Youth Room Stage Design

Another option for the dual-projector scenario is giving up on having a semblance of 1 continuous image and just putting a thin-ish strip of masking down the center that's just enough to hide the spill. When running content across both "screens" people might notice it at first, but if the show is so boring that people are left to contemplate the setup of your projection, you have bigger issues.
 
Now, if it were my design, under the constraints of the two projectors to get a larger image, I would personally have a hard seam between the two halves of the image (essentially simulating two monitors, even if the fabric is seamless). This way, I could stick with the two ultra short throw projectors. The perception will remain as a continuous image as people will end up ignoring the seam. However, this would give you flexibility to have two separate images side by side without it looking "off". While adding in the mirrors and standard lens could get you the semblance of a seamless image, the complexity and aggravation would not make it worth the time. Every minor tweak could ruin the illusion of the seamless image while having the seam will allow you much more flexibility.

That's a great idea. I'll draw that out, and present it to the team. If the projectors turn out to create a perfect seamless image (which they probably won't) we are lucky and won't have to create the seam. That way we'll be able to have a Plan "B" if positioning the projectors will prove too difficult or like you said, the short throw lens will not make an even edge.

You should see if you can get two projectors as a demo and see how the image looks.

I don't know any place where I can get two projectors to test the image in Seattle. Maybe you have any references?
 
The projectors do not create that clean an edge, one reason why you see front projection screens with non-reflective borders. You can probably make what you are considering work well enough to get an image, but you're likely to have some noticeable issues at the center and really wonder if it might not be acceptable and much simpler with a single image.

What we'll probably end up doing is what ruinexplorer suggested. That way, we have a shot at the original plan but also have something that won't sacrifice too much -- a seam in the middle to cover up the unevenness in the middle.

I'm not sure that you understand the issues regarding setup and maintenance. To have a clean transition where the two images meet you are talking about getting 800 0.078" high pixels from each projector to line up with one another other with their edges exactly meeting and doing so with projectors with a fixed short throw lens, no lens shift and limited geometry correction. If you can get that to work then you are also looking at changes that occur over time, movement in the mounts, etc. meaning having to readjust the projectors. In general, you are almost certainly looking at much greater setup and ongoing maintenance than if it were simply two projectors independent of one another.

Are you mentioning that mounts will move around over time, even though they're tightened? Or is the building ceiling, in this case, that you're talking about?
 
Another option for the dual-projector scenario is giving up on having a semblance of 1 continuous image and just putting a thin-ish strip of masking down the center that's just enough to hide the spill. When running content across both "screens" people might notice it at first, but if the show is so boring that people are left to contemplate the setup of your projection, you have bigger issues.

What about when we have, let's say, a red background color? The yellow in the photo is just a rendering example that I did. We plan to be able to change colors.

Or were you talking about just hiding the rough join in the center with tape and having it be thin enough for no one to notice?
 
Are you mentioning that mounts will move around over time, even though they're tightened? Or is the building ceiling, in this case, that you're talking about?
All of the above. Buildings settle, mounts shift and both move with changes in temperature and humidity. That may or may not become an issue, but don't be too surprised if it happens. Another thing people often overlook, the optics of a projector lens can change as it heats up and cools down and for critical applications such as edge blending or matched images you may want to turn the projectors on in advance and let everything heat up to a nominal level.

Also consider that lamps may not age exactly the same, electronics can drift and so on, so if you really want the two images to match in terms of color and brightness then not only will you have to do a fairly comprehensive initial setup but you will likely also have to routinely tweak one or both of the projectors' settings.
 
All of the above. Buildings settle, mounts shift and both move with changes in temperature and humidity. That may or may not become an issue, but don't be too surprised if it happens. Another thing people often overlook, the optics of a projector lens can change as it heats up and cools down and for critical applications such as edge blending or matched images you may want to turn the projectors on in advance and let everything heat up to a nominal level.

Although what your saying is true, won't these shifts be too subtle to notice immediately? If we had to re-adjust the projectors once a month, that wouldn't be a problem.

Also, if we were to do what gafftaper suggested, there would be even less of a problem because of the frame in the middle.

Also consider that lamps may not age exactly the same, electronics can drift and so on, so if you really want the two images to match in terms of color and brightness then not only will you have to do a fairly comprehensive initial setup but you will likely also have to routinely tweak one or both of the projectors' settings.

That's what I'm currently wondering. In our main sanctuary we recently installed new projectors (in fact the ones that I made a thread about because of problems with them). It has been about 2 months, and there is a slight variation between the left and right projector images, as the left one seems to be a tiny bit brighter than the right. It's nothing that a normal person will notice, but if I turn off all the lights and tell someone that the right projector is less bright, they will see and agree.

