Equipment Setup Advice/Assistance with Video?

[Tee]

We've been running QLab as a primarily audio controller for our theatre for over a year now.  We have, for a couple of productions used video projections, but never more than one projector at a time.

I'm now facing a set design that is going to rely on three separate projectors being shot from three completely separate points backstage (rear projected).  Currently, we are planning on having two QLab machines running in the theatre, one primarily for the sound effects and midi-controlled wireless microphone cues and another for the video projections.  Two of our screens are going to be stage mounted and should stand approximately 6' wide by 14' tall on opposite sides of the stage with a third screen slightly wider (8' to 10' wide) and 14' tall flown from a batten at a yet-to-be-determined angle to the floor and slightly tilted toward the audience (maybe).  We are pretty sure we've got projector placement worked out to avoid revealing the "hot spots" to the audience.  

Here are my questions:

We are primarily going to be projecting still images as part of this scenic design, but would like to have the option of using digital animations or videos if we want to, perhaps even a combination of all three. Is it possible to run all three of these projectors from one iMac computer (not sure of the exact specs, but it was purchased within the last year, so not too shabby).  We would need to have the ability to isolate the images to one screen or project one solid image across all three, even if the image appears to be broken by the negative space between the screens.  What type of device do we need to attach the three projectors to the iMac to have QLab recognize all three video outputs?  I have seen several people on here recommend a Matrox (sp?) TripleHead2Go, but it seems that this would just create one large desktop area that we would then have to program with Quarz Composer. This seems to be able to solve my problem of one image across all three screens...I think. However, the programming of the Quartz Composer for each of the individual cues (or screens) is knowledge that no one on my team has.

Incidentally, with regards to my one image across all three screens:  I'm imagining the entire stage as one big "canvas" that has been torn or cut.  So, I would like our projectors to be displaying only those "pieces" of the image that would be seen by those pieces of the canvas that are left.  That's a horrible description, but it's the best I can do here.  It looks great in my head, I swear.  ;)

Next, what projectors should we look for?  We are in a 400 seat proscenium theatre that has a fairly deep stage.  Our screens will be approximately 20'-30' upstage of the plasterline and we have plenty of space backstage with which to project.  I would like to have the images be as crystal clear as possible and consistency with regards to color temperature and brightness between all three is crucial, so I was thinking of something that is a fairly high resolution projector, but I would also like to have something that will project these images with a brightness enough to be effective.  We are looking to rent these projectors, not purchase them...for now.

Which brings up the final question regarding this:  Is it possible to "dim" the images as part of the QLab cue?  I know that fade-ins and -outs are possible, but is it possible to only have the image projected at say 50% of the total brightness available via the projector?  Can this setting be controlled in QLab?

Thanks for the input on this.  I read the posts here all the time and, while most of them are above my pay grade, I enjoy hearing about the issues that people are having and the solutions that other like-minded people can provide.

Tee

[Lucas Krech]

Depending on what iMac you have there are one or two discrete video outputs making something like a Matrox THTG necessary to get three discrete imaages projected.

The Matrox does create a single wides desktop. Managing this can be approached via Quartz Compose,r or custom geometry, or in a video/image editing software. Let's say your projectors are all 1024x768 display resolution. The THTG gives you a single 3072x768 screen to deal with as far as the computer is concerned. So for still images it is easy enough to make full res (3072x768) PNGs with transparency. If you want to display on the middle screen for example you make a 3072x768 image where the first 1024 and last 1024 are all transparent with the image is in the center. Alternately you can make all your images 1024x768 and use custom geometry to offset by 1024 or 2048 depending on what screen you are sending the image to. Or you can use Quartz Composer. For something so simple as sending images to discrete screens Quartz may be overkill, but it really is quite easy to learn with a little bit of poking around.

I find Quartz to take a little more time setting up initially but *much* faster in tech. Especially when you learn fun things like manipulating color values via animation cues or transition effects or blend modes. "Oh you want a transition effect here, no probs give me 5 minutes." Versus "I'll do that tonight after tech and we can look atit in the morning." Quartz is well worth learning especially if you are dealing with anything other than a straight on rectangular projection surface. Being able to do 3 dimensional keystonging is invaluable as is masking images etc. So if you have your projector angled at all relative to the projection surface QC is really the best way to go.

HTH.

-L

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[Chris Bakos]

I second the Matrox THTG but might also suggest looking into USB-> DVI converters. 2 of those plus the built in extra display on the iMac will give you your 3 discrete screens with no need for Quartz composer. It will make the "one image across all three screens" a bit more of a challenge and the latency can be a problem, so you will need to balance your decision based on this information. 

[Lucas Krech]

You may yet find that Quartz is worth investigating for the ability to do perspective transforms. So long as everything can be solved in the projectors keystoning you are fine, but I have on regular occasion found I needed more that the projector could do, or that the projector inteface was not so user friendly.

And the latency issue plus being able to easily pan a single image across all screens may well make the THTG a better option.

Really it comes down to what you need for hte show and how much time you have. There is no single best set up. 

-L

On Feb 4, 2013, at 12:28 PM, Chris Bakos wrote:

I second the Matrox THTG but might also suggest looking into USB-> DVI converters. 2 of those plus the built in extra display on the iMac will give you your 3 discrete screens with no need for Quartz composer. It will make the "one image across all three screens" a bit more of a challenge and the latency can be a problem, so you will need to balance your decision based on this information.