Comments and questions about the
APOD on the main view screen.
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APOD Robot
- Otto Posterman
- Posts: 5604
- Joined: Fri Dec 04, 2009 3:27 am
Post
by APOD Robot » Sat Mar 06, 2021 5:05 am
Perseverance Takes a Spin
Explanation: After arriving at Jezero Crater on Mars,
Perseverance went for a spin on March 4.
This sharp image from the car-sized rover's Navcam shows tracks left by its
wheels in the martian soil. In preparation for operations on the surface of the Red Planet, its first drive lasted about 33 minutes. On a short and successful test drive
Perseverance moved forward 4 meters, made a 150 degree turn, backed up for 2.5 meters, and now occupies a different
parking space at its newly christened
Octavia E. Butler Landing location. Though the total travel distance of the rover's first outing was about 6.5 meters (21 feet), regular commutes of 200 meters or more
can be expected in the future.
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neufer
- Vacationer at Tralfamadore
- Posts: 18805
- Joined: Mon Jan 21, 2008 1:57 pm
- Location: Alexandria, Virginia
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by neufer » Sat Mar 06, 2021 2:35 pm
I was exceedingly surprised with the print of a man's naked foot on the shore, which was very plain to be seen on the sand. I stood like one thunderstruck, or as if I had seen an apparition. I listened, I looked round me, but I could hear nothing, nor see anything; I went up to a rising ground to look farther; I went up the shore and down the shore, but it was all one; I could see no other impression but that one. I went to it again to see if there were any more, and to observe if it might not be my fancy; but there was no room for that, for there was exactly the print of a foot - toes, heel, and every part of a foot. How it came thither I knew not, nor could I in the least imagine; but after innumerable fluttering thoughts, perfectly confused and out of myself, I came home not feeling, as we say, the ground I went on, but terrified to the last degree, looking behind me at every two or three steps, mistaking every bush and tree, and fancying every stump at a distance to be a man. Nor is it possible to describe how many various shapes my affrighted imagination represented things to me in, how many wild ideas were found every moment in my fancy, and what strange, unaccountable whimsies came into my thoughts by the way.
Art Neuendorffer
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Wadsworth
- Science Officer
- Posts: 131
- Joined: Tue Jun 20, 2006 3:12 pm
- Location: TX
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by Wadsworth » Sat Mar 06, 2021 4:41 pm
I have a feeling of satisfaction that images like this from the surface of Mars have become 'common place' in my day-to-day viewing pleasure.
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johnnydeep
- Commodore
- Posts: 3257
- Joined: Sun Feb 20, 2011 8:57 pm
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by johnnydeep » Sat Mar 06, 2021 5:07 pm
neufer wrote: ↑Sat Mar 06, 2021 2:35 pm
I was exceedingly surprised with the print of a man's naked foot on the shore, which was very plain to be seen on the sand. I stood like one thunderstruck, or as if I had seen an apparition. I listened, I looked round me, but I could hear nothing, nor see anything; I went up to a rising ground to look farther; I went up the shore and down the shore, but it was all one; I could see no other impression but that one. I went to it again to see if there were any more, and to observe if it might not be my fancy; but there was no room for that, for there was exactly the print of a foot - toes, heel, and every part of a foot. How it came thither I knew not, nor could I in the least imagine; but after innumerable fluttering thoughts, perfectly confused and out of myself, I came home not feeling, as we say, the ground I went on, but terrified to the last degree, looking behind me at every two or three steps, mistaking every bush and tree, and fancying every stump at a distance to be a man. Nor is it possible to describe how many various shapes my affrighted imagination represented things to me in, how many wild ideas were found every moment in my fancy, and what strange, unaccountable whimsies came into my thoughts by the way.
I didn't recognize the quote, but you made me google this lucid prose, and Lo! it's from Robinson Crusoe! More context can be seen here (Not a believer myself, but I assume "BibleHub" is a resource for bible references in literature, among the many other biblical stuff I see there):
https://biblehub.com/library/defoe/robi ... ed_one.htm
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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orin stepanek
- Plutopian
- Posts: 8200
- Joined: Wed Jul 27, 2005 3:41 pm
- Location: Nebraska
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by orin stepanek » Sat Mar 06, 2021 5:22 pm
I hope JPL/NASA flood us with pictures from Perseverance!
