From: "Tim" <tjp314@pacbell.net>
Date: May 1, 2008 6:12:44 PM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Re: Moon Anaglyph
Alberto:
When I tried to open that file, I got a "file not found" message, so I
haven't seen it.
I'm a geologist, and work with stereo orbiter images of Mars all the
time. 20 years ago, all we had was Viking Orbiter, which was seldom
intentionally stereo (except for landing site selection for the Viking
Landers), so the parallax is all over the place. But The Viking
orbiters did acquire enough data such that there is a fair amount of
stereo over much of the planet, at least at regional scales. Most of
the pairs listed as "useable" for stereo viewing of topography have
parallax or separation angles on the order of several degrees to 45
degrees (or even more). In my experience, separation angles of at
least 15 degrees were necessary to see much topography, particularly
in plains regions.
The HiRISE camera team on the Mars Reconnaissance Orbiter mission does
targeted stereo of areas of high scientific interest and landing
sites. To get the conjugate image, the spacecraft has to be rolled
off nadir, so they often have to "take what they can", but they
typically try to acquire stereo pairs with a separation angle of about
20 degrees.
-Tim.
--- In Astro_IIDC@yahoogroups.com, "richter1956" <richter1956@...> wrote:
Tim,
2 degrees are a normal working condition for our eyes.
Looking at an object 2 meters far from our eyes we have a 2 degree
separation
angle.(depending on the distance between the eyes)
You surely agree that at 2 meters far we still perceive a strong 3D
effect... but at 4 meters
too (1 degreee).
Of course our brain can process even bigger angles with stronger 3d
effect, but 2 degrees
are considered as the base-rule for the 3d vision (distance between
cameras= 1/30 of the
distance from the object).
Did you check the test image i uploaded with red/cyan glasses?
The 3D Moon roundness is perfectly detectable.
I guess that our eyes/brain can help more than expected.
The 3D perception through stereograms (later through
autostereograms too)
demonstrated also that 3D synthesis is not influenced by the main
subject of the image.
The 3D perception is a direct brain synthesis based on viewing
difference and happens
even with a meaningless random series of dots or patterns
represented in the image.
http://www.makina.it/Shuttle-Autostereo.jpg
Anyway do exist an easier 3rd option: no libration, no spaceflight
but simply connect an air
compressor to some old unused oil pipe going deep in the ground, and
inflate the Earth
until the necessary diameter is reached!
regards
Alberto
--- In Astro_IIDC@yahoogroups.com, "Tim" <tjp314@> wrote:
A few degrees isn't enough of a baseline for stereo viewing. You'd
need libration (or leaving the Earth!) to get more.
-Tim.
--- In Astro_IIDC@yahoogroups.com, "richter1956" <richter1956@> wrote:
Hi Jeff,
i know the other possibilities for 3D imaging of the Moon.
The one i choose is the easier for a single person / single night
because it is not so
difficult to get some image approx 3 hours before and 3 hours after
the meridian (4 hours
could be even better of course).
In this case we could get approx 1° of difference.
That is not much (2° could be better) but enough to get some 3d
effect.
Did you check with 3d glasses the image i uploaded into the Lunar
section?
The sphere shape could be easily detected.
The limit of this method is the NON.realtime imaging like the
simultaneous photos do,
Another little problem is caused by the terminator and the shadows
that move a little
within the 6 hours interval.
Anyway i like this kind of imaging not for scientific purposes but
for the emotional impact
caused by the 3D view.
If that method will work even on detailed images, like the Alan
Friedman ones, then we
could dream to fly with an Apollo mission :-)
Regards
Alberto
--- In Astro_IIDC@yahoogroups.com, Jeff Phillips <imjeffp@> wrote:
I was involved briefly with a Luna 3D project a couple of
years ago
where we were trying to coordinate photographers in both
hemispheres
to make simultaneous photos of a feature, using the Earth's
diameter
as a baseline. IIRC, we were never able to coordinate dates and
weather.
The other problem was that the eastern photographer had to shoot
early in the morning. If I were going to try again, I'd try to
coordinate two cameras, one in S. Africa and the other in
eastern
Europe (around 20°E for both, 30°S & 50°N).
One thing to try for a single observer would be to use
libration to
create your baseline. I'd need to do more research to
determine two
nights with the moon at the same age (within several hours at
least)
and opposite librations (if that's the word).
On Apr 28, 2008, at 12:05 PM, Alan Friedman wrote:
Hi Alberto,
Thanks for the interesting project idea.
I am afraid if I ever experienced six hours of good seeing,
I will
be flying with a harp in heaven! But I will keep it in mind
should
I encounter such a fine night on earth.
best wishes,
Alan
On Apr 28, 2008, at 6:26 AM, richter1956 wrote:
Hello to all,
i recently added 2 files in the Lunar section.
One of them is an anaglyph to be watched with red/cyan 3D
glasses:
Anaglyph-SouthPole 3000x2000.jpg
I! 'm wondering about doing some anaglyph starting from
high-end
quality images like Alan Friedman ones... :-)
Maybe Alan could kindly take a wonderful detail (like the
delicious Plato or Copernicus i can see on his site ) 3 hours
before the meridian transit and 3 hours after that
transit....pleeease!!
I guess that 6 hours-difference could be enough to reveal
the
internal 3d structures of the craters but i'm not sure of that.
The sine-qua-non condition is to have the very best image
quality
and the most similar settings (exposure, contrast etc) for
the 2
images.
I attempted to get single craters images but my quality was
not
enough even because i found bad seeing in almost one of the 2
shots (yes you need 6 hours of good seeing).
The other file added is a Moon mosaic grabbed with my C8.
I printed a 70x100 cm poster of it:
080214-The Moon 6353 x 4326.jpg
kind regards to all
Alberto
PS: i did some experiment with DMK on well known DSO (M51)
not
guided: really interesting results.
========================
http://imjeffp.blogspot.com