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GodAtum
07-19-2013, 11:01 AM
What's the best value 1080p short-throw projector? The BenQ (http://www.overclockers.co.uk/mfrList.php?mfrid=16&campaign=social/forum/textlink) W1080ST looks quite good?


I will have 3 projecting onto a 180 degree 2m curved screen. it would be nice to have a zoom feature too.

OmniAtlas
07-20-2013, 01:50 AM
The BenQ W1080ST has a 0.69 ST and this may be insufficient for a 3x180 degree warp. Of course you could always use mirrors to increase that ratio.

I am going to attempt to experiment with dome mirrors with 1 projector and see how well that works.

GodAtum
07-20-2013, 04:16 AM
The BenQ W1080ST has a 0.69 ST and this may be insufficient for a 3x180 degree warp. Of course you could always use mirrors to increase that ratio.

I am going to attempt to experiment with dome mirrors with 1 projector and see how well that works.

What part of the specs should I look at to tell if its Ok for warping?

OmniAtlas
07-20-2013, 04:27 AM
You need a good throw ratio, usually below 0.60 so they say.

I suggest you read this document -- http://www.flightdecksolutions.com/pcupload/Projector-Design-Tutorial.pdf

GodAtum
07-20-2013, 06:18 AM
You need a good throw ratio, usually below 0.60 so they say.

I suggest you read this document -- http://www.flightdecksolutions.com/pcupload/Projector-Design-Tutorial.pdf


Thanks for the link, very helpful. The BenQ MW817ST or the BenQ LW61ST have a 0.49 throw ratio.

NedHamilton
07-20-2013, 07:09 AM
The BenQ W1080ST has a 0.69 ST and this may be insufficient for a 3x180 degree warp.
Not true. TR of .69 is fine for 180 degree warp.

GodAtum
07-20-2013, 07:19 AM
The BenQ MW817ST and LW61ST has a thow ratio of 0.49

OmniAtlas
07-20-2013, 12:34 PM
Not true. TR of .69 is fine for 180 degree warp.

The article I posted above mentions the BenW1080St would be inadequate for the job.

OmniAtlas
07-20-2013, 12:36 PM
The BenQ MW817ST and LW61ST has a thow ratio of 0.49

Both of these projectors are 760p and not 1080p projectors.

GodAtum
07-20-2013, 01:55 PM
Both of these projectors are 760p and not 1080p projectors.

Yes I might have to forgo 1080p if I want to get a short throw at a decent price.

NedHamilton
07-20-2013, 02:38 PM
Both of these projectors are 760p and not 1080p projectors.

I noticed that (actually it's 720p). It's not the 1080p or 720p that you have to consider on computers but rather the resolution. Both these two projectors are lower resolution, with a native resolution of 1280x800 versus a resolution of a huge 1920 x 1080 for the W1080ST. But the W1080ST has a much higher Throw Ratio. I wonder how much difference the lower resolution makes. Will you notice the pixels??? If you use 3 projectors a Throw Ratio of .69 works fine. The need for a lower Throw Ratio is if you have a small radius screen, large angles of projection, or fewer than three projectors--in general terms. Always do the "projector math" before you buy.

GodAtum
07-20-2013, 02:50 PM
I'll think I might something like this screen: http://www.immersivedisplay.co.uk/pdf/3.2m%20HSP.pdf

It has a 3.2m diameter and is 1.6m high.

NedHamilton
07-20-2013, 03:12 PM
Wow, those are nice screens. They are small and they are curved vertically. With 1.6m radius you'll definitely need a short throw projector. And because of the small radius you'll need to worry about shadowing from the sim frame.

OmniAtlas
07-20-2013, 03:27 PM
I'll think I might something like this screen: http://www.immersivedisplay.co.uk/pdf/3.2m%20HSP.pdf

It has a 3.2m diameter and is 1.6m high.

This other thing you might want to consider is something like the Cobra Curve Screen -- basically one projector with a 180 degree warp using first surface mirrors. The idea originated from Paul Bourkes work with the idome.

I am hoping to go this way because I want some flexibility with my system -- this will allow me to use the projector also for cinema viewing, perhaps a indoor golf system, and of course flight simulation :)

The Cobra is expensive, so I in the process of figuring out how to make my own screen.

