Variables

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.

Main

These will alter settings about how and in what way 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.

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

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.

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

Wind

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

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.

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.

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