they are mapped to areas of the model.
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