As one of the inaugural videos for The Artists Guild, this very simple demonstration shows how to make a flat surface seem dimensional—the quintessential problem in realist painting. David deliberately does a very basic explanation for beginners in how to create form.
When painting the form shadow on the side of the tangerine, David explains a prevalent optical illusion where the shadow on the shoulder meets the body of the tangerine—it appears concave instead of convex. For dramatic effect he paints the shape of the light very flat. At first, it seems as though it will be impossible for David to transform it into a three-dimensional object. But with some subtle manipulation of the brush he drags the light into the shadow to remove the hard edge as a place of focus and the tangerine looks real.
David explains how interior and exterior edges work to create form. Another device involves changing the value of the background next to the object.
This video is deceptively simple but goes to the heart of the problem of creating form on a flat surface, which is making three-dimensional form on a two-dimensional surface. David ends with an image of a finished painting where he carries this concept to completion.