Simviation Forum - Projection Monitor Question?

Dec 25^th, 2003 at 11:49am

JBaymore Offline
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OK... so color me dumb. This might be a pretty basic question....but it's got me stumped.

I am trying to see if my current cockpit setup design will allow me to use a projector for the front out the windscreen view within the footprint I have allowed myself. I need to know how large an image a projection monitor will "throw" if I know the distance from the lens of the unit to the screen?

Is this something that I can find out without actual testing? The aspect ratio of width to height I understand.... but the general image size is puzzling me.

Thanks in advance.

best,

.................john

Intel i7 960 quad 3.2G LGA 1366, Asus P6X58D Premium, 750W Corsair, 6 gig 1600 DDR3, Spinpoint 1TB 7200 HD, Caviar 500G 7200 HD, GTX275 1280M, Logitec Z640, Win7 Pro 64b, CH Products yoke, pedals + throttle quad, simpit

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Reply #1 - Dec 25^th, 2003 at 3:12pm

KnightStryker Offline
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Hey John.

Just a thought here but this might be a question to contact the manufacturer of the projector you are interested in. I know you can get projectors that can throw an image 100 inches or larger so there is probably one out there that would fit your needs.
And just another thought, while using a projector might give a larger image what would it do to the quality of the image. I am all about looks for my sim so I personally would not sacrifice quality for a larger display. Just a thought though you may feel differently.
Good luck,

Kevin

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Reply #2 - Dec 25^th, 2003 at 9:39pm

JBaymore Offline
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Kevin,

Thanks for the reply.

Yeah... the image quailty IS an issue....... but in trying to "up" the realism level, I think that I want the image out the "windscreen" to look a bit more like actually looking OUT a windscreen. I know that I will have to go with a high rez projector.....not one of the real low end ones.

I won't be enlarging it TOO much........ I only need about 2 1/4 feet of display height to "fit" the windscreen configuration..... and since I am modeling only the left seat to the center console .... it doesn't have to be the full width of the aircraft.

The ideal would be some really LARGE liquid crystal displays that are actually a tad larger than the windscreen openings..... but those size lcd screens would get expensive FAST! Then there is the framerate issue with that many pixels being redrawn.

Just starting to explore this projector idea. My main concern is that the throw distance (projector to screen) that I have available for my simpit is quite limited...... and I am not sure that I can get an image large enough to fit my needs with that throw.

I may still end up with an array of probably three used 20"+/- monitors to sort of accomplish the goal..... but that will look far from "real".

best,

...................john

Intel i7 960 quad 3.2G LGA 1366, Asus P6X58D Premium, 750W Corsair, 6 gig 1600 DDR3, Spinpoint 1TB 7200 HD, Caviar 500G 7200 HD, GTX275 1280M, Logitec Z640, Win7 Pro 64b, CH Products yoke, pedals + throttle quad, simpit

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Reply #3 - Dec 26^th, 2003 at 5:10pm

KnightStryker Offline
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Just had a quick thought as I read your reply.
Have you given the Fresnal Lens any thought? take the monitor and set a fresnal lense infront of it a certain distance away and BAM, bigger picture and it doesn't cost you even one FPS. I have seen this application on numerous sites about building a simpit and have seriously thought about going this way with my pit when I get back on track with it.

Kevin

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Reply #4 - Dec 26^th, 2003 at 8:57pm

JBaymore Offline
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KnightStryker,

Yeah...... I have thought of the Fresnel lens idea. I even purchased a small cheap one (8" x 10") to test the general concept. It is pretty interesting and makes a good depth of field....... so I spent some time looking up "collimated displays".......... the stuff often used on real simulators. Not doable "on the cheap".

One problem with uing a regular monitor and the lens is the footprint issue. I have pretty tightly tied myself to a 5' x 5' space to make this work with the space I can "steal" in ther house. Using a monitor and the fresnel would likely extend the distance on the long dimension........ unless I use lcd monitors behind the Fresnel lens(s).

The cockpit setup will allow a projector to come down from the top at the rear and project to a screen "outside" the simulated windscreen. It will have a "throw" of about 6'. This is my limiting factor on the projection idea....... can I get the image the size I neede in that distance.

best,

..................john

Intel i7 960 quad 3.2G LGA 1366, Asus P6X58D Premium, 750W Corsair, 6 gig 1600 DDR3, Spinpoint 1TB 7200 HD, Caviar 500G 7200 HD, GTX275 1280M, Logitec Z640, Win7 Pro 64b, CH Products yoke, pedals + throttle quad, simpit

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Reply #5 - Dec 30^th, 2003 at 4:29am

RIC_BARKER Offline
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Any projector will be able to throw a massive image, no problem. The problem lies in that there is an exponential fall off in image "brightness" as the image becomes larger.

I've used projectors over the years for shows at my old photography club (projecting digital images) and the only advice I can really give you is this:

A fixed focal length lens will give you the best quality image.
A lens that has been multicoated will reduce chromatic aberrations (the coloured banding present at the edge of a focussed image).

As a rule of thumb with XGA or WXGA resolution projectors, a viewing distance of less than 1.5 times the screen width will get you into the trouble zone where pixelation and artifacts become more visibly intrusive. While it is true you have a very BIG image in front of you, these distractions can compromise viewing satisfaction.

On the other hand a viewing distance of 2.0 times the screen width or greater gives you beautiful image integration in which pixelation is invisible, artifacts are minimized, and the picture appears as a solid unified video image.

The range in between these two, that is a viewing distance of between 1.5 to 2.0 times the screen width, is the area where the trade-off happens—the closer you sit, the bigger the screen looks obviously, but the more you begin to see the flaws in the image also. In my personal experience, with XGA or WXGA projectors, a viewing distance of 2.0 times the screen width is the perfect solution, yielding large screen drama with just enough distance to cause the image to be fully integrated and resolved visually. But that is just me. Your preferences may be different than mine. You may want to sit a bit closer and live with a bit more pixelation or artifact noise than I would. Or you may find that an image that is 2.0 times the screen width is still too large for your tastes.

Now these are just rules of thumb. Clearly the projector you choose will have some impact upon ideal viewing ranges. Very high resolution projectors will allow for larger screens and closer viewing distances without compromising image integrity. Alternatively, if you go with a lower resolution SVGA projector, you will need to sit back a bit further to eliminate visible pixelation, scanline artifacts, etc., than you would with a higher resolution machine.

Have you considered using a TV projector? In America you're on the NTSC (525 lines of res) so you could affods to run your sim at a lower res (better FPS) although it might make some text hard to read.

The advantage of a TV projector is they are generally cheaper than digital LCD projectors used for computers, so you could afford to get a bigger/brighter version.

Here is a good link, the first page should answer alot of your questions. http://www.projectorcentral.com/

Good luck John!!

Ric B.

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Reply #6 - Feb 1^st, 2004 at 1:09pm

JBaymore Offline
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Ric,

In my setup I am not looking at all that big an image. So sitting about 1.5 x the width of the image is not a big problem.

The image width that I am likely looking at will be no more than about 2 1/2 feet wide.

Thanks for all the info.... and I'll check out the website when I get a chance.

best,

....................john

Intel i7 960 quad 3.2G LGA 1366, Asus P6X58D Premium, 750W Corsair, 6 gig 1600 DDR3, Spinpoint 1TB 7200 HD, Caviar 500G 7200 HD, GTX275 1280M, Logitec Z640, Win7 Pro 64b, CH Products yoke, pedals + throttle quad, simpit

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