Redshift Sky
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| Model by Brad Goldsworthy, Lighting and Rendering by Saul Espinosa | by Saul Espinosa |
The Redshift Sun & Sky offers a quick and easy way to add realistic outdoor lighting from sun up to sun down and it pairs well with a Redshift Cloud object for added realism. Sun & Sky is based on the PRG Clear Sky model from the paper "A Fitted Radiance and Attenuation Model for Realistic Atmospheres" which improves upon the Hosek-Wilkie sky model. PRG Clear Sky is able to better represent scenarios where the sun is very near or below the horizon, allowing for much more accurate and aesthetically pleasing sunrises and sunsets.
Functionally the Sun & Sky is very similar to a Dome Light, offering the same familiar light parameters like contribution scale and light linking.
Examples
Physically Accurate Lighting
For best accuracy, the Sun & Sky uses a physically accurate light intensity by default. Because of the intense light of the sun at midday cameras in the scene should be adjusted to compensate. This can be accomplished by reducing the Exposure for the camera or using the "Sunny 16 rule" used in photography.
Camera Exposure
The simplest way to compensate for the intense sun light is to reduce the Camera's "Exposure (EV)" value. At the default value of 0 the scene will be blown out, but an Exposure value of -5 closely matches the Sunny 16 rule described below while a value of -4 leaves things nice and bright. Set it to any value you prefer most.
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| Camera Exposure 0 (default) | Camera Exposure -4 | Camera Exposure -5 |
Sunny 16 rule
This rule provides a good starting guideline for achieving pleasant exposure in daylight. Start with a Redshift camera and set the following parameters:
- Exposure Type: "Filmic"
- Aperture: 16
- ISO: 100
- Shutter Speed: 100
The examples below illustrate the change made with each adjustment, and remember, these are just a suggestion — feel free to adjust the settings to your liking. For more information, have a look at the Wikipedia entry.
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| Filmic camera defaults | Setting Aperture to f /16 | Setting ISO to 100 | Setting Shutter Speed to 1/100 |
Non-Physical Intensity
If physical accuracy is not important the Sun & Sky can quickly be brought down to a visually acceptable light intensity without the need to adjust any camera settings simply by enabling "Use Non-Physical Intensity."
The first image shows a brand new scene with no camera exposure adjustments, resulting in a blown out scene. In the second image Non-Physical Intensity is enabled — this brings the sun intensity into a range that is visually appealing without the need for further adjustment. Please note, using a non-physical intensity reduces the natural impact sunlight has on a scene, like reducing the intensity of global illumination bounce lighting, subsurface scattering, and overall contrast.
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| Use Non-Physical Intensity: Disabled (default) Camera Exposure: 0 (default) |
Enabled 0 (default) |