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"wave" distortion patterns in Cassini ring images
I'm sure there's probably some kind of simple, elegant explanation for the wavelike banding distortion in Cassini's initial ring images, such as the one at http://saturn.jpl.nasa.gov/cgi-bin/g...jpg&type=image, containing http://saturn.jpl.nasa.gov/multimedi...mages/SOI1.jpg . I'm sure the answer probably involves rapid, periodic occultation of the signal by chunks of ring material at such close range. I recall seeing one image where the wave banding almost matches the dispersal patterns in the rings. I've also noticed a lot of "grain" in the close-up ring images; am I right assuming this is due to having a camera close enough to begin resolving individual chunks of "ring stuff"? (****, that thing's got real _texture_!) And damn, but I hope there were able to get some composite color of that section. Still, they already got the cake, huh? (%^ Congrats again, JPL! -- "All over, people changing their votes, along with their overcoats; if Adolf Hitler flew in today, they'd send a limousine anyway!" --the clash. __________________________________________________ _________________ Mike Flugennock, flugennock at sinkers dot org Mike Flugennock's Mikey'zine, dubya dubya dubya dot sinkers dot org |
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Mike Flugennock wrote: I'm sure there's probably some kind of simple, elegant explanation for the wavelike banding distortion in Cassini's initial ring images, such as the one at http://saturn.jpl.nasa.gov/cgi-bin/g...jpg&type=image, containing http://saturn.jpl.nasa.gov/multimedi...mages/SOI1.jpg . I'm sure the answer probably involves rapid, periodic occultation of the signal by chunks of ring material at such close range. I recall seeing one image where the wave banding almost matches the dispersal patterns in the rings. Actually, that is what the rings really look like at close range- there is a explanation of what causes the "waves" he http://spaceflightnow.com/cassini/040701science.html There are also spiral rings! This is one cool looking planet. Pat |
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Mike Flugennock wrote:
I'm sure there's probably some kind of simple, elegant explanation for the wavelike banding distortion in Cassini's initial ring images, such as the one at http://saturn.jpl.nasa.gov/cgi-bin/g...jpg&type=image, containing http://saturn.jpl.nasa.gov/multimedi...mages/SOI1.jpg . I'm sure the answer probably involves rapid, periodic occultation of the signal by chunks of ring material at such close range. I recall seeing one image where the wave banding almost matches the dispersal patterns in the rings. I've also noticed a lot of "grain" in the close-up ring images; am I right assuming this is due to having a camera close enough to begin resolving individual chunks of "ring stuff"? (****, that thing's got real _texture_!) And damn, but I hope there were able to get some composite color of that section. Still, they already got the cake, huh? (%^ Congrats again, JPL! Black and white only I'm afraid. It was going too fast to take separate RGB frames. A shame, too. When the Mariner Mark II was first designed it was to have had multiple, independently targettable scan platforms, but budget cutbacks did away with those. On the plus side, the mission cost "only" $3.3 billion and likely would have been much more if the original design had prevailed. Fewer moving parts also lead to a more reliable spacecraft. -- bp Proud Member of the Human O-Ring Society Since 2003 |
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In article , Pat Flannery
wrote: Mike Flugennock wrote: I'm sure there's probably some kind of simple, elegant explanation for the wavelike banding distortion in Cassini's initial ring images, such as the one at http://saturn.jpl.nasa.gov/cgi-bin/g...images/rings/i mages/SOI1.jpg&type=image, containing http://saturn.jpl.nasa.gov/multimedi...mages/SOI1.jpg . I'm sure the answer probably involves rapid, periodic occultation of the signal by chunks of ring material at such close range. I recall seeing one image where the wave banding almost matches the dispersal patterns in the rings. Actually, that is what the rings really look like at close range- there is a explanation of what causes the "waves" he http://spaceflightnow.com/cassini/040701science.html There are also spiral rings! This is one cool looking planet. The original poster was asking about something else: groups of scan lines that are brighter and darker, giving the image a corrugated appearance. You can tell that they are artifacts by the fact that they are aligned with the image raster, and you can see the actual structure of the rings underneath at an angle that follows the rings. Also there are some of the same pictures 'after post-processing' that don't show the banding. (Post-processing is not just to remove the face sculptures and ring-cities from the images.) I would guess that there's some sort of oscillation in the readout of the CCD. -- David M. Palmer (formerly @clark.net, @ematic.com) |
