'Lightwave'

 
'A Realistic Lighting Rig' by Andy Nicholas



This tutorial will show you how to create a lighting rig that will simulate daytime lighting conditions. Most importantly, it will allow you to easily adjust the rig so you can reuse the rig in many different scenes.

With support for lighting based on HDRI images and radiosity techniques, the need to create this sort of lighting rig is reduced. But it is still a useful trick to pull out of the bag when rendering times need to be reduced.

Luxigons:

A much overlooked feature of Lightwave is the ability to create lights based on polygons created in Modeller. This is invaluable as it allows us to create our lighting rig with as many lights as we want.

To start, create a single polygon centered at ( x = 0 , y = 0 , z = 1m ), and make an array (using the radial option) about the y axis by the number of lights you wish to have in your rig (I'll be using 16 to keep it simple for this tutorial, but you'll probably want to use a higher number to improve shadow quality).

Luxigon array

This lighting set-up was adequate for my Mitsubishi composite (see the movie gallery), but for more realism, you might want to use the polygons from a tesselated sphere.

Now select all the polygons and use the "Add Luxigons" command (which can usually be found in the Construct>>Additional menu). Don't worry about the options here, just click on OK.

Now you've made your Luxigons (how easy was that huh!), save your object as "Luxigons.lwo" and start up Layout. This object is available for download with the finished rig at the end of this tutorial.

In Layout, clear the scene and create two null objects at the world origin called "LightRigTarget" and "LightRigParent".

Now load up the "Luxigons.lwo" object you created on the last page, and run the "Convert Luxigons" plugin which can be found in the Layout>>Plug-ins>>Generic Plug-ins menu. In the dialog box that appears, call the new lights "SkyLight".

Delete the first original light (called "Light") and also the Luxigons object (without clearing it's decendents). Also, you must make sure you rename "SkyLight(1)" to "ControlSkyLight", as otherwise, expressions will have difficulty in finding the object after a Load From Scene.

Now comes the fun stuff!

Light array created

Multiple object expression assignment:

Open up the Spreadsheet and change the property bank to "Light Properties: Basic". Click on ControlSkyLight's intensity entry and then shift click on SkyLight(15)'s intensity to highlight them all. Now click on the little box with the "E" in it and click "yes" to create intensity envelopes for all the lights. Repeat this process for the color property of the lights.

Still in Spreadsheet click on the name entry for ControlSkyLight, shift click on the name entry for SkyLight(15), and then double click anywhere in the highlighted area. This should select all the lights in the Layout viewport.



Creating light envelopes

Close Spreadsheet and open the Graph Editor with all the lights still selected. Use Selection>>Get Layout Selected at the top of the Graph Editor window. Now from the same menu, select "Filter Curves" and enter:

*.Intensity

This will get rid of all the channels we don't want to see. Use Channels>>Create Favourite Set to save this set as "Rig Intensity". Repeat this process (starting from "Get Layout Selected" from the Selection menu) and create the following sets using these filters:

Channel Set Name Filter Rig Red *.Color.R Rig Green *.Color.G Rig Blue *.Color.B

 

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