I’ve seen balls used in digital art video tutorials that show the direction of light, but what’s the point of them? Jason Treadwell, US
Those balls help an artist to paint the light correctly in an image. Sometimes it’s easy to forget where the light is coming from, especially on a large image with lots of elements, which requires you to zoom in to work. Placing one of those balls next to your image means you’ll always be reminded where the light is coming from – as long as you remember to refer to it, of course! You can also use the ball as a palette for picking the right colours every time, or even treat it as a base to start your painting in some cases.
To create one of these balls, you just need to use a circular selection to create a circle, fill it with a base colour, and then add the lights with the Gradient tool or a brush if necessary. You can (and should) also add any secondary light source, or paint the light on the ball according to the material you’re going to paint.