Brainstorming for a collimated mirror display

[s4sha]

Ok guys, admit it - - we are always looking for some way to improve our "pilot's perspective" when simming after a long nine-to-five. I personally use a DLP projector with both MSFS and X-Plane. It is definitely an improvement over a small CRT or LCD panel, but of course does not provide the true depth cues needed for a "real-as-it-gets" flight sim. I've been studying the collimated display design for years, and have all but given up on that level of display for the average simmer. "All but" meaning that I have an idea that may be worth investigating. I am planning on trying this myself after the holidays, but I thought you all might find an interest and expand upon it...

Has anyone ever tried something related to the following:

Build a plywood/plexi enclosure to accomodate a large section of mirror sheeting with both vertical and horizontal curves to provide needed "radius of curvature" for a flight display. The "box" would need to be sealed with silicone or a similar material, then again on the concave edges that would contact the mirror sheeting. Vaccuum would be provided by a vacuum pump, with possibly a relief-valve if needed. Amount of curvature of course would be determined by the location of the pilot in reference to the mirror.

The actual projection screen is another interesting idea, as it would need to be suspended/supported above and behind the pilot, with adequate curvature to reduce distortion. I thought maybe a thin bedsheet draped within a convex frame may do well, or maybe as far as soaking a sheet in a clear polyurethane-type coating that would help with rigidity. I have experimented with my DLP projector and there is quite a bit of forgiveness when projecting on a curved screen. Not near as much blurring on the edges as I expected!

Well, there is a challenge for my fellow simulator addicts - build a true collimated display!

Like I said, I will try this and may end up sadly disappointed but maybe you guys may be able to pull it off! I just couldn't help but share this idea.

Here's some links to get you started:

www.mirrorsheeting.com (the 7ml 10ft should work well)
http://www.harborfreight.com/cpi/cta...temnumber=3952 (would multiples be necessary?)

Keep on simming,

s4sha

[Trevor Hale]

S4sha,


What I have done is similar to your second idea, and I find it gives excellent depth. I have placed my Projector aprox 10 feet in the front of the screen. So it shines directly at the pilot sitting in the box. I took a sheet that was purchased at wallmart (aprox 200 Thread count). and placed a few staples at the top and then at the bottom dead in the middle of the framethen pulled the screen tight and on about a 30 degree angle (where the sheet meets the wall on each side)I placed another series of staples all the way down keeping the sheet tight. then along the top and the bottom I used a couple staples to get rid of all the wrinkles. See the ascii pic below for a better representation.






This is not a rounded curve, however from this top down view I am sure you get the idea. What happens is as the image moves across the angles sheet it gives you the feeling that there is motion past you, thus increasing the feeling of motion.

NOTE: #1 The sheet must extend past your normal view out the cockpit windows, otherwise the setup is useless.

***************** WARNING********** "Ask your wife before you staple the crumbs out of one of her sheets" ****************************


Best,

Trev

[Matt Olieman]

Collimated mirror display. You hit the mother load of all challenges of cockpit building.

Is it possible and do we have information on how it can be done? The answer is yes. HERE COMES THE BUT
We don't have the technology and the curvature of the mirror information.

The technology to be able to be able to build a collimating mirror is absolutely crucial, and the precise curvature is also crucial, otherwise the mirror would easily be flawed.

I've spent 100's of hours in research and testing to duplicate this process. I've seen this brought up in several forums and with such enthusiasm, only for the subject slowly dissipate.

Don't even think of buying one of these...... $$$$$$$$$$$$$$$$

Collimating mirror is the way to go, ultimately. If someone finds a way... I want to know

[s4sha]

Trev,

Thanks for sharing a great idea to enhance motion cues!

I've been thinking (that's a scary thought) -- Here's another interesting idea that you could try:

Since the projection surface is relatively close to you, you probably lack the vertical and horizontal parallax cues that you would experience if the observed view was at an infinite distance (your view out-the-window does not change relative to your head position, left-right or up-down). For example, when piloting an aircraft or even driving a car and you see a cell tower in the distance, if you move your head from left to right while fixating on the tower you will notice that the tower seems to move right and left in relation to a point on your glareshield/dashboard. Now if you do that with your current setup i would imagine the relative difference between the two points(the tower and panel) is limited.

You may be familiar with NaturalPoint's TrackIR device for 6 DOF (degrees of freedom) viewability. I was thinking that one could have a large single-projector view out front, then utilize the TrackIR device to simulate the horizontal and vertical parallax.

