Purpose

Sky adds atmosphere and sunlight around a Scene. Clouds drift overhead, filtering the light and casting shadows across your objects.

Use Physical for weather, HDR for an environment image, Procedural for a simpler sky, or Solid for uniform colour.

Use

Place Sky under Geometry / Render and select it in the Sky field on Scene’s Collection page.

For a renderer in Local mode, select it on the renderer’s Scene page instead.

Start with Physical and choose Weather on the Sky page. Move Time of Day to change the sun’s position, the sky’s colour and the shadows. Adjust Coverage for more or fewer clouds.

For an environment image, choose HDR and connect it to hdr. HDR Rotation turns the image around the scene, and HDR Tint changes its colour. Leave Add Sun off when the image already carries its own sun.

Inputs and outputs

• hdr supplies a linear lat-long RGBA image for the HDR source.
• weather_map controls where Physical clouds form. Red sets coverage, green sets cloud type.

scene carries the environment and its sun. In TouchDesigner, selecting Sky on the Scene or renderer connects it. In a Lab graph, wire scene into a free object input on Scene.

Controls

• Weather chooses Clear, Fair Cumulus, Stratocumulus, Overcast or Storm. In TouchDesigner, choosing a weather fills in its cloud and haze settings. Adjust them afterwards for your own weather.
• Time of Day is local solar time in hours. Latitude and Day of Year on Advanced set when dawn and dusk happen. Sun Heading turns the sun’s path around the scene. To aim the sun directly, set Sun Position to Direction and use Sun Direction.
• Wind and Wind Direction move the clouds. Cloud Shadows sets how much they hold back the sunlight. Sun Intensity and Sky Intensity set the direct and scattered light.
• Meters Per Unit matches the atmosphere to your scene’s scale. Use 1 for metres or 0.01 for centimetres. Ground Height sets the planet’s ground level in scene units.
• Time Scale and Time Offset control cloud motion. Cloud time is scene time multiplied by Time Scale, plus Time Offset in seconds.
• Quality controls the steps through the clouds. Cloud Detail Quality chooses Fine, Medium or Coarse. Lower detail costs less and softens small wisps. For another speed control, use Sky Resolution on Realtime Trace’s Environment page.

Notes

Realtime Trace draws the Physical atmosphere and moving clouds from the camera’s view. Path Trace uses a map baked at the scene’s origin. Surface Renderer uses Sky to light surfaces and keeps its background transparent.

Surface Renderer takes diffuse environment light from the Sky, but its reflections use a procedural sky. Use either tracer when reflections must show the HDR image.

A Scene keeps one Sky. If another reaches it, the Scene leaves that Sky and its sun out and reports it in Status. A renderer in Scene + Local mode uses its local Sky in preference to the Scene’s.

Ports

Inputs

• hdr image
  RGBA
• weather_map image
  RGBA

Outputs

• scene scene required

Parameters

Sky

Source (Skysource) Menu op('sky').par.Skysource

Physical: an atmosphere with a distant cloud layer, lit by the sun. HDR: the image on the hdr input. Procedural: a simple analytic sky. Solid: one colour all round.

Default:

0

Options:

Physical, HDR, Procedural, Solid

Weather (Weather) Menu op('sky').par.Weather

The kind of sky: each sets the clouds and the haze below. A control you move is yours; one left at its default follows the Weather.

Default:

1

Options:

Clear, Fair Cumulus, Stratocumulus, Overcast, Storm

Time of Day (Timeofday) Float op('sky').par.Timeofday

Hours, local solar time: moves the sun, and with it the sky's colour, the clouds' light and the shadows. Dawn and dusk depend on Latitude and Day of Year.

Default:

15.5

Range:

0 to 24

Sun Heading (Sunheading) Float op('sky').par.Sunheading

Turns the sun's whole path about the vertical, degrees: at 0 it rises toward +x and sets toward -x, noon toward +z.

Default:

0

Range:

-180 to 180

Coverage (Coverage) Float op('sky').par.Coverage

How much of the sky the clouds cover.

