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Voyager mosaics and images of Jupiter, A fresh look at some ancient stuff
Bjorn Jonsson
post Sep 5 2010, 11:01 PM
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QUOTE (DrShank @ Sep 4 2010, 04:22 PM) *
beauty! would you call this close to natural color now?

The upper one should be fairly close to natural color but this is subjective. It might be a bit too reddish but I'm not sure. After some channel mixing I processed it to make the oval SSE of the GRS roughly white.

A few notes on the mosaics and on images I have noticed in the Voyager dataset:

(1) As should be obvious I have been looking at lots of high-res Voyager images of Jupiter recently. When doing this I have come across several images that show interesting features that I had not noticed before. An example (processed to increase contrast and sharpness):

Attached Image

And a wide angle context image shuttered at the same time:
Attached Image


The features near the top of the image are interesting. These images where obtained on March 4, 1979 at a range of 1.3 million km from Jupiter's center.

Another example (processed to increase contrast and sharpness):

Attached Image

And a context image:
Attached Image


The features (clouds?) at upper right in the narrow angle image look somewhat weird. They are located near (435,375) in the context image. The images were obtained on March 5, 1979 at a range of 630,000 km from Jupiter's center.

(2) I noticed an interesting comment in several images in a brown barge imaging sequence. For example in image C1635958.IMQ:

"ATMOS DYNAMICS 3X2 NA GR MOSAIC OF BARGE, STEREOSCOPIC WITH 16359.50 - 60.07"

This seems to have been an attempt to image Jupiter in stereo - I don't think I'm misunderstanding anything here. However, I don't think imaging Jupiter in stereo using a single spacecraft would work due to cloud motions. Two spacecraft are a different story so here's today's crazy idea: Imaging parts of Jupiter in stereo if both NASA and ESA send spacecraft there simultaneously. I'm not sure it would work though - it requires high resolution and I'm not sure ESA's JGO spacecraft is going to be capable of that due to its distance from Jupiter and maybe due to its camera as well.

(3) I haven't been able to confirm that it is indeed vertical relief and/or shadows that is visble in my mosaic. I've been looking for scientific papers and I haven't found any but I haven't searched very carefully. I also did some simple 3D test renders to see which cloud thickness and altitude might reproduce the appearance of the clouds in the mosaic but the results are inconclusive. Still this looks a lot like vertical relief and it should be noted that cloud shadows are visible in high-phase Voyager images of Jupiter. It would be interesting if someone here knew something about this topic. Also see the cloud shadow thread which has a hi-res image showing what might be shadows or vertical relief.

(4) I'm in the early stages of starting work on yet another mosaic and it's going to be a bit different from the ones I have posted here because OGV is available, not just OV. Actually there is a huge amount of Voyager stuff I'd like to process but this takes a lot of time if high quality results are desired. In particular, the lack of accurate camera pointing angles is a constant source of frustration and requires me to reverse engineer this information for every image. Fortunately, the spacecraft location is available and that data seems accurate - without it this would be even more time consuming.
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tedstryk
post Sep 6 2010, 01:48 AM
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QUOTE (Bjorn Jonsson @ Sep 6 2010, 12:01 AM) *
In particular, the lack of accurate camera pointing angles is a constant source of frustration and requires me to reverse engineer this information for every image. Fortunately, the spacecraft location is available and that data seems accurate - without it this would be even more time consuming.


So true. When I was at the New Horizons team meeting in December, I was asked if I used the camera pointing information for my work. I had to be honest - only in situations where I could not ascertain the pointing by studying the image. When it could be done, determining the pointing from the image was significantly more accurate (though much more time consuming).


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DrShank
post Sep 10 2010, 10:19 PM
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QUOTE (tedstryk @ Sep 5 2010, 07:48 PM) *
So true. When I was at the New Horizons team meeting in December, I was asked if I used the camera pointing information for my work. I had to be honest - only in situations where I could not ascertain the pointing by studying the image. When it could be done, determining the pointing from the image was significantly more accurate (though much more time consuming).


blink.gif

i spend far more time accurately controlling all the images than i do anything else!


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tedstryk
post Sep 11 2010, 01:04 AM
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I found the pointing information for the Neptune images to be limited.


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DrShank
post Sep 11 2010, 01:10 AM
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QUOTE (tedstryk @ Sep 10 2010, 07:04 PM) *
I found the pointing information for the Neptune images to be limited.



yeah, all the published data are predicts based on the original pointing commands. Ive had to update all the pointing
vectors iteratively for all the satellites to get the images to properly mosaic. but then, thats my job!


