Short-Throw Projectors

[dcutugno]

This is interesting as i was planning for widescreen projector but my room size is about little more 13x13 feet (4x4 meters).

So you say i will have problem with those? too much distorsion?

With 5:4 projectors are we not limited by the high? we will hit the floor or the top way before, than wide format i think, so will cover less lateral fov.

Those are my thought based on no experience at all, advice are welcome.

Those are some picture of my curved screen still in building made of some MDF sheet and then i will add the screen material made for projection in white i just bought...

[FredK]

Be sure to do the math....

First-off, XGA projectors are 4:3 aspect ratio not 5:4, unless I'm missing something else here.

I have approximately a 13x13 foot space to work with. My intent is to maintain a constant 7 foot radial from pilot eyepoint perpendicular to the screen to avoid perspective distortion (which is a separate issue from the projector distortion). That radial is about the maximum possible within the space. I am even planning to offset placement of the curved screen slightly to accommodate (left of center of cockpit).

Given those constraints screen size for each projector segment (3 projectors) calculates to about 68 inches wide x 51 inches high (calculated simply as linear width - curved arc width will be slightly wider). The 51 inches will just about fill the upper/lower view space from the pilot perspective for forward view. Such would be less for the wide perspective projectors since width would need to be the same to maintain a constant radial distance.

Your setup appears to have a flatter arc (??). Such is a workable solution but gets involved with "zoom" adjustments etc. resulting in a narrower actual FOV. That's the way I see the logic but perhaps others with actual in-place experience can comment on all that.

Nice job with the screen - what material are you using for the surface and how do you plan to attach?

FredK

[dcutugno]

Screen not yet completed so the arc must be defined, today the fabric arrived it's the same material that you will find in the pre-made screen that you can buy in stores.

But as i can't find a screen wide enough i have ordered a custom one 8,30 x 2,20 meters just to be sure to cover all and then cut or fold the excess.

[Airhogg]

To clarify what I mean about lost pixels, here is an uncorrected projection vs. a pre-warped Sol7 projection. Same exact perspective of camera. The "humps" are essentially "lost pixels".

The bow would be less pronounced with more of a direct projection vs the angle from projector on floor to higher screen.

[BHawthorne]

The bow would be less pronounced with more of a direct projection vs the angle from projector on floor to higher screen.

Yes, but that requires a long projection distance, plus a relatively flat screen. I have none of that in my build

[FredK]

Hi All -

After some thorough research I finally made a decision on my projectors....

Going with 3 Mitsubishi WD500U-ST's.

My logic:

Short-throw (non-mirror type), DLP, and WXGA are musts: That leaves only 4 possibilities: Mitsubishi WD500U-ST, Toshiba EW25U, Sanyo PDG-DWL 100, and 3M SCP740.

Of those the Mitsubishi had the lowest short-throw ratio (0.51) giving me some added flexibility. Also, the Sanyo and 3M models also had much lower contrast ratios, Mitsubishi the highest of all (2500).

Not the cheapest option compared with the LCD models.

Regarding WXGA, my configuration will allow for a completely level screen projection which will avoid complications with the arched pixelation reported here.

I am in the process of constructing my curved screen - hope to have the visuals running within a couple of weeks using Sol7.

Many thanks to all that provided input here and elsewhere! Such info and understanding is invaluable! Each of our installations has it's own set of unique issues so it is important to see the complete picture on all this (no pun intended).

Fred K.

[Sean Nixon]

Any progress updates Fred?

[FredK]

Have been busy with other priorities but have made some progress. Framework for the curved screen is completed (see photos). Note the support structures for the projectors...short-throw projectors do not have a zoom feature so my plan is to precisely adjust zoom by simply moving the projectors forward/backward on those rails.

I did purchase and have received one of the Mitsubishi's. I want to try it with the Sol7 software before I purchase the other two. Very compact and well-designed unit.

Will post further as project progresses.

Fred

[BHawthorne]

Looks like a good build. Certainly a lot more permanant of a screen build than mine.

[Sean Nixon]

I've sourced a reasonably priced projector, the BenQ MP522ST. Here are the main specs:

Display Technology DLP® by Texas Instruments
Native Resolution XGA (1024 x 76
Resolution Supported VGA (640 x 350) to SXGA (1280 x 1024)
Brightness 2000 ANSI lumens
Contrast 1000:1
Image Size 27.5" to 300"
Throw Ratio 0.9:1

It's not as short as the Optoma at 0.9:1 versus 0.6:1, will this present a problem to me? My available width is 15ft, I have plenty of space depth wise.

How do the other specs compare?

Thanks

Sean