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Perijove 1 (PJ1), August 27, 2016
Gerald
post Sep 6 2016, 03:00 PM
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An enhanced crop of a processed raw JNC #06166 shows, that RGB alignment is good now, despite the inaccurate shape model:
Attached Image

Time for fine-tuning, and for focusing on deriving common perspective for two different raw images.
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Phil Stooke
post Sep 6 2016, 06:13 PM
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This is just Gerald's image processed to emphasise cloud patterns, especially near the terminator.

Phil

Attached Image


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Brian Burns
post Sep 6 2016, 08:14 PM
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I get a resolution of ~14km/px for that image (altitude 19,900km) - not sure if it's correct.

Just for comparison the Voyager images that Bjorn posted here have a resolution of ~5km/px - it's amazing to see what look like thunderclouds (?) on top of the other clouds -

http://www.unmannedspaceflight.com/index.p...st&p=232324

It'll be great if it catches some interesting clouds in future orbits at the higher resolutions - I read somewhere also that future images might be better as the perijoves will be more in the sun.
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Gerald
post Sep 6 2016, 09:50 PM
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Once you know of the corresponding cloud structures between images #06160 and #06166
Attached Image

you can find those in the hazy reprojections of similar perspective:
Attached Image
Attached Image

Not very easy, but feasible.
Besides the change of perspective, there might even be discernible some real motion. To decide this unambiguously, more accurate processing may be required. But it's at least a first step towards measuring cloud dynamics.
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Bjorn Jonsson
post Sep 6 2016, 10:01 PM
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QUOTE (Gerald @ Sep 6 2016, 09:50 PM) *
Besides the change of perspective, there might even be discernible some real motion. To decide this unambiguously, more accurate processing may be required. But it's at least a first step towards measuring cloud dynamics.

From my experience with Voyager images (and also from reading some Voyager Jupiter papers), cloud motions can be measured/detected in images taken ~30 minutes apart once the resolution is ~15 km/pixel or better. Of course this depends on how big the changes are - the winds are probably slower in the polar regions than closer to the equator, at least the east/west winds are slower.
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Gerald
post Sep 7 2016, 12:50 AM
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Sorry for a short interruption of the JunoCam image processing, but
-- when googling for Juno, I come repeatedly across references to and citations of the recent press release of PJ1 stating
QUOTE
The download of six megabytes of data collected during the six-hour transit, from above Jupiterís north pole to below its south pole, took one-and-a-half days.

With a data rate of 119.56 kb/s,
Attached Image
this sounds like an understatement by at least two orders of magnitude,
since 119.56 kb/s x 36 x 3600s = 15.4e6 kb = 1.9e6 kB = 1.9 GB >> 4 MB.
If the data have been compressed, and only occasional error corrections have become necessary, the decompressed data should have been closer to 4 GB.

---

Regarding the winds, we have now the opportunity to verify or adjust the models of the polar wind systems. I'd think, that within vortices wind velocities can be much higher than mean regional or global winds. I'm curious, what we can find out. A pixel isn't necessarily the accuracy limit for displacement measurements. It depends much on the actual structure of the respective clouds.

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mcaplinger
post Sep 7 2016, 02:46 AM
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QUOTE (Gerald @ Sep 6 2016, 04:50 PM) *
this sounds like an understatement by at least two orders of magnitude,

I didn't write this part of the press release so I can't say what was intended, but a few points:

1) Not all passes are to 70m antennas. To the 34m HEF subnet the data rate is only 22 kbit/sec. And DSN passes weren't continuous through this period, especially because some of the 70m time was lost to STEREO B.

2) Junocam only gets a small fraction of the total downlink rate (about 5%) with the remainder going to the rest of the payload.

3) Any dropped packets during transmission have to be explicitly commanded to be retransmitted, which takes a day or so typically.


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Matt Brealey
post Sep 7 2016, 04:56 PM
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Hi all,

Iíve recently started a few experiments in using Visual Effects software to process/align raw space imagery - specifically from the Voyager/JUNO missions. I've spent a few hours over the last few days attempting to resolve my own image of Jupiterís poles using the raw images from PJ1 and some common VFX techniques, and whilst Iíve still got a long way to go (Iím constantly in awe of the quality of work posted here) I thought Iíd post my first results. All credits of course go to NASA/SwRI/MSSS.



I'm a lot happier with the south pole image (JNCE_2016240_00C06186_V01-raw), as the north pole image (JNCE_2016240_00C06162_V01-raw) sadly seems to contain more compression artefacts. I'd love to get my hands on the NON-PNG versions smile.gif

Again, thanks for posting such incredible imagery.

