IES Lights in XSI

This is something I posted at XSIbase on June 8, 2007, I'm putting it here for ease of finding:

I started playing around with the IES plugin for Softimage XSI from Ctrl studio called ctrl.light profile and wanted to establish a workflow that yealded some good results. (see link to original post for download: http://forums.cgsociety.org/showthread.php?f=24&t=300617&page=1&pp=15)

Anyway, Ctrl.light profile does seem to display a reasonably accurate visual appearence of a luminaire, if used correctly:-

To get a hold on how to use the plugin do the following:-

1. Firstly: find a light fitting that you know about, it helps to have
photographs of it installed and working. I chose some uplighters from Erco;
(Erco are good because provide both 3d meshes and IES data for all their
products as well as comprehensive brochures.)

2. Then: Get > Primitive > Geoshader and add the plugin to the
Geoshader.

3. Import the appropriate IES data into the IES filename section.

4. Create a point light. Important: Reduce the intensity of the point light
you are going to use as an IES to 0 or you will not get a correct result - you'll end up getting light from the pointlight as well as the IES shader (which is extra bad if you are using GI or/and FG.)

5. In the light part of the plugins ppg attach the new point light.

6. Now do a test render of the light positioned near a surface and go
forward from there.

7. Important: DON'T rotate the point light. After all, there is no logical reason to. IES data for an uplighter will automatically cast light upwards, a downlighter will always cast light downwards. Just placing the pointlight above or below a specific light (depending on the type) is all you need to do.

Finally, if you need more than one light of the same type, use Instances. Create a model from the light mesh object (if used), point light and geoshader, then instance them around the scene - Works well.