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mcaplinger
Posted on: Oct 7 2012, 08:10 PM


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QUOTE (jmknapp @ Oct 7 2012, 12:23 PM) *
There are some vertical lines...wonder what that's from?

It's excess column charge from a hot pixel. Hot pixels are always forming from neutron hits from the RTG.

If somebody wants to do part of my job for me, you can find and track these as they develop in all four MSSS cameras.
  Forum: MSL · Post Preview: #192924 · Replies: 520 · Views: 732940

mcaplinger
Posted on: Oct 1 2012, 02:50 PM


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QUOTE (elakdawalla @ Sep 30 2012, 10:43 PM) *
To be fair, the Moon's is a much more challenging thermal environment than Mars'. I think.

That's certainly true. We ended up using every trick in the book to get LROC to perform in a low lunar orbit.
  Forum: ISRO Mars Orbiter Mission · Post Preview: #192525 · Replies: 95 · Views: 639590

mcaplinger
Posted on: Sep 30 2012, 09:43 PM


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QUOTE (tolis @ Sep 30 2012, 01:08 PM) *
2. Such a fast schedule is not unheard of. The Mariner 9 mission, the US's first Mars orbiter,
was launched in May 1971, 2.5 yr after the formal project start in November 1968.

There's rather a large difference between 2.5 years and 1.3 years, though it's not clear when Mangalyaan actually started. Also, Mariner Mars 1971 was a direct follow-on to the Mariner 6-7 flyby missions with a lot of heritage, see http://history.nasa.gov/SP-4212/ch6.html

I wish them the best, but it's just not a lot of time.
  Forum: ISRO Mars Orbiter Mission · Post Preview: #192474 · Replies: 95 · Views: 639590

mcaplinger
Posted on: Sep 28 2012, 04:20 AM


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QUOTE (Eyesonmars @ Sep 27 2012, 02:31 PM) *
And being seasonal and the result of precipitation they can't be much else besides pure ethane or methane.

I guess you haven't heard of the carbon cycle on Titan. See http://www.kiss.caltech.edu/workshops/tita...s/aharonson.pdf for starters. The science goals of a Titan lake mission were rather well studied by the TiME Phase A study, alas not selected. See http://en.wikipedia.org/wiki/Titan_Mare_Explorer
  Forum: Saturn · Post Preview: #192291 · Replies: 21 · Views: 34511

mcaplinger
Posted on: Sep 26 2012, 01:20 PM


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QUOTE (Explorer1 @ Sep 26 2012, 12:31 AM) *
Do you mean the little fleck on the middle top of the recent daylight Phobos pics?

This is crud on the focal plane. It's been there since before launch, see http://www.msss.com/images/science/mastcam/m100cwb.jpg just above the red sign.
  Forum: MSL · Post Preview: #192160 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 24 2012, 05:59 PM


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QUOTE (jmknapp @ Sep 24 2012, 10:31 AM) *
why wasn't the situation fixed...

In my opinion, the instruments were well-calibrated on the ground and the calibration target is not really needed. Given the number of images being taken of the cal target, this seems to be a minority opinion. rolleyes.gif

With all due respect to the people supplying the magnets, I'm not sure they understood the needs of imaging or the dynamics of the landing dust environment.
  Forum: MSL · Post Preview: #192016 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 22 2012, 09:47 PM


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QUOTE (Phil Stooke @ Sep 21 2012, 09:20 PM) *
Maybe the Moon as well?

I haven't looked at this in detail yet, but I think the closest approach distance is around 200,000 km, so the Junocam view will not be that great (30 pixels or so.)
  Forum: Juno · Post Preview: #191949 · Replies: 597 · Views: 607347

mcaplinger
Posted on: Sep 21 2012, 11:07 PM


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QUOTE (Spaceflight101 @ Sep 21 2012, 03:34 PM) *
So, I guess this is based on the most-recent data...

Latest SPICE file ftp://naif.jpl.nasa.gov/pub/naif/JUNO/ker..._TCM5prelim.bsp shows perigee over South Africa.
Should get a reasonable view of the Americas on the inbound leg.
Attached Image

  Forum: Juno · Post Preview: #191900 · Replies: 597 · Views: 607347

mcaplinger
Posted on: Sep 20 2012, 08:57 PM


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QUOTE (ronald @ Sep 20 2012, 12:48 PM) *
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.

  Forum: MSL · Post Preview: #191828 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 16 2012, 02:57 PM


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QUOTE (Eluchil @ Sep 15 2012, 11:54 PM) *
looking at http://www.msss.com/msl/mastcam/MastCam_description.html the Mastcam34 sun filter is 440 nm which should be blue/violet and the Mastcam100 is 880 nm which should be near infrared.

