uds-clouds

name	uds-clouds
description	Configure clouds in Ultra Dynamic Sky — Volumetric, Static, 2D Dynamic, Voxel clouds, plus Cloud Movement, Cloud Wisps, the Volumetric Cloud Painter, Volumetric Cloud Light Rays, and the Cloud Profile Authoring Tool. Use this skill any time the user mentions clouds in UDS — appearance, altitude, scale, performance, second cloud layer, painting coverage, hard mesh intersections, blurry/streaky when moving fast, looking dark, custom cloud shapes, cloud direction/speed, looping clouds, the wispy high-altitude texture, light rays through clouds, or making a custom static cloud texture. Trigger even when the user just says "the clouds" without naming the system.
metadata	{"asset":"Ultra Dynamic Sky (marketplace)","category":"clouds","source-docs":"https://www.ultradynamicsky.com/Documentation/V9/9-5"}

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 uds-setup-and-modes.

Sky Mode	What it draws	GPU cost	Notable per-mode tool
Volumetric Clouds	Full 3D clouds, real shadows	Heaviest	Volumetric Cloud Painter, Cloud Profile Authoring Tool
Static Clouds	Static texture with packed lighting angles	Cheap	Static Clouds Authoring Tool
2D Dynamic Clouds	Panning 2D textures on the sky sphere	Cheap	—
Voxel Clouds	Hard cubic voxel render of Volumetric Clouds	Heavy	Same tools as Volumetric Clouds

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.

Setting	What it does
Volumetric Cloud Rendering Mode	Exposes r.volumetricrendertarget.mode. Each mode prioritizes a tradeoff — Performance, Quality, Mesh Intersections, Long Trail, etc.
Bottom Altitude	Cloud layer height. Use this, not actor translation (which breaks atmosphere/fog).
Volumetric Clouds Scale	Uniform scale of the cloud field
View Sample Scale / Shadow Sample Scale	Sample counts. Lower = cheaper but noisier.
Max High Frequency Noise Levels	Detail when close/zoomed in. Cost scales with the High Frequency Noise Distance Scale.
Second Cloud Layer → Two Layers	Adds a second layer with offset. Requires much higher sample count; significant cost increase.

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:

Area	Function
Top bar	Brush: texture, strength, falloff, spacing
Viewport	LMB paint, RMB pan, MMB zoom (or buttons lower-right)
View modes (lower-left)	Three options; lock icon ties painter view to level viewport
Left side	Three coverage levels (red/green/blue) and erase (black)
Bottom	Save to Textures — commits painting to texture assets in UDS_LevelData/ next to the level

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.

Setting	Behavior
Cloud Speed	Overall speed
Cloud Direction	Degrees. UDW's wind direction overrides if UDW is in the scene.
Cloud Phase	Phase variable. Useful when Cloud Speed = 0; primary control for looping / keyframed movement.
Randomize Cloud Formation On Run	New random formation each play
Clouds Move With Time of Day	Keeps cloud movement synced when time speed varies (good for time-lapses)
Formation Change Speed	Used in seamless looping (see below)

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 uds-performance-mobile-troubleshooting.

Performance

Lever	Cost impact
Sky Mode (Volumetric → Static → 2D → None)	Largest GPU perf lever on the system
Volumetric Cloud Rendering Mode (use Performance variants)	Significant
View Sample Scale, Shadow Sample Scale (reduce)	Cheaper but noisier
Two Layers (off)	Big saving
Max High Frequency Noise Levels (lower)	Cheaper close-up
One Cloud Layer (on, for 2D Dynamic)	Reduces sky shader cost
Individual Cloud Light Rays (off)	Saves many ray cards

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