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LRO development
FordPrefect
post Sep 5 2006, 12:02 PM
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Thanks Doug and Phil for your replies!

I am just wondering if in the future, thanks to LRO, we will get a hi-resolution true colour map of the moon along with a precise elevation map, just as they are available for Earth (-> Blue Marble) and Mars today, enabling us to render the moon in 3d applictions with a high degree of accuracy? If LRO is going to map the surface at lower sun angles than Clementine, probably with shadows casting that would be a disadvantage for such a task though...
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Phil Stooke
post Sep 5 2006, 12:43 PM
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If most or all the planned orbiters fly successfully, between them we should have a pretty good combination of images to assemble plenty of high quality digital maps.

If people want a good map with oblique lighting but not too many shadows, the new USGS mosaic of Lunar Orbiter images should be the first one available - not ready yet but it won't be too long. It can be patched here and there with Clementine. As for true colour, just set the image mode to grayscale instead of RGB and you have it! The level of elevation resolution and accuracy you want will come from stereo, probably, rather than altimetry, and that would take a fairly long time to put together. Altimetry will be quicker but lower resolution, but it's necessary as a base for the stereo mapping.

Phil


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FordPrefect
post Sep 5 2006, 03:03 PM
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Thanks Phil. I remember to have read that the LRO will be equipped with a laser altimeter for elevation mapping as well, wouldn't that be sufficient to create an elevation map?
Phil, do you really consider the lunar surface just shades of grey, c'mon... there are colours present, even if they're subtle... rolleyes.gif
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djellison
post Sep 5 2006, 03:07 PM
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If Phil thinks the Moon is greyscale - it means his publisher saves a fortune on printing costs wink.gif

Seriously - yes - there are some very subtle colours on the moon - but not so much as one would notice with the naked eye really.

Doug
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dvandorn
post Sep 5 2006, 11:25 PM
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QUOTE (djellison @ Sep 5 2006, 10:07 AM) *
Seriously - yes - there are some very subtle colours on the moon - but not so much as one would notice with the naked eye really.

It all seems to depend on your phase angle relative to the Sun. Many of the Apollo astronauts saw brownish tints in the Moon at high phase (Sun directly or near-directly overhead), while some others never saw anything except shades of gray. I think you have to be a lot closer than Earth-Moon distances to get enough sunlight off the lunar surface to really see much color there with the naked eye, though.

In actuality, sensitive spectrographic studies have shown that some portions of the visible lunar surface have a reddish tint, while others have a bluish tint. I believe reddish tints include much of the anorthositic highlands and a few of the maria, and bluish tints predominate in high-titanium mares.

Also, some of the more sharp-eyed Apollo CMPs have seen streaks of both yellow-orange and light green glasses deposited in various areas where fire fountains once emplaced basaltic glass droplets. I recall that Ron Evans, in particular, was able to see orange and red glass streaks in the Sulpicius Galles (sp?) region.

-the other Doug


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Guest_DonPMitchell_*
post Sep 6 2006, 12:03 AM
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[attachment=7296:attachment]

You can convert the measured spectral reflectivity of planets into CIE XYZ, and from there into gamma-corrected sRGB 24-bit colors. In my "planetary paint-chip" image above, I adjusted the Y values to be proportional to the albedos of the objects.
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ugordan
post Sep 6 2006, 07:12 AM
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QUOTE (DonPMitchell @ Sep 6 2006, 01:03 AM) *
You can convert the measured spectral reflectivity of planets into CIE XYZ, and from there into gamma-corrected sRGB 24-bit colors. In my "planetary paint-chip" image above, I adjusted the Y values to be proportional to the albedos of the objects.

Very interesting. Did you use average spectra of the objects, that is does Saturn's color include both the rings and the planet itself? Hence the color Saturn reduced to a point source would have, just as Saturn appears in the night sky?

EDIT: When you say gamma-corrected, do you mean compensating for the CRT 2.2 gamma or something else? I'm having trouble getting a grasp just what gamma value should be set, when converting linear-light images for viewing on monitors, escpecially not knowing whether the LUT in the video card's RAMDAC already takes care of that. Most modern video card drivers do allow setting the gamma manually, but I'm uncertain whether this is just applying another one on top of the 0.45 gamma.

BTW, here's a nice page about the subtle colors of the moon: http://www.colormoon.pt.to/


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ljk4-1
post Sep 6 2006, 01:48 PM
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Will LRO be able to detect the orange regolith exposed by Apollo 17 in Taurus-Littrow?

http://www.psrd.hawaii.edu/Feb97/MoonVolcanics.html


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and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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paxdan
post Sep 6 2006, 01:55 PM
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Saturated Colour Photo of the Moon

exposure details

This image is a mosaic of 15 separate and slightly overlapping 8.2 megapixel images from my Canon EOS-20D (unmodified), taken in Raw mode and converted and stitched together in Photoshop CS2. As you can see from the EXIF data, the exposures were each 1/5 second at ISO 100.

