Seeing the POV of a light

One exercise that is used in painting classes is to give students a non-flat surface, and an origin point of light, and asking them to decide how a shadow would be cast by that light.

Direct and indirect light

When light waves travel to your eyes they aren't combining along the way, they are still individual waves of blue and red, etc, which is how we can again split them up with a prism. The perception of two colors mixing is entirely in the human eye.

To be clear, unless you are illustrating the point of view of night vision goggles, infrared cameras or some alien being, in other words - things that see different areas of the light spectrum that we do.

The weird thing about direct VS indirect lighting is that they shouldn't really even be considered different things. It is simply easiest to divide them that way. It's easier to tell someone to make the side of an object facing the light to be bright than the side facing away from it.

Opaque an antonym for translucency or transparency, you can't see through opaque objects.

Light picks up the properties of the surfaces it bounces from and passes through. These two things are not that different. If light picks up a color in the atmosphere, it's because the light is bouncing off the particles in our atmosphere, this is similar to when light bounces off a hard, opaque surface and continues to your eye. It's one single particle changing the degree it vibrates at based on what it collides with, that's all.

But it does change with every bounce.

If you are seeing an object, there is light hitting it and bouncing off to your eyes.

Shadows & Highlights

One key rule when adding highlights, where an objects gets brighter, and shadows, where there is less light hitting an object, is to not use white and black.

Let's look at a quick example.