Frensnel lens collimation question?

[737aqua]

If I were to line up 4 screens around a cockpit shell, and use frensel lenses over each one, would I have a panoramic collimated view for one person? I realize the co-pilot would not, but would the captain?

[Trevor Hale]

No.

Because the Fresnel lense only works when you are directly in front of it. everything else would look like light, but you wouldn't be able to make anything out. it would all be blurry.

[rt72]

Kind of. Although I think the result would be less than satisfactory.

If the pro's could do this adequately with Fresnel lenses I think they would have done it already.

[737aqua]

Yeah, I guessed so... Oh well, I suppose if the Sol7 thing works out it would be the best option until someone figures out how to manufacture a cheap projection collimator.

[Mike.Powell]

While not impossible, it's unlikely that you could make a workable, true collimated display with commonly available Fresnel lenses. There have been a number of professionals who have addressed the problem and been issued patents. (Check patents.google.com) However, each approach has had significant shortcomings, and what we see in commercial use today are mirror collimated systems.

What you can do is use lenses to blend adjacent images together to boost the feeling of immersion.

Several years ago people at Boeing developed a display system for fighter simulators based on Fresnel lenses. You can read about the technology on Rick Lee's site here: http://www.rickleephoto.com/mosaicfresnel.htm . The technology was spun off and formed the basis of Bugeye Technologies (http://www.bugeyetech.com/home.php).

[Trevor Hale]

While not impossible, it's unlikely that you could make a workable, true collimated display with commonly available Fresnel lenses. There have been a number of professionals who have addressed the problem and been issued patents. (Check patents.google.com) However, each approach has had significant shortcomings, and what we see in commercial use today are mirror collimated systems.

What you can do is use lenses to blend adjacent images together to boost the feeling of immersion.

Several years ago people at Boeing developed a display system for fighter simulators based on Fresnel lenses. You can read about the technology on Rick Lee's site here: http://www.rickleephoto.com/mosaicfresnel.htm . The technology was spun off and formed the basis of Bugeye Technologies (http://www.bugeyetech.com/home.php).

Mike you are so knowledgeable.. I think you should consider writing a book.. Perhaps 2 LOL :)

Great stuff buddy. Thanks for your input.

[737aqua]

If there were such thing as 3d glasses that turned to regular clear lenses when you moved your line of site to certain portions of the cockpit (instruments, etc), monitored by a head tracker, could that possibly be a solution for a collimated display for home users?

[Mike.Powell]

In very general and vague terms, yes. Waffle, waffle. Let me explain.

What you try to do is remove the 3D clues that correctly tell your visual cortex that the outside imagery is actually a 2D image 20 some inches from your eyes. Two key clues are the unconscious knowledge of the muscular tension focusing your eyes, and the tension pointing your eyes inward (you get more cross-eyed as you look at things closer to you).

If you remove these clues your visual cortex downshifts and starts using secondary clues: if something known to be big looks small, it must be far away; if something moves in front of something else, it must be the closer of the two; and so on. So, although you're looking at a 2D image, you perceive it a 3D world viewed at a distance.

Can you build an adaptive head-mounted optical system that defeats the appropriate 3D visual clues, and make a 3D world spring into existence? Well, some military simulators have a systems that does. It's a head mounted display with a head tracker. The HMD displays imagery of the outside scenery with the optical focus set at infinity so this portion of the display is "collimated". The HMD also allows the wearer to directly view the cabin interior without the collimation optics. The head tracker moves the collimated imagery so, from the viewer perspective, it's always lined up with the window opening.

When I first started writing this, I thought I was moving toward a long-winded "Yes, but not practical". But I wonder if we're not too far from this today. FSX lets you move the camera angle pretty easily, and there's TrackIR... You'd want to make the image line up with the sim's virtual window frame from the viewer's perspective. I'm sure other issues would surface, but looks like it could work.

Sounds like an interesting project.

[saabpilot]

If I were to line up 4 screens around a cockpit shell, and use frensel lenses over each one, would I have a panoramic collimated view for one person? I realize the co-pilot would not, but would the captain?

Yes - BUT only when you sit exactly in focus!
That is impossible, even the slightest movement of your head would distort the view.

I have a friend who did try that out with 4 screens - no success at all.