GodAtum
07-20-2013, 04:00 PM
immersive Displays have screens which go up to 4.5m radius but I dont have enough room.

How much is the Cobra? Looks good and small footprint but for flight simming I would use trackir as it only gives a 150 degree field of view (Cobra Simulation - Cobra Features (http://www.cobrasimulation.com/index.php/features))

OmniAtlas
07-21-2013, 01:53 AM
How much is the Cobra? Looks good and small footprint but for flight simming I would use trackir as it only gives a 150 degree field of view (Cobra Simulation - Cobra Features (http://www.cobrasimulation.com/index.php/features))

Over 5000 pounds.

GodAtum
07-21-2013, 06:12 AM
Over 5000 pounds.

wow, the full dome one i showed is 4000.

NedHamilton
07-21-2013, 08:11 AM
The article I posted above mentions the BenW1080St would be inadequate for the job.

It would be inadequate for the 225 degree projection in the article. The original poster was going for 180 degrees which will work with TR=.69.

OmniAtlas
07-21-2013, 11:50 AM
That's good to hear ned. Have you see. The videos by immersive display? They e managed to get 180 warp with 2 projectors. However it is is a GA they are flying so no shell top.

NedHamilton
07-21-2013, 12:01 PM
I've seen the Immersive display videos for 3 projectors but I haven't seen the ones for two projectors. Theoretically you can do 180 degrees with 2 projectors. A throw ratio of .5 will do it but with no overlap between the two images so there won't be any edge blending. You need a lower throw ratio if you are going to blend the images (or be OK with a little less than 180 degrees)

GodAtum
07-21-2013, 12:10 PM
I'll probably go for a 180 screen first then add two straight sections to make a 225.

ridgenj
07-22-2013, 12:04 AM
I noticed that (actually it's 720p). It's not the 1080p or 720p that you have to consider on computers but rather the resolution. Both these two projectors are lower resolution, with a native resolution of 1280x800 versus a resolution of a huge 1920 x 1080 for the W1080ST. But the W1080ST has a much higher Throw Ratio. I wonder how much difference the lower resolution makes. Will you notice the pixels??? If you use 3 projectors a Throw Ratio of .69 works fine. The need for a lower Throw Ratio is if you have a small radius screen, large angles of projection, or fewer than three projectors--in general terms. Always do the "projector math" before you buy.

Ned, I am still thinking about the BenQ 1080 and the more I read the more confused I get. As you know I am looking at two of the most popular fora and following the discussions. My room is 13 x 16 feet and I would like to accommodate at least 180 degrees. What is the magical minimum radius to be able to use three 1080's with an FDS Shell. I will be using a 8'x8'x8" base and have almost 8.7' ceiling clearance.
Opinions are welcome...

Cheers
Luis

OmniAtlas
07-22-2013, 12:41 AM
I've seen the Immersive display videos for 3 projectors but I haven't seen the ones for two projectors. Theoretically you can do 180 degrees with 2 projectors. A throw ratio of .5 will do it but with no overlap between the two images so there won't be any edge blending. You need a lower throw ratio if you are going to blend the images (or be OK with a little less than 180 degrees)


Hi Ned --

2 projectors with overlap Multi Projector + Multi Camera + Curved Screen Calibration - YouTube (http://www.youtube.com/watch?v=vqAbOCDmX30&list=PL5AD6478797E86393&index=33)
180 degree warp
According to the author of Immersive Display they are using 2x 720p projectors with a 0.6 ST

NedHamilton
07-22-2013, 07:45 AM
Well most projector calculations (and the tutorial) are based on the three (or two) projectors' internal image source being very close to each other. If you mount the projectors so they are farther back from the screen a throw ratio > .5 will work but it will introduce some distortion because the projectors are farther apart. I don't know how bad the distortion is. Maybe the warping software can compensate for this.

zahry
04-13-2014, 01:22 AM
I can really recommend BenQ 1080ST - it is ICC certified and it has awesome contrast ratio and the zoom is handy as well - you can do 180 with 2 projectors and 270 with 3 projectors (with the right projection material).
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