Determining FOV with 3 projectors

[Naitouk2]

Hello again everyone! We’ve made some great progress with our 747-400 simpit. Got the glare shield built as well as the beginning of our front panel. Since we have very limited space in our simpit room, we are trying to ensure we maximize FOV. So i’m back again to try and get more good advice from you guys on how to do this.

I’m trying to determine how to calculate the field of view for a generic 3 projector configuration. How does one go about doing this? I thought I understood how this was done, but unfortunately, I was mistaken.

For example, if I have a projector that produces an image with width w at x feet, etc… How is this done? I was trying to create a triangle using the image width and distance from the projector lens to the image, then dividing that into two right triangles and trying to determine the angle by taking the arc-tangent, then doubling it. I think I’m missing something here…

Any guidance?

[wledzian]

2 * atan(width / (2 * throw)) = beam angle.

For field of view, instead of using the distance from the lens to the screen, measure the distance from your eyes to the screen and do the same calculation. That is the field of view for each projector.

[Naitouk2]

2 * atan(width / (2 * throw)) = beam angle.

For field of view, instead of using the distance from the lens to the screen, measure the distance from your eyes to the screen and do the same calculation. That is the field of view for each projector.

Thank you very much for the reply. One quick question I have before I give the calculation another try is the 2 * throw component. Is throw the throw ratio of the projector?

[wledzian]

'throw' is distance from the lens to the screen.
'throw ratio' is (image width) / throw.

[Naitouk2]

Thank you very much! Just to be sure I'm correct about this...

If my eyes are, for example, 66" from the screen, and my image width given the distance from projector to screen is 102", then ...

2 * atan(102 / (2 * 66)) ~= 75.38

Or ~= 226.16 degrees for three projectors in the same configuration.

[wledzian]

That's correct. For that FOV, set zoom = 0.42

[Naitouk2]

That's correct. For that FOV, set zoom = 0.42


Thanks again for all of your help.

How is the 0.42 zoom determined? I assume this is a FSX camera configuration option?

[wledzian]

It's a camera setting. I'm also building a display which uses multiple projectors, and got tired of the trial-and-error method of matching the zooms, so I reverse-engineered the zoom formula and made a tool to do it for me.
http://www.mycockpit.org/forums/showthread.php/23199-Windowmaker-tool-updated!

[Naitouk2]

Excellent.

I didn't realize you had created the WindowMaker tool. Thanks very much for all of the help.

[Delphi]

Check this web site, might help....

http://www.flying-the-winglets.de/Visual5.html

Ruediger

http://www.flying-the-winglets.de

[Naitouk2]

I wanted to thank everyone again for all of the help. Given the amount of space we have for our simpit as well as the specs on our projectors (Optoma TW610 STi), we were able to find a configuration that gives us a 225 degree FOV. The next problem we're having is relating to the keystone effect of the curved screen.

How did you guys overcome this?

We keep adjusting the curvature of the screen based on trial and error ... some guidance here would be awesome.

Thanks again for all the advice. You guys really are awesome.

[Aaron]

I think you are doing "opposite" than everybody. You should make your screen to admit overlapping between projectors and you desired field of view. After that, you should warp your projections with warping software to fit your screen and not correct the screen to adjust to the projectors.

You have many options out there like: nthusim, sol7, warpalizer, inmersive display lite... every one with different pros-cons

[Naitouk2]

I understand what you're saying, but my confusion comes from the keystone. I was under the impression that before any warping could be done, you'd have to be in a situation where ZERO keystone effect was visible on the screen. Is this correct? How did you deal with this?

[Aaron]

You dont need the keystone. Lets projection as simple as posible. All the tweaks you need to do (adjust keystones, parallels, horizontal lines, overlapping, color corrections) you should do it via the warping software.

The aim of the clean projection (with no image, just the projectors light) its cover your screen and a little more, to let margin to warping software.

Something like this (our setup)
http://2.bp.blogspot.com/-dYVjxmKgj3o/ToiNEINL9xI/AAAAAAAAAD8/LnF4SIr8thM/s1600/right.jpg

As you can see, there is no keystone or other adjust. You can see a little sticky at the top of the projected colors. These little sticky are just for reference in the high of the screen.

After the warping and before blending, you should get something like:
http://2.bp.blogspot.com/-1MS_8l32u9c/TpNatdlMH0I/AAAAAAAAAEU/9trRN0hq-es/s1600/first.jpg

Both images are panoramas (8 photos everyone)

Get the idea? If not, download the warping software and just go to play with it (all of them have demo versions) All that the software does, its just an "advanced" keystone, much much better than the simply config the projectors admit.