Image projection and warping for curved screens

[TheRedBarron]

Hi Folks,
My first post here on mycockpit.org! I am starting a very long term 737 build, starting with the visual system, so I can enjoy car driving and other sims while I plan the difficult bits.
I'm sure some of you will think I am being too picky, but I would really appreciate some help with the projection system. Here is the story so far....


I did a lot of research before building a 3.6m diameter 180 degree curved screen approx 2m high. Should be just big enough for a 737 (thanks to Ivar Hestnes for his sim photos). After much consideration went for the Optoma GT1080. Main reason being low input lag, good price and short throw distance. Will buy more of them if I can get the first to work well. Whilst I expected distortion when projecting onto a curved screen, I wasn't expecting the bottom of the image to be very flat and the top of the image to be so curved. See photo.
http://www.mycockpit.org/forums/attachment.php?attachmentid=11942&stc=1
Although I can warp the image (have a copy of immersive display pro), the size of each pixel in the centre of the screen is much taller than at the edges. Seated in the pilot's position my eye can distinguish the pixels in the centre, but not at the edges. So I am looking for a way to fix this. Options considered so far.
1) Move projector closer to the screen - makes image too small (height wise).
2) Move viewpoint back - will lose immersion created by the 180 degree screen, plus won't have the room to move the cockpit much further back.
3) Use a 4k projector (cost is £6000 vs £600 for Optoma).
4) Use VR - then won't be a full sized sim project.
5) Use a mirror to warp the image - have tried with an acrylic mirror that I deliberately curved, but the light cone from the projector expands so fast that even an A4 sized mirror right infront of the projector does not reflect the whole image.
6) Use a lens to warp the image - still looking for one.
7) Build a high res projector using an Mac retina display (2440x1800). Have considered this, but it's another project in its own right and would be much larger that the Optoma - so run into space issues.
8) Dismantle the Optoma and tinker with lenses / mirrors. Easy to damage an otherwise good piece of kit!


What other options are there that could work given the usual constraints?


Many thanks


TheRedBarron

[iwik]

Hi,
Welcome to this crazy hobby. Pop on over to Cockpitbuilders.com where you will
find a wealth of knowledgeable guys. Only to willing to give advice.
Hope this helps.
Les

[TheRedBarron]

Thanks Les, will give them a try too!

[OmniAtlas]

Hi,
Welcome to this crazy hobby. Pop on over to Cockpitbuilders.com where you will
find a wealth of knowledgeable guys. Only to willing to give advice.
Hope this helps.
Les

On the contrary I would stay away from cockpitbuilders because It is run by an egomanic individual, and I've run into a few non-friendly users.

I recommend to use projector planning software such as the one developed by Fly Elise and that could assist with your problem.

Regards.

[iwik]

Ben,
I am just being helpful and don't try to colour others judgement, i have never had any problem so i will continue to provide as many avenues as i know to anyone asking.
Thanks
Les

[OmniAtlas]

Hi Les - everyone is entitled to their own opinion -- I am glad that forum is working well for you.

I still keep e-mails from these certain individuals and would be happy to share. I am not the first one to have problems, and likely will not be the last. In fact, I believe your fellow Kiwi (developer of Links2fs) also had an issue at one stage.

IMHO, Best if you are going to recommend another cockpit builder forum, to do so by PM.

Regards.

[TheRedBarron]

To be honest, I appreciate any help I can get, so thanks to those who are contributing.
With regards to the immersive design software, I am sure it would help if I knew how to correct the distortion with an optical solution.
That is the key piece of knowledge which I am lacking right now. I had also considered changing the screen shape to spherical or conical to tilt the screen towards the projector.

Any help appreciated

The Barron

[bindook]

Is the image the same when the projector is on the ceiling?

[fordgt40]

Ben, you would be better advised to follow your own advice, "IMHO, Best if you are going to recommend another cockpit builder forum, to do so by PM", in your case, the contrary argument can also apply!

This is not the place to air previous perceived grievances.

David

[TheRedBarron]

To bindook: yes the image is the other way up, so the top is nice and flat, but the bottom is badly bowed. I reckon after using warping software I get an image about 700 pixels high in the middle and 1080 at the left and right edges. If I could just get 1080 across the image then it would be fine.

[OmniAtlas]

To be honest, I appreciate any help I can get, so thanks to those who are contributing.
With regards to the immersive design software, I am sure it would help if I knew how to correct the distortion with an optical solution.
That is the key piece of knowledge which I am lacking right now. I had also considered changing the screen shape to spherical or conical to tilt the screen towards the projector.

