Cloud Materials

Cloud materials paint a moving sky of clouds onto a surface in your scene. Put one on a large flat plane or a backdrop and it becomes a window onto drifting clouds; the clouds form, thin out and slide past over time. There are nine presets, all built on the same sky clouds look: Bright, Sunset, Dawn, Silver Lining, God Rays, Stormy, Overcast, Wispy and Dramatic. They differ in colour, how much of the sky is covered, how soft the clouds are, and which lighting effects are switched on.

How the cloud materials work

The clouds are generated, not photographed. Three layers of smooth noise at different sizes are stacked, so each cloud has a large overall shape, smaller lumps and fine detail at its edges. The pattern scrolls slowly in the wind direction, and each layer moves at its own pace, so the clouds change shape as they travel instead of sliding by as a flat picture.

A few things to know when placing them:

• The clouds fade out toward the edges of the surface, so they blend into the background instead of ending at a hard border. A big plane behind the scene works best.
• Even the thickest cloud stays partly see-through, so whatever colour or sky is behind the surface shows through the gaps and the edges.
• The surface is drawn behind everything else, so every other object in the scene always sits in front of the clouds.

The lighting is drawn from a sun position set in the material. Edges that face the sun can get a bright rim, the thin parts of each cloud can fall into a shadow colour, and light shafts can break through the gaps toward the sun.

Settings

The studio shows these settings for each cloud material:

• Cloud Coverage: how much of the surface is cloud. Low values leave scattered puffs over a clear sky; high values close into overcast.
• Cloud Scale: the size of the clouds. Higher values give more, smaller clouds.
• Softness: low gives sharp-edged, cotton-ball clouds; high gives a diffuse haze.
• Wind Direction: which way, and how fast, the clouds drift.
• Cloud Color and Ambient Color: the sunlit colour and the shadow colour.
• Silver Lining: the bright rim on edges facing the sun.
• Self Shading: how strongly the thin parts of each cloud shift to the shadow colour. It grows the higher the sun is.
• God Rays: light shafts through the gaps, strongest close to the sun.
• Storminess: darkens the clouds, thickens them and adds a turbulent, churning distortion.
• Bloom Intensity: pushes the bright edges past white, so they glow when Bloom post-processing is on.

Choosing a preset

For a calm daytime backdrop, start with Bright or Wispy. For warm evening or early morning light, use Sky Clouds Sunset or Dawn. For a cinematic scene with light breaking through, use Sky Clouds God Rays, Silver Lining or Dramatic. For bad weather, Sky Clouds Stormy or Overcast.

These materials put clouds on an object of your choice. To fill the whole sky of a scene, use the environment's own clouds instead.