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Mylar Collimated Screen System Discussion

(Original thread started on 06-05-11 by Eric Tomlin)

For the record, this is just for discussion and conversation on the subject of a home-built collimated visual system. So far, this is the only home-built collimated visual system that I am aware of (that has been built to the level that this one has).

 

NOTE: This link is showing only the process leading up to a partially-completed unit:

http://www.cockpitbuilders.com/community/index.php?topic=1703.0

 

This link is discussing how great this unit came out, but not much more information:

http://www.cockpitbuilders.com/community/index.php?topic=4102.msg38402;topicseen#new

 

I've been quietly watching these guys for months now. It's likely that Shane and Vince are aware of this project but if you never go to http://www.Cockpitbuilders.com, then you likely aren't aware of what Gene and his team have accomplished. To say the least, it's impressive.




 

There's tons more of earlier videos on this from the same guy- he goes by "F15sim" there at YouTube.

 

(Posted by Alaxus on 06-06-11)

Impressive, but I was a little let down when this is all he did with the screen:




 

Maybe he should give it to me, I would use it properly!

 

(Posted by Eric Tomlin on 06-06-11)

It's not nuts when you consider it gives you the proper depth of view, meaning by collimation it creates a more realistic distance focus. My only question is how accurate is this collimation in this setup? See more here: http://en.wikipedia.org/wiki/Collimated_light

 

Additionally, I got to thinking and wanted to add this snippet of opinion. Everything we can add to the sim to increase the realism and immersion is a good thing, but not always required. A Collimated Visual System is a great example of one of these "extra" items. To have a quality visual system is more important to me than a motion system, as proved by the fact that I know too many folks that have flown the Level D sims with the motion turned OFF and they had no clue until they were told. Yes, you get better visual quality with HDTVs, but it's not as immersive. You get better immersion with a large wrap around visual like Scott, Ivar, and Ron will soon have. However, the collimated system when done right is superior. I feel the same way about a motion system. I really don't care to ever have a motion system unless it was professionally built and properly interfaced with FS and of course, I had the space to put it. All of this conveys that I'd have the extra money for it, which I don't foresee ever happening. The point: I think there's always a higher level of perfection but we have to settle for what we can pay for.

 

I heard a rumor one time that when you fly a real Learjet 45, the frame rate is unbelievably great and that's with ALL the detail sliders to MAX. It's also the most realistic water, sky and scenery you will ever see!

 

(Posted by Tom Goldberg on 06-06-11)

I have been watching these guys since the beginning and while its very cool stuff, there is a whole lot of issues that you would have to overcome to make the setup large enough to surround your sim with something like this. You think setting up a three projector setup is difficult, try making this thing!

 

I'm just waiting for someone to come out with some 1080P short throw projectors at a reasonable price, that would make me happy.

 

(Posted by Geneb on 06-30-11)

Thanks for the compliments guys. Right now I'm at the "what will fit in there?" point. The Lear45 might, but I'm not in a position to check yet. I've asked Wayne about it since he might know off the top of his head.  A chopped down version of Ron's shell design may fit. (nose is too long)

 

The display is as large as it can be - the restriction is caused by the width of commercially available Mylar rolls. Ours use a 54" wide roll which is the largest you can buy without going to the $5000.00 and up price point. (You can by Mylar right from L3, CAE and Rockwell-Collins, but it's VERY pricey!)

 

At the design eye-point, the collimation effect is no different than what you'd experience in a commercial FFS. For single seat & smaller 2 seat cockpits, it should be dead on as well. You'll never fit a 7n7 flight deck into this display, that's for sure!

 

Up until Wayne & I did this, it was a reasonable expectation that it couldn't be done. What made it technically feasible was the convergence of three elements - the introduction of affordable image pre-warp software for the scene generator, inexpensive, high-resolution projectors and ready access to a CNC machine that could cut the parts. Throw in free design software (SketchUp) and it got "simple", really fast.

 

If we didn't have lives & day jobs, we could have gone from the prototype to the finished version in less than 30 days, barring machine problems or resources.

 

Now that it's all said and done, you don't even need a CNC machine if you can create one good master pattern for each individual part. You can use it as a router template and make as many identical parts as you need. That being said, a collimated display isn't for everyone, especially if you don't want the display system dictating the choice of aircraft. At some point in the future I may create a "conic" screen that could provide a similar FOV but would be a direct-projection, non-collimated system. That is something that would scale pretty easily and would be pretty simple to build.

 

(Posted by Wledzian on 06-30-11)

The short answer is:

I haven't checked any actual models against the display model, but on cursory examination...

Yes, the lear45 cockpit will fit, provided the nose is lopped off below the window and forward of the MIP.

 

The long answer is:

There's a good chance you won't be happy with it. The optics of this particular display are configured for a single, centrally-located pilot. With two pilots, the eyepoint is shifted significantly outboard. As you are closer to the mirror, the image you see out your side window will include the as-designed screen, as well as a significant space above and below the screen, possibly including cockpit structure and/or the projectors, thus killing the illusion. The full-size simulators get around this by using a very large mirror, an oversized screen, and an optical configuration specifically designed to accommodate this "feature".

 

To answer the questions regarding "how good is the collimation": on our 60-degree prototype, I can only describe the collimation as excellent. Even with the large pixels you'd expect from an 800x600 display that fills 40° of your vertical field of view, it didn't feel like I was looking at a display. It felt like I was looking out a window. When I move my head side-to-side, the center of the image still appears directly in front of me. There is some distortion caused by the uneven stretching of the Mylar around the edges of the mirror, but this area will be masked off.

 

(Posted by Alaxus on 07-01-11)

I was of the understanding that the way FS puts the visuals to the screen, a collimated display wouldn't have much effect on the crabbing that is noticeable, especially with big projector screens.

 

From what I have read, the Level D sims have a different view point on the screen than FS, most likely because FS was targeted to the desktop monitor whereas the Level D ones are specifically set up for the collimated displays.  Still its an awesome screen.

 

(Posted by Wledzian on 07-01-11)

The on-screen viewpoint is dependent on the eyepoint in the model.  For a direct-view screen, if the eyepoint is centered and the screen is centered, the captain will see anything directly in front as slightly to the right, and the co-pilot will see the same thing as slightly to the left. This applies for close objects (good when you're looking at the runway), but also for distant objects (not so good when you're looking at a mountaintop.

 

For a collimated display, the centerpoint of the projected image will appear dead-center on the horizon for both the captain and co-pilot. When you're looking at your destination off in the distance, you're actually looking straight ahead, rather than 10° or so inward. Again, since the actual image is 2-D, this applies to close objects and distant objects alike. In this regard, things look correct when you're flying, but on landing you don't get the same 'pilot is left of centerline, copilot is right of centerline' effect. If you land on-centerline, both the pilot and co-pilot will see the centerline passing directly below them.

 

That said, there are several advantages to a collimated display:

No 'crabbing' effect for distant objects (just about everything is "distant" when you're off the ground)

No immediate parallax cues when you move your head to tell you that the image is close.

No stereopsis cues to tell you that the image is close.

No focus-accommodation cues to tell you that the image is close.

 

The only remaining cues are the perspective cues (a given object will appear larger when it's close, and will appear to move faster relative to the background). With this being the only thing your brain has to go on, your eyes relax and the image feels 3D and far away. It's more like looking out a window than looking at a screen.