Voyager mosaics and images of Jupiter, A fresh look at some ancient stuff |
Voyager mosaics and images of Jupiter, A fresh look at some ancient stuff |
Aug 20 2010, 05:47 PM
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#1
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IMG to PNG GOD Group: Moderator Posts: 2256 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Thanks to modern computers and software the old, 'official' Voyager Jupiter images can be reprocessed into something much better. There is also a lot of Voyager data there that was never processed into color composites and/or mosaics (or at least it has not appeared on the WWW). With proper processing the apparent image quality approaches the quality of the Cassini images but needless to say the wavelength coverage is (vastly) inferior.
I have recently been taking a close look at the high resolution Voyager 1 images, i.e. the images obtained in early March 1979. This is going to result in some new and/or reprocessed mosaics. The first one is now complete and I'm working on another one. The image below is a 12 image mosaic (12 orange + 12 violet + 12 synthetic green images). The images were obtained on March 2, 1979 at a range of 4.3 million km. The first image (C1629045.IMQ) was obtained at 05:09:23 and the last one (C1629131.IMQ) at 05:46:11. The resolution is roughly 43 km/pixel. The raw images were calibrated, reprojected to simple cylindrical projection, mosaicked and then rendered using a typical viewing geometry (there is no such thing as a "correct viewing geometry" because the images were obtained over a 37 minute period with Jupiter rotating). I then fixed the color balance. I still haven't 'standardized' how I process the Voyager color. I wasn't completely satisfied with the color I got using an approach similar to what's described in another thread but I think the color could be improved a bit. The final step was to sharpen the resulting image a bit, mainly to compensate for all of the resampling that the previous processing steps required. This image shows lots of features: The Great Red Spot and one of the three white ovals present during the Voyager flybys, smaller spots, scallopped belt/zone boundaries, gravity waves, a bright equatorial plume and the dusky south polar region. I don't think I'm bragging by saying that this is probably the best Voyager 1 Jupiter mosaic that I know of, mainly because of its size (12 images). I will be posting more Jupiter stuff in this thread in the coming days/weeks, both mosaics and interesting images (and needless to say, others are welcome to post images and mosaics as well). |
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Aug 20 2010, 05:50 PM
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#2
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Member Group: Members Posts: 293 Joined: 29-August 06 From: Columbia, MD Member No.: 1083 |
Fantastic pic! Did you use ISIS? If so, what were your processing steps?
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Aug 20 2010, 06:00 PM
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#3
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Senior Member Group: Members Posts: 3652 Joined: 1-October 05 From: Croatia Member No.: 523 |
I don't think I'm bragging by saying that this is probably the best Voyager 1 Jupiter mosaic that I know of, mainly because of its size (12 images). You have every right to brag as this is the best Voyager Jupiter product I've seen. The resolution and image quality reminds of New Horizons LORRI images and yet the colors remind of Cassini. With the filter set you had to work with, I think the color looks great. Jealous mode = ON -------------------- |
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Aug 20 2010, 07:54 PM
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#4
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Member Group: Members Posts: 146 Joined: 23-August 06 From: Vriezenveen, Netherlands Member No.: 1067 |
Wow! That's stunning!
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Aug 20 2010, 08:02 PM
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#5
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Senior Member Group: Members Posts: 1278 Joined: 25-November 04 Member No.: 114 |
This is wonderful stuff!
Its so nice to see these images processed with today's technology. The Images from the 70s and 80s where always over saturated. |
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Aug 20 2010, 10:08 PM
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#6
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Interplanetary Dumpster Diver Group: Admin Posts: 4405 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Awesome. Voyager images are quite good once you remove the gunk.
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Aug 20 2010, 11:51 PM
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#7
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Member Group: Members Posts: 808 Joined: 10-October 06 From: Maynard Mass USA Member No.: 1241 |
Bjorn,
S T U N N I N G thank you! -------------------- CLA CLL
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Aug 21 2010, 06:12 AM
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#8
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Member Group: Members Posts: 796 Joined: 27-February 08 From: Heart of Europe Member No.: 4057 |
Fantastic result Bjorn! I think, that it's biggest published mosaic of Jupiter.
