All artists need a solid foundation in drawing to understand form and represent it realistically in 3D. Training your eyes and hands in basic forms will prove valuable, as all objects can be reduced to one of four basic forms: sphere, cube, cylinder, or egg.
Each form has five distinct planes, or surfaces: light, halftone or midtone, shadow, reflected light, and highlight. Each form also creates a cast shadow onto a nearby surface. You can represent each of these planes by varying the value of your drawing medium or paint.
VALUE REFERS TO THE LIGHTNESS OR DARKNESS OF A COLOR OR OF BLACK. VARIATIONS IN VALUE CREATE THE ILLUSION OF FORM ON A THREE-DIMENSIONAL SURFACE. ACCURATELY REPRESENTING AN OBJECT’S VALUE PATTERN ...