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Voyager 2 Saturn Revisited, Still a lot to be processed and reprocessed
Bjorn Jonsson
post Jan 20 2007, 02:36 AM
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Emily recently mentioned in her blog the availability of calibrated and geometrically corrected Voyager images. Actually I had 'discovered' this dataset several months earlier but then managed to completely forget about it. Now I decided to do something so I downloaded volume 37 and decided to do some quick-and-dirty processing, mainly to check if it was feasible to do a very high resolution map (probably 25 degrees/pixel to match my Cassini map of the southern hemisphere) of Saturn's entire northern hemisphere by colorizing green filtered images using lower resolution color data I processed several years ago - at the resolution I want only green filtered images are available.

This was successful, opening the door to a new 'monster project': A very high resolution full color map of Saturn's entire northern hemisphere.

First a color composite made from wide angle orange, green and blue images:
Attached Image

This one was made from images C4386547_GEOMED.IMG, C4386554_GEOMED.IMG and C4386608_GEOMED.IMG. I adjusted the color to something more realistic than I initially got and removed some reseau marks in Photoshop that were visible, especially near ring edges and Saturn's limb. Some color fringing was also visible on Saturn's disk due to Saturn's rotation while the three images were obtained; I removed this by cloning the color of adjacent areas. The spokes in the rings presented similar problems.

I then colorized a green filtered image obtained at a similar time as the wide angle images above. This was the result:
Attached Image

The image should be fairly realistic and I was happy with the result, especially because I didn't do this very carefully - something better should be possible.

Finally the same image sharpened with an unsharp mask:
Attached Image

Lots of small scale details are visible, especially near the pole.

I will probably post several additional Voyager Saturn images in the next several weeks. As previously mentioned, the plan now is to do a very high resolution map of Saturn's entire northern hemisphere based on these calibrated and rectified images. This means reprojecting the images to simple cylindrical projection. To do this I need to know the viewing geometry. Does anyone know if this information is available somewhere (or if not, if it's likely to ever become available)? I have some SPICE kernels which give me Voyager 2's location relative to Saturn. These are probably fairly accurate. However, the limited instrument pointing information I have is very inaccurate so it's useless to me. I can reverse engineer the viewing geometry/pointing but it's a lot of extra work.
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elakdawalla
post Jun 4 2007, 04:32 PM
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It could be that large file sizes are creating a problem somewhere. However, I know that wget works to download large files; it's what I used to download the New Horizons LORRI data file (nearly 6 GB!) so if there is a large-file-size problem I don't believe it's on my end. That page you pointed to on the Small Bodies Node says: "We have ensured that we are serving our large files through a specially-built HTTP server that contains large file support, so that we can at least guarantee that we can pump the files out." I wonder if the Rings Node HTTP server has been configured for large file support.

What did you use to download the files?

