Does Nvidia SLI require 3 projectors?

[reuben.ahmed]

I have all the parts for my simulation projector's PC. I purchased two GTX970s to execute in SLI. I'm in the process of building the PC now, but of course the tougher part now is the projectors to use and screen build/edge blending software.

From what I understand, I'll need 3 projectors in order to take advantage of output, or can I use just 2 projectors?

Thanks!
ElmO

[BHawthorne]

Apparently a new feature in the 900-series is to be able to span between 2 and 5 displays. Before the 900-series Nvidia was only triple display for Nvidia Surround. As it's so new and I only have a GTX770, I don't know the updated mechanics of it yet personally. If you find out any details, let me know. I'd like to experiment with it myself, but I'm low on $$$ at the moment.

[BHawthorne]

I just saw this post, it should help give a bit more insight.

http://www.wsgf.org/forums/viewtopic.ph ... 36#p155636

[reuben.ahmed]

Thanks Brad - I'll check that post out. Can I fly you out to Ohio to help me out with the install once I have the PC setup? I'll need to decide on which projectors also which you can help with beforehand.

I'm guessing 2x1080p based on your recommendation. I think 2x970s isn't enough to drive 3x1080p with high frame rates in most games.

[BHawthorne]

Sure, no problem. I only do on-site stuff 2 or 3 times a year, but as long as my transportation, room and food are accounted for I'm ok with doing it. Currently also have someone from Toronto that wants me to do an install in a few weeks. It gives me an excuse to visit someplace new a few times a year.

Nothing too magical about 3 x 1080p. People have been doing it around here for years. Really depends upon what you're using it for and how high the settings in-game/in-sim are.

[BHawthorne]

Cybereality just posted that his GTX980 has 2x1 option, so at the very least it's available on the GTX980. It's pretty much guaranteed to be available on the GTX970 if it's on the GTX980.

[reuben.ahmed]

OK, excellent. Well this happened last year too (lol), I owe a fairly sizable tax return. I have to fix my withholdings.

Anyway it shouldn't put a huge hamper on the plan.

Do you have any recommended triple 1080p projector I should try? I know earlier you mentioned maybe people should start with 2 projectors just to see if they like it.

Thanks!

[BHawthorne]

My current two favorites are the BenQ W1080ST and the Optoma GT1080. The BenQ has variable lens zoom and lens shift ability while the Optoma has a bit shorter throw. Both are good 1080p short throws though.

[reuben.ahmed]

Good, I'll probably go with the BenQs just so we don't run into any problem with mounting them, but I read in the reviews the 1080ST doesn't have lens shift. Typically the short throws have no lens shift, or only up/down or left/right, if I recall.

Secondly, I'm most worried about the screen out of everything. What on earth are we going to do about that?

I'm repurposing my 3D theater room for this, I'll be blacking out the full front wall with black velvet. Approximately how far back from the center of the screen do you sit? I have an immovable stage in the way, if I bring the screen wall out too much, with the curvature you won't be able to enter/exit the room (lol).

Here's the room we're going to work with:
https://www.facebook.com/reuben.ahmed/m ... 159&type=3






Thanks!

[cybereality]

That's a sick theater setup!

[BHawthorne]

I might be off on saying the W1080ST has lens shift. I have a W1070 I'm basing my experience on and I has both lens zoom and shift. My understanding the only difference between the W1080ST and the W1070 was lens throw ratio. I might be wrong though.

[reuben.ahmed]

That's OK, I'll research both projectors.

Yeah, please don't say that room is sick because I'm about to change it into a simulation room with BHawthorne - lol. I don't know how it'll turn out, we'll see.

The problem is the stage, I can't really demolish that because it has 1000lbs of sand in it. We'll figure something out.

[BHawthorne]

I'm repurposing my 3D theater room for this, I'll be blacking out the full front wall with black velvet. Approximately how far back from the center of the screen do you sit? I have an immovable stage in the way, if I bring the screen wall out too much, with the curvature you won't be able to enter/exit the room (lol).

I suppose if the entry way is a key factor, that you could put the screen into the corner or on a different wall? That way it's not interfering with the door. Typically, for simulator content you'd want to be at or near the screen radius centerpoint. The thought is that gives you significant forward looking peripheral view. On regular gaming content that is limited by less accommodating in-game camera controls you'd be 3 or 4 foot back from the centerpoint. For movie content you'd be even further back in the room. The viewing location is sensitive to the content type. There is really no single definitive answer to viewing location.

I hope that helps a bit, although it might confuse matters further.

-Brad

[reuben.ahmed]

Brad,

Makes sense, but a few questions:

• When you say near the radius, what is a typical radius for a triple projector FOV (10-15ft wide)?
• Do you typically do 120 or 180 degree FOV with simulation setups?
• If the radius of the screen is, say, 3ft, does that mean you should be 3ft away from the center point as well (so peripherally your eyes are in exact horizontal line with the edge of the screen area)?

I only plan to use this setup for simulation (car racing, flight sims) - no other games or movie watching.

That will help me figure out screen placement and if my stage area is in the way.

You can see that I have approximately 3 ft before the door starts, here. It seems like I can't have much more of a radius than that, given both the door and the stupid stage are in the way (lol).

I can rearrange the room, just thought most of it is wired up (audio) and front wall is relatively complete the way it is. I'd have to build a screen in front of that pillar you see in the image (so if you walked into the room, you'd be facing the screen). That'd reduce my throw length, and it'd be odd with the stage being to the right, but I can live with that. The throw length shouldn't matter much since we're working with short throws, I'd still have at least 10-12 ft of throw if necessary.


Thanks,
ELmO

[BHawthorne]

On diameter/radius, typically between 10-20 foot diameter with a radius of 5-10 feet range. 10 foot wide diameter pushes the extreme I'd be willing to do because the smaller radius means tighter curvature for the screen arcs for the projectors to cover. That pushes the extremes of the focus depth most projectos can do. For example, the minimum I'd recommend is a two-projector 5 foot radius, 10 foot wide screen, 5 foot tall screen height, 180 degrees. That pushes pretty much the limits of focus depth, pixel size and screen radius. 90 degrees per projector is pretty extreme, but works. I'd prefer suggesting between 60 and 75 degrees per projector on a simulator setup. Anything over 180 degrees total is limited to flight simulation because I'm not sure of any racing simulations that allow multi-camera slices like flight simulators do. FSX, P3D and DCS all allow custom multi-camera scripting to get around the 180 degree limitation. I'm not enough well versed on racing sims to know if there is a like solution on some of the racing sims. However it would be cool if iRcaning, Assetto Corsa or Project CARS allowed it. Once you get past that 180 degree FOV mark around 225 degrees FOV you truly get real forward facing full peripheral view. This becomes especially impressive if the room is fully blacked out. The ideal location for flight simulation is at the centerpoint of the screen radius with a 220 or more screen so you get total peripheral view. Although I would not recommend going 3 foot away from a 3 foot radius screen. That's probably too tight a radius and too small a screen for it to work right. I'd do no less than 5 foot away from a 5 foot radius screen. I was much more happier with a 6.5 foot radius screen triple-projector setup back in 2010. The 2013 5 foot radius screen was designed because convention booths are 10x10 foot sized footprints and I needed a screen I could setup in a booth. I wouldn't of done 5 foot radius otherwise. It's very tight radius for a dual projector.

[BHawthorne]

Just a brief follow up. I have Nvidia Surround working on my GTX770 running 2x1 span. Not sure what all cards they enabled this on, but it's at the very least on 700 and 900-series.