Reprocessing Historical Images, Looking for REALLY big challenges? Options

[Bob Shaw]

Which reminds me: does anyone have access to this globe? http://libweb5.princeton.edu/visual_materi...s/hmc05.html#g7

It was drawn using Mariner 6/7 images and (I suspect) a good deal of imagination. I'd love to get a good set of photos of the entire surface.

Mike:

Phil Stooke and I both have that globe, but mine is not on the natty little stand shown in your link (I don't know about Phil's) but on an unattractive grey plastic thing similar to the mounting for an Armillary Sphere.

You're quite correct - it owes much to imagination, but also to the the long-distance far encounter shots taken by Mariner 6 and 7 in 1969. If you look at those images you can clearly see the albedo changes associated with Valles Marineris, with the 'W' of Noctis Labyrinthus being quite clear, and this is reflected on the globe. The interpretation of 'Nix Olympica' as a huge double crater was quite wrong, but again based on albedo - the supposed outer rampart is clearly the offset aureole around Olympus Mons itself. Look sideways and you can almost identify the other three great Tharsis volcanoes too. The globe is fascinationg because it captures a moment in time in the exploration of Mars before the gross facts of the planet were fully captured.

Some areas are slightly more detailed, such as the swathe of features imaged by Mariner 7 around the South Pole, and Mariner 6's observations of (I think) Deucalion.

I'll try to take some photos of my globe at some point and will send them to you if you like. This globe sometimes turns up on eBay, often poorly identified, so obtaining one yourself is not an impossible task!


Bob Shaw

[nprev]

Thanks for posting that link, mcaplinger...neat stuff!

Possibly OT here, but does anyone know if the naming of albedo features vs. actual topographical features on Mars has been reconciled by the IAU? It doesn't look like a lot of the traditional names (e.g., Xanthe, Solis Lacus) are still used by modern cartographers.

[tedstryk]

Thanks for posting that link, mcaplinger...neat stuff!

Possibly OT here, but does anyone know if the naming of albedo features vs. actual topographical features on Mars has been reconciled by the IAU? It doesn't look like a lot of the traditional names (e.g., Xanthe, Solis Lacus) are still used by modern cartographers.

There has definitely been an attempt - for example, Sinus Meridiani, the fork-like albedo feature, became Meridiani planum. That globe does look somewhat fictionalized -either that or it is sloppy.

Incidentally, Mariner 4 was also supposed to get the south pole, but missed, although it did catch some frost. Finding out that it was off its intended groundtrack explained a lot, since I wondered why pictures 20-22 were shot off the limb (As for the lack of detail in pictures 17-19, that had to do with a design-flaw related light leak that could be compensated for through stretching in the earlier images, but, given the 6-bit encoding, nearly completely overwhelmed the last frames taken over the shadowy zone near the terminator.

[tim53]

Mike:

Phil Stooke and I both have that globe, but mine is not on the natty little stand shown in your link (I don't know about Phil's) but on an unattractive grey plastic thing similar to the mounting for an Armillary Sphere.

You're quite correct - it owes much to imagination, but also to the the long-distance far encounter shots taken by Mariner 6 and 7 in 1969. If you look at those images you can clearly see the albedo changes associated with Valles Marineris, with the 'W' of Noctis Labyrinthus being quite clear, and this is reflected on the globe. The interpretation of 'Nix Olympica' as a huge double crater was quite wrong, but again based on albedo - the supposed outer rampart is clearly the offset aureole around Olympus Mons itself. Look sideways and you can almost identify the other three great Tharsis volcanoes too. The globe is fascinationg because it captures a moment in time in the exploration of Mars before the gross facts of the planet were fully captured.

Some areas are slightly more detailed, such as the swathe of features imaged by Mariner 7 around the South Pole, and Mariner 6's observations of (I think) Deucalion.

I'll try to take some photos of my globe at some point and will send them to you if you like. This globe sometimes turns up on eBay, often poorly identified, so obtaining one yourself is not an impossible task!
Bob Shaw

I also have a copy of this globe, with the stand. It was in mint condition until several years ago when it got knocked off the bookshelf it was sitting on. Now it's got a dent (I suppose I should see if it could be repaired without damaging it more).

My wife found it at one of those car wash gift shops about 20 years ago!

-Tim.

[edstrick]

The Mariner 4 camera was designed to adjust exposure based on previous image data, but the design was conservative so exposures wouldn't vary widely. It used only <I think> green filter exposures for checking output data levels (images were red/green/red/green, with every 3'rd image not recorded), and if data values were out of range, it would increment one exposure change per green frame cycle. So as they approached the terminator, exposures increased (also increasing light fog from the camera design error), but not fast enough to compensate for dropping light levels.

The Mariner 69 cameras dumped data to twin Mariner 64 tape recorders, one recording analog data, the other recording bit-clipped versions of every 7'th pixels in digital form (more complicated than that, but...). The tape flaked and shed inflight and gummed up the recorder heads a bit, causing high streaky noise levels, equivalent to that on a VHS tape recorded with dirty tape heads. The image reconstruction postflight was a nightmare, but they got much more total pixels than Mariner 4 times two.

Mariner 71 had a new tape design that could hold some 33 fully digital images of (approx) 600 x 800 pixels. The same recorder was used on Mariner Venus/Mercury 73, but new telecommunications ability let them transmit most data in real time.

[tedstryk]

I have added a Mars 3 Orbiter page to my new site.

Ted

[tty]

A small quibble about one of images, shouldn't "Impygia" be "Iapygia"?

tty

[tedstryk]

A small quibble about one of images, shouldn't "Impygia" be "Iapygia"?

tty

I transcribed it from a translation of a Russian document, and it had it as "Impygia." Good catch!

[tedstryk]

The image I am happiest with is the February 28 crescent. The original image looked like this:



And, after much work, I got this:



This is the only image that I have seen from the mission with underlying data good enough to make a somewhat pretty picture. The December image isn't that bad, but seems to be washed out in some filters.

[Stu]

A crescent Mars... that's one of the most beautiful images you've given us, thank you.

[helvick]

Ted,

I'm going to have to stop being so cynical about those image processing guru's on CSI\24\Alias - how on earth did you manage to pull such an astonishingly beautiful shot out of so much crud and noise?

Sweet!

[djellison]

He pressed zoom 3 times, and 'enhance' twice. Works every time.

[tedstryk]

http://www.strykfoto.org/mars3.htm

In case you missed my earlier post, this link has more of my images from Mars-3. The Soviets published response curves for the RGB filters, and wrote extensive papers on photometric studies of the Mars-3 images. The February 28 set is the only one that they published crude isophot maps for all 3 filters. Whle the resolution is awful on these, it provided a "ground truth" of sorts to remove noise from the images. Also sampling various areas of the disk and correcting for the actual image variations to subtract the scanning streaks helped.

[remcook]

He pressed zoom 3 times, and 'enhance' twice. Works every time.

LOL with some more clicks he will certainly be able to read Spirit's numberplate (timing issues aside). Or some reflection on the solar panel.

[edstrick]

"A crescent Mars... that's one of the most beautiful images you've given us, thank you."

Viking Orbiter 2 got a series of nice crescent views on approach to Mars. One has a nice plume-cloud trailing downwind from Olympus or one of the 3 Tharsis big'uns: Curly, Larry, or Moe.