Name: Painting Light and Form
Uploaded: 2025-04-26T05:04:33.000Z
Duration: 15 min 39 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Choosing the right type of light source can have a huge impact on the mood of our piece.

So how do these different types of light work?

Adverbs of manner

Light can be thought of as beams traveling outward from the light source.

So our light bulb will be emitting light in all directions.

Objects around the light bulb will be lit according to which plane is facing the light bulb.

Additionally, we have a concept called light falloff where objects further away from the light bulb will become exponentially darker.

If we double the distance of these cubes from the light bulb, they become dramatically darker.

Now you might be thinking, hold up a minute.

In the last lesson, the light was always just coming from one angle and you never mentioned light falloff.

But don't worry, the rules haven't changed.

If we zoom out to a cosmic scale, the sun is behaving exactly like our light bulb.

It's a spherical light source emitting light in all directions.

What's different is that the sun is unfathomably bigger, brighter, and further away from us than the light bulb.

Although the sun is emitting light in all directions, because of its size and distance, by the time we're looking at objects on earth, the light is, for all intents and purposes, traveling in a single direction.

Well, it does, just not on a perceptible level here on earth, because light falloff has to do with the brightness of the light source and the relative distance of the object to that light source.

In order for us to get even 1% farther away from the sun than we are, we'd have to travel about 930,000 miles.

In the first example, these cubes are about three feet away from the light bulb, and their lightest planes have a value around six.

If we double the distance of the cubes from the light to six feet, the planes drop to a value of two.

This gives us two important things to remember about light falloff.

First, light falloff is dependent on relative distance of the object to the light source.

This is all kind of technical, but we have to learn the rules if we're going to create convincing illusions of reality on our canvas.

With this understanding of the sun versus the light bulb, we've described two of the most important light sources we can use in our paintings to create the right kind of mood.

We can either use a strong, distant light source like the sun, which is very even and consistent in its direction and brightness, or we can use weaker and closer light sources, which have more varied direction and are subject to falloff.

Many paintings will use a combination of the two.

When we understand the properties of light, it becomes much easier to imagine how different light sources might work in our paintings.

For example, a flashlight is a very bright light source, so it can travel quite a distance before being affected by falloff.

Also, the light is blocked on all sides except the front-facing glass, so the beam expands outward as it travels.

Compare that to a candle, which is a weaker light source than a flashlight, so it'll fall off more quickly, but it travels in all directions and will light all nearby objects.

All this is to emphasize that no matter what kind of light source you're using, the rules of light always stay the same.

The main things we always have to consider are how bright is the light source, how close is the light source, and what direction is the light traveling in.

But there's one more parameter that we can throw into the mix, hard light versus soft light.

Let's return to the sun as our light source.

We know that it travels in one direction and creates hard-edged shadows, or hard light.

There's still plenty of light, but it doesn't seem to be coming from any one particular direction, and the shadows become very soft and subtle.

This is soft light, and it's the result of scattering.

In the previous lesson, we learned that when light hits an opaque surface, it bounces right off at the same angle.

When light hits a transparent surface, like air or glass, it's allowed to pass right through.

But when light hits a partially transparent surface, which we call translucent, some of it bounces off and some of it continues passing through.

Clouds are a translucent surface, so when light hits them, some of it is reflected normally and some of it passes through the surface, bouncing repeatedly and changing direction as it goes until it eventually reemerges back into the open air.

This means that by the time the sunlight reaches us on the ground, it's no longer coming from the direct angle of the sun, but rather from lots of different directions all at once.

In this scenario, we do still have a general lighting direction.

The light is coming from above because the sun is still above us, but it's also coming from our right, from our left, in front of us and behind us.

The result of this scattered lighting is that all of our shadows become very soft edged, hence the term soft lighting.

Remember how the softness of the form shadow on our planar sphere versus our smooth sphere was simply the number of transitional planes between them?

This is basically the same principle that causes soft lighting, except in this case, it's not the number of planes, but rather the number of light sources that softens the edges.

If we create one light source coming directly from above, we get the same hard shadows that we've seen before.

If we split this one light source into four light sources and spread them out, the form of the sphere is now being lit more evenly and we have four cast shadows.

If we split these light sources again to eight, the effect repeats.

The form shadow of the sphere is even more evenly lit and the multiple cast shadows begin to look like a soft edge.

If we repeat this process enough, we eventually have soft lighting and soft shadows.

Compare the hard light of our single light source versus the soft light of our scattered light source and you can clearly see the difference.

With hard light, the form has a very clear light side and shadow side and it casts a hard edged shadow.

With soft light, the form rolls almost imperceptibly towards shadows and may not have a true shadow side at all.

The cast shadow is also completely soft edged and fades seamlessly onto the form it's being casted onto.

This soft light, sometimes called ambient light, is what happens when light is scattered.

The sun's light is strong enough to pierce through the clouds, but it's scattered along the way so that by the time it reaches us, it doesn't seem to be coming from any one direction, just generally from above.

This kind of soft light also creates our final type of shadow, occlusion shadows.

These are soft dark shadows that appear where none of our scattered light sources can reach and they often occur where two forms are touching each other.

If we look at our simplified soft lighting with only four light sources, we can see four cast shadows from our sphere.

The shadows furthest away from the sphere are being lit by three of our four light sources, but as the shadows get closer to the sphere, we see zones that are only lit by two of our four light sources.

Even closer, there are zones only being lit by one of the four lights.

Finally, directly between the sphere and the floor, there is a zone where none of our four light sources can reach.

If we double our light sources to eight, this same effect occurs, but with more subdivisions.

If we repeat this enough, our shadow becomes very soft and subtle, except for the suddenly very dark area where the sphere and the floor touch.

If you find objects in your paintings are looking floaty or not really grounded, then they're probably lacking occlusion shadows.

Now, how do we make this a bit more practical?

We can't calculate these shadows, but if we understand how they work, we can approximate them.

The general rule to keep in mind is that occlusion shadows appear where it's difficult for light to reach.

Or think of an open doorway on a cloudy day.

There's no clear cast shadow, but the further into the doorway we go, the harder it is for the light from the outside to reach the interior.

Since the bricks protrude outwards, it's difficult for the light to reach in between them to the recessed grout lines.

There's lots of places occlusion shadows can occur, and they're not functionally different from cast shadows.

They're just the result of soft light rather than hard light.

Now, here's where things get a little bit tricky.

There'll be occlusion shadows in basically every painting that you do, even the ones primarily lit by hard light.

Because almost every realistic situation has both hard and soft lights involved.

Let's take a person outside on a bright, sunny day.

We know that the hard light of the sun will create hard-edged cast shadows, but there's also going to be soft light and occlusion shadows because there's a second softer light source, the sky.

This is the same kind of scattering that happened with our cloudy day.

It's just a much more transparent surface.

This scattering turns the sky into a gigantic, soft, blue light source.

If we look at a portrait with just the sun's light, we can see the hard form and cast shadows we'd expect.

If we look at the same portrait with just the sky's light, we see very soft shadows and occlusion shadows in the nostrils and lips.

When we combine the two, we get a more realistic impression of outdoor lighting.

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Painting Light and Form

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subtle

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