Phobos |
Phobos |
Nov 11 2007, 09:43 PM
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#46
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Senior Member Group: Members Posts: 1276 Joined: 25-November 04 Member No.: 114 |
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Feb 16 2008, 05:03 PM
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#47
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
The High Resolution Stereo Camera (HRSC) on Mars Express is not the best instrument.
Orbit 3802, Phobos, image h3802_0003_sr2 Orbit 3802, Phobos, image h3802_0004_sr2 -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Feb 16 2008, 05:19 PM
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#48
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
HRSC itself is great, but the super resolution bolt-on camera from which those two frames came from has never achieved good focus.
Doug |
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Feb 16 2008, 06:39 PM
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#49
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
Mars Express (MEX) release #2.
February 14, 2008 Online Data Volumes - Mars Express Orbit 3310, Phobos, image h3310_0000_s22 Orbit 3310, Phobos, image h3310_0000_s12 -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Feb 16 2008, 06:50 PM
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#50
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
-------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Feb 16 2008, 09:09 PM
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#51
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
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Feb 16 2008, 10:57 PM
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#52
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
...has never achieved good focus. I tried running Helicon Focus software on a few images. Looks like a combination of motion smear + out of focus, but the dominant effect seems to be motion smear. Due to the jpeg artifacts it's a little difficult to do a good job of this, but here are some images with the motion smear (somewhat) corrected. I think that if I had uncompressed versions of the images then I could pull quite a bit of fine detail from them. |
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Feb 16 2008, 11:13 PM
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#53
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
I don't think it's motion smear, more like noncircular PSF due to out of focus deformity in some part of the optics. It gives an appearance of vertical motion smear. It would probably be possible to do a proper deconvolution if we knew the PSF exactly (say by imaging a star), but as I recall the amount of defocus isn't constant either.
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Feb 17 2008, 01:37 AM
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#54
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Solar System Cartographer Group: Members Posts: 10231 Joined: 5-April 05 From: Canada Member No.: 227 |
It certainly is not motion smear, but it does look like it because there is a 'double exposure' effect. Regardless, they are still nice images in other respects, and are being used to improve the shape model of Phobos (The other HRSC images are less useful for that because they are from a scanning rather than framing camera). The top one just above is inside Stickney. These pics come in sets of 4 or 5 making up strips across the surface, and would make nice mosaics.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Feb 17 2008, 03:26 AM
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#55
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Member Group: Members Posts: 121 Joined: 26-September 05 From: Philadelphia Member No.: 507 |
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Feb 17 2008, 07:34 AM
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#56
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
It certainly is not motion smear, but it does look like it because there is a 'double exposure' effect. 'Double exposure' effect. Orbit 3196, Deimos, image h3196_0005_sr2. -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Feb 17 2008, 07:46 AM
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#57
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
These pics come in sets of 4 or 5 making up strips across the surface, and would make nice mosaics. Orbit 3802 - images h3802_0003_sr2, h3802_0005_sr2, h3802_0005_sr2 Orbit 3802 - image h3802_0000_s12 -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Feb 17 2008, 02:05 PM
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#58
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Member Group: Members Posts: 656 Joined: 20-April 05 From: League City, Texas Member No.: 285 |
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Feb 17 2008, 02:51 PM
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#59
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
the S12 image is pushbroom.
PSF = Point Spread Function. i.e. the contribution of surrounding pixels to the pixel in question. With accurate info on that, you can subtract it all back out again..ish...roughly. Doug |
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Feb 17 2008, 06:08 PM
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#60
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Here is a quick attempt. There does seem to be motion blurring in some of the data, almost as if it is a double exposure with one of the two slightly smeared in a direction almost but not quite perpendicular to the direction of the double exposure offset.
Edit: The bit of motion blur I mentioned could also be explained by optics being slightly out of alignment. Normally, the difference between the two is obvious, but this is too slight for that. -------------------- |
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