Sketches can range from quick 15 minutes sketches to help convey an idea or they can be more detailed to assist with visualisation and birds eye view plans. Sketches can be elevation, perspective or isometric drawings that help to give depth to CAD plans as well as encourage new and inspirational ideas. All CAD concept drawings come with some form of sketches to help convey the ideas. Sketches can be drawn in the very beginning at the research stage before any CAD plans are drawn up and/or during the CAD plan development.