The TrackIR does allow you to also "roll and yaw" and zoom (z-axis) to "look around", which is great-- but if it could be used to help that cell tower in the above example to appear to move left in relation to the panel when a left head movement occurs, one could experience the same sense of "infinite depth", albeit artificially.

I hope you understand my concept, and if anyone thinks I have too much time to daydream about flight simulation displays, please tell me to shut up and have a beer...

S4sha

[Trevor Hale]

Actually,

I have seen some people use that. My only problem with the track IR is I am sure it is used in Virtual cockpit. That being the case you need to create an mdl file that has no VC. Secondly, if you talking with a copilot in your sim and you turn your heas to the right to talk to him the entire view will rotate right.

Not sure if that works, but I would think it would be a bit confusing.

Any thoughts?

Trev

[Matt Olieman]

s4sha,
Interesting concept. I can see that working.... Then I can understand the confusing bit Trev mentioned if you were the F/O or a passenger.

The challenge continues

[s4sha]

Yes, I did forget to mention that this experiment would only apply to a single-pilot configuration. Matt, I'm glad you understand my idea. Trev, you are absolutely right, the VC would have to be omitted, and I was thinking of utilizing only the vertical and horizontal head movements that are parallel to the screen, and not the head turning capability. I would imagine that this would induce an artificial parallax perception that may be worth the small investment to enhance the experience. I only have the TrackIR 1st generation, but hope to research the TrackIR 4 to see if you can indeed isolate certain axies. Anyway - again, just a thought...

[PhilM]

Evening guys...I'm new here so Hello

A little about me, working as part of a team building a BAe 146 STA simulator -- its a bit generic since the 146 STA was only a concept, so the cockpit is a modern EFIS/ECAM system, with 737/A320 style panels and systems that are true to the 146. I work as an aircraft engineer on B737 and A320s also.

Anyyyway...collimated visuals! On a par with Motion really, hard work, and awesome!

Ignoring for now the rear projection collimated visuals, as I don't know enough about those (bar you need a HUGE spherical mirror!).

If we look at the mirror based collimated displays such as this:


Image courtesy of 737sim.com

We have a few elements here as you can see.....a CRT montitor ona frame, a partially reflective mirror (beam splitter) and a spherical mirror.

Now, the CRT part is easy and cheap! People can't give them away these days!.

The beam splitter looks a rather simple affair, it's a sheet of glass with a very fine layer of metal on it, that reflects the light back onto the mirror. I havent been able to find these yet, but I don't expect they are too "bad" price-wise, of course new, from an optics supplier they will be! I am sure they can be found elsewhere!

Spherical Mirror, ok, this is the hard part. The mirror surface itself is easy, materials such as mylar and others (as linked at the top of the page) are availible and make life very easy, the difficult bit is how to get the spherical/parabolic mirror shape. Well, I had a thought....


Satellite dishes are actually parabolic mirrors! And they are like CRTs, availbile everywhere, ten-a-penny Of course, to our eyes they are not very mirror like, but they do a fine job of reflecting electromagnetic waves! Of course, for them to reflect visible lght, we will have to take some mirror film......seal it round the edges of the dish, drill a small hole in the centre of the dish, and apply a small vacuum - tada...parabolic mirror

Alternativly, we could take a metal dish to be chrome plated or something similar, there are even Chrome paints availble....Audi did a Chrome A6 I believe for a Middle Eastern customer.

Providing we can then find suitbale beam splitters, which to me seems the easy part, we have collimated visuals el cheapo. Repeat 3 times and have a decent field of view too

[Pochflyboy]

Sounds good, but much harder than one would think. In my first days of researching sims, I decided I was going to do something similar to what you are thinking. The only problems are a) the mirrors have to be EXACTLY the same (not really possible to do at home. b) the beam splitter mirrors are VERY $$$$$. Anywere I found them, I would have to contact the company and could not just buy them. Usually they were in the multi-thousands of dollars. I never found one low enough in price that it would make the difference. So thats what I have found. Hope it helps.

[Trevor Hale]

I was at an Electronics shop, and a guy showed me a can of reflective spray. $18 CDN per can and you spray it directly on a sheet of glass, it makes the glass reflective. Makes an excellent "Transparent Mirror"

Maybe that would be a route to go.

Trev