This is probably the wrong forum but Revit is the piece I deal with materials most: The material editor window offers a variety of scenes to get an idea of the looks of what you are setting up. Picking the wall scene provides a chair for scale reference, the cloth scene seems to be about table height. Using the plane or the canvas however I miss some scale reference. How about a trivial dimension line giving us say three feet or a metre?
If given a hint, where to find the preview scene geometry, I would happily add it myself.
