Versions Compared

Old Version 35

changes.mady.by.user 3Delight

Saved on

compared with

New Version Current

changes.mady.by.user 3Delight

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

Intensity

This drives the overall intensity of the sky. It is a direct multiplier of the sky radiance function.

Excerpt

Characteristics of the Sky Shader

The 3Delight Sky shader is used for image-based lighting of daylight conditions. 3Delight can extract sharp shadows using this shader so that no directional light is needed to cast shadows from the sun. This shader is based on the Hosek-Wilkie sky model. It is an analytical model of the daytime sky that includes the latest improvement in this field of research. This model is able to properly picture sunsets and lighting in high turbidity environments – such as lighting during a moist day.

Parameters of the Sky Shader

Parameters 
Description 
Gallery
columns3
includeLabelintensity

Turbidity 

Tubidity

This parameter determines the overall aerosol content of the air. As an example, a moist day will have higher turbidity values than a dry day. Values range between 1 and 10. Note how high turbidity values affect cast shadows.

Gallery
includeLabelturbidity
reversetrue

 

Also note that turbidity affects the look of the sun when near the horizon. The following renders show the effect of turbidity for different sun elevations.

Elevation 0.75
Image Modified
Image Modified
Image Modified
Elevation 0.50
Image Modified
Image Modified
Image Modified
Elevation 0.25
Image Modified
Image Modified
Image Modified
 Turbidity 6.0Turbidity 7.0Turbidity 8.0
 

 


Ground

Color 

Color

Changing ground color (also called albedo) affects the brightness of the whole sky-dome, especially in high turbidity settings. High albedo values can occur in winter scenes - snow reflectance is very bright so almost all incident radiation is reflected and backscattered towards the viewer.

Gallery
includeLabelground_color

Elevation

This the elevation of the sun, in degrees. The range is 0 to 90.

Gallery
includeLabelelevation

Azimuth 

Azimuth

This is the azimutal position of the sun, in degrees. Range is 0 to 360.

Gallery
includeLabelazimuth

Sky Tint

A convenient artistic control to change the overall color of the sky dome. If physically correct renders are desired this parameter should be set to [1,1,1].

Gallery
includeLabelsky_tint

Sun Tint

A convenient artistic control of the sun's color. If physically correct renders are desired this parameter should be set to (1,1,1).

Gallery
includeLabelsun_tint

Sun Size

The size of the sun in the sky, in degrees. The default value (0.51 degrees) is the size of the sun as seen on earth. Note that changing the size of the sun doesn't affect the overall radiance of the sky in this model but the objects will receive more light, as seen in the images below.

Gallery
includeLabelsun_size

Draw Sun

Disk

disk

This enables or disable the sun in the sky. Disabling the sun will disable the drawing of the sharp component of the shadows (the strongly directional shadow).

Gallery
includeLabeldraw_sun

Draw Ground

Draws the ground (the space under the horizon) using the color specified in Ground Color.