Default:

0.45

Range:

0 to 1

Wind (m/s) (Wind) Float op('sky').par.Wind

How fast the clouds drift, metres a second.

Default:

9

Range:

0 to 60

Wind Direction (Winddirection) Float op('sky').par.Winddirection

Where the clouds drift to, degrees from +x toward +z.

Default:

20

Range:

-180 to 180

Cloud Shadows (Cloudshadows) Float op('sky').par.Cloudshadows

How much the clouds hold back the sun on the scene.

Default:

1

Range:

0 to 1

Sun Intensity (Sunintensity) Float op('sky').par.Sunintensity

The sun's light: 1 lights a white surface facing it to 1.0; the default 3 is a bright day at Exposure 1. The sky's light is scattered sunlight and follows it.

Default:

3

Range:

0 to 20

Sky Intensity (Skyintensity) Float op('sky').par.Skyintensity

The sky's light, relative to what the sun makes it (1 is as the air scatters it).

Default:

1

Range:

0 to 4

HDR Rotation (Hdrrotation) Float op('sky').par.Hdrrotation

Default:

0

Range:

-180 to 180

HDR Tint (Hdrtintr) Float op('sky').par.Hdrtintr

Default:

1

Range:

0 to 4

HDR Tint (Hdrtintg) Float op('sky').par.Hdrtintg

Default:

1

Range:

0 to 4

HDR Tint (Hdrtintb) Float op('sky').par.Hdrtintb

Default:

1

Range:

0 to 4

Solid Color (Solidcolorr) Float op('sky').par.Solidcolorr

Default:

0.5

Range:

0 to 1

Solid Color (Solidcolorg) Float op('sky').par.Solidcolorg

Default:

0.5

Range:

0 to 1

Solid Color (Solidcolorb) Float op('sky').par.Solidcolorb

Default:

0.5

Range:

0 to 1

Add Sun (Extrasun) Toggle op('sky').par.Extrasun

HDR and Solid: add a sun at Time of Day as well (off when the map carries its own).

Default:

Off

Options:

Off, On

Advanced

Sun Position (Sunmode) Menu op('sky').par.Sunmode

Time of Day places the sun from the clock, Latitude and Day of Year; Direction takes Sun Direction.

Default:

0

Options:

Time of Day, Direction

Latitude (Latitude) Float op('sky').par.Latitude

Default:

40

Range:

-89 to 89

Day of Year (Dayofyear) Float op('sky').par.Dayofyear

Default:

200

Range:

1 to 365

Sun Direction (Sundirx) Float op('sky').par.Sundirx

Default:

0.2

Range:

-1 to 1

Sun Direction (Sundiry) Float op('sky').par.Sundiry

Default:

0.5

Range:

-1 to 1

Sun Direction (Sundirz) Float op('sky').par.Sundirz

Default:

0.4

Range:

-1 to 1

Sun Angular Diameter (Sundiameter) Float op('sky').par.Sundiameter

Default:

0.53

Range:

0.1 to 10

Clouds (Clouds) Toggle op('sky').par.Clouds

Default:

On

Options:

Off, On

Cloud Base (m) (Cloudbase) Float op('sky').par.Cloudbase

Default:

1500

Range:

0 to 15000

Cloud Top (m) (Cloudtop) Float op('sky').par.Cloudtop

Default:

5000

Range:

200 to 20000

Cloud Type (Cloudtype) Float op('sky').par.Cloudtype

Default:

0.55

Range:

0 to 1

Type Variation (Typevariation) Float op('sky').par.Typevariation

Default:

0.35

Range:

0 to 1

Density (Density) Float op('sky').par.Density

Default:

1

Range:

0 to 8

Detail (Detail) Float op('sky').par.Detail

Default:

0.45

Range:

0 to 1

Softness (Softness) Float op('sky').par.Softness

Default:

0.35

Range:

0 to 1

Anvil (Anvil) Float op('sky').par.Anvil

Default:

0

Range:

0 to 1

Evolution (m/s) (Evolution) Float op('sky').par.Evolution

Default:

1.2

Range:

