A mixture of cloth and wood is often used to create the illusion of a complete building: the Interior of a Palace (attributed to Bibiena), the Designs for Stage Scenery by Serafino Brizzi, and the Perspective View of an Interior by an unknown artist all provide good examples of this technique.
The Interior of a Palace would have required a solid wooden staircase. However, whilst the surrounding plinths would have been created by a painted canvas supported by a solid wooden structure, the columns and everything above them would have been painted onto a series of cloths, each cut to create the impression of arches.
In Brizzi's Designs for Stage Scenery, the area seen through the large arch stage-right would have been a hung cloth. The arch and stage-left part of the building would have been made from wood covered in canvas, and painted so the cloth and building blended together. Unlike the Interior of a Palace, the arch and stage-left building need to support each other and would have been solid from top to bottom. The diagram at the bottom of the drawing gives us clues about how the various wooden and solid parts of the scenery relate to each other.
The Perspective View of an Interior shows a detail of a cloth that might have been used at the top of a curved set. The illusion here would be a sense of height - as if looking up to a great ceiling. The solid base of the set (not shown here) would have been built in a semi-circle with the arc travelling up-stage and covered in painted canvas. The cloth shown in the drawing would have formed the continuation of that canvas; the correct curve being maintained with a shaped fly bar or track.
Canvas itself is also used as a floor covering and in this context is known as a stage cloth. It is stretched and tacked down along the edges and may of course be painted to mimic floorboards, tiles, flagstones, gravel, grass or any other real or imaginary surface.