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On Fri, 02 Jul 2004 23:55:49 -0600, "David M. Palmer"
wrote: Also there are some of the same pictures 'after post-processing' that don't show the banding. (Post-processing is not just to remove the face sculptures and ring-cities from the images.) I would guess that there's some sort of oscillation in the readout of the CCD. ....This is the same banding I talked about last night. There's *something* being introduced in the data pre-processing that's causing these bands, because they look basically the same from picture to picture. Not sure if it's the CCD, or if there's something actually introducing the digital equivalent to TVI, but it *is* an annoying side to some otherwise spectacular pics. Alex? Any comments from your friends at JPL on what's up with this? OM -- "No ******* ever won a war by dying for | http://www.io.com/~o_m his country. He won it by making the other | Sergeant-At-Arms poor dumb ******* die for his country." | Human O-Ring Society - General George S. Patton, Jr |
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OM wrote:
Alex? Any comments from your friends at JPL on what's up with this? I'm not sure what you are referring to. However, I understand there's a 2 Hz signal in some of the ISS raw data but these are being deconvolved in the processed imagery. Typically, "banding" in raw imagery is due to some hardware problem such as stray light (i.e., a "light leak" of the type in the Mars Odyssey THEMIS system), though I haven't heard of that problem with ISS. -- Alex R. Blackwell University of Hawaii |
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Mike Flugennock wrote:
And damn, but I hope there were able to get some composite color of that section. Still, they already got the cake, huh? Black and white only I'm afraid. It was going too fast to take separate RGB frames. A shame, too. When the Mariner Mark II was first designed it was to have had multiple, independently targettable scan platforms, but budget cutbacks did away with those. On the plus side, the mission cost "only" $3.3 billion and likely would have been much more if the original design had prevailed. Fewer moving parts also lead to a more reliable spacecraft. -- bp Proud O-Ring |
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On Fri, 02 Jul 2004 20:21:34 -1000, "Alex R. Blackwell"
wrote: I understand there's a 2 Hz signal in some of the ISS raw data but these are being deconvolved in the processed imagery. ....If I understand the imaging system, that would be just about right to produce the TVI. Any clue as to what's producing the 2Hz interference, or was this expected all along? OM -- "No ******* ever won a war by dying for | http://www.io.com/~o_m his country. He won it by making the other | Sergeant-At-Arms poor dumb ******* die for his country." | Human O-Ring Society - General George S. Patton, Jr |
#9
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In article ,
Revision wrote: ...When the Mariner Mark II was first designed it was to have had multiple, independently targettable scan platforms, but budget cutbacks did away with those... If (dim) memory serves, by the time Cassini got to detailed design, there was only one scan platform with precision pointing, although there was a second low-precision one. That and some other things vanished in the big cost-reduction scrub. On the plus side, the mission cost "only" $3.3 billion and likely would have been much more if the original design had prevailed... Moreover, it only barely survived as it was -- it would probably be dead and largely forgotten, like its brother CRAF, had not the Huygens probe represented a major international commitment that was difficult to cancel. -- "Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | |
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OM wrote:
...If I understand the imaging system, that would be just about right to produce the TVI. Any clue as to what's producing the 2Hz interference, or was this expected all along? I haven't kept up too closely with this particular ISS issue, as opposed to, say, the contamination problem during cruise phase, so I'm not sure if it was unexpected or not. Fortunately, though, everyone I know who is processing the imagery, including me, says removing the 2Hz noise is no sweat. -- Alex R. Blackwell University of Hawaii |
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