# Size Issues



## loki (Oct 4, 2009)

Hey All,

I am currently working on a Dance show that requires images to be projected onto the dances, I have one DVD that was going to be run into a Distribution amp, I was then going to run the identical split images into three Sony: VPL-CX105 Data projectors Spaced across the Setting Line (10m Away from the Projection surface)

However, when we tried this it turned out the image is 4m to wide for the 11m screen, Even with all the projectors at their smallest setting, At 10m (Which is where they MUST be) the throw distance just ends up making the images to wide for the space, Even set to 4:3 and shrunk.

I had the idea this morning to fix it, i'm just not shore how to do it,
My idea is to use one of the new Mac Towers we just brought, they have 3 Video cards in them, And use the computer to create the 3 images out of the one DVD, Then somehow only use 2 projectors to project all three images...

Anyways, Any and all help and suggestions would he great,

Thanks, Aaron


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## seanandkate (Oct 4, 2009)

And you don't want to just use two of the projectors to fill the screen with _two _identical images? Do you absolutely need three images? (Just trying to think of what three identical images buys you that two doesn't.)


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## loki (Oct 5, 2009)

Yeh, Unfortunately, i just talked to the powers that be and have been told it must not only have three images, but it must be done from 3 projectors.

Its to do with the way the dancers and the images interact apparently


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## NickJones (Oct 5, 2009)

There is a product available, (I have info on it somewhere in the abiss that is my hard drive) that you plug into the VGA port, it shows up as an insanely wide monitor, but is actualy a box with 3 VGA outputs, if you get what I mean, so the you hook it up, and it streaches the image across all 3 VGA outputs, but shows up as one screen. If thats what you wanted I'll dig out the info.
Nick
I'm quite happy with my size


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## museav (Oct 5, 2009)

You're probably thinking of the Matrox TripleHead2Go. However, I think the goal here is the same image on all three screens rather than one image spread across three screens. That also would not do anything to alter the size of the image the projectors can project.


I can't find any information on a Sony VPL-CX105 projector, might it be a VPL-CX150? The VPL-CX150 has a 1.5-1.8:1 lens, a relatively short throw lens with limited adjustment, which is unfortunately not what you really want for your application. I do not think there are any lens options so that is not a viable alternative.

You might be able to use a software, hardware or combination solution to display three images edge blended across two projectors, but that could get much more complex and expensive. You would basically have to create a single image that is the same image multiplied three across and then edge blend that image across two projectors.

There could also be a concern with the original concept. A projector is not going to project a perfectly clean edge that can be butted right up against another image with a clean line between them, so I'm not sure you would get the desired effect or result. You might come close with rear projection and using a narrow divider perpendicular to the screen that prevents any spill from one image to another but that is not usually a practical approach with front projection. You could probably mask each projector to help but that could take some time and effort to get it right.

Another factor could be brightness. If the projector is the VPL-CX150 then that model is rated at 3,500 lumens (and that is with a new lamp). If you could get a smaller image from the projector, with three projectors and an 11m wide screen that is a 3.67m (12') wide by 2.75m (9') high image for each projector and around 32ftL for the resulting image brightness. But if you went to two projectors that is a 5.5m (18') wide by 4.125m (13.5') image for each and only around 14.4ftL due to the larger image from each projector. Both options would require control of any ambient light hitting the screen, something that may be difficult with the application defined, but the two projector solution would probably be borderline even in very low ambient lighting conditions.

This may be a situation where what they want is possible provided they are willing to fund it, such as renting three different projectors that could support smaller images with a 10m throw distance, and perhaps with more output.


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## seanandkate (Oct 5, 2009)

Might you be able to resize the images in your video file or DVD? If it's not already 16:9 then that might shrink the image enough. You'll lose some contrast on the overlap depending on how black your non-image black is, but that might be a pretty simple solution.


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## SHARYNF (Oct 5, 2009)

since you cannot move the projector distance to the screen, and you must use 3 projectors, and there are no lens options to change the projections side of things, you probably are stuck with just altering the original image.

It is not an ideal solution, but you could import the image into a video editing program and then shrink the image down so that when you triple the image you now move the projectors closer to one another (still 10m from the screen) but with more projector overlap. The cropped black border on the image will overlap with the next projector but should not be overly visible especially if you are projecting on dancers. 

I have used a version of this technique when I want to project onto an odd shaped surface or when O want to take a single image and have a non projection area in the image.

Obviously the best thing would be to simply move the distance of the projectors from the surface you want to project on to, but since this is impossible this would work

Sharyn


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## museav (Oct 5, 2009)

Sharyn offered a good option, just remember that the brightness of the projector is spread across its entire projected area and not just the part you might use for an image. What would be happening is having a larger projected image with some of it black, if the black area only represents 50% of the overall image area then it also represents half the projector's potential output. To get a brighter image by making the image smaller requires using optics to focus the projector output over a smaller area and not using only part of the projected area.

So if you create three images by using only a 3.67m wide by 2.75m high part of the approximately 5m by 3.75m image area the projector displays you still have the same image brightness, just a smaller viewing image.


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