Projector help

[tennyson]

Hoping that one of you visual guru's might lend me a hand.

I'm looking to buy 3 of these Benq W1080ST projectors for my sim.

Here are the dimensions of my new room.

The height of the ceiling is 2.4 metres and the width of the room is 3.6 metres.



Now, here is the pic that I generated from the Benq site for the W1080ST projector.



I am going to build a wrap around screen for the three projectors, but looking at the above table, do I take it that if I hang my projector .33 metre from the roof and 2.07 metres from the screen that I will get an image that will be 1.69 metres in height and 3.0 metres in width?

I am guessing that using the curved screen, I have to allow for loss on the sides, thus I have made it 3 metres and not 3.6 metres or can I go further with this size?

I don't want to go out there and buy 3 expensive boat anchors, so any help would be greatly appreciated.

What about you, Nat? You eat this stuff up for breakfast, any help?

Thanx guys,


Frank Cooper

[Jon Boe]

Hi Frank,

Take a look at the following PDF and see if it helps clarify the screen design.

Cheers,

Jon

[Nat Crea]

Frank,

My gut feeling is they wont work...sorry..unless you are happy with a much
smaller image than what you calculated above. I hinted that a few weeks ago 
Use Jon link and re-calculate the image size, then see if you will be satisfied.

Nat

[HarryZ]

Frank,

The size of the image from a short throw projector can be adjusted by moving the projectors slightly forward or backwards.  There is a math formula that can be used to determine the height of screen you will need depending at what distance from your eyesight (radius) you want.  The top of the projector lens should be at the same level as the top of the screen. If this can be done, it eliminates any keystone correction required.

Have you determined what viewing angle you want?  Can I presume 180 degrees?

Also remember that you will need blending software to adapt the flat projector images to fit the curved screen and that requires an approx 20% overlap of your projector images to make it work properly.

I have a business (announced earlier on this board) that handles the kind of project you are attempting.  Please drop me a PM if you want to pursue this with me.  Thanks.

Harry

[tennyson]

Firstly, thank you to all three of you guys.

Jon, I downloaded the pdf, but the calculator does not work within the pdf. Is it just an example?

It kind of confused me more....

Nat, I thought you might chime in, but know how busy you are all the time, mate. I took your comments on board about those projectors, but I wanna make sure and I'm ready to start building screens and buying projectors, so it would be a really good time for me to know exactly what I should be buying.

And harry, I have a full FDS shell, so apart from that, I can't see why I couldn't have the projectors at the top of the screen, thus eliminating the keystone correction.
I did note, tho, that this model has a +_20 degree Keystone correction available.

And I'm hoping to build a 220 degree screen and projection system. My back two windows are not blocked out, so I need the extra few degrees.

I've also shot you off an email, Harry.

Thanx again guys, I'll go back and do some more research,



Frank Cooper

[tennyson]

Okay, so I went back and took another look at the formula that Jon provided.....doh!

The penny drops.
I worked out, with the aid of a small drawn model, that the sagitta was 1 metre (wow, that's a complicated formulae), so I add that to my original 2.07 metre calculation and I now have a 3.07 metre distance for each of the three projectors.

Hmmm, as my room is only 3.6 metres wide, I guess the only way to mount 3 projectors at 3 metre distances, would be to offset, so they don't cut throo each others beam, but will that work?

Surely other builders have faced this very problem. How do you guys compensate for this?

Is it the throw that is the problem, here?

If it is, what is the better projectors to buy?

This stuff is doing my head in already.......


Frank Cooper

[Nat Crea]

You hit the nail on the head Frank.

Without doing the calcs myself, I can see you have three things going against you...and they are the most critical things:

Ceiling height
Room width
Throw ratio.

The BenQ's wont work. No magic software will fix plain old physics...don't let anyone tell you otherwise 

PM me if you wont to brain storm some other options.

Nat

[Sudden81]

But how many degres can he get?

I have as simular setup and would be happy whit 160-180 degres  just to have 3x FULL HD!

Best regardes  Jacob!

[Nat Crea]

Jacob,

Nothing really to do with the FOV Frank can get. Its more a case of not being
able to project a large enough image over the shell from that distance.

Nat

[Sudden81]

I think you are wrong.

All cases if you think like I do.

So here I am:

If you have a picture in front of you at 1 meters distance, which is 1 meter wide you get a 45 degree view. Is this true?

We ignore radius, but imagine that the views are square, for simplicity.

Imagine that you put 3 pieces 50 "tv sets 1 meter in front of him. This should then give about 135 degrees view.

But what happens to the angles if you move forward all television sets everything to let's say 180 cm. You get the angle 29.05 degrees. Which gives a front view of 29,05 x3 = 87.15 degrees.

