IPB

Welcome Guest ( Log In | Register )

4 Pages V   1 2 3 > »   
Reply to this topicStart new topic
Juno, perijove 11, February 07, 2018
Gerald
post Feb 8 2018, 12:41 AM
Post #1


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



Part of the perijove-11 data have already been downlinked. So, we should start an according topic.
Here a thumbnail simulation I've rendered a few days ago, in order to see, how Jupiter may appear in JunoCam images:

Attached Image

The simulation is based on SPICE kernels as they have been available last week. Simulated shading is of Lambertian type by solar incidence.

The short appearance of a small portion of a mirror image of Jupiter in the upper and lower left corner indicates an apparent vertical extension of Jupiter of more than 180 degrees in cylindrical coordinates, which is strange. I wonder, whether that's a glitch in my calculations, or whether it can be explained by Juno's curved trajectory close to Jupiter, while JunoCam is taking the simulated image over about 15 seconds.
I don't mean the mirror image (which doesn't appear in real images), but the extension of more than 180 vertical cylindrical degrees.
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:02 AM
Post #2


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



Perijove-11 images, #001, #003, #004, #006, and #007:
Attached Image
Attached Image

Attached Image
Attached Image


Attached Image
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:04 AM
Post #3


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#008, and #009:
Attached Image
Attached Image

Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:05 AM
Post #4


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#010:
Attached Image

Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:07 AM
Post #5


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#011:
Attached Image

Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:08 AM
Post #6


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#012:
Attached Image
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:09 AM
Post #7


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#013:
Attached Image
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:11 AM
Post #8


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#014:
Attached Image
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:13 AM
Post #9


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



#015, and #016:
Attached Image
Attached Image
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 04:20 AM
Post #10


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



... and #017:
Attached Image


Those are the RGB images of Perijove-11, downlinked and available as raws on the missionjuno site thus far.
I've rendered with 60 deg x 180 deg FOV, cylindrical equidistant seen from the spacecraft at image stop time.

The PNG version is submitted to the missionjuno site.

Some images actually cover more than 180 degrees vertically. After some pondering, I think, that's mostly due to the spacecraft's spin axis relative to Jupiter's surface.
Go to the top of the page
 
+Quote Post
Explorer1
post Feb 9 2018, 04:44 AM
Post #11


Senior Member
****

Group: Members
Posts: 1567
Joined: 13-February 10
From: Ontario
Member No.: 5221



Gosh, that's one bright cloud pattern at #13 (and near the edge in #12)! It almost looks overexposed...
Go to the top of the page
 
+Quote Post
mcaplinger
post Feb 9 2018, 06:49 AM
Post #12


Senior Member
****

Group: Members
Posts: 1766
Joined: 13-September 05
Member No.: 497



QUOTE (Explorer1 @ Feb 8 2018, 08:44 PM) *
Gosh, that's one bright cloud pattern at #13 (and near the edge in #12)! It almost looks overexposed...

It's bright but not that bright in the MSSS processed version, so I'm thinking this is an artifact of Gerald's processing.


--------------------
Disclaimer: This post is based on public information only. Any opinions are my own.
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 10:57 AM
Post #13


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



The images are enhanced to the 4th power of radiometric values after approximate illumination adjustment. Small locally slightly brighter areas of linearized data can result much brighter. I'm allowing a small area (less than 0.1%) of the image to be saturated. Otherwise I'd either allow the majority of the image to be very dark, or else use another method to stretch brightness. But this would either reduce reproducibility and physical simplicity (and hence natural appearence), or reduce contrast (by using a smaller gamma). So, the applied solution is a compromise I've assessed as reasonable for most of the cases.
Overexposed portions of raw images usually show up as a strong colored cast, since the camera channels differ in their sensitivity, and overall bright areas are usually divided away to moderate values by the applied illumination adjustment method.

I'll upload drafts later, where you can check for overall brightness in the raws, although they might be saturated, too, in the blue channel, despite the raws not being saturated. That's then due to a fixed radiometric correction factor of larger than one for the blue channel. Again, the images would be very dark, or much less systematic and comparable, if I would strictly rule out this scenario.

Nevertheless, it can well be reasonable to apply different ways of processing, depending on the respective purpose.

In this special case of the bright cloud, we've seen bright clouds near the center of storm systems, before. Those are likely particularly high clouds, possibly due to a fast upwelling near the center of some (cyclonic) FFRs. And with the perihelion of Juno's orbit gradually drifting towards northern latitudes, we get closer to these FFRs.
Go to the top of the page
 
+Quote Post
Gerald
post Feb 9 2018, 03:54 PM
Post #14


Senior Member
****

Group: Members
Posts: 2170
Joined: 7-December 12
Member No.: 6780



The PNG versions of the above images are online on missionjuno, since several hours now. Here another copy, together with the applied masks.
And here the drafts with gamma=0.5, and without trajectory nor shape data, if you like to get close to whatever "natural colors" might mean for electronic displays.

Here a 50% reduced JPG, where you can see structure within the bright cloud, again enhanced to the 4th power of approximately illumination-adjusted radiometric data:
Attached Image


The twice supersampled PNG version is submitted to the missionjuno site.
Go to the top of the page
 
+Quote Post
JRehling
post Feb 9 2018, 06:24 PM
Post #15


Senior Member
****

Group: Members
Posts: 2078
Joined: 20-April 05
Member No.: 321



There's so much to like here. Great work, once again!

I am struck by the color in that bright cloud: Specifically, the nonuniformity of it. And, again on the note that this non-science instrument may yield some impressive science, I wonder of the utility of this image, and others like it, for providing insight as to the still-unknown chromophores in Jupiter's clouds. If the chemical reactions that produce chromophores are produced at different combinations of altitude and solar incidence, images showing variations in hue in cloud surfaces that have freshly risen could potentially rule out some candidate reactions/compounds.

There is certainly variation in hue over that bright cloud. How much is due to compositional variation and how much due to variations in illumination is another question. I'm sure it wouldn't be trivial to perform the required analysis, but this is one of the first images I've seen that suggests that it's possible.
Go to the top of the page
 
+Quote Post

4 Pages V   1 2 3 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 22nd October 2018 - 11:24 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and copyright.

OPINIONS AND MODERATION
Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators.
SUPPORT THE FORUM
Unmannedspaceflight.com is a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.