Table Of Contents
Introduction
The Redshift Physical Sun light is a physically accurate representation of real sun-light based on the paper 'A Practical Analytic Model for Daylight', by A.J. Preetham, Peter Shirley and Brian Smits. Physical Sun is generally used in conjunction with the Physical Sky environment shader.
For additional information about the Redshift Physical Sun & Sky system, please refer to the Physical Sky topic.
Physical Sun emits light at an extremely high intensity (to model the physical intensity of sunlight that hits the Earth's surface) and you should therefore always use a Photographic Exposure lens shader to achieve useful results when using Physical Sun. Without a Photographic Exposure lens shader, the scene will likely render completely white.
General
On
Turns the sun light on or off.
Intensity Multiplier
Specifies an intensity multiplier for the sun light. This parameter can be used to scale the intensity of the sun up or down.
Use Non-Physical Intensity
Reduces the intensity of the sun light to a range that can be used without a Photographic Exposure lens shader.
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| Use Non-Physical Intensity: Enabled | Disabled | Enabled | Disabled |
Ray Contribution
See Common Redshift Light Parameters.
Atmosphere
Turbidity
Specifies the haziness of the air – a measure of dust particle pollution. A value of 2.0 represents a very clear, blue sky, while larger values will make the sky a dirty, orange color.
Below is a turbidity example demonstrating lower values on the left resulting in a clearer more bluish sky to higher values on the right resulting in a dirtier looking more orange colored sky:
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Ozone
Specifies the amount of ozone in the atmosphere, with values ranging from 0.0 to 1.0. The default is 0.35, which is commonly used for the Earth's atmosphere. Smaller values will increase the amount of orange in the sunlight, while larger values will make it more blue.
Below shows an ozone demonstration showing lower values resulting in a warmer result on the left to higher values resulting in a cooler result on the right:
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Horizon Height
Specifies the position of the horizon. Values below 0 will push the horizon down, while values above 0 will raise the horizon.
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| Horizon Height: -2 | -1 | 0.0 | 1 |
1.75 |
Color Adjustment
Red-Blue Shift
Specifies a hue shift for the color of the sun light. The default value of 0 will yield physically accurate sun light color. Negative values will shift the sun light color towards blue, while positive values will shift it towards red.
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| Red-Blue Shift: -0.5 | 0.0 | 0.5 |
Saturation
Specifies the color saturation of the sun light. The default value of 1 will yield physically accurate sun light color. Smaller values will reduce the color saturation of the sun light, with a value of 0 producing pure white light. Values above 1 will exaggerate the color of the sun light.
Shadow
See Common Redshift Light Parameters.
Volume
See Common Redshift Light Parameters.