# Video Wall Using Projectors



## Dsync (Oct 10, 2011)

Can someone give me advice on how to go about this project? I'm setting out to make a video wall in a fairly small space using projectors. I have a 12 feet of headroom behind the stage before I start hitting trusses. So I can't go up really high, but I can make it super wide. I was planning on lining up 5 projectors (not little presentation projectors, but ones suited for this). Now I realize that this aspect ratio is totally crazy, but we won't be outputting traditional media to this wall. My team will be custom designing all of our material to fit whatever the resolution ends up being. Budget is $15,000 for this project. 

My software is ProPresenter 4, but I have access to ProVideoPlayer if needed. As far as hardware, I can get whatever is needed as long as it fits within that budget. I'd like a solution that employs RGBHV cables as I already have those running through my rig. But if this project requires something else, it's not a big deal.

So my question to you guys is this: Would you do it like this? If not, how would you go about it? What hardware/software would work best? And what issues could I run into by doing this?

Thanks for your help!


----------



## metti (Oct 10, 2011)

You are going to want to employ a technique called edge blending that will allow you to overlap and smoothly blend the projectors on the adjacent edges to create the illusion of a single image source. Unfortunately ProPresenter only supports 3 edge blended projectors and I can't seem to find any documentation of any edge blending capabilities within PVP so you may need to look to some different software. Something like Watchout would be ideal but it is also way outside your budget by the time hardware and the projectors themselves are factored in.

Regarding projectors, ignoring playback hardware $15k divided by 5 gives us $3k for each projector as well as mounting hardware for it. This could be workable depending on how wide/tall the stage is and how much ambient light there is but it could also be completely insufficient. More information could be helpful.


----------



## Dsync (Oct 10, 2011)

Thanks for your reply! Here's some more details:

I already have 3 projectors from another project that I would like to use for this. So I would only need 2 more. That opens up more of the budget for other hardware/software. The projectors I have right now were about $3k each, so they are decent projectors for what they do. They are 1080p and support a whole slew of signals/connections. So I would like to continue with these and not get all new ones unless I have to.

As far as the space... right now, the stage is 25-30 feet wide and I have 12 feet of headroom before hitting stuff. Lighting could be the biggest issue. But the rig can be adjusted as needed to make this work. During scenes when I have to use my front wash, I just accept that the lower part of the screen will get blown out. That isn't when I really need the wall though. This wall will really be used when I'm lighting the stage with out-focused movers with colors and LEDs.

When you say "playback hardware", what exactly do you mean? I still don't quite understand how this works. Is there some sort of hardware unit that will trick the software into thinking it is some kind of screen with a weird resolution when actually it is just taking that signal and distributing it out to make one large screen? I guess that is where I'm most confused.


----------



## museav (Oct 10, 2011)

Where to start...

You probably want all projectors to match. You could get by with them not matching but that will make many other aspects more difficult.

You apparently know the space you have for the projectors and if you have three projectors you should be able to find the throw distance information for them. Other than looking at the 12' height, have you considered the space necessary for this?

How did you arrive at five projectors? Are the projectors actually 1920x1080 native resolution or is it that they support 1080p but may be some other native resolution? Just for some reference, assuming the projectors are used in normal landscape orientation and 10% overlap for edge blending, five 1920x1080 edge blended projectors would result in around a 67.2:9 or roughly 7.5:1 format overall image. With a 25' to 30' stage width that equates to something like a 40" to 48" high image with an 8064x1080 resolution.

Have you considered what you are doing for a screen?

I get the sense that either there has been a lot of planning involved that has not been noted or there was some jumping to specific hardware aspects of a solution before fully developing the concept. For example, could you clarify some basics such as whether you are looking at front or rear projection, how large an image you are trying to create, how smooth an image you desire, how much room you have behind (rear projection) or in front of (front projection) the screen, how you envision mounting the projectors, what projectors (and lenses if appropriate) you have and so on?

If you could work with two or three projectors that have the same native resolution and are essentially creating three separate images then there potentially are some relatively inexpensive hardware options available. However, if you want one seamless image from five projectors, including three existing projectors, then that may require a much different approach. In either case, it is probably best to start with defining what you are trying to do or achieve and the constraints that would apply, then working toward what hardware and software solutions may be appropriate.


----------



## chausman (Oct 10, 2011)

To slightly go along with what Museav said, what are you planning on showing on this 25' x 4' (roughly) wall?


