Taking a look at how to get a UV Coordinate render pass out of V-Ray in Maya, Timothy Hanson shares two techniques which use the V-Ray Render Elements. In actuality the UV Coordinate pass is not one that is listed in the render elements in V-Ray, but one that can easily be obtained from the ExtraTex.
two methods for creating a UV coordinate pass using the “Extra Tex” render element in Vray for Maya
Timothy shows how to set each up, making the proper connections in the Connection Editor. While both techniques use the V-Ray ExtreTex Render Element, Timothy shows one method using Maya’s Sampler Info node, and then shows a different process using the 2D Place Texture Node. There really is no visible difference in results between using the Sampler Info Node versus the 2D Placement Node, so it would be just a matter of personal preference.
Be sure to check out Timothy’s MaxDepth site for more great Maya and Rendering tutorials here.