[simpits-tech] Falcon views 360? (Long)

Thu Oct 16 20:27:04 PDT 2003

1:  Version of Falcon (or other flight sim software) to support multiple
monitors (either directly or through some sort of network).  The narrow FOV
will need a way to be switched to any desired panned position rapidly.

2:  Displayable dome (Can be partial or full depending on your needs).
Probably 15 feet in diameter is the minimum size.

3:  Two projectors.  You will need some optics to narrow the field of view
for one and a fish eye optic lens for the wide view.  Edmund Scientific,
here we come!

4:  2 Optical grade flat mirrors.  One is stationary, the second would be
mounted to a two-axis gimbal controlled by high-speed servos.  Basically,
the pair form a periscope so that the narrow view projector image can be
aimed at the pilots field of view.  This can be done without the mirrors,
but that would require the projector be mounted on the gimbal.  The problem
with that approach is mass.  Rapid movements would require overcoming larger
amounts of inertia and can result in over shoot or ringing as the system
stops.  The ringing could be computer dampened, but the mechanical stress
would most likely be detrimental to the projector and the bulb.

5:  Head Tracking hardware and a PC to control the servo actuated mirror.
Software to drive the servo system.

Obviously, the dome would require a lot of space, but you could reduce the
size by limiting the view area to whatever works well.

A slight modification of the above plan would be to reduce the wide angle
projector to something closer to 180 degrees or less.  The second projector
would also be slaved to the narrow view projector¹s image so it would move
in tandem.

A low tech solution would be to use one projector and project the image
where the pilot is gazing.  You loose peripheral images, but you save buying
two projectors.  This may be a good plan for getting started.  Getting the
head tracking and image projection  working would be the lion¹s share of the
technical hurdles out of the way.  Adding a second projector would be
relatively easy.

However, all of those ideas require a large room for a dome of some sort.  I
don¹t have a theater in my home!

Another thought would be to project the image from above onto a cockpit
canopy that is translucent.  This would reduce the amount of room size
required and reduce the amount of swept area for the second projector.  One
problem with this approach would be a loss in depth perception.  Your focal
distance would be very close.  I don¹t know how that would be interpreted,
but I would not think that it would be too bad.  Still, I¹ll bet that it
will look like someone has projected an image onto your  canopy, rather than
an out the window view.   Might be an interesting experiment.

Projection onto a canopy has another interesting challenge.  The image would
need to be projected from at least two positions and the focal length would
need to be a function of angular position.  When you project onto a concaved
curved surface from the inside and the radius of the curved surface
coincides with the optic lens, the focal length is the same at every point
on the sphere¹s surface.  Think of a very large ping pong ball with a
projector at the very center.  Now, if you project from the outside of that
ball onto a convex surface, the focal length changes over the surface of the
sphere you project onto.

I think this can be compensated for optically.  You will need to do this
anyway since the image will also be grossly distorted.  Imagine trying to
project a uniform grid (like the Earth¹s latitude and longitude lines) from
inside a ball.  If it was projected from the inside radius, as I cited in
the first example, the grid would look perfectly uniform.  When projected
from the outside onto a sphere the grid would be highly distorted.

Since a canopy is not a perfect sphere, but an irregular shaped object, the
distortion would be even more complex.  Again, if you can model the surface
to be projected onto mathematically, then you could, in theory, grind a
special lens or mirror to compensate for this.  Well, to a point.

Additionally, you need to also add either additional projectors to cover the
outside surface or beam splitters to split off the projector¹s output and
project from multiple angles onto the canopy.  Why do we need more
projectors?  Well the best coverage you can get for illumination of a sphere
from the outside is no more than half a sphere.  Even at that, the edges
have a high degree of distortion.  Since a full cockpit view is technically
larger  than 1/2 a sphere, multiple sources are the only answer.

A compromise would be to construct a canopy that is faceted and project
separate images onto each flat facet.  Maybe 4 to 6 projectors could cover a
very large field of view.  At some point with enough facets, the projector
resolution for a given area or facet becomes good enough that the head
tracking is no longer needed.  Flat surfaces provide a wonderful way to
relieve the problem of complex optics, but you still have seams between the
facets.

Another problem with projecting onto a surface that is in close proximity to
the pilot is the parallax effect.  When you view some object out the window
and the observer moves slightly side to side, the object moves relative to
the window.  You loose this with an image that is close to your field of
view.  Head tracking can be used to apply an image shift to compensate for
the movement and would give back that illusion of the object¹s intended
distance.  I think that would greatly reduce the painted on my canopy
feeling.

Personally, I think that there may be some advantages to this system.  While
more projection systems are required, the space needed to do it would be
much less than a full or even a partial dome!  You also could eliminate some
of the complexity of having head tracking.

Further down the road would be the use of VR goggles.  As we mentioned
before, the current resolution is poor and you don¹t have the ability to see
real objects such as your real cockpit.  However, that problem is not really
a technological barrier that hasn¹t already been solved.  There has been
work already for specialized application (such as surgery) where both real
world and virtual images are mixed.  This can be done via small cameras on
the glasses for the real world view or a complex shuttering mechanism that
allows external light to pass through selectively.  Both systems would
require a computer to have a programmed field of view that is predetermined
(such as the cockpit rails where the canopy intersects).  Either pattern
recognition or head tracking system would determine where the virtual and
real world intersect.

Obviously, there are cost issues with this since the technology is new and
high resolution images for VR goggles are very expensive.  If the market for
this type of technology expands, the cost may someday drop to a point where
we could afford it.

However, today we are seeing a significant drop in the price of projectors
and a new family of projectors that use DLP.  DLP essentially is a high
density array of miniature mirrors that are electronically steered by a
silicon chip.  Rather than pass light through a LCD, light is reflected off
of the DLP mirrors which are precisely positioned electronically to produce
an image.  The result is a much, much improved image brightness.  And, no
smoke is required.  :-)

Marv

On 10/14/03 9:56 PM, "JL" <Johnlimd at bellsouth.net> wrote:

>> What I proposed is not a perfect solution (you would have to fly a real jet),
>> but think of the possibilities.  First, you only need two views.  You could
>> easily build this system today for under $3,000.  Probably under $2,000.  The
>> projectors are 80% to 90% the total cost.   What are the alternatives?
>> Placing a half dozen monitors around your desk?  What about all those seems?
>> How much area can 6 monitors really cover?   VR goggles?  Good field of view,
>> but lousy resolution.  You get 60 degrees or so of FOV at 1024 by 768 pixels
>> on a really good pair.  Most goggles have mush less resolution and still cost
>> some bucks.  Of course if you have $100,000 you buy what the military uses.
>> Add to that you can¹t see your cockpit (which you just spent years putting
>> all that detail into).  Would you rather flip a virtual switch or a real one
>> you can feel?
>> 
>> Marv
>>  
>>  
>>  
>> Alright Marv!
>> I dare say that many of us would love to see your idea work for $2000.
>> I'm in, even at a cost of $3000.  Who else is in?
>>  
>> Design and implementation plan? -- All smoke and mirrors??
>> Doesn't Falcon 5 need to be written to support the low rez 360 view?
>>  
>> H ere's another idea....  With projectors getting so lightweight (< 3 lb) and
>> relatively less expensive, how about mounting one on your helmet so it paints
>> hi rez where you're looking. Gives new meaning to "Hot headed pilot"
>>  
>> B ut seriously,  can you enumerate the steps that need to happen to make this
>> reality? (not that you don't have enough to do...  ;- )
>>  
>> John 
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