----------



## Dsync (Oct 11, 2011)

museav said:


> Where to start...
> 
> You probably want all projectors to match. You could get by with them not matching but that will make many other aspects more difficult.
> 
> ...


 
Alrighty, here's some more details. 

I will definitely get matching projectors. Wether or not I use the same ones I have right now is still unknown. I would just like to be able to stick with these instead of putting most of my budget into totally new units. I will check on the model and post that soon. I don't know it off the top of my head.

I should have enough space to do this. I had my current three projectors putting mirrored images behind my stage in a previous project. (Three separate screens all showing the same image) So I know the space will handle it. After I get the model number of these current projectors, I'll be able to find the throw distance.

I arrived at 5 projectors after seeing the coverage I was getting with 3 separate screens. 4 isn't enough, and 6 would be overkill. I was running a 1440x1080 to these projectors. Yes, 4:3. Just kill me now 
I realize that this wall will be a strange aspect ratio. I will be running custom designed 3D motion backgrounds to this and if I should ever need to run traditional 16:9 media to this wall, I will simply put the media into a super wide project and just have really really large black bars on the sides of the video. That works for my needs. 

I haven't put extensive thought into the screen itself. 

There hasn't been any major planning involved. Just a few brainstorming sessions with my team. We are looking at front projection only as we don't have the required space for rear projection. I would like the image to fill the full space. (25-30x12). I have decent mounts for these that don't have any unwanted movement whatsoever. Not even noticeable vibrations from the subs. 

I am definitely set on doing a seamless image. Although, if I needed to split each screen by a 1 or 2 inch black stripe for blending, I would't be opposed to that. (So long as all the screens form one image.)

I still don't know how to get all these projectors to act as one screen. I understand the blending concepts and all, but what hardware will do this?


----------



## jbrem003 (Oct 11, 2011)

I just finished doing a few things like this for Enron and a local production of Sweeney Todd. There are two ways to go about it. You can "edge blend" in software and hire a media editor to use AfterEffects to build a template that fits your edge blending (Isadora is a program that I highly recomend for it's ability to chop/distort video without losing much if done properly.) 

Or you can have projectors that perform edge blending and just output video in the custom resolution that fits your space.

Either way for something this complicated I recommend finding a projection engineer that can help consult your install if you haven't done one before. It took us about 2 months doing it on our own and I had extensive experience with projectors leading into the project.

Also, consider using short throw lenses on your projectors. They are an AMAZING way to get your projectors closer to the screen and therefore seriously maximize your brightness and clarity under stage lights. 

You can also consider overlapping projectors to double the brightness, but they CANNOT be bumped (same as with edge blending, seriously, make sure nobody is near them.)

Also know that as soon as you keystone you lose your 1080p HD signal. Not usually a big deal, and you can still say it's HD if you're rendering HD quality source video, but technically you could go both ways about it. 

Those are some of the basics. I'm interested to hear how it turns out for you  Pictures?

Feel free to visit our website if you have any further questions. We are a theater media technologies lab recently specializing in video.

GenericLABS - Non-Profit Organization - Norfolk, VA | Facebook

Best!
-Jon


----------



## jbrem003 (Oct 11, 2011)

TroikaTronix - Home

ISADORA website, it has a bit of a learning curve which is why I recommend hiring out for your first job with it if you don't have a few months to get it under your belt. It allows for edge blending

AfterEffects is available on adobe.com and was what worked best for a completely seamless image, you have to account (logarithmically) for a blending of gamma, brightness and saturation between each edge. 

KRAMER matrix switcher

best piece of equipment if you plan on manipulating where your video feeds go.

Also, have you discussed how you would go about controlling all this video? You're going to need one beast of a machine to do it. I was able to recently get 6 outputs from a Mac Pro tower with two HD 4770 video cards using a combination of VGA and DVI cables to pull it off. You need to get the $100 "dual - link" DVI adapters to do it though where a USB cable helps power the video output.


----------



## derekleffew (Oct 11, 2011)

Some interesting reading:
Event Management-Event Planning-Widescreen Edge Blending-New England
Edge blending using commodity projectors
Multi-Projector Edge Blending with Overlap | Matrox Edge Overlap


----------



## jbrem003 (Oct 11, 2011)

derekleffew said:


> Some interesting reading:
> Event Management-Event Planning-Widescreen Edge Blending-New England
> Edge blending using commodity projectors
> Multi-Projector Edge Blending with Overlap | Matrox Edge Overlap



Cool! Thanks for sharing


----------



## Footer (Apr 25, 2013)

Mod Note: Thread closed due to spamming.


----------

