how to give volume to a shape or a character ?

It’s projected light onto the form which will give its relief. It’s a play of shadow and light. For a cube or another flat forms, it’s rather easy but how to to do for the round or oval forms ?

An exercise of the course of drawing DTO shows good how  the light works. Once we have understood it, we draw better a human body. Indeed, our body has no angle, but bumps and hollows, either for face,arm or other.

We find a very clear zone if the lighting is powerful (high light), a zone in light halftonewith a  board soft, a dark halftone,   then a zone with the reflected light, and the accent at the base. You do not have to forget the cast shadow of the shape.

A ball to explain the light and the shadow to do the form

The featured  image is of Scubadive67