Ue Uds Clouds

UDS clouds

UDS renders clouds via one of four mutually exclusive systems plus a shared movement/wisp/light-ray layer. This skill covers each system's settings, the cloud painter, the light-ray effect, and the looping/troubleshooting recipes. For which cloud mode to choose, see ue-uds-setup-and-modes.

When to use this skill

• Tuning the look (altitude, scale, density, color, second layer) of any cloud type.
• Cutting cloud-rendering GPU cost.
• Painting localised cloud coverage (gaps over mountains, clouds in a basin).
• Authoring a custom cloud shape profile, or generating a custom static cloud texture.
• Configuring volumetric cloud light rays (god rays through cloud gaps).
• Making the clouds loop seamlessly for a film render.
• Diagnosing dark clouds, hard mesh intersections, blurry-when-moving, or in-layer artifacts.

Volumetric Clouds

Richest and most expensive cloud option. Category: Volumetric Clouds.

Authoring custom cloud shape

The Cloud Profile Authoring Tool generates the Cloud Profile LUT texture UDS samples for cloud shape.

• Launch: Ultra Dynamic Sky dropdown on the level editor toolbar, or run the editor utility at Blueprints/Tools/.

Volumetric Cloud Painter

Paint local cloud coverage on top of the global Cloud Coverage value. Carve gaps over a mountain, or paint clouds into a basin.

• UDS must be in the scene with Sky Mode = Volumetric Clouds.
• Launch: Ultra Dynamic Sky dropdown on the toolbar, or the editor utility in Blueprints/.
• Painting data is held in UDS Cloud Paint Container actors. One level can hold many; the painter creates a new one or opens an existing one.

Painter UI:

Container resolution / mapping to the cloud coverage render target is configured on UDS in the Volumetric Cloud Painting category.

// Switching active container at runtime:
ContainerA.Deactivate()
ContainerB.Activate()

Volumetric Cloud Light Rays

When the cloud layer has a gap (painted or just low coverage), UDS renders distant light rays through it. Category: Volumetric Cloud Light Rays (enabled by default).

Rays are giant additive cards driven by a Niagara system — not volumetric fog and not screen-space light shafts.

• Adjust color and spacing of ray cards.
• Individual Cloud Light Rays — also casts rays through gaps in overall high-coverage formations (not just painted gaps). Can render many more ray cards; cost rises significantly.

2D Dynamic Clouds

Panning 2D textures on the sky sphere. Category: 2D Dynamic Clouds.

These are a material effect on the sky sphere — they don't exist in 3D space. Cloud Height is fake-perspective distortion in the sky material, not real altitude.

Advanced dropdown: distribution settings (concentrate around horizon, reduce around the moon, etc.).

Perf: enabling One Cloud Layer reduces sky shader cost (already on at Low material quality).

Static Clouds

Static texture with multiple lighting angles packed in, approximating lighting changes as sun/moon move. Category: Static Clouds — swap texture, control rotation.

Static Clouds Authoring Tool

Generates a new static clouds texture by rendering UDS's volumetric clouds.

• Launch: Ultra Dynamic Sky dropdown on the toolbar, or the editor utility at Blueprints/Tools/.

Voxel Clouds

Hard cubic voxel rendering style; internally an alternate renderer for Volumetric Clouds. Category: Voxel Clouds holds voxel-specific settings, but most cloud settings come from the Volumetric Clouds category (textures, altitude, colors). Affected by the Volumetric Cloud Painter and Radial Storm local coverage.

Cloud Movement

Category: Cloud Movement — controls movement of Volumetric Clouds and 2D Dynamic Clouds.

Seamless looping (for film renders)

The loop requires the cloud formation texture to complete one full 0–1 UV cycle. Steps:

In Cloud Movement:

• Cloud Speed = 0 (drive time via Cloud Phase).
• Cloud Direction along a single axis (0, 90, 180, or 270).
• Formation Change Speed = 1 (or 0.5 → loop twice as long).