Bjorn

[mauriceb]

Several years ago people at Boeing developed a display system for fighter simulators based on Fresnel lenses. You can read about the technology on Rick Lee's site here: http://www.rickleephoto.com/mosaicfresnel.htm . The technology was spun off and formed the basis of Bugeye Technologies (http://www.bugeyetech.com/home.php).

I just love this quote from Rick Lees homepage: :D

"A quick note about Microsoft FS 2002. WOW. Holy cow.... this is the FS we've always wanted. Graphic accellerator cards have finally advanced to the point that home simulation is stunningly sophiticated. Get a GeForce3 video card and get FS2002. The results are mind boggling. "

We are indeed fortunate and one can only dream about how things will be like in another 10 years or so.

Maurice

[mikesblack]

Perhaps this has been discussed more in another thread, but I haven't found it yet. I was wondering about head tracking and collimated optical view. Has there been anyone who has found a way to make this work? I understand Track IR will only work with one window and not decoupled multiples as per Wide View or fast PC 3 windows etc. on a curved screen. I believe one FSX window provides only 120 degreed?? Perhaps, a forward view with head tracking for depth view and runway alignment and fixed views from the other image generators? Not perfect, but I wonder if it would be a good enhancement. I plan on building a spherical screen of 220 degrees and N Thusim. Any ideas on head tracking or other relavent info would be greatly appreciated.

[Neil Hewitt]

Here's a thought - if you used the nVidia shutter-glass 3D system to view FSX in 3D (which is possible, the driver will support it), would the outside view be effectively collimated, with the 3D perspective tricking your eye into seeing things at the 'right' focal length?

Apparently there are some problems with texture and lighting effects when using FSX in 3D, but nothing that's insoluble. A (relatively) cheap pair of glasses would let you get the equivalent of an expensive collimated display while still seeing the cockpit interior etc unchanged.

Anyone try this? I'm tempted to go out and buy the glasses now just to experiment...

[Mike.Powell]

In a collimated display the image is moved far from the viewpoint with several results:

The left eye and the right eye see the same image with no perspective difference. It may seem that viewing a non-stereographic monitor would present the same image to each eye, but that's not so. Because the eyes are about 2.5 inches apart, each sees a different, slightly skewed view of the monitor surface. This small difference has a huge impact on what's perceived. Although the pixels are the same, the perspective difference is enough for the visual center in the brain to say, "Those pixels are painted on a flat screen about 18 inches away". When a collimated display is viewed, that same visual center says, "Those pixels aren't very close. They may be flat, or maybe not".


Because a collimated display moves the image away, the eyes focus for distance vision, and they point straight ahead.

When the viewer moves sideways, the image appears to move with him. This is the difference between looking at your monitor on your desk and moving your head a few inches sideways, and looking out the window and moving your head. In the first case the monitor and image on the monitor begin to move out of your field of view. In the second, the window frame begins to move out of your field of view but the outside view seems to be stationary. A collimated display presents an image that acts more like a window and less like a desktop monitor.

So, if you wanted to get the same effects as a collimated display, perhaps you could...

Develop a driver that generates imagery for each eye that removes the normal left/right perspective difference of viewing the monitor on your desk. This is actually an "anti-3D" driver. It's not putting binocular 3D visual clues into the image. It's making sure there aren't any. Use the LCD shutter glasses for viewing.

Use a head tracker to change the viewpoint dynamically. When you move your head relative to the monitor the image shifts as though the monitor were a window frame.

There are few limitations. The eyes will still focus on a screen that is close by. Initially this may feel uncomfortable because they will not be rotated inward slightly as they normally would be when viewing close images.

Also, this approach would work for only a single viewer at a time.


While I've read of an application that varies the displayed image based on viewer position to simulate a window to the outside, I don't know of anyone doing the "anti-3D". I think it would be a very interesting experiment.

[castle]

It might produce the desired visual effect if the OTW scene was a large screen projection 3 or 4 feet in front of the viewer bounded by the frame of a cockpit window. But it would not solve the perspective problem of side by side seating.

The optics of collimated and 3D displays are different. But it is certainly cheaper and worth a try.

Have not messed with 3D systems. Would it work for a multi-screen display and is there sufficient horsepower ( video pipeline, GPU, CPU ) to provide a minimum frame rate suitable for stutter free viewing.

JW