Any help appreciated

The Barron

Hi Barron,

3 projectors has been proven to work with either the optoma GT1080 or the BenQ ST projectors. Check out this sim builders website - http://b737home.blogspot.com.au/

There is a pretty good diagram on how he set it up, and perhaps that can give you some additional ideas.

[OmniAtlas]

Ben, you would be better advised to follow your own advice, "IMHO, Best if you are going to recommend another cockpit builder forum, to do so by PM", in your case, the contrary argument can also apply!

This is not the place to air previous perceived grievances.

David

I agree with you David, and would be happy to share and state my case by PM. The previous response was just a caution about venturing out to Mr T Forum.

Regards.

[TheRedBarron]

Thanks OmniAtlas and others for your ideas. I have no problem reproducing what others have shown in their videos with the warping software. It appears that they too have the same issue of bowed images. See photo.
http://www.mycockpit.org/forums/attachment.php?attachmentid=11944&stc=1

Anyone tried using optics (lenses or mirrors to correct this)?

Regards

The Barron

[TheRedBarron]

Some progress!!
Using a slightly curved mirror and back projecting I have eliminated a lot of the distortion. Hence I think it is possible to optically correct most of the distortion. I may even be able to eliminate the need for warping software :) Perhaps that's a bit optimistic!
PS the mirror is not first surface hence the ghosting at the edges.
http://www.mycockpit.org/forums/attachment.php?attachmentid=11945&stc=1

Set up ...
http://www.mycockpit.org/forums/attachment.php?attachmentid=11946&stc=1

[TheRedBarron]

Some progress!
By facing the projector away from the screen and back projecting using a curved mirror, I have managed to eliminate much of the distortion.

Here is the trial setup
http://www.mycockpit.org/forums/attachment.php?attachmentid=11948&stc=1
Here is the resulting image...
Top left / right are out of focus because of the way I distorted the mirror.
http://www.mycockpit.org/forums/attachment.php?attachmentid=11949&stc=1

I reckon with a first surface mirror (only using 3mm acrylic for now) and some careful clamping I can get the image pretty close to what's required.
Anyone else tried this?
Should be able to mount on the ceiling very close to the screen, which may give more room for the cockpit. That would be a double win if I can work it all out.:p

Regards

The Barron

[TheRedBarron]

This is my third attempt to send an update, but the two previous replies have not been published. Not sure what is going on.
Anyway, good progress has been made.
Using a curved mirror I have been able to project a much less distorted image - see pictures.
http://www.mycockpit.org/forums/attachment.php?attachmentid=11951&stc=1

Using this set up...more later after I fine tune it (some problems with focusing due to curvature)
http://www.mycockpit.org/forums/attachment.php?attachmentid=11952&stc=1

[OmniAtlas]

Hi Barron -- I don't think mirrors or lenses are required. You will just need careful positioning.

Nat also has some good case studies up on his website -- http://www.natvis.com.au

[iwik]

Ben has provided a great link as this guy is a real pro.
He also pops up on the site i mentioned so a post there may be of some value.
Les

[Melnato]

G'Day everyone,

Been a while since I've been here!
When I first read Murrays question, honestly it took me back 10 years prior to pre-warp software days :)
Although I can understand you don't want to lose pixels, you are fighting a real battle with the method you are pursuing. I can only imagine the chance of finding the perfect mirror that will result in the perfect image on the curve screen...software is so much easier...just saying.

Nat

[OmniAtlas]

Thats very interesting Barron, reminds me of some of the work with Paul Burke's iDome http://paulbourke.net/dome/iDome/

In fact, someone commericalise his stuff, and produced the Cobra Dome.

I have considered this route but First Surface Curved mirrors are expensive (>900 AUD) and might as well purchase another projector for the effect.

Have you heard of the Star Wars Pod?


https://www.youtube.com/watch?v=KZgvcAzCesg

I tried it out in Monte Carlo and was quite impressed. They also use one Canon projector but a very expensive spherical lens.

Ben


Some progress!
By facing the projector away from the screen and back projecting using a curved mirror, I have managed to eliminate much of the distortion.

Here is the trial setup

Here is the resulting image...
Top left / right are out of focus because of the way I distorted the mirror.

I reckon with a first surface mirror (only using 3mm acrylic for now) and some careful clamping I can get the image pretty close to what's required.
Anyone else tried this?
Should be able to mount on the ceiling very close to the screen, which may give more room for the cockpit. That would be a double win if I can work it all out.:p

Regards

The Barron