Keyframes Layers trueSKY Actor

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This list of variables is grouped by how they affect the clouds, along with where they are located. Variables in the Red tables are located on the Keyframe, Green are in the Layer and Blue variables are on the trueSKYSequenceActor.


These setting will alter setting about how and in what are the clouds are generated, as there are variables such as the ray-tracing methods used, the area which they are created within and the resolution at which they are rendered.

Variable Definition Value
Cloudiness How much cloud in the cloud layer. 0.0 to 1.0
Cloudbase Base altitude of cloud layer, in km. -1.0 to 20.0
Layer Height Height of cloud layer, in km. -1.0 to 20.0
Volume Width Width of cloud layer, in km -1.0 to 20.0
Variable Definition Value
Class How the renderer should raytrace Clouds. If you want a layer of Whispy Clouds, set this to Cirrus Standard = 0, Cirrus = 1
Default Slices Number of slices in main view. Between 80 and 255
Grid Width The Grid clouds are rendered on when using the Grid Integration Scheme. Lower values produce better Quality. Powers of 2 between 16 and 512
Grid Height Height of the Cloud Grid Powers of 2 between 1 and 64
Precipitation Grid Divisor X A Divisor againt Grid Width to specify the size of the precipitation volume. Powers of 2 between 1 and 1024
Precipitation Grid Divisor Z A Divisor againt Grid Height to specify the size of the precipitation volume. Powers of 2 between 1 and 128
Variable Definition Value
Max Cloud Resolution Resolution of clouds, ideally in powers of 2. Recommended values of 512 or 1024 128 to 4096
Max Cloud distance Distance of furthest cloud layer. 100.0 to 500.0
Render Grid X Detail size of grid used to render clouds. Smaller grid means higher quality clouds. 0.01 to 10km
Render Grid Y Detail size of grid used to render clouds. Smaller grid means higher quality clouds. 0.01 to 10km
Default Num Steps Approximate number of raytrace steps. 40 to 300
Amortization How rendering clouds is spread over frames. For 1, all pixels are drawn every frame, for 2, its 2x1, 3 for 3x2 etc. 1 to 8
Cloud Threshold Distance A heuristic distance to discard near depths from depth interpolation, improving accuracy of upscaling. 0.0 to 10.0
Depth Sampling Pixel Range The size of the sampling area, in pixels, in the full-resolution depth buffer. Used to find near/far depths. 0.0 to 4.0
Depth Temporal Alpha The alpha for temporal blending of the solid depth buffer used for cloud rendering. 1.0 is instant. 0.01 to 1.0
Integration Scheme Which method to use for grid rendering. Fixed is good for static, fluffy clouds. Not recommened for flying through Grid or Fixed
Depth Blending If trueSKY should blend clouds with scenery, or draw them in front/behind depending on altitude. Bool
Share Buffers for VR Share Buffer for VR. Bool


Shape values alter the general look of the clouds, such as how transparent the cloud is. If you have unusual looking clouds or incorrect artefacts, these are the setting to investigate.

The clouds are made up of a base layer, a transition area and the upper layer.

Clouds are thicker on the bottom, so the base layer is almost always the largest, and the transition area is where the base and upper layers meet.

The upper density is a multiplier for the amount of clouds in the upper layer. A value of 1 will produce the same amount of clouds as the base layer.

There are individual settings to help customise each of the different layers, allowing you to create unique but realistic clouds.

By default, the cloud volume repeats at the edges, and the volume width is controlled by the keyframe value Cloud Width. You can change the size of this volume freely, but to increase the size while retaining the same level of detail, you will also need to modify the size of the volumetric grid. For example, to double the size of the volume, select all the 3D cloud keyframes, and double the size of Cloud Width. Select the cloud layer, and increase both the Cloud Grid Width, and the Generation Noise Resolution, by a factor of two.

Variable Definition Value
Max Density Maximum density of the cloud layer. 0.0 to 1.0
Local Density Current density of the clouds. Not Editable, calculated from other densities. 0.0 to 1.0
Base layer Density of clouds in the lower layer. Clouds are always denser at the lower portions of the clouds, so this can also act as Max Density 0.0 to 2.0
Transition Density of middle layer of clouds - the transition from cloudbase to upper cloud. 0.0 to 1.0
Upper Density Density of clouds in the upper layer. 0.0 to 1.0
Worley Noise How much Worley noise to apply. 0.0 to 1.0
Worley Scale Scale of Worley noise. 0.0 to 12.0
Diffusivity How much cloud edges should be diffused. 0.0 to 1.0
Persistence Fractal persistence for generating clouds. 0.0 to 1.0
Octaves Number of noise octaves to generate clouds. 1 to 5


Using Wind to create a dynamic sky and moving shadows is an effective way to make an environment feel alive. There are different ways to shift the clouds, however for clouds to move the time must be progressing. Learn how to control time here.

To control the movement of the clouds you should use the Cloud Window.

For one keyframe you should select the position of the clouds, then create a new keyframe and select the new position. Then the clouds will move between the positions.

With the 4.3 update you can now choose which method to control your cloud movement via wind. To do this navigate to your cloud layer - and un-check the “manually position keyframe” check-box. This will allow for wind direction (set within the trueSKY actor within the scene) to control and move the clouds location.


Noise is the best way to make sure your clouds don’t look too flat or repetitive. Values in noise are very sensitive and can produce unusual results if you’re not careful.

Variable Definition Value
Base Factor Proportion of noise applied at cloudbase. 0.0 to 1.0
Amplitude Strength of fractal edge effect. 0.01 to 100.0
Worley Amplitude Wavelength of fractal Worley noise. 0.1 to 10000.0
Sharpness Sharpness applied at boundary. 0.0 to 1.0
Churn Strength of cloud edge churning effect (larger values = more turbulent clouds). 0.001 to 1000.0
Variable Definition Value
Noise Period Fractal noise period, in days. 0.001 to 1000.0
Noise Phase Phase of the cloud-generation noise texture 0 to 2pi
Noise Resolution 3D Perlin noise resolution, for cloud generation. Powers of 2 between 4 and 64
Variable Definition Value
Edge Noise Persistence Persistence for edge noise texture. 0.0 to 1.0
Edge Noise Frequency Frequency of edge noise. Powers of 2 between 1 and 16
Edge Noise Texture Size Size of edge noise texture. Powers of 2 between 4 and 64
Edge Noise Wavelength Wavelength of the edge noise. (Great for hiding Grid Patterns) 0.1 to 100
Cell Noise Wavelength Wavelength of Cell Noise. 0.1 to 100
Cell Noise Texture Size Size of cell noise texture. Powers of 2 from 16 to 256
Max Fractal Amplitude Strength of edge noise effect. 0.1 to 10

Cloud Shadows

Clouds Shadows will affect the ground below the clouds, as well as other cloud layers. Shadows are automatic and require no extra setup.

Variable Definition Value
Shadow Range Range of cloud shadow texture, in km. 0.5 to 200.0.
Shadow Texture Size Size of cloud shadow texture. Powers of 2 between 32 and 2048.
Shadow Strength Amount of shadow produced. Large values can produce obvious edges if the resolution is too low. 0.0 to 1.0
Cloud Shadow RT Render texture that is used to draw cloud shadow texture at runtime Render Texture

God Rays

Variable Definition Value
Crepuscular Ray (God-Rays) Strength Strength of god-ray effect. 0.0 to 1.0
Crepuscular Grid Grid size for God-rays. X, Y, Z. 8 to 256