This simulates light from a sphere or dome above the scene, representing the sky. It can also be used with high dynamic range (HDR) images to perform image-based environment lighting. This is the node which is typically used for lighting exterior scenes.
This light is designed for outdoor scenes and is represented by a spherical dome in the background. Importance sampling will trace rays to specific directions of this dome. However, in an interior scene, most of these rays will hit an object, getting no contribution from the light at all and thus creating noise. In this situation, adding light_portals to the windows will help to reduce noise in an interior scene when using the skydome_light.
Simply adding an Environment Map automatically enables a skydome_light with no other input required. The 'skydome_light' and background shader is constructed under the hood, and no extra light creation is required.
The lights page has more detail about the controls. The only additional parameters are:
The color of the light. The skydome_light has a texturable color slot so that you can map a texture to be used for IBL.
Intensity controls the brightness of light emitted by the light source by multiplying the color.
The resolution controls the detail of reflections of the skydome. For most accurate results the Skydome light resolution must be set to match the HDRI image resolution, however, in many cases it can be set lower without a noticeable loss of detail in reflections. By default, the parameter is set to 1000. The higher the resolution parameter, the longer the skydome_light will take to precompute the importance tables for the light, which increases scene startup time.
The resolution attribute should be used with care. The higher the resolution value, the longer the skydome_light will take to precompute the importance tables for that light. For high-resolution maps, this can be very slow.
The type of map being connected. It can be set to Lat-long (most common), Mirrored Ball or Angular.
- off: turns off portals.
- interior_only: blocks any light outside portals for interior only scenes.
- interior_exterior: lets light outside portals through for mixed interior and exterior scenes.
By default, skydome lights are directly visible as a background. Lowering the influence of the light of camera rays makes them invisible to the camera, and makes the background transparent.
Per-light scaling for transmission. Should be left at 1 to produce physically accurate results.
Diffuse / Specular / SSS / Volume
Per-light scaling for Camera, Transmission, Diffuse, Specular, SSS, Indirect and Volume. Weights scaling the light contribution to each of those components independently. Should be left at 1 to produce physically accurate results.
Only Area lights and Point lights (non-0 radius) are visible to the camera. Camera and Transmission values default to 0 with Area lights.