The web page is in error. http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2541.pdf is correct.
  Forum: MSL · Post Preview: #191552 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 15 2012, 08:06 PM


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QUOTE (mhoward @ Sep 15 2012, 12:47 PM) *
The MSL version still seems lossy to me.

At this point I'm tempted to give into my bias and say that all Navcam images look bad to me. (Sorry, Justin. smile.gif Not all, but some.)

I've always been a bit surprised that the MER Navcams were so grainy-looking. This might be dark current from the relatively long readout time. They're a bit blurry but what can you do with only four elements and fixed focus?

As for wavelet compression, having ICER artifacts interact with JPEG artifacts isn't going to improve the images.

But to recap -- are the public release images on MSL being compressed on the ground more than for MER? Could well be.
  Forum: MSL · Post Preview: #191493 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 15 2012, 07:52 PM


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QUOTE (fredk @ Sep 15 2012, 12:36 PM) *
We've discussed before (image thread?) that the MSL public navcams appear to be stretched/lut'ed/delut'ed differently from the MER navcams.

I don't about MER, but as far as I can tell there is no stretching being done on any of the MSL images. They are typically autoexposed, which by its nature might be a little on the dark side but shouldn't really need much processing.
  Forum: MSL · Post Preview: #191491 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 15 2012, 07:23 PM


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QUOTE (mhoward @ Sep 15 2012, 11:19 AM) *
But for MER Navcam images, the JPGs on the web usually are about 200K or more in size; MSL Navcam JPGs on the web seem to be usually around 100K or less.

Well, that speaks for itself. Assuming full 1024x1024 frames, 200K would be about 5:1 and 100K would be about 10:1. I did a quick spot check of some recent Navcams and they were more like 120K, but close enough.

I don't know how they chose the JPEG quality for MER and I don't know how they chose it for MSL, but I would think that 10:1 would be about quality 50 and 5:1 would be about quality 75. My own personal opinion is that 75 would be a more appropriate choice, but nobody's asking me.

As for your example, at that scale they both look pretty crummy (the MSL one has more JPEG artifacts, clearly), but I don't think zooming the image is really a fair test. That said, I wouldn't pick a fight with anyone who says the web release images are compressed too much, but I'm not sure I would use the phrase "compressing the living daylights out of" -- YMMV.
  Forum: MSL · Post Preview: #191483 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 15 2012, 06:03 PM


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QUOTE (ugordan @ Sep 15 2012, 10:35 AM) *
I though the cameras basically return JPEG compliant data so that there shouldn't be a need to decompress/recompress the stream again. Are they really doing that for color images?

http://pds.nasa.gov/tools/policy/ExplicitP...tsStatement.pdf
QUOTE
PDS Archives must comply with the following
• All EDR image data delivered for archiving must consist of simple raster images with PDS labels

Now, you could claim that this doesn't have to apply to public release images and I wouldn't argue with you, but it would require delivery in two forms unless there was a decompress/recompress cycle.
  Forum: MSL · Post Preview: #191478 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 15 2012, 05:29 PM


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QUOTE (mhoward @ Sep 15 2012, 09:06 AM) *
I've noticed that they're really compressing the living daylights out of MSL images before putting them on the web...

I think they're just using a fixed quality (75, maybe?). Of course it doesn't help that there is sometimes a decompress/recompress and that they JPEG-compress Bayer-pattern data. The final compression ratio seems to be around 8:1 to 9:1. Are the MER images really a lot lower compression ratio?

For the 100mm sun image, since the filter cuts out all of the pixels besides blue anyway, you'd be better off just tossing the other Bayer positions and then upsampling as desired. But it's still going to be a round slightly-fuzzy circle with a bite out of one side.
  Forum: MSL · Post Preview: #191475 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 14 2012, 05:35 PM


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QUOTE (charleski @ Sep 14 2012, 02:43 AM) *
Unfortunately NASA/JPL stripped the EXIF so we can't say what camera they used.

It was a Nikon D3 at f/5.7, ISO 200, 70mm focal length, pattern metering mode, and the flash was fired.

At over $3K list, I guess I wouldn't call that a "lower-end commercial camera" but I stand by my comments about the color accuracy (sorry, Nikon.)
  Forum: MSL · Post Preview: #191401 · Replies: 313 · Views: 278336

mcaplinger
Posted on: Sep 13 2012, 08:44 PM


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QUOTE (charleski @ Sep 12 2012, 03:17 PM) *
there appears to have been a small void in the adhesive pre-flight and the roof of the void has now been removed.

I think this is an artifact of somewhat different viewing angle and quite different lighting direction and type of lighting. That RTV would be pretty hard to remove even if you tried to dig it out with an X-acto knife or a dental pick.