0 to 20

Cirrus (Cirrus) Float op('sky').par.Cirrus

Default:

0.35

Range:

0 to 1

Cirrus Altitude (m) (Cirrusaltitude) Float op('sky').par.Cirrusaltitude

Default:

9500

Range:

3000 to 16000

Droplet Size (um) (Droplet) Float op('sky').par.Droplet

Default:

18

Range:

5 to 50

Multiple Scattering (Multiplescattering) Float op('sky').par.Multiplescattering

Default:

0.65

Range:

0 to 0.95

Cloud Ambient (Ambient) Float op('sky').par.Ambient

Default:

1

Range:

0 to 4

Weather Offset (m) (Weatheroffsetx) Float op('sky').par.Weatheroffsetx

Default:

0

Range:

-1000000 to 1000000

Weather Offset (m) (Weatheroffsety) Float op('sky').par.Weatheroffsety

Default:

0

Range:

-1000000 to 1000000

Weather Offset (m) (Weatheroffsetz) Float op('sky').par.Weatheroffsetz

Default:

0

Range:

-1000000 to 1000000

Weather Scale (m) (Weatherscale) Float op('sky').par.Weatherscale

Default:

36000

Range:

2000 to 200000

Weather Map Size (m) (Weathermapsize) Float op('sky').par.Weathermapsize

The width of ground the weather_map image covers, centred on the origin: red paints where clouds form, green how tall they build.

Default:

40000

Range:

100 to 1000000

Haze (Haze) Float op('sky').par.Haze

Default:

1

Range:

0 to 20

Air Density (Airdensity) Float op('sky').par.Airdensity

Default:

1

Range:

0 to 4

Ozone (Ozone) Float op('sky').par.Ozone

Default:

1

Range:

0 to 4

God Rays (Godrays) Float op('sky').par.Godrays

Default:

1

Range:

0 to 4

Meters Per Unit (Metersperunit) Float op('sky').par.Metersperunit

How many metres one scene unit is. The clouds sit kilometres up, so a scene built in centimetres wants 0.01.

Default:

1

Range:

0.001 to 100000

Ground Height (Groundheight) Float op('sky').par.Groundheight

The scene height of the planet's ground.

Default:

0

Range:

-100000 to 100000

Ground Albedo (Groundalbedor) Float op('sky').par.Groundalbedor

Default:

0.1

Range:

0 to 1

Ground Albedo (Groundalbedog) Float op('sky').par.Groundalbedog

Default:

0.1

Range:

0 to 1

Ground Albedo (Groundalbedob) Float op('sky').par.Groundalbedob

Default:

0.1

Range:

0 to 1

Time Scale (Timescale) Float op('sky').par.Timescale

Cloud time is scene time x Time Scale + Time Offset.

Default:

1

Range:

0 to 1000

Time Offset (s) (Timeoffset) Float op('sky').par.Timeoffset

Default:

0

Range:

-1000000 to 1000000

Quality (Quality) Float op('sky').par.Quality

More steps through the clouds: slower, finer.

Default:

1

Range:

0.25 to 4

Cloud Detail Quality (Detailquality) Menu op('sky').par.Detailquality

Fine, Medium or Coarse erosion sampling. Lower detail costs less and softens the small wisps; Detail still controls the erosion amount. Applies to Physical Sky in every renderer.

Default:

0

Options:

Fine, Medium, Coarse

Turbidity (Turbidity) Float op('sky').par.Turbidity

Default:

2.5

Range:

1 to 10

Horizon Fade (Horizonfade) Float op('sky').par.Horizonfade

Default:

0.18

Range:

0 to 1

Ground Falloff (Groundfalloff) Float op('sky').par.Groundfalloff

Default:

0.65

Range:

0.05 to 4

Ozone / Sunset (Skyozone) Float op('sky').par.Skyozone

Default:

0.6

Range:

0 to 3

Sky Saturation (Skysaturation) Float op('sky').par.Skysaturation

Default:

1

Range:

0 to 2

Overcast (Skyovercast) Float op('sky').par.Skyovercast

Default:

0

Range:

0 to 1