--Emily


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- Bjorn Jonsson   Voyager 2 Saturn Revisited   Jan 20 2007, 02:36 AM
- - elakdawalla   This is great; I can't wait to see what you...   Jan 20 2007, 03:45 AM
|- - tedstryk   This is some incredible work, Bjorn. Do you know ...   Jan 20 2007, 05:07 AM
- - PhilCo126   Great work to celebrate the 30th anniversary of th...   Jan 20 2007, 02:19 PM
- - elakdawalla   QUOTE (Bjorn Jonsson @ Jan 19 2007, 06:36...   Jan 20 2007, 05:36 PM
|- - Bjorn Jonsson   No, I didn't know of these - they are new. Tha...   Jan 20 2007, 08:45 PM
- - elakdawalla   Hi Bjorn, I tried downloading the zipped versions...   May 18 2007, 04:46 PM
- - Bjorn Jonsson   QUOTE (elakdawalla @ May 18 2007, 04:46 P...   May 25 2007, 01:22 AM
- - elakdawalla   Great, thanks. It's nice to know I didn't...   May 25 2007, 03:17 PM
- - Bjorn Jonsson   I have now fixed this bug. The new version is avai...   May 26 2007, 01:46 PM
- - elakdawalla   Thanks! I tried the new version on one folder...   May 26 2007, 02:00 PM
- - elakdawalla   Just posting an update here to mention that I...   May 29 2007, 10:38 PM
- - elakdawalla   Seems I posted too soon. I was really rolling alo...   Jun 4 2007, 03:28 PM
- - Bjorn Jonsson   Volumes 34-38 are there but you'll need to dow...   Jun 4 2007, 04:11 PM
- - elakdawalla   I tried going to that Zip archives page but still ...   Jun 4 2007, 04:17 PM
- - Bjorn Jonsson   QUOTE (elakdawalla @ Jun 4 2007, 04:17 PM...   Jun 4 2007, 04:27 PM
- - elakdawalla   It could be that large file sizes are creating a p...   Jun 4 2007, 04:32 PM
- - Bjorn Jonsson   I used GetRight for most/all of them. I don't ...   Jun 4 2007, 04:39 PM
- - elakdawalla   Bjorn, your suspicion turns out to be right on tar...   Jun 4 2007, 08:15 PM
|- - brellis   QUOTE (elakdawalla @ Jun 4 2007, 01:15 PM...   Jun 4 2007, 08:47 PM
|- - Bjorn Jonsson   QUOTE (elakdawalla @ Jun 4 2007, 08:15 PM...   Jun 5 2007, 12:45 AM
- - elakdawalla   I just heard again from Mark Showalter, who says t...   Jun 21 2007, 08:58 PM
- - elakdawalla   All right, it's all downloaded, and I've n...   Jun 26 2007, 04:26 PM
|- - Bjorn Jonsson   QUOTE (elakdawalla @ Jun 26 2007, 04:26 P...   Jun 27 2007, 12:45 AM
||- - tedstryk   QUOTE (Bjorn Jonsson @ Jun 27 2007, 12:45...   Jun 27 2007, 01:13 AM
|- - ChrisP   QUOTE (elakdawalla @ Jun 26 2007, 05:26 P...   Jul 23 2007, 06:36 AM
||- - elakdawalla   QUOTE (ChrisP @ Jul 22 2007, 11:36 PM) No...   Jul 23 2007, 04:09 PM
|- - ChrisP   QUOTE (elakdawalla @ Jun 26 2007, 05:26 P...   Jul 23 2007, 08:01 AM
- - AlexBlackwell   I just wanted to say that your space imaging effor...   Jun 26 2007, 06:26 PM
- - ChrisP   One minor nit on your new raw images page Emily, t...   Jun 26 2007, 10:51 PM
- - elakdawalla   Woops. I fixed the Mimas and Tethys links. The p...   Jun 26 2007, 11:27 PM
- - ChrisP   Thanks for fixing the links. The GIMP doesn't...   Jun 26 2007, 11:54 PM
- - elakdawalla   Hi Chris, I'd be happy to add instructions reg...   Jun 27 2007, 02:02 AM
|- - ChrisP   QUOTE (elakdawalla @ Jun 27 2007, 03:02 A...   Jun 28 2007, 12:34 AM
- - ugordan   Wow, the Voyager data is certainly ress rewarding ...   Jun 27 2007, 12:39 PM
|- - tedstryk   QUOTE (ugordan @ Jun 27 2007, 12:39 PM) W...   Jun 28 2007, 03:36 AM
|- - tedstryk   QUOTE (ugordan @ Jun 27 2007, 12:39 PM) W...   Nov 1 2007, 02:52 AM
|- - ugordan   That's a really nice Enceladus image. Very Cas...   Nov 2 2007, 02:00 PM
- - edstrick   I did some systematic experimental work on partial...   Jul 23 2007, 07:05 AM
|- - ChrisP   QUOTE (edstrick @ Jul 23 2007, 08:05 AM) ...   Jul 23 2007, 08:16 AM
- - ChrisP   Thanks for that link to the reviews webpage Emily,...   Jul 24 2007, 01:00 AM
- - PhilCo126   Time flies...   Nov 2 2007, 06:28 PM
- - PhilCo126   At least for Voyager 2 there was the 1986 prospect   Nov 3 2007, 06:25 PM
- - machi   Old Hyperion flyby movie. It's maked from six ...   Dec 4 2009, 03:06 PM
|- - ElkGroveDan   Wow. Good work.   Dec 4 2009, 03:20 PM
- - Ian R   Machi, you are rapidly becoming one of my favourit...   Dec 4 2009, 04:18 PM
|- - tedstryk   Amazing animation!   Dec 8 2009, 02:03 AM
- - lyford   At the risk of sounding like a cliche, that was pr...   Dec 8 2009, 02:21 AM
- - nprev   I'll second that cliche... VERY cool, Machi...   Dec 8 2009, 03:04 AM
- - Hungry4info   That is pretty cool. You can just make out the dee...   Dec 8 2009, 07:59 AM
|- - tedstryk   I worked on this sequence back in 2005 but never t...   Dec 8 2009, 07:30 PM
- - elakdawalla   Since no one else has mentioned it yet, I just wan...   Dec 8 2009, 07:57 PM
|- - tedstryk   Holy Cow! I never clicked to enlarge, so I th...   Dec 8 2009, 08:08 PM
|- - ugordan   Yep, Bjorn posted the image here a while ago and i...   Dec 8 2009, 08:12 PM
|- - Bjorn Jonsson   QUOTE (elakdawalla @ Dec 8 2009, 07:57 PM...   Dec 9 2009, 11:59 AM
|- - tedstryk   My closer Galileo mosaic is also very high resolut...   Dec 9 2009, 04:22 PM
- - jasedm   I second this - I've nabbed it for my desktop ...   Dec 8 2009, 08:11 PM
- - elakdawalla   Actually, this one is better than the one you saw ...   Dec 8 2009, 08:23 PM
- - machi   Thanks for comments! And Jupiter from Björ...   Dec 8 2009, 08:38 PM
- - JohnVV   i could have used that vid of Hyperion when i did ...   Dec 8 2009, 11:05 PM
- - Phil Stooke   Very interesting! Phil   Dec 8 2009, 11:37 PM


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