Orin
Smile today; tomorrow's another day!
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De58te
- Commander
- Posts: 584
- Joined: Mon Sep 30, 2013 6:35 pm
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by De58te » Sat Mar 06, 2021 10:16 pm
orin stepanek wrote: ↑Sat Mar 06, 2021 5:22 pm
I hope JPL/NASA flood us with pictures from Perseverance!
According to the first link, Perseverance has already sent back about 7,000 raw images.
https://mars.nasa.gov/mars2020/multimedia/raw-images/
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orin stepanek
- Plutopian
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- Location: Nebraska
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by orin stepanek » Sat Mar 06, 2021 10:32 pm
Be nice if Asterisk could show them!
Orin
Smile today; tomorrow's another day!
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johnnydeep
- Commodore
- Posts: 3257
- Joined: Sun Feb 20, 2011 8:57 pm
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by johnnydeep » Sun Mar 07, 2021 4:17 pm
Hmm. Many or most of these raw images seem to "only" be 1648x1200 (or less) resolution. I somehow thought we'd get better than that?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
- Abominable Snowman
- Posts: 18618
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
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by Chris Peterson » Sun Mar 07, 2021 4:58 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 4:17 pm
Hmm. Many or most of these raw images seem to "only" be 1648x1200 (or less) resolution. I somehow thought we'd get better than that?
The camera has a 1200x1600 pixel sensor.
The number of pixels isn't really what's important (we've all been fed this bogus nonsense with the silly pixel counts of many phones and cameras these days). What matters is the resolution. Packing more pixels in if the optics can't provide the necessary resolution is pointless. The Mastcam-Z cameras are fairly narrow field. Wide fields are provided by building panoramic mosaics, which are, of course, many thousands of pixels wide.
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johnnydeep
- Commodore
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- Joined: Sun Feb 20, 2011 8:57 pm
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by johnnydeep » Sun Mar 07, 2021 5:09 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 4:58 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 4:17 pm
Hmm. Many or most of these raw images seem to "only" be 1648x1200 (or less) resolution. I somehow thought we'd get better than that?
The camera has a 1200x1600 pixel sensor.
The number of pixels isn't really what's important (we've all been fed this bogus nonsense with the silly pixel counts of many phones and cameras these days). What matters is the resolution. Packing more pixels in if the optics can't provide the necessary resolution is pointless. The Mastcam-Z cameras are fairly narrow field. Wide fields are provided by building panoramic mosaics, which are, of course, many thousands of pixels wide.
I see. So, if you only had a 100x100 pixel sensor, that would still be pretty great if it had a1x1 mm area resolution?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
- Abominable Snowman
- Posts: 18618
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
Post
by Chris Peterson » Sun Mar 07, 2021 5:21 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 5:09 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 4:58 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 4:17 pm
Hmm. Many or most of these raw images seem to "only" be 1648x1200 (or less) resolution. I somehow thought we'd get better than that?
The camera has a 1200x1600 pixel sensor.
The number of pixels isn't really what's important (we've all been fed this bogus nonsense with the silly pixel counts of many phones and cameras these days). What matters is the resolution. Packing more pixels in if the optics can't provide the necessary resolution is pointless. The Mastcam-Z cameras are fairly narrow field. Wide fields are provided by building panoramic mosaics, which are, of course, many thousands of pixels wide.
I see. So, if you only had a 100x100 pixel sensor, that would still be pretty great if it had a1x1 mm area resolution?
Exactly. When you have more pixels than the optics can support, it's called
oversampling. A small amount of oversampling can provide additional information that specialized processing can take advantage of. But beyond that, there is no benefit, and the smaller pixels may actually result in poorer images since they have less dynamic range and may introduce more readout noise. The designers of these cameras knew what they were doing. I'd be very surprised if the pixel size and count aren't intelligently matched to the optics.
