View Full Version : Photometric lights useful for video and theatre

David McCall
07-15-2011, 10:33 AM
I do theatre lighting and set design using Lightwave so my needs are a little specialized.

When I add photometric lights the orientation is not the same as for other types of light and the light seems to go everywhere instead of any attempt at approximating the actual light being used. I have also found that some photometric lights work OK while others seem questionable or immediately crash lightwave.

The only solution I have found so far is to parent the photometric light to a spotlight that simulates the desired fixture. Then I make the spotlight seen in GL but not used for renders, and the opposite for the photometric light. Of course you need to adjust the levels individually or setup a follower or something to track the photometric to the spot. At least you can use the the view from the light's perspective to focus the lights.

The next thing is that most motion picture and theater lights have either shutters or barn doors to shape the lights. One solution is to go to photoshop and create a projection image that looks like the shutter configuration desired, but that doesn't work with the photometrics.
Another solution is to create a box or matt that can go in front of the light and be distorted and rotated to simulate the shutters. Both of these solutions are pretty crude.

I've also done this by parenting 4 shutters to the same spotlight so that the shaping moves with the light.

Another issue with the photometric lights is the lack of support for a projected image. We often use gobos to project an image and that can be accomplished by using a projection image in a spotlight, but not in photometrics. I have not tried it yet, but I think I might be able to simulate this effect by placing am image with transparency in front of the light.

Some lights (fresnels zoom ellipsoidals for instance) have "zoom" capabilities where a soft edge light can go from a very small spot to a pretty wide flood by adjusting the lamp position. One characteristic of these lights is that they get much brighter in spot position than they do in the flood position. I have not found a work around for this one yet.

While not photometric specific, you also need a way to control the individual lights, or groups of lights, from a simulated "dimmer board". I have done this on a small scale by creating a little dimmer board and having the light intensity track the vertical position of the sliders. This light board gets parented to the camera and placed to the top of the frame so that I can make adjustments.

OK, so it appears that I've solved my own problem here, but it not uncommon for there to be a couple hundred lights and that many dimmers in a theater setup. Custom creation of these light assemblies for a large number of lights is pretty daunting.

What I would like to have is a way to create a light and save it as something that I can recall multiple copies to use as lights in different positions in my scene. I'd like the parenting and tracking to load with the light. Then assign a color to it and connect it to one of those dimmers.

Does anybody else have an interest in this kind of use for lights, or is it just me?

07-15-2011, 10:37 AM
Someone has a tutorial somewhere about having sets of lights as saved setups. Not sure where. Have you done a search in the forums for lights setup?

07-15-2011, 10:41 AM
Using lights and saving instances, if that's possible?


07-15-2011, 01:44 PM
I have use for this as well for live production visualization.

I have attempted using photometric lights, and I think there's some understanding in their settings that I don't have quite down yet, so I've stuck with spotlights and DP Lights for the moment. The DP Lights are REALLY nice because they allow you to not only use a gobo, but you can blur the image too. LW's built-in spotlight doesn't have that blur feature so what you'd have to do is created a blurred version of your gobo image and use that instead. This kinda sucks because it may take several attempts to get the desired blur amount.

Dimmer Board and Light Groups
Here's where Expressions are your friend. Larry Shultz's DVD on Expressions went into a great example for this usage. Basically it entailed creating a Null object, then attaching an expression to the Null that would control light intensity based on say the Y-value of the Null's position. You should even be able to use a slider control to sim a dimmer board. I'm sure the same control could be added to control lighting gels.

I don't have a solution for that many lights. I had a small project fairly recently that had maybe 30 lights in it. Since the trusses were a part of the render I had geometry for the lights. It was a lot of parenting, Clone Hierarchy, and manual positioning and focusing. Other than creating geometry, setting it up in a scene, then importing the LWO and parented light into new scenes, I haven't found another solution.

I also have not found a solution for lamp position. Alas, these darned 3D lights just don't behave like analogue. :)

07-17-2011, 07:59 AM

I deal with IES files on daily basis in LW and i can tell you that some things are BEST in industry in LW (like data showed in photometric info) and some are not quite yet there :(.

- LW don't read photometric file intensity properly (better to say LW don't use it) which should be in Candelas not "intensity" value which LW uses so you have very unprecise Light emitting source if you just left it at 100%.

- So i used various IES files form different manufacturers (Philips, Schreder, Thorn, iGuzzini, Bega, Dissano,....) and even manufacturers don't save them equally and they can be rotated differently (there is no standard obviously :() so you need to rotate them manually up on loading. DP Web light have nice feature called "align to Z+" which i would like to have in LW Photometric native also. That would solve many problems with mirroring Photometric lights and similar stuff when rotating many of them at once.

- As for intensity you have to eyeball it by comparing to real lights :( which is very bad. Through last 4 years I've managed to set some standard "intensity" values for different manufacturers but it goes from 300% up to 25000% so it's hardly an easy task to explain :(. BTW i just recently posted feature request video to NT abotu that system so let's hope they'll include candelas/m2 soon :).

- Yes you can't use projection images on it (so gobos are problem and Ive mainly used classic spotlights with handmade textures to make gobo but that's ugly process since yyu need to put light at one position and never move it since your gobo is useles if you move it then :(.

- I've had several IES files what crash LW and sent to NT and in 10.1 situation is better than in 10.0 or 9.6 so if you have any which crash 10.1 please send them ASAP so they can fix it.

- As for many lights at once (my record so far was little over 5000 IE slights at one massive City facade lighting project) you can parent them to Null object and Clone hierarchy or LoadFromScene for next scene setup.