Fantastic Fog

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It's a summer morning.

You get out of bed. You shuffle to the window, open the blinds.

Sunlight pours in. You can see it in the air.

But how? How can you see the light?

That's the power of fog. It lets you see light, and shadows, in the air.

"Fog" can be many different things. It could be dust in the air. It could be smoke. It could be steam, or mist, or clouds. All of these fill the air with tiny particles.

Millions of them.

When you turn on the light, or open the window, the light hits all those particles and bounces off in crazy directions. And you see it as "beams" of light.

Adding fog to a 3D scene does 2 things.

• Adds depth. Even a light amount of fog adds an amazing sense of depth. The further away something is, the harder it is to see (because of the fog.) This mimics the way real life works (especially for outdoor scenes.)

• Makes it feel cinematic. Adding fog, even if it's very subtle, highlights your lighting work. Softens things. Professional movies make heavy use of fog.

Fog makes a huge difference. Here's what the same scene looks like with no fog:

All I did was delete the fog. Nothing else.

Way better with the fog, right? The fog adds a sense of atmosphere. Builds depth.

It does makes the sphere slightly harder to see—that's because I went with really heavy fog in this scene.

Now you know what it does. And why.

Let's learn how to make it.

The first thing you need is a light.

Any kind of light will work. It depends what kind of scene you have. In my experience, fog works best with sunlight.

There's 2 great ways to make sunlight.

The first one is a Sun light. A Sun light illuminates the entire scene with light from 1 direction. These are great when you have a large area to illuminate, like a nature scene.

For the render above, I used an Area light.

An Area light is like a plane that emits light in 1 direction. You can rotate it to point it at different things.

You can also adjust the Size of the Area light to control how soft it is:

• Smaller Size = tighter beam with shaper shadows.

• Larger Size = wider beam, softer shadows.

The light is this render is using a Size of 0.001 and a Power of 2500.

Once you have a light, you need something for it to shine through.

In real life, light is always coming through something:

• A lamp shape

• A window

• Blinds

• Jail bars

• Leaves

When you let your light trickle through something, it makes patterns and shapes that add a lot of visual interest to your render.

In the render above, I just cut 4 holes in a wall to make a window-shaped cutout.

Now you have a light. And something for it to trickle through.

Time to add the fog. This is really the easy part.

• Add a cube to the scene. This will be the fog—think of it like a big "brick" of fog.

• Scale the cube so that it fills everywhere you want fog. In the example above, my fog cube was slightly bigger than the whole room.

• Give it a new material, and name the material "Fog."

• Delete the Principled node.

• Add a new Principled Volume node.

• Connect it to the Volume socket on the Output node. <- This is very important!

Now switch to rendered view (Cycles works best) to see the fog!

It's way too thick by default, so change the Density on the node to a tiny number, like 0.01. Another thing you'll need to tweak is the strength of your lights—you might have to make them stronger or weaker to get the fog looking just right.

It's always better to have too little fog than too much.

You now have fog! Great work.

You just learned:

• What fog does for a scene

• How to best set up a light for fog

• How to make fog

And it wasn't that hard!

Have a great week. I'll see you again next Monday!

P.S. (unrelated) Love reading fiction? Check out Voyage. You get a new, original piece of short fiction every other Friday. (And it's totally free.)

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