It's also worth noting that while the big widefield images are impressive, they are pretty secondary to the majority of science images the cameras will be used for, which are high pixel resolution single frames of interesting objects.
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johnnydeep
- Commodore
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- Joined: Sun Feb 20, 2011 8:57 pm
Post
by johnnydeep » Sun Mar 07, 2021 5:46 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 5:21 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 5:09 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 4:58 pm
The camera has a 1200x1600 pixel sensor.
The number of pixels isn't really what's important (we've all been fed this bogus nonsense with the silly pixel counts of many phones and cameras these days). What matters is the resolution. Packing more pixels in if the optics can't provide the necessary resolution is pointless. The Mastcam-Z cameras are fairly narrow field. Wide fields are provided by building panoramic mosaics, which are, of course, many thousands of pixels wide.
I see. So, if you only had a 100x100 pixel sensor, that would still be pretty great if it had a 1x1 mm area resolution?
Exactly. When you have more pixels than the optics can support, it's called
oversampling. A small amount of oversampling can provide additional information that specialized processing can take advantage of. But beyond that, there is no benefit, and the smaller pixels may actually result in poorer images since they have less dynamic range and may introduce more readout noise. The designers of these cameras knew what they were doing. I'd be very surprised if the pixel size and count aren't intelligently matched to the optics.
It's also worth noting that while the big widefield images are impressive, they are pretty secondary to the majority of science images the cameras will be used for, which are high pixel resolution single frames of interesting objects.
Thanks again! And I suppose I should have more accurately referred not to a 1x1 mm area, but say, a 1 arc second x 1 arc second field of view, correct?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
- Abominable Snowman
- Posts: 18618
- Joined: Wed Jan 31, 2007 11:13 pm
- Location: Guffey, Colorado, USA
Post
by Chris Peterson » Sun Mar 07, 2021 5:50 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 5:46 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 5:21 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 5:09 pm
I see. So, if you only had a 100x100 pixel sensor, that would still be pretty great if it had a 1x1 mm area resolution?
Exactly. When you have more pixels than the optics can support, it's called
oversampling. A small amount of oversampling can provide additional information that specialized processing can take advantage of. But beyond that, there is no benefit, and the smaller pixels may actually result in poorer images since they have less dynamic range and may introduce more readout noise. The designers of these cameras knew what they were doing. I'd be very surprised if the pixel size and count aren't intelligently matched to the optics.
It's also worth noting that while the big widefield images are impressive, they are pretty secondary to the majority of science images the cameras will be used for, which are high pixel resolution single frames of interesting objects.
Thanks again! And I suppose I should have more accurately referred not to a 1x1 mm area, but say, a 1 arc second x 1 arc second field of view, correct?
The physical size of the imaged zone is, of course, related to the angular size. Which units you use depends upon context; either may be the better choice. Either way, the concept you expressed is correct, though.
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johnnydeep
- Commodore
- Posts: 3257
- Joined: Sun Feb 20, 2011 8:57 pm
Post
by johnnydeep » Sun Mar 07, 2021 6:22 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 5:50 pm
johnnydeep wrote: ↑Sun Mar 07, 2021 5:46 pm
Chris Peterson wrote: ↑Sun Mar 07, 2021 5:21 pm
Exactly. When you have more pixels than the optics can support, it's called
oversampling. A small amount of oversampling can provide additional information that specialized processing can take advantage of. But beyond that, there is no benefit, and the smaller pixels may actually result in poorer images since they have less dynamic range and may introduce more readout noise. The designers of these cameras knew what they were doing. I'd be very surprised if the pixel size and count aren't intelligently matched to the optics.
It's also worth noting that while the big widefield images are impressive, they are pretty secondary to the majority of science images the cameras will be used for, which are high pixel resolution single frames of interesting objects.
Thanks again! And I suppose I should have more accurately referred not to a 1x1 mm area, but say, a 1 arc second x 1 arc second field of view, correct?
The physical size of the imaged zone is, of course, related to the angular size. Which units you use depends upon context; either may be the better choice. Either way, the concept you expressed is correct, though.
Cool.
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}