Also, the ground photo is the unrealistic saturated color of a typical lower-end commercial camera.
  Forum: MSL · Post Preview: #191338 · Replies: 313 · Views: 278336

mcaplinger
Posted on: Sep 13 2012, 03:09 PM


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QUOTE (jmknapp @ Sep 12 2012, 07:20 PM) *
This should should be about the relative sizes of things in the mastcam34 frame.

I'm not sure how this was derived. The 34mm should look more or less like the MER image below, since this transit was grazing, and the 100mm will be 3x bigger.
Attached Image
Again, this is a MER image; I got it from http://pancam.astro.cornell.edu/pancam_ins...projects_4.html And of course it's been blown up; the sun is about 15 pixels across in Pancam IIRC.
  Forum: MSL · Post Preview: #191308 · Replies: 252 · Views: 429901

mcaplinger
Posted on: Sep 12 2012, 09:22 PM


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QUOTE (fredk @ Sep 12 2012, 02:10 PM) *
Maybe software could use sparsely timed images (like Spirit's DD sequences) to detect a DD with software and then trigger high frame rate video (without motion detection).

Certainly it's conceivable that we could run a Navcam sequence looking for dust devils, find one, slew the Mastcam to it and start a video acquisition. That capability doesn't exist right now, though, and I don't know if the science value would be worth the effort.
  Forum: MSL · Post Preview: #191262 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 12 2012, 09:11 PM


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QUOTE (Doc @ Sep 12 2012, 01:53 PM) *
Eyes on the Solar System says the transit should be happening at the moment...

http://meetingorganizer.copernicus.org/EPS...PSC2012-326.pdf says the transit is at 05:15 UT on 9/13, which is about 8 hours from now.
  Forum: MSL · Post Preview: #191261 · Replies: 252 · Views: 429901

mcaplinger
Posted on: Sep 12 2012, 08:30 PM


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QUOTE (Eyesonmars @ Sep 12 2012, 12:35 PM) *
I've been wondering if it is technically feasible to use the Mastcam Video capability to search for and record dust devil activity.

IMHO, not really.

1) Even the 34mm Mastcam has a fairly narrow FOV (about 15 degrees.) Dust devil searching on MER was done with Navcam, see http://trs-new.jpl.nasa.gov/dspace/bitstre...8/1/08-0444.pdf

2) There's no motion detection capability in the Mastcam hardware and doing it in software would be limited to a frame rate of maybe 1/4 to 1/10 fps at best.

3) There are power limitations and running the camera all the time isn't possible.
  Forum: MSL · Post Preview: #191255 · Replies: 529 · Views: 461044

mcaplinger
Posted on: Sep 12 2012, 07:11 PM


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QUOTE (jmknapp @ Sep 12 2012, 12:05 PM) *
since MEX is over the horizon for hours sometimes, do they plan to take advantage of its communications capability.

It may be visible but it's far away and inverse-square law makes the data rate uselessly low, I'm guessing.
  Forum: MSL · Post Preview: #191248 · Replies: 313 · Views: 278336

mcaplinger
Posted on: Sep 12 2012, 04:16 PM


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QUOTE (Doc @ Sep 12 2012, 08:31 AM) *
Sub frame image of the same view but haven't a clue why it's gray.

It's a derived depth map from the focus merge.
  Forum: MSL · Post Preview: #191231 · Replies: 252 · Views: 429901

mcaplinger
Posted on: Sep 12 2012, 02:24 PM


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QUOTE (Stellingwerff @ Sep 12 2012, 04:35 AM) *
MAHLI is sending a set of new images with a slightly different filenames...

I believe these are associated with focus stacking products. See 7.6 Focus Stack Acquisition and Merge in the MAHLI paper. Not sure which is which but it should be fairly obvious.
  Forum: MSL · Post Preview: #191224 · Replies: 373 · Views: 260807

mcaplinger
Posted on: Sep 12 2012, 02:12 PM


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QUOTE (vikingmars @ Sep 12 2012, 12:33 AM) *
[The MAHLI cal target is] dusty, but not so much when compared under same light conditions.

I'm pretty sure that the image you have labeled "calibration" ( http://mars.jpl.nasa.gov/msl/images/PIA152...immonds-br2.jpg ) was taken with a commercial camera using a flash. I'd be cautious drawing any conclusions from that.

I'd say the calibration target is pretty dirty. For example, the white and gray color chips are almost certainly useless for white balance now. Fortunately the rover has a lot of white thermal control paint which is comparatively clean.
  Forum: MSL · Post Preview: #191222 · Replies: 252 · Views: 429901

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