Though the moon is generally made of gray, dusty material it is very bright, photographically, since it is bathed in sunlight.

I mounted my 20D to my Meade LX200 GPS UHTC 10" Schmidt-Cassegrain telescope via my 2x Televue Powermate (a focal length doubler, similar to a teleconverter, which also serves to mate my camera to the 2" telescope eyepiece tube). Effective focal length was 5000mm f/20.

Looking through the viewfinder I swept across the surface in a zig-zag fashion, trying for about 1/3 overlap between frames. I triggered the shutter with my TC80-N3 remote timer/controller. I did the stitching by hand in Photoshop.

Since it is tremendously downsized from the original mosaic, which was almost 40 megapixels, and was taken at the camera's most noise-free setting (ISO 100), the data is very accurate, and thus I was able to strongly increase the saturation via Photoshop's Image - Adjust - Hue/Saturation function.



Somebody send this guy an invite to UMSF that is truely a stunning image and an impressive bit of processing.
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ugordan
post Sep 6 2006, 02:01 PM
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QUOTE (paxdan @ Sep 6 2006, 02:55 PM) *
Somebody send this guy an invite to UMSF that is truely a stunning image and an impressive bit of processing.

Indeed. Good equipment doesn't hurt, either.


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RNeuhaus
post Sep 6 2006, 03:56 PM
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QUOTE (paxdan @ Sep 6 2006, 08:55 AM) *
Saturated Colour Photo of the Moon

exposure details

Somebody send this guy an invite to UMSF that is truely a stunning image and an impressive bit of processing.

Thanks Paxdan, I have just robed your picture. For me, that is the most beautiful Moon's picture. wink.gif

Rodolfo
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dvandorn
post Sep 6 2006, 09:25 PM
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wowsh the moon..... tongue.gif


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“The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Guest_AlexBlackwell_*
post Sep 11 2006, 08:38 PM
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QUOTE (AlexBlackwell @ Jul 24 2006, 10:29 AM) *
The Workshop on Lunar Crater Observing and Sensing Satellite (LCROSS) Site Selection
October 16–17, 2006
NASA Ames Research Center, Moffett Field, California
First Announcement

The program with embedded links to abstracts is online.
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Phil Stooke
post Sep 12 2006, 01:09 PM
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The abstracts are interesting... for not being very interesting!

One gets the impression that the meeting has not attracted a lot of interest. Of course, the opportunity to select from a large pool of sites is really not there. It's a far cry from the vast array of choice for MSL or MER. The Arecibo DEM modelling really only gives about 5 good crater floor candidates for holding ice, and two are better than the others for being potentially visible to earth-based radar (pre and post impact imaging) and line of sight viewing. So those two sites are suggested (southern Shoemaker, and south of Malapert). What other choices are there?

Two interesting asides... the chance for about 4 m/pixel radar imaging from Goldstone is tantalizing... and in the Print-only section Jack Green is still promoting his volcanic views. Check out Don Wilhelms' "To a Rocky Moon" to see the beginnings of that story, 40+ years ago!

PS - in my view... the probability that useful quantities of ice exist at the poles is small...

Phil


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... because the Solar System ain't gonna map itself.

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NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain)
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Guest_DonPMitchell_*
post Sep 12 2006, 04:07 PM
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Gorgeous super-saturated moon images!


QUOTE (ugordan @ Sep 6 2006, 12:12 AM) *
EDIT: When you say gamma-corrected, do you mean compensating for the CRT 2.2 gamma or something else? I'm having trouble getting a grasp just what gamma value should be set, when converting linear-light images for viewing on monitors, escpecially not knowing whether the LUT in the video card's RAMDAC already takes care of that. Most modern video card drivers do allow setting the gamma manually, but I'm uncertain whether this is just applying another one on top of the 0.45 gamma.


It's better to not set the LUT on a monitor, because many of them do a mapping of 8-bit to 8-bit values. Anything except the identify function actually causes you to lose some of the 256 possible values that can be displayed.

Modern monitors are supposed to obey the sRGB spec, or the closely-related new HDTV specs. So the best practice is to generate an image in floating point, as linear radiance values, L. Than calculate an 8-bit display value n, as follows:

n = int( pow( L, 1.0/2.2 ) * 255.0 + 0.5 )

and when loading an sRGB image:

L = pow( float(n)/255.0, 2.2 )
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