This with throratio 1.0. On W1080ST is the best Throw Ratio 0.69-0.83 (65.7 "@ 1M) Wide = 59" = 151 cm on a flat surface. (You do not have to have a rounded screen)

What if there is no image blending: on 1 meter distance from the eye point 151 cm wide picture which gives 56.59 degrees view, which gives 56.59 x 3 = 169.77 degrees view from a meter. But of course, I also realize that you can not have a projector 1 meter from the eye point if you have a FDS shell. Using the same calculation at 180 cm it will be if I did not think wrong .....

First Throw Ratio: 180 cm = 267 cm wide image

56 x 3 = 168 degrees view of 180 cm distance if you do not have a rounded screen or image blending.

With a little imagination, one could then get at least 150 degrees view with some image blending and rounded screen. Or do I think completely wrong?

Starting to experiment with mirrors so you can maybe get to 160-170 degrees view.

If you have the right lenses and mirrors and the screen can also make the picture very close. But then it starts to get complicated.

Boeing F-18 CRVS Immersive 360 degree flight simulator demo

Time Lapse - I/ITSEC Screen Build

3D Perception's Northstar™ w/ Aurora™ auto-calibration

http://www.northernflightsim.com/projectionscreen.shtml

[Nat Crea]

I think you are wrong.

LOL...You are trying to use simple trigonometry to make things "work" in your mind.
I do this for a living, from real world experience, I can tell you that you will not be able
to place your left and right projectors lens's 1.8m form the screen.
You cannot physically get all three lens in the "center" of the screens arc.

You will get an image, but by the time you move the L/R projectors close enough to the screen so as to not get any shadow from the shell, the vertical height of the image will be too small in MY opinion.

Not sure what the videos prove...big screens and nice expensive projectors, nothing to do with Franks application.

Yes imagination and mirrors can help

Like I always say, be my guest...buy three BenQ's and let us know how it goes.

Nat

[tennyson]

Sorry Sudden, but I've seen Nat's set-up and that is why I asked him to chip in. He talks the talk and walks the walk.

Trouble is, he's so damn busy, hard to get hold of him.

I've looked at my room again today, trying to figure out what I can do.
As it turns out, I must have been smoking drugs or some such thing, because the measurements were not correct.

When I re-measured the width of the room is actually 3.2 metres wide, not 3.6.
And the ceiling is actually 2.7metres high, not 2.4.
The length of the room is 5.6metres and after measuring up my base, if I make some major changes (which I 'd be prepared to do), I could turn it 90 degrees, so I have about 4.5metres to play with.

So, after that bombshell, what do you think, Nat. Are the 1080St's still out?

Thanx again guys, appreciate the help tremendously,



Frank Cooper

[Sudden81]

I think you are wrong.

LOL...You are trying to use simple trigonometry to make things "work" in your mind.
I do this for a living, from real world experience, I can tell you that you will not be able
to place your left and right projectors lens's 1.8m form the screen.
You cannot physically get all three lens in the "center" of the screens arc.

You will get an image, but by the time you move the L/R projectors close enough to the screen so as to not get any shadow from the shell, the vertical height of the image will be too small in MY opinion.

Not sure what the videos prove...big screens and nice expensive projectors, nothing to do with Franks application.

Yes imagination and mirrors can help

Like I always say, be my guest...buy three BenQ's and let us know how it goes.

Nat

But if you work with projector setup you should be able to have an exact answer to how many degrees you can get out verticalt and horizontally, and how much of the image is obscured by shell and so on.

Or have an answer to exactly how to get 1080P minimum a projector, and what to do in the wide and length and height of the room.

How do you do?

I had not been able to limit myself with 1280!

[saabpilot]

For projected images measurements vs. distance to screen you can use the calculator at projectorcentral.com.
Likely this Benq is available in their database now or it will be so soon.

Normally you mount the 3 (or 2) projectors close to the ceiling but need to take the cockpit enclosure masking into account.

With the semicircular screen close to the cockpit windows the image will be sharper but lose a bit of the 3D impression.
Optimal throw ratio is in my opinion 0.5 or better.

Also needed is an overlap for adjacent pictures which horisontal size depends on the warping software used.

Just my 5 eurocents.

Bjorn

Sent via Tapatalk.

[tennyson]

That's good info, Bjorn.

And just for info sake, the Benq 1080ST will not work in my situation. I need a much shorter throw projector, but we've come up with a semi-solution, to turn the sim sideways, which will allow for a better fit with existing short throw projectors.

Now I gotta go build the screen, so thanx again for all your help, guys, it was very much appreciated,



Frank Cooper

[HarryZ]

Initially, when looking up the numbers for the BenQ 1080P ST projector,  I also thought that this unit could not be used in Frank's situation.  But when checking again, I saw that I was using the numbers for the 1070 projector whose number chart was included along in the same manual as the 1080P.  Here is the link to the 1080P projector's numbers.  I think it could work.

http://www.projectorcentral.com/pdf/projector_spec_7436.pdf

Harry