Welcome to part one of my value tutorial. The idea is to convey the proper knowledge of how to apply value correctly to a scene or object. I've covered what value is and what makes it so important in a previous post, so I recommend you go and check that out if you're a bit lost as to what I'm talking about here. So let's start at the beginning, value at it's core is the effect of light. So what, specifically, is light in the first place?
The best way to approach understanding of painting is the break things down to their basic and simplest form. I'm not going to present this information in a hugely scientific way, more in a general, easy to digest fashion, simplified purposefully for artists to understand in a functional way. Light is electromagnetic radiation that consists of photons, tiny particles that move in a (most commonly) linear fashion. Light sources will emit rays (think of tiny little laser beams) outward, and those rays will either decay, be absorbed by the environment, or bounce off.
For this tutorial, we're going to be covering light from a VALUE point of view, as opposed to colour. We'll cover colour at a later stage, and take the opportunity to reiterate on some knowledge.
At it's most basic, Light reacts to surfaces in three different ways...
When light hits a surface, part of it bounces off and is reflected into the atmosphere. The intensity of the reflected light depends on the material properties of the surface. For example, a matte surface such as clay reflects very little light, while polished metal reflects it with far more clarity, albeit distorted by the form depending.
Refracted light consists of light rays being distorted and bent through transparent or translucent surfaces. This causes objects seen through that surface to appear fractured or displaced. This is what happens when you look through a glass of water. Rainbows are also the result of light being reflected and refracted through water droplets, projecting the spectrum of light into the sky. Note also that while the image shows the light bending, the degree of it depends on the properties of the material.
Point light is a source of light that emits from a given location, such as a light bulb, torch of fire. As light radiates from the source, shadows become relative to the point of light. Point lights are also more likely to show decay, or falloff. As you get further from the light source, the environment is less affected by the light.
Due to the size of the Sun relative to our planet Earth, light casts on the environment in rays that are perceivable parallel to each other. Light either reaches Earth unhindered, or is distorted and diffused by clouds. This causes overcast weather, and makes light appear flat and dull. While it becomes more difficult to render the form, overcast light can add drama to an image narrative.
A little bit above, we talked about reflected light. This is light that results from the effects of that reflected, or bounced light. As each ray strikes a surface, it will bounce off at roughly a perpendicular angle to it's point of contact. This light will then continue bouncing until reaching complete decay (or falloff). This will continue to illuminate surfaces, objects and environments until the light no longer carries any strength. Keep in mind that bounce light in isolation will never be stronger than the primary light ray. As a result of this, reflected light on an object, while lighter than the core shadow (terminator), should never be lighter than the light side of an object. That is to say, the sides of an object that are exposed to and facing the light source will ALWAYS be lighter in value than the shadow side, reflected light included.
That covers the basics of light for now. Next time we'll look at some examples of these effects happening and some ways to apply them to value painting. In the meantime, take a look around and see if you can spot these effects going on in the real world. Observe light and colour bouncing off objects and hitting something else, or how a glass of water will make a straw appear distorted. As always, have fun observing your surroundings and applying light knowledge to them, and keep learning. Thanks for reading! Onward to part 2!!