As for the electronics, we're going to buy DLP projectors, and since this is "digital" projection, technically we shouldn't have any problems on the electronics part.
 
As for the electronics, we're going to buy DLP projectors, and since this is "digital" projection, technically we shouldn't have any problems on the electronics part.
The projectors being 'digital' will not eliminate the potential issues. The simple fact is that getting multiple projected displays to match in terms of pixel alignment, color, brightness and so on can be challenging to initially obtain and require periodic if not almost constant adjustment to maintain. And as you noted, the closer the displays are to one another, the more visually obvious any difference between them. Of course the displays matching is going to be more critical in some applications than others.

One factor is that there is going to be some variation in initial lamp and light engine output even within factory specs. Another is that the lamps are going to age differently, lamps start losing brightness almost immediately and the rated lamp life is generally an estimate of the hours of use to when the lamp would typically be expected to provide half the initial brightness. However, a number of factors other than just hours of use can affect how the lamp ages such as whether the total use consists of fewer long periods of use or more short periods, filter care, allowing the projector to properly heat cycle when turned off or not, environmental conditions and so on.
 
Although what your saying is true, won't these shifts be too subtle to notice immediately? If we had to re-adjust the projectors once a month, that wouldn't be a problem.
I have three projectors with a stacked image (one on top of the other to achieve greater brightness) and have to adjust the image a couple times per week. I check them daily, always allowing for at least fifteen minutes for the units to warm up before I touch them at all. Granted, my projectors have lenses that move and the heating/cooling can make them shift day to day, but it is a lot easier to re-adjust them than it will be with fixed lenses. Depending on your content, a one pixel shift could be very noticeable or completely imperceptable. By framing the images or somehow putting a physical masking between them, the eye will be tricked into not noticing slight imperfections.

I highly recommend that you check out Da-lite's education series (you don't have to read them all) before doing your installation. It will help you choose your materials and understand how to create a great image.
 
The projectors being 'digital' will not eliminate the potential issues. The simple fact is that getting multiple projected displays to match in terms of pixel alignment, color, brightness and so on can be challenging to initially obtain and require periodic if not almost constant adjustment to maintain. And as you noted, the closer the displays are to one another, the more visually obvious any difference between them. Of course the displays matching is going to be more critical in some applications than others.

Well, what this screen is for is mostly worship, which consists of a background and lyrics on top. I'm not sure that for this application it always needs to be perfectly aligned pixel-to-pixel, but I do acknowledge that adjustments are going to be needed, and that colors, contrast, and brightness will probably pose a problem.

One factor is that there is going to be some variation in initial lamp and light engine output even within factory specs. Another is that the lamps are going to age differently, lamps start losing brightness almost immediately and the rated lamp life is generally an estimate of the hours of use to when the lamp would typically be expected to provide half the initial brightness. However, a number of factors other than just hours of use can affect how the lamp ages such as whether the total use consists of fewer long periods of use or more short periods, filter care, allowing the projector to properly heat cycle when turned off or not, environmental conditions and so on.

Yeah I've actually seen that in action with our other projectors downstairs. There is a difference between the two, although they were used together each time.
 
I have three projectors with a stacked image (one on top of the other to achieve greater brightness) and have to adjust the image a couple times per week. I check them daily, always allowing for at least fifteen minutes for the units to warm up before I touch them at all. Granted, my projectors have lenses that move and the heating/cooling can make them shift day to day, but it is a lot easier to re-adjust them than it will be with fixed lenses. Depending on your content, a one pixel shift could be very noticeable or completely imperceptable. By framing the images or somehow putting a physical masking between them, the eye will be tricked into not noticing slight imperfections.

I highly recommend that you check out Da-lite's education series (you don't have to read them all) before doing your installation. It will help you choose your materials and understand how to create a great image.

Thanks for the recommendation. I will definitely look into that if we continue on with this plan.

Are there any short-throw projectors with lens shift? I've looked around and couldn't find anything, but maybe you know something?

As for content, I want to clarify on that. We will usually use this screen to present lyrics over some kind of background. Usually we use abstract backgrounds and not anything that requires a perfect pixel matchup. Once in a while (about once every two months), our youth has a movie night. I'm guessing that we'll want to pay close attention before a movie night, because any offset will be more noticeable than when presenting just lyrics.
 
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Do you guys think that there is no way that this will be a reasonable setup? If not, I will start to change the design to something else. I'd really love to have this screen work out, but it looks like either it's going to be too troublesome or not going to work out at all.