Cheers!

Matt
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elakdawalla
post Sep 7 2016, 05:04 PM
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The compression artifacts are probably present in the original data as transmitted from the spacecraft. I think the plan for PJ1 was to experiment with different compression levels in order to find the right balance between number of images and image quality within JunoCam's limited data volume budget.

Nice looking work, especially for a first post! You might want to fiddle with the color a bit (you can use Bjorn's work from the Voyager threads for guidance) since we know the raw stuff out of JunoCam is noticeably yellow.


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mcaplinger
post Sep 7 2016, 05:25 PM
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QUOTE (Matt Brealey @ Sep 7 2016, 08:56 AM) *
I'd love to get my hands on the NON-PNG versions smile.gif

PNG is lossless, so you are not losing anything. Any compression artifacts are there in the images as received. The south polar images were transmitted lossless (metadata notwithstanding, there's a bug in how we report that.)

BTW, this is pretty remarkable processing; more detail about how you did it would be interesting.


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Matt Brealey
post Sep 7 2016, 05:53 PM
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elakdawalla : Thanks very much! To be honest I hadnít really considered that the colour would be anything other than the result of the merged rgb channels. Iíll take a look at Bjornís work now, as if I can find suitable reference for the actual offset required, applying it should be relatively straightforward (famous last wordsÖ)

And that makes a lot of sense about the compression. Itíd be very interesting to see a comparison of the different levels (as much as that would be possible with different features in frame).

mcaplinger : Gotcha. And thanks! Iíll be writing it up over at thestateofspace in the next few days, but the short version is that I use a piece of industry-standard compositing software called Nuke to isolate the individual elements of the raw image, remove calibration marks, stitch/align the RGB channels and then merge everything back together. Iím slightly amazed at how suitable the software actually is to this kind of work! Iíll be sure to post a link here (if thatís not against the rules) when the article is posted.

As an aside, Iíve also recently used the same application to auto-process the JUNO approach data, (producing a single 1648x128 RGB frame per raw image that looks a little like the attached) and then stitch it together into a crude version of the approach movie! Though Iím not quite ready to show that one just yet smile.gif

Cheers!

Attached Image
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Gerald
post Sep 7 2016, 06:22 PM
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Hi Matt, I've seen your work before on imgur. Intersting approach. As far as I understand, you are working merely in 2d. That's an approach similar to the one I've used for my first EFB processings in 2013. It's always astonishing, that it works without 3d information.

In the meanwhile I've composed a synopsis of the 16 RGB images of PJ1, in a level 1 style:
Attached Image

(credit: NASA / JPL / SwRI / MSSS / Gerald Eichstšdt)
That's a 7.5 pixels/degree version.
This version doesn't use 3d data either, except camera and spacecraft angular velocity parameters, the same method as for my Marble Movie level 1 processings.
I'd think that it works reasonably well, because Juno's trajectory has been almost parallel to the line Juno - Jupiter.

I may notify later in this post, when I've uploaded the 30 pixel/degree png version.

EDIT: Upload completed.
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tanjent
post Sep 8 2016, 01:57 AM
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In the North Pole image of Matt's are a couple almost-linear large scale features unlike anything I have seen on Jupiter before.
They are not the least bit subtle - easily exceeding one Earth diameter in length.
One is centered in the image and nearly horizontal. It looks almost like a ridge. The other is to the right and lower down, and looks more like a groove.
Are these suspected to be artifacts? Otherwise, I would be scratching my head to figure out how they could develop and persist in a gassy environment.
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mcaplinger
post Sep 8 2016, 02:48 AM
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QUOTE (tanjent @ Sep 7 2016, 05:57 PM) *
In the North Pole image of Matt's are a couple almost-linear large scale features unlike anything I have seen on Jupiter before.

https://en.wikipedia.org/wiki/Rossby_wave as noted in the press release https://www.nasa.gov/image-feature/jpl/pia1...ters-north-pole


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Gerald
post Sep 8 2016, 06:39 AM
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That has been one of the first things that jumped into my eyes, too, when I enhanced the last pre-PJ1 marble movie image.
But at that time I hadn't yet considered the laminar feature as a jet stream feature. I first thought, it would separate two regions of turbulence.
With the higher-resolved images however, one can perceive, that the laminar and the turbulent cloud features overlap. So it need to be two different cloud/haze layers.
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