The Parhelia triple scenery monitor setup can be enhanced by adding a large fresnel lens for the
spanned scenery. The 40" fresnel lens was just wide enough for the 3x 15"
LCD panels. The final result is really nice, as the magnification and depth
added by the fresnel lens makes the front view really feel "out of the
The distance lens - LCD will determine the magnification factor.
Compromises have to be made with respect to distortion, color aberration and
ease of view. (no headache). Below drawing shows the optical magnification:
And a picture of the result:
to make this picture, the 3 views were photographed separately
Comparing with the 18" cockpit view gives you a rough idea
of the magnification factor.
The actual view is quite
good, only some color aberration at the sides. The field of view is pretty
large, you have to turn your head to take a look left or right.
Experiments with my 93x44cm lens with 56cm focal distance have shown that
for optimal results, this lens had to be about 33cm way from the LCD
screens. Viewing distance from the lens should be equal or less than the
focal length. I'm sitting about 55 ~ 60cm from the lens, which is already a
bit far. 50cm would be better. Larger viewing distance will result
in magnifying distortion at the edges. The lens 93cm width is just a bit too
short to see the full 3x15" LCD's (totally 96cm wide) in one view, but a
slight turn with you head will show the edges as well. A100cm width lens
would be a bit better for this view setup.
I find the above solution the best of all my view setup experiments so
far. It requires less space, is easy to setup, does not require room lights
to be dimmed, no noise or room heating (like with projectors). Screen breakup over L/C/R view is quite
acceptable, and contrast , light output, and surround view feeling is
better than with projector setup, probably because the room in front of you
is blocked by the fresnel lens.
The frame on which the three LCD monitors and the Fresnel were mounted
was build with adjustment flexibility in mind: The shelf-rack metal is very
handy for this kind of construction. The whole display is mounted under a
slight angle, as I'm looking up to the screen. The outside scenery sits a
little too high as the big 40" Fresnel aspect ratio does not really fit the
three LCD panels in height. I could cut off part of the top and bottom of
the Fresnel, but I didn't have the courage to do so yet.
The fresnel sits in isolation foam
tubing. Fresnel lenses are very easy to scratch.
It is also possible to use three smaller lenses placed next to each
other. See here
for more info.
Finding shops that sell large Fresnel lenses is not easy. Sometimes they
are used as screen magnifiers for TV sets. Someone recommended
3Dlens.com also sells Fresnel lenses,
F550 type seems most used with LCD's. Update: 3DLens.com no
longer sells the F550 type lenses. I have been told that TV magnifier lenses
also can be used.
Google ebay for
these type of products.
This factory in China also sells lenses, up
but I did not have any contact with them.
Update: To fit the screens to the DIY
Motion Platform II, I build a lightweight wooden structure to mount the
whole thing fixed to the simpit.
The final setup should have the area from lens to LCD's enclosed in a black
coated box, see full enclosure pictures below.
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