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tedstryk
post Sep 11 2010, 01:14 AM
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OK, so you do have to correct the data somewhat. That makes sense.


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elakdawalla
post Sep 11 2010, 03:08 AM
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QUOTE (DrShank @ Sep 10 2010, 06:10 PM) *
...thats my job...

Paul, I hope you realize how many people reading this forum wish "iteratively updating Voyager 2 spacecraft pointing vectors" was a part of their job description smile.gif


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volcanopele
post Sep 11 2010, 03:29 AM
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Substitute Cassini for Voyager 2, and that's half my job...


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Phil Stooke
post Sep 11 2010, 02:14 PM
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Perhaps the most important question here is, will those corrected numbers get into the public record somewhere?

Phil


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DrShank
post Sep 12 2010, 06:59 AM
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all my work, especially the stereo stuff requires precise pointing, so every cassini release is spent 2 weeks or more calibrating and geometrically registering and revising the pointing vectors for all the new satellite images (altho the past year has been rather a dry spell!). what fun. but then i get to make mosaics like these.
release of the pointing info is a bit more complicated. my Galileo pointing is now public in the form of the Atlas, at least in labeled image map format. beyond that Im not sure yet . . .
Attached thumbnail(s)
Attached Image
 


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Bjorn Jonsson
post Sep 13 2010, 12:15 AM
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QUOTE (DrShank @ Sep 12 2010, 06:59 AM) *
my Galileo pointing is now public in the form of the Atlas, at least in labeled image map format.

This is great, I have always found the lack of accurate pointing info a bit strange. It means that everyone working on images with inaccuarate (or missing) pointing info must either obtain it from someone else or spend lots of time determining the correct pointing. So I suspect the same thing sometimes gets done by more than one person/team when it seems a lot of work could be saved by doing it only once.

Even the spacecraft position can be a source of problems. Today I wanted Voyager 1's position in late January 1979 but my software responded with a SPICE error so I tried the Jupiter Viewer at the PDS Rings Node but got similar results. I suspect that SPICE kernels containing Voyager 1's position aren't available for dates before 6 February but I need to check this more thorougly. I'm working on a Voyager 1 atmospheric movie by the way.
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Ian R
post Sep 13 2010, 09:08 AM
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QUOTE (Bjorn Jonsson @ Sep 13 2010, 01:15 AM) *
I'm working on a Voyager 1 atmospheric movie by the way.


I'm also fiddling with some of the Voyager 1 movie data, Bjorn -- it goes without saying that I'm sure your work will be superior to mine, but here's what I've done so far, in any case:

Jupiter Voyager 1 Approach Movie - Green Filter Only:
http://www.youtube.com/watch?v=4jBir5hix6g

Jupiter Voyager 1 Approach Movie - Color / Rotated:
http://www.youtube.com/watch?v=jZrJ0D8IfB8

Jupiter Voyager 1 Atmospheric Features Movie - Color:
http://www.youtube.com/watch?v=YVMc5PTChwE

I really am a glutton for punishment - at various points during this process, I have resisted the urge to put my fist through the monitor, and throw the tower out of the window! rolleyes.gif


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Bjorn Jonsson
post Sep 13 2010, 09:41 AM
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QUOTE (Ian R @ Sep 13 2010, 09:08 AM) *
it goes without saying that I'm sure your work will be superior to mine

Only time will tell - at the moment my 'movie' consists of exactly one image...
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tedstryk
post Sep 13 2010, 02:15 PM
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Paul, I'm really glad to hear you are doing this. To clarify my earlier comment, I was talking about desmearing images and aligning images for stacking purposes. As it stands, the current pointing data that is publicly available isn't adequate.


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DrShank
post Sep 13 2010, 03:05 PM
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Ted,
typically, one or two active team members (Cassini is an example) do their own pointing updates as well, sometimes on an as need basis, but sometimes also for cartography. That is how the satellite maps they published are done. I do not know if they do all images or only those that are required for the global maps. I do just about everything because i do a lot of stereo and mapping work (I have a late DPS abstract in on this topic) and require a lot of images. I cant wait for any team releases (i dont know if a mechanism even exists for that) so I do my own! There are a few others out there who do it on as need basis but I may be the only non-team-member doing the whole bunch of it.
cheers
paul


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