A Web distribution uses a photometric web definition to distribute the light. A photometric web is a 3D representation of the light intensity distribution of a light source. Web distributions are stored in an IES files available from lighting manufacturers. You can assign an IES, LTLI, or CIBSE file to a photometric light using the Web Parameters rollout.

Example of web distribution

Various web distributions
Target Point Light (Photometric)
Free Point Light (Photometric)
Target Linear Light (Photometric)
Free Linear Light (Photometric)
Target Area Light (Photometric)
To create a light from a manufacturer's IES file:
On the Create panel, click Lights.
Choose Photometric from the drop-down list. (The default is Standard.)
In the Object Type rollout, select any photometric light type.
In the Intensity/Color/Distribution rollout, select Web from the Distribution list.
If you are creating a Target Point, Linear, or Area light, drag in a viewport. The initial point of the drag is the location of the light, and the point where you release the mouse is the location of the target. If you are creating a Free Point, Linear or Area light, click in a viewport to position the light.
A light is created using the default photometric web which is a diffuse distribution shining from one edge.
Go to the Web Parameters rollout, and select the IES file that you want to use. See Web Parameters.
Set the creation parameters.
You can use the Move transform to position the light. You can also use the Place Highlight command to change a light's position.
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