projector stacking/blending: how to choose a projector?

[ghosttrain]

I need 3 5000 lumen+ projectors to be stacked. I've seen youtube videos of someone using a Epson Powerlite1960 for it. It has geometric correction and seems good. But I've also found another candidate, Optoma W501. They seem very similar except Optoma is a newer model (so longer support) and has more resolution and contrast. I didn't find any mention of geometric correction on Optoma though.

Is that an issue and should I get the projector which has geometric correction on-board, or are stuff like that generally done in VJing programs anyway and so wouldn't make difference when using with Resolume? It seems I'll need to be doing blending in Resolume with any projector in this price range, but wanted to know what's the case with geometric correction (for stacking).

If there's something else crucial for stacking/blending I don't know and need to check when choosing projectors please let me know.

[ghosttrain]

bump...

[Oaktown]

I need 3 5000 lumen+ projectors to be stacked.

Keep in mind that stacking 3 projectors will give you a brighter image but it will also make the video black much brighter!

Also lining up 3 projectors especially projectors without lens shift takes some work to get crisp images.

I've seen youtube videos of someone using a Epson Powerlite1960 for it. It has geometric correction and seems good. But I've also found another candidate, Optoma W501. They seem very similar except Optoma is a newer model (so longer support) and has more resolution and contrast. I didn't find any mention of geometric correction on Optoma though.

If you are going to use Resolume Arena, you don't need geometric correction in the projector but having lens shift (at least vertical) will make your life much much easier!

Is that an issue and should I get the projector which has geometric correction on-board, or are stuff like that generally done in VJing programs anyway and so wouldn't make difference when using with Resolume? It seems I'll need to be doing blending in Resolume with any projector in this price range, but wanted to know what's the case with geometric correction (for stacking).

See answer above.

If there's something else crucial for stacking/blending I don't know and need to check when choosing projectors please let me know.

I personally don't like to stack more than 2 projectors but i know people do it so it's probably a matter of preference.

As far as blending goes, Arena does a very good job at blending projectors but for best result make sure you have identical projectors so that you images look even all the way across.

[ghosttrain]

I need 3 5000 lumen+ projectors to be stacked.

Keep in mind that stacking 3 projectors will give you a brighter image but it will also make the video black much brighter!

Sure. But thanks for mentioning. It will still be 3000:1 contrast if each projector is 3000:1 contrast, just that both dimmest and brightest pixels will be around 3x brighter, right? The only reference I have of knowing if the contrast will be acceptable is I've seen 4 15,000 lumen Christie projectors with 2000:1 contrast stacked together. And I have few videos as reference.
I think 3000:1 will be fine for 14000-15000 lumens, but please let me know if I got something wrong.

If you are going to use Resolume Arena, you don't need geometric correction in the projector but having lens shift (at least vertical) will make your life much much easier!

Okay.
Can I do geometric correction on the projectors, but blending on Arena? I'll explain why I'm asking below.

As far as blending goes, Arena does a very good job at blending projectors but for best result make sure you have identical projectors so that you images look even all the way across.

Thank you. One question though, can I blend 3 1024x768 videos if my PCs monitor is only 1920x1080? If not, how do people do it?
And how CPU/GPU intensive is doing geometric correction for 3 projectors in software (Arena)? Can you even do 3 separate geometric correction? How will 3 different video signals be sent from the PC to each projector? I changed the subject, I know. But it is related. If doing geometric correction as well as blending in Arena is easy and not costy/requiring special hardware, then I don't need geometric correction on the projector itself as a requirement when choosing the projector.

[Oaktown]

I've seen 4 15,000 lumen Christie projectors with 2000:1 contrast stacked together. I've seen 4 15,000 lumen Christie projectors with 2000:1 contrast stacked together.

As a head's up, the 15K Christie projectors are a very different type of projector than what you plan to use. The Epson Powerlite1960 is a consumer-grade table-top projector with no lens shift (Epson Powerlite 1960 manual) so regardless of contrast stacking 3 of them is going to take some work to get an acceptable blend.

Is that an issue and should I get the projector which has geometric correction on-board, or are stuff like that generally done in VJing programs anyway and so wouldn't make difference when using with Resolume? It seems I'll need to be doing blending in Resolume with any projector in this price range, but wanted to know what's the case with geometric correction (for stacking).

I personally never use projector's on-board geometric correction options. I do all my work either in software such as Resolume or with a dual-output Barco ImagePro II. When available, tyically projectors' on-board adjustement are not precise enough unless you use high-end projectors (such as the 15K Christies you saw in your video)

Can I do geometric correction on the projectors, but blending on Arena? I'll explain why I'm asking below.

Stacking doesn't involve blending at all. You blend projectors when your images are overlapping to create a larger image than what your projectors can do.

The ideal stack is two (or three in your case) projectors perfectly lined up physically with no geometric correction and with all the pixels that match. Any area where pixels don't line up precisely will look muddy. If you do any geometric correction (on-board or software, it will get muddy because your image will be scaled onto your native resolution so not all pixels will be used (video black).

Keep in mind that the moment you move one corner of your image one pixel in any direction, your image gets some amount of distortion to trick your eyes into believing that the image is right. That's what mapping is all about! It all looks great from enough distance but if you walk up to the projected surfaces it won't look clean.

One question though, can I blend 3 1024x768 videos if my PCs monitor is only 1920x1080? If not, how do people do it?

Yes and there is plenty of how-to posts in this forum.

And how CPU/GPU intensive is doing geometric correction for 3 projectors in software (Arena)?

That's a question for the Resolume team but I don't think it's very intensive.

Can you even do 3 separate geometric correction?

Yes, no problem! I did an installation a few months ago with 15 projectors and each one of them was mapped onto the architecture.

How will 3 different video signals be sent from the PC to each projector?

You'll need 4 outputs (1 UI + 3 projectors). If you have less than 4, you'll need a way to split one output into what you need (Matrox D2G or T2G, Datapath X4, MST Hub, etc...)

Keep in mind that in theory, you could do a stack by splitting an output in however many projectors you have in your stack. That's what I do when I work in theatres where there is enough space to stack two projectors behind an RP screen. To split my output, I use a dual-output Barco ImagePro II. I take one signal and split it into two independent outputs that I can manipulate individually. It works great but the Barco hardware is super expensive (~$12,500) so it's probably not something you'll be able to use for this project.