MSL Images & Cameras, technical discussions of images, image processing and cameras |
MSL Images & Cameras, technical discussions of images, image processing and cameras |
Aug 16 2012, 11:05 PM
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Senior Member Group: Members Posts: 2228 Joined: 1-December 04 From: Marble Falls, Texas, USA Member No.: 116 |
I'm still trying to figure out a number of things about the new images we are trying to work with. Assuming others are likewise trying to learn, I thought I would open this thread to create a place for such discussions.
I'd like to start out with a comment about raw image contrast. There have been several postings in the main threads about whether or not the MSL raw images have been stretched like those from the MER missions. I am certainly no expert on this, but it looks to me as if the MSL images have not been stretched at all. I haven't tried to analyze all of the image types, but the hazcams and navcams have pixel brightness histograms that are very different from their MER counterparts. This attached image compares MER and MSL navcams along with their luminosity histograms. The MSL images clearly are not using the entire, available range of brightness values, whereas the MER raws do. For this reason, the MSL raw images can usually be nicely enhanced by simply stretching the distribution of brightness across the full 256 value range. -------------------- ...Tom
I'm not a Space Fan, I'm a Space Exploration Enthusiast. |
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Sep 20 2012, 07:48 PM
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Member Group: Members Posts: 154 Joined: 19-September 12 Member No.: 6658 |
Couldn't find an answer so far - can please someone explain why the calibration target on MSL does not have a dustcover or some sort of dust removal technology? What did they calibrate for when all the grey and coloured patches are full of dust? Even here on earth a photographer has to buy a new greycard now and then (at least he should because of colour changing) ...
Thank you! |
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Sep 20 2012, 08:57 PM
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#3
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
can please someone explain why the calibration target on MSL does not have a dustcover or some sort of dust removal technology? http://www.nbi.ku.dk/english/research/phd_...011/line_drube/ QUOTE Permanent ring-magnets have also been built into the calibration target of the Mars Science Laboratory (MSL), the same type of ring-magnet used in the Sweep magnet experiment on the Mars Exploration Rovers (MERs). Unfortunately, on MSL the ring-magnets were included at a very late stage in the development of the target (actually the target was a flight spare unit from the MER mission). This resulted in the ring-magnets being positioned at a depth of 0.8-1.0 mm below the surface instead of the 0.4 mm used on the MERs and Phoenix. From preliminary computer simulations this didn't appear to make a significant difference, other than in the size of the magnetically protected area. However, wind tunnel experiments using Salten Skov dust have now demonstrated that this relatively small difference in depth causes the "protected" area to disappear, so that with this new configuration the ring center will accumulate more dust than the reference areas free of influence from any magnetic field. With no clean area at all, magnets in this configuration will have the opposite effect to what they were intended to provide, attracting significant amounts of dust and retaining it on areas that are meant to be used as "dust-free" calibration standards. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Sep 21 2012, 06:09 AM
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#4
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Member Group: Members Posts: 154 Joined: 19-September 12 Member No.: 6658 |
Thank you for the link. Two more:
The combined CalTarget and iSweep experiment Magnetic properties experiments [...] Design, calibration, and science goals Quote form the second link: QUOTE From this we have concluded that essentially all particles in the Martian atmosphere are magnetic in the sense that they are attracted to permanent magnets. Too bad it didn't work now on MSL. Edit: Interesting lecture video from Morten Bo Madsen unfortunately in danish |
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Sep 23 2012, 11:50 AM
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Senior Member Group: Members Posts: 1089 Joined: 19-February 05 From: Close to Meudon Observatory in France Member No.: 172 |
Thank you for the link. Two more: The combined CalTarget and iSweep experiment Too bad it didn't work now on MSL. Well... Those experiments are too much "combined" on the MSL for my own color calibration tests... The 4 color calibration targets are now "polluted" by the magnet experiments... See sections from MastCam Sol 13 vs. Sol 44 image. It's a real pity... And even more than a pity. This was a foreseen event as per page 58 of the "Martian Airborne Dust - Magnetic Properties on Phoenix and Dust on the MSL Calibration Target " thesis by Line Drube in 2011 : http://www.nbi.ku.dk/english/research/phd_...e_juni2011.pdf/ "It is apparent from Figure 50 that keeping the magnets in the MSL calibration target will quickly ruin much of the blue, green, yellow and red colored calibration areas for their intended purpose. Since less than a year to launch is too late for removing the magnets from the calibration target..." |
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Sep 23 2012, 09:08 PM
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Founder Group: Chairman Posts: 14433 Joined: 8-February 04 Member No.: 1 |
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