In Volumetric Clouds:

• 3D Noise Scale = 1.
• Cloud Formation Texture Scale = 1.
• Macro Variation = 0.
• 3D Noise Vertical Movement = 0.

// Keyframe in Sequencer:
CloudPhase: 0 → 100   (loops seamlessly)
// (Or with Formation Change Speed = 0.5: 0 → 200)

Cloud Wisps

High-altitude wispy layer rendered as a static texture on the sky behind every Sky Mode except Space. Category: Cloud Wisps.

How it works: samples a grayscale texture (R channel only) and applies a wisp color that varies with time of day. Opacity is scaled by two Cloud Wisps Opacity settings — one for low cloud coverage, one for high.

• Cloud Wisps Texture — swap. Keep grayscale.
• Movement effect (default on) warps the texture over time with cloud direction, fading with an offset mapping to create a seamless loop.

Runtime / Blueprint control

// Active properties — set directly, cache picks up automatically:
UDS.CloudCoverage = 0.8   // (use UDW instead if present)
UDS.CloudPhase    = 47.5
UDS.CloudSpeed    = 0.3
UDS.CloudDirection = 90

// Container actors (Cloud Painter data):
ContainerA.Activate() / ContainerA.Deactivate()

For static cloud properties (texture swaps, noise scales, etc.), call Static Properties - Volumetric Clouds (or the relevant category function) after changing the variable; or Hard Reset Cache for a complete refresh. See ue-uds-performance-mobile-troubleshooting.

Performance

Gotchas

• Volumetric clouds look dark/gray — usually the directional light. If using Custom Sun/Moon Light Actor, copy Cloud Scattered Luminance Scale exactly from UDS's built-in component (UDS can't set this on a custom actor). Otherwise it's a leftover directional light in the level that wasn't removed before adding UDS.
• Hard mesh intersections — default rendering mode prioritizes background quality. Switch Volumetric Cloud Rendering Mode to a mode that prioritizes Mesh Intersections.
• Clouds blurry/streaky when moving fast (e.g. time-lapse) — default mode resolves with a long history trail. Switch to any other Volumetric Cloud Rendering Mode.
• Translucent materials render in front of clouds — on the material → Translucency settings → enable Apply Fogging and Apply Cloud Fogging. For some meshes also enable Compute Fog Per Pixel (otherwise cloud fogging is per-vertex).
• Banding/noise inside or above the layer — defaults tuned for ground viewing. Raise View Sample Count Scale (costs perf), lower Tracing Max Distance (two settings: inside/outside layer), adjust Close View Sample Ratio.
• Moving the UDS actor to change altitude — wrong; use Bottom Altitude.
• Setting Cloud Coverage on UDS has no effect — UDW is in the scene. Set on UDW's weather state instead.
• Voxel mode looking for unique settings — most live in Volumetric Clouds, not Voxel Clouds.

References & source material

Docs (Ultra Dynamic Sky 9.5):

• Volumetric Clouds
• 2D Dynamic Clouds
• Static Clouds
• Voxel Clouds
• Cloud Movement
• Looping the Volumetric Cloud Movement (for cinematics)
• Cloud Wisps
• Painting Volumetric Cloud Coverage (Volumetric Cloud Painter)
• Volumetric Cloud Light Rays
• Common Issues — Volumetric Clouds

Plugin asset paths:

• Blueprints/Tools/ — Cloud Profile Authoring Tool, Static Clouds Authoring Tool, Volumetric Cloud Painter editor utility
• UDS_LevelData/ (created next to the level) — saved cloud paint cell textures
• Materials/ — UDS_VolumetricClouds_MPC parameter collection (used by cloud fog / cloud shadow materials sharing properties with the visible clouds)

Related skills: ue-uds-setup-and-modes, ue-uds-fog-and-atmosphere, ue-uds-cinematics-rendering, ue-uds-lighting-and-shadows, ue-uds-performance-mobile-troubleshooting.