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When running IPR in "It", objects or their materials can easily be selected from the render.  Click on one of these icons in "It" to activate object or material picking.  Then click in the render.  The corresponding object or material will become selected in Maya.

Hidden Objects

When rendering to IPR, templated nodes are pruned from export but hidden objects are not (in case you wish to unhide them interactively). During a batch render, both hidden and templated nodes are pruned from export

The preference called "Prune Invisible Nodes" which applies during IPR can be found in the render settings.  By default, during IPR invisible nodes are not pruned, to allow for easily changing visibility interactively. You can find this in Preferences > RenderMan > IPR

Crop Rendering in It

To crop render in "It" during IPR, click on the crop button.

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