I really like ruinexplorer's idea about creating a frame or a strip in the middle, but I'm not sure how it'll look when we present a video or have a movie night. What do you think it'll look like during videos?
 
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For regular service, the seam will be ignored. With a movie, it might be distracting. Depending on how thick the division is and the distance to the nearest audience member (and how visually picky they are), it may be acceptable. Look at these two pictures, which are essentially video walls, not large screen projection, which shows different bezels.
View attachment 7797View attachment 7798
The smaller the bezel, the less noticeable and the sooner you will forget it is there. However, if the movie isn't completely riveting, then your audience will probably notice the divider.

There are projectors which you can have lens shift and a short throw lens (not ultra short throw) but you will dramatically increase your cost per projector. Also, with this style projector, you will need your projectors to be mounted as close to the center axis of the screen as possible, which can present a challenge with "hot spots", especially if you have a high-gain screen. With the ultra short throw, or other fixed position lens, they are generally made to sit off axis, which will help you avoid the noticeable hot spot.
 
Do you guys think that there is no way that this will be a reasonable setup? If not, I will start to change the design to something else. I'd really love to have this screen work out, but it looks like either it's going to be too troublesome or not going to work out at all.

I really like gafftaper's idea about creating a frame or a strip in the middle, but I'm not sure how it'll look when we present a video or have a movie night. What do you think it'll look like during videos?
I seem to have recently been seeing a number of "we put in two new projectors a year ago and now the images look noticeably different" discussions lately so that is probably making me more sensitive to issues related to differences in the images/ The difficulty is that what differences are noticeable. much less acceptable, can be so subjective and so dependent on the situation. I have also found that sometimes how you envision using projection may not be how it is used once it is installed much less a couple of years later.

For videos and movie night the aspect that jumps out to me is that with the dual projector setup a 16:9 or 4:3 video image would seem to use just over half half of the total screen width for 16:9 images and less than half for 4:3 format images. If you are running a DualHead2Go and using the computer for DVD or Blu-Ray playback then you might be able to move the playback window to one screen but you still have the rest of the computer image on the other screen, otherwise you'd seem to have a centered image with black to either side and the 'seam' in the middle.

You might also have to consider the 'seam' in your other images, not necessarily in the backgrounds but in relation to any text. Think a bright "I" in the center of the screen on a dark background, how would that appear with the center 'seam'? Just something you may have to consider when preparing graphics. Not nearly as critical but it reminds me of a project I did some years ago for the FAA where they noted that individual planes could be just a few pixels wide in the images and thus any seam or mullion more than a pixel or so wide could make it look like a plane disappeared, the point being that it may not be a matter of the absolute 'gap' the seam represents but rather how it affects what is being presented.
 
Just an idea, but what if we overlap the two projectors by an inch or two in the middle, and then shift the left/right images digitally to the left/right, respectively? Either way, because of the constraints of the design, we have extra on both sides that was originally to be absorbed by felt or something.

That way, if we notice that there is some kind of gap or overlap between the two images, we just simply shift digitally to as close to a seamless image as possible. Same thing can be done for the top and bottom as well.

I've looked up the manual for these projectors, and they do in fact have digital image shift.

What do you guys think of this? Will the fact that projectors cannot project "total black" create a noticeable increase in brightness in the middle during a movie in a dark scene, with all the lights turned off?
 
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I seem to have recently been seeing a number of "we put in two new projectors a year ago and now the images look noticeably different" discussions lately so that is probably making me more sensitive to issues related to differences in the images/ The difficulty is that what differences are noticeable. much less acceptable, can be so subjective and so dependent on the situation. I have also found that sometimes how you envision using projection may not be how it is used once it is installed much less a couple of years later.

Yes, I know what you're talking about. The audience that is going to be looking at this screen isn't particularly "picky". In fact, I doubt that even three-quarters of them will never know that there are two projectors making up the image, if we were to continue on with this.

For videos and movie night the aspect that jumps out to me is that with the dual projector setup a 16:9 or 4:3 video image would seem to use just over half half of the total screen width for 16:9 images and less than half for 4:3 format images. If you are running a DualHead2Go and using the computer for DVD or Blu-Ray playback then you might be able to move the playback window to one screen but you still have the rest of the computer image on the other screen, otherwise you'd seem to have a centered image with black to either side and the 'seam' in the middle.

Yes, I was planning for that. I thought that this wouldn't play a large role, because when all the lights are turned off nothing but the now "16:9" screen is visible in the middle. I'm just wondering how bright will the gray be on both sides of the unused space during movies (since there aren't real blacks being projected).
 

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