Another Mars pano

[mmcirvin]

Via Emily Lakdawalla: A QuickTime VR version (not full-screen, but fair-sized) of the biggest of the hilltop Mars rover panoramas. This one is complete enough that you can pan down and look at the rover's view of itself; the star-shaped hole in the picture is where the camera mast attaches.

Sam asked about the accuracy of the colors in these images, based on something Stephen Fry said on QI. I'll link to what I wrote before on this subject: Viking photos published in the 1970s were often unrealistically "redded up", more because the calibration was done by guessing than anything else, but pictures from Mars Pathfinder and later are typically pretty well-calibrated unless they are explicitly false-color images. Mars is red in more or less the same sense that Sedona, Arizona is red, and the sky is usually dusty tan. Statements to the contrary are fueled by a mixture of conspiracy theory and some outdated statements from Gilbert Levin.

I think this particular pano is a visible-light one and the color should be pretty accurate (though the sky is probably heavily fiddled with to remove visible seams where the individual shots join up). How you can tell: Look at the sundial calibration target, the thing on the rover deck that looks sort of like an old Atari joystick (making it a sundial was the suggestion of none other than Bill Nye the Science Guy). The paint chips on its corners are green, yellow, blue and red, though after a couple of years driving around on Mars they've gotten a little dusty. That looks right to me. They look different in the photos taken with an infrared channel, though JPL tries pretty hard to give those a quasi-realistic color balance as well by reference to the visible-light photos.

Comments

[jarai.livejournal.com]

The link "Viking photos published in the 1970s" was the first thing that caught my attention on this page. It confused me because I imagined that someone had make some badly faked photographs of vikings which there were trying to pass off as being of real vikings from over a thousand years ago. Bear in mind that my morning coffee has not yet worked its way into my system.

[mmcirvin.livejournal.com]

The link on the page I linked to is, unfortunately, broken. Here's a page with some Viking Mars pictures (http://www.windows.ucar.edu/tour/link=/mars/mars_il.html); you can see that the color balance is all over the map, and the sky looks pink in some pictures and yellow or blue-gray in others.

I said in that post that the difficulty of calibration was because of dust on the Viking calibration target, but this NASA FAQ (http://nssdc.gsfc.nasa.gov/planetary/planetaryfaq.html#Mars) implies that it was more because the filters they used had a weird spectral response.

[mmcirvin.livejournal.com]

...Also, some of the Pathfinder photos available there have deliberately false color to exaggerate subtle color differences, though the page doesn't mention that.

[iayork.livejournal.com]

That panorama is absolutely astounding. Thanks for the pointer.

[mmcirvin.livejournal.com]

I'm partial to the bigger but less complete version on the panoramas.dk Mars page (http://www.panoramas.dk/fullscreen3/f2_mars.html) (it's missing the portions looking down at the rover, but there's more landscape detail). The ones from the hillside are good too.

Also, I wish he had more color panos from Opportunity at Meridiani Planum; the one that's there, from the inside of Eagle Crater at the very beginning of the mission (marked with landing-balloon bounce prints so clear that you can see the seams), is profoundly eerie.

[sultmhoor.livejournal.com]

It looks like they edited out the sun, too (or didn't point the camera at it?)

[mmcirvin.livejournal.com]

Often a large chunk of the sky in these pano shots is fake. They may have just extrapolated from the part near the horizon.

Also, the pano is assembled from a huge number of shots, because the rover pancam sensor is basically a 1-megapixel monochrome square. It can take many hours, maybe even multiple days, to get them all, and the sun angle can vary. You can see some conflicting shadows on the rover deck.

[mmcirvin.livejournal.com]

...I suspect that the sky outside the strip visible here (http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20051205a.html) is entirely fabricated, and the part in that strip was probably considerably smoothed out by JPL to begin with.