View Full Version : Spinning Light Rig v1.1

03-16-2004, 05:06 AM

Boy this sure was a popular item! Close to 200 downloads on both sites I believe... So here's a minor update. The distribution of the lights are just a little better, making less banding in the shadows. I think there are a few more lights this time.

In this image, I used the rig plus one key light. It rendered in exactly 2 minutes:
(Enhanced Medium AA)


(Documentation included [and updated])

Have fun!

03-16-2004, 05:07 AM
Oops here's the file..

03-16-2004, 05:27 AM
Very nice render, Carm!

03-16-2004, 05:30 AM
Well thanks! It's a snap with my new rig! ;)

03-16-2004, 11:52 PM
Thanks, i like this tool/trick !!! :)

05-26-2004, 10:33 AM
thanks much for the lighting file, very helpful indeed!
one thing, for some reason, I can see the sliders, but I'm not able to adjust them or slide them?
I'm on a Mac using LW 7.5c, OS 10.2.6


05-26-2004, 10:37 AM
Gotta be in sliders mode to animate them (as opposed to move or rotate mode). Enjoy.

05-26-2004, 10:54 AM
ok, got it now,

*(still learning all the nuances in LW)

05-26-2004, 11:08 AM
U can also animate them via the graph editor. Look for MC (Master Channels).

05-26-2004, 02:09 PM
Hi Carm3d,

Okay, just getting into lighting, and whilst I am trying to find time to read Nicholas Boughen's LW3d 8 Lighting book (which initially looks a great resource!), could you explain (and I mean in SIMPLE terms!) the idea of your light rig.

I have seen your posts before this version, and am roughly aware that it is a pre-set lighting setup or something, but what I ask is that you pretend I am a complete dufus who is trying to understand for the first time...(more of a tutorial really as to how to recreate something like your image)

Oh, and in the documentation you mention G2. Is this a necessary plugin or just icing on the cake?

I will understand if you don't have the time to explain in this detail the theory and use of your rig, and thank you anyway for making it avaialable, but if you could break it down for me it would be appreciated...(and by maybe a few others aswell)


Kevin McPoland

05-26-2004, 03:31 PM
> could you explain (and I mean in SIMPLE terms!) the idea of your light rig.

Ah... So you want to know what's the big idea, eh?

Well, skylight rigs are the "next best thing" to rendering with global illumination (A.K.A. Radiosity). It simulates the effect of light coming from the atmosphere. The sun will give you direct lighting, but the sun also illuminates all the particles in the atmosphere, and this light bounces back to us, giving us higly diffused (un-focused) shadows. So if you have a blue sky, set your sky lights to be the same colour then add a sun (key) light and you got a quickly-lit outdoor scene. Radiosity gives you the effect of bounced lights, so that will have a quality edge over this rig. But the render speed more than makes up for it. Radiosity is many times slower.

This skylight rig does it's magic by using motion blur. Instead of placing dozens (or even close to a hundred) of lights in your sky, this rig takes the 15 or so lights and spins it over the course of one frame. The higher the motion blur quality, the more rendering passes occur, and the more times your lights are hitting your subjects from different locations. Since this rig uses less lights, it renders faster. It also renders faster because it uses the fastest-rendering light in Lightwave: The shadow-mapped spotlight.

Spotlights have the unique option of using shadow maps to generate shadows. You specify the resolution of these map images. The higher the resolution, the cleaner the shadows -and the more memory is consumed at render-time. Shadow-mapped spotights render noticably quicker than the other lights casting ray-traced shadows.

The drawback to using spotlights is that they don't shine light in every direction. So the spotlight cone angle also is an important setting. Select one of the spotlights (I usually choose one of the C lights in my rig) and look through it via the Light View option in your window. Using the spreadsheet (or scene in LW8) editor, change all of the spotlight rig's spotlight cone angles so that everything you want to be lit is encompassed in the light view. Also tweak the soft-edge angle while you're there.

Just as a side note, other drawbacks to shadowmapped spotlights is they don't "see" transparency, nor do they work well when an object fades out by animating it's dissolve setting. The subject in both scenarios will cast a shadow as if it were opaque. If you want to have glass in your scene make it a seperate object (or object layer) and tell this object/layer not to cast shadows. problem solved. If you must use an animated dissolve effect, render the dissolve sequence twice. Once with the subject fully opaque, and again with the subject gone (or at 100% dissolve). Then use a video editor or compositing program such as DFX+ to dissolve from the opaque animation to the second animation.

The wider you make your spotlight cone angle, the more light coverage you get. But it also means your shadowmap will stretch out to fit the cone as well. So for a wide angle, a higher shadowmap resolution may be desired.

The one saving grace of this is that your shadowmapped shadows don't usually need to be as high resolution as your key light (if you key is also a shadowmapped spotlight). Your key light will usually (but not always) be much brighter than the light coming from the atmosphere, so the skylight rig's shadows won't be as obvious as the key shadow. So you can sometimes lower the shadowmap resolution for your rig and still get away with a nice-looking render.

> Oh, and in the documentation you mention G2. Is this a necessary plugin or just icing on the cake?

It's not necessary. It's most definently icing. You get instant feedback as to how the skylight intensity is effecting your rendered scene. But using the trial-and-error method (A.K.A. Lots of F9's) you can do the same thing.. Just not as quickly.

There's one thing I didn't mention in it's documentation... Add the skylight rig to your scene by choosing "Load Items from Scene" and then selecting the skylight rig scene. This will load and install all the expressions and lights to your current scene. Of course, when it asks if you want to load lights with the scene, say "YES PLEASE."

I hope this information helps you.

05-26-2004, 03:41 PM

Now thats a reply I like! Very informative........but leading me to a question....(sorry!)

If the lights are spinning for the frame, can it still work in an animation, because surely if the lights spin and aren't in exactly the same place for each frame it will be noticeable?

I did explain I was just getting into lighting, so if the answer is they reset the exact positions everytime they spin, I apologise (I'm just curious now....)


Kevin McPoland

05-26-2004, 03:44 PM
> Now thats a reply I like! Very informative........

Thanks... skim through my previous message.. I made some changes / additions.

> If the lights are spinning for the frame, can it still work in an animation, because surely if the lights spin and aren't in exactly the same place for each frame it will be noticeable?

Fortunately, they are in exactly the same place for every frame. So it works just fine with animation.

05-26-2004, 03:53 PM
Noted Carm3d,

I am just about to retire for the night (it's nealry 11pm over here in the UK and I have an early start in the morning!), but you have given me a toy to experiment with for the weekend, and for that I am grateful (although my wife says something about a"hit man" and a "contract"....not sure what shes mumbling about now...

Thanks again,

Kevin McPoland