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Aug 21 2010, 02:39 PM
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#9
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Member Group: Members Posts: 903 Joined: 30-January 05 Member No.: 162 |
You're throwing meat in the tiger cage.
We want MORE! If you're looking for ideas for more work; were there any mosaics shot on the departure side from either Voyager? A big enhanced crescent/dark side shot might be pretty dramatic. |
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Aug 21 2010, 11:10 PM
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#10
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Member Group: Members Posts: 318 Joined: 1-October 06 Member No.: 1206 |
Golly. I spent a good 15 minutes just wandering around the infinite complexities of that image.
Are we seeing cloud shadows new the top of the image? P |
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Aug 21 2010, 11:48 PM
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#11
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
Really nice job! This is beautiful!
-------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Aug 22 2010, 12:24 AM
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#12
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Merciless Robot Group: Admin Posts: 8789 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Absolutely hypnotic. I've looked at it several times over the past two days, and Antipode's right: you see new things each time. Phenomenal, Bjorn.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Aug 22 2010, 04:20 PM
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#13
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Senior Member Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 |
Taking Bjorn's awesome image above as "reference", I created a blink animation that compares it to a Galileo image of the Great Red Spot almost 20 years later.
The Galileo image had used a synthetic green channel, so I adjusted the colors to match closest to Bjorn's image. I also took some liberties with warping and resizing the Galileo image to match Bjorn's image. I wanted to highlight structural, not color or size differences. [Animated GIF: click to animate] In the Galileo 1996 image, the clear zone to the S of the GRS is much thinner. The S belt also seems less affected by the GRS. Interestingly, the thin red band to the SE (standing wave?) is present in both images. There is also much more chaos in the region to the NE. In the Voyager 1 image, the NE section shows a smoother transition between zones. -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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Aug 25 2010, 03:39 PM
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#14
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IMG to PNG GOD Group: Moderator Posts: 2256 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Fantastic pic! Did you use ISIS? If so, what were your processing steps? I didn't use ISIS. Voyager calibration isn't available yet in ISIS 3 and ISIS 2 doesn't work properly on my computer. I think I now know why but I didn't when I made the mosaic. Awesome. Voyager images are quite good once you remove the gunk. Yes, that's my experience as well. The problem is that this wasn't done carefully enough ~30 years ago so those old, 'official' color composites and mosaics really need to be reprocessed. Are we seeing cloud shadows new the top of the image? I don't think so. You need higher resolution and/or lower solar elevation angles (mainly the former) for cloud shadows/vertical relief to become apparent. Vertical relief (if one can speak of that in the context of gaseous planets) is visible in higher resolution images but it is usually not obvious unless the images are sharpened. Incidentally, the Voyager images are better than the Galileo images if you are interested in cloud shadows and vertical relief. The highest reolution Voyager images are of higher resolution than the Galileo images. In addition, compression artifacts can be an issue if you want to examine small scale features in the Galileo images. Actually I now think (after taking a careful look at lots of Voyager images) that the Voyager dataset still is in some ways better than the Galileo dataset. While the Galileo images are more carefully targeted and the wavelength coverage is far better (near infrared filters) the Voyager images have no compression artifacts, there is a significant amount of images of higher resolution than anything Galileo obtained and the Voyager images are a better data source for atmospheric movies. So if you are interested in very small scale details in the Jovian atmosphere the Voyager 1 images are what you want. I'm currently working on another 12 image mosaic that should be finished soon, possibly this week. |
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Aug 27 2010, 12:53 AM
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#15
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Interplanetary Dumpster Diver Group: Admin Posts: 4405 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Yes, that's my experience as well. The problem is that this wasn't done carefully enough ~30 years ago so those old, 'official' color composites and mosaics really need to be reprocessed. Even when they did go through the proper steps, doing all the steps with the 8 bit data rather than converting to 16 bit, something beyond the capability of the vax computers they were using, really degraded the images. -------------------- |
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