Global True Color View Of Venus? |
Global True Color View Of Venus? |
Oct 15 2010, 09:26 PM
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#46
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Member Group: Members Posts: 796 Joined: 27-February 08 From: Heart of Europe Member No.: 4057 |
It looks like old UV image from Pioneer Venus.
I think this one: http://www.nasaimages.org/luna/servlet/det...ioneering-Venus -------------------- |
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Oct 16 2010, 12:26 AM
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#47
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Newbie Group: Members Posts: 2 Joined: 16-June 10 Member No.: 5375 |
Is this web page with a Venus image showing some real data or an artistic work? http://rocksfromspace.open.ac.uk/Venus.htm If I can find a "full" Venus image I can try to see what it looks like with Science On A Sphere. Thanks, Steve I agree- that is a UV image of Venus. True color images look pretty much like a billiard ball. See this thread for more information. CJSF -------------------- Two years ago moved from my town
I was looking up past the city lights But the city lights got in my way See the constellation ride across the sky No cigar, no lady on his arm Just a guy made of dots and lines -from "See The Constellation" by They Might Be Giants |
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Oct 16 2010, 03:33 PM
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#48
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
Here's my Pioneer Venus image galery: http://www.astrosurf.com/nunes/explor/explor_pvenus.htm
Most of the images I had acess to were very degraded and from old magazines and books, but at least they are organized by date. I think most of the images were taken with the Near UV (365nm?) filter, but the camera was capable of operating on other wavelengths. -------------------- _______________________
www.astrosurf.com/nunes |
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Oct 16 2010, 04:18 PM
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#49
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Solar System Cartographer Group: Members Posts: 10197 Joined: 5-April 05 From: Canada Member No.: 227 |
Nice set of pictures! The last image on your page, the one with the question mark, looks like it is probably from Mariner 10.
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 PD: 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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Oct 16 2010, 05:53 PM
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#50
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Senior Member Group: Members Posts: 1656 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
I agree- that is a UV image of Venus. True color images look pretty much like a billiard ball. See this thread for more information. CJSF Right, though perhaps it might be interesting to try colorizing the Pioneer UV images by using information from missions like Venus Express and MESSENGER? Perhaps some subtle color might be visible and would give us a reasonable approximation of a "global true color" image. -------------------- Steve [ my home page and planetary maps page ]
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Oct 16 2010, 06:01 PM
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#51
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
It's not merely about color, it's about contrast. And quite frankly, in visible wavelengths there just isn't any appreciable contrast.
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Oct 16 2010, 06:06 PM
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#52
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Senior Member Group: Members Posts: 1656 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Yes indeed the actual contrast is much more subtle than in the Pioneer UV images. For example Ricardo Nune's images show Venus Express processed into approximate RGB, showing rather subtle hues. This procedure might be applied to the Pioneer UV images perhaps, even though these are monochromatic. It's kind of interesting to me to consider whether the human eye can perceive at least some faint contrast/color with Venus. Perhaps it relates to violet light sensitivity that can vary between individuals.
I haven't found too many spectra of Venus or its cloud features. Here is a VIMS spectrum of Venus for reference, though I'm unsure of the field of view. http://vims.artov.rm.cnr.it/data/res-ven.html More discussion is here: http://www.unmannedspaceflight.com/index.p...amp;#entry20237 Here is a book excerpt showing illustrations of visual observations of Venus' clouds, so the contrast is detectable to some, seen right here from planet Earth: http://books.google.com/books?id=LqwUuMYIE...ope&f=false -------------------- Steve [ my home page and planetary maps page ]
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Oct 17 2010, 12:52 AM
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#53
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Junior Member Group: Members Posts: 74 Joined: 9-October 10 From: Victoria, BC Member No.: 5483 |
Has anyone actually tried to make a true-colour map of Venus' surface directly from the Magellan radar data? I know there's separate topo data available but IIRC that was pretty low resolution - is it possible to extract data directly from the SAR images (e.g. pulse travel time) to get higher-res altimetry? And then make a global topography map from that, coloured as if we were looking at basalts?
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Oct 17 2010, 01:37 AM
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#54
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Merciless Robot Group: Admin Posts: 8784 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
I don't know how you could ever make a 'true color' map of the surface of Venus. We've only seen a very few small spots from the Venera probes--not enough to generalize about the entire planet--and there's no way to extract color from radar data. If that wasn't enough, lighting conditions, surface compositions, etc. undoubtedly do vary for a variety of reasons, so even if we could somehow obtain visible-light surface images of the entire surface that wouldn't necessarily correspond with what the human eye would actually see.
Even doing this for Mars is a formidable challenge; there's inevitably some degree of interpolation/assumption involved, as our resident imagemages will surely attest. -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Oct 17 2010, 01:26 PM
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#55
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Member Group: Members Posts: 378 Joined: 21-April 05 From: Portugal Member No.: 347 |
...It's kind of interesting to me to consider whether the human eye can perceive at least some faint contrast/color with Venus. Perhaps it relates to violet light sensitivity that can vary between individuals... My personal experience is positive. I can see "something" on Venus through a telescope. My best description would be of a white crescent with some brighter parts. Those bright spots look slightly fluorescent. But it's not obvious, the contrast is very subtle and there's no color at all. Like looking at snow deposited over snow. I think it has to do with the Rod cells on our eyes. Those are most sensitive to wavelengths of light around 498 nm and are responsable for the Purkinje effect http://en.wikipedia.org/wiki/Purkinje_effect. Perhaps something like that works for Venus. -------------------- _______________________
www.astrosurf.com/nunes |
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Oct 17 2010, 07:02 PM
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#56
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Junior Member Group: Members Posts: 74 Joined: 9-October 10 From: Victoria, BC Member No.: 5483 |
I don't know how you could ever make a 'true color' map of the surface of Venus. We've only seen a very few small spots from the Venera probes--not enough to generalize about the entire planet--and there's no way to extract color from radar data. Well, it'd definitely be "simulated true colour". I was thinking more "this is what the surface could look like, assuming basaltic composition". I know that bright (reflective) radar patches aren't necessarily bright in visible light, for example - they're just rough surface (unless they're on mountaintops IIRC, in which case they might actually be pyrite deposits?). Someone could take a small feature on Venus (e.g. a dome or crater) and translate the radar bright/dark into visible (using appropriate rules like "radar bright = rough surface, radar dark = smooth surface") that would be nice. I guess it's more a space art/visualisation thing than anything "scientific", but it'd be nice to be able to look at a view of Venus and say "that's what we might see if we looked at this feature in visible light". |
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Oct 17 2010, 07:45 PM
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#57
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
How on earth would that be any less simulated than one based on the Venera pictures?
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Oct 17 2010, 08:59 PM
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#58
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Senior Member Group: Members Posts: 1656 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
My personal experience is positive. I can see "something" on Venus through a telescope. My best description would be of a white crescent with some brighter parts. Those bright spots look slightly fluorescent. But it's not obvious, the contrast is very subtle and there's no color at all. Like looking at snow deposited over snow. I think it has to do with the Rod cells on our eyes. Those are most sensitive to wavelengths of light around 498 nm and are responsable for the Purkinje effect <a href="http://en.wikipedia.org/wiki/Purkinje_effect" target="_blank">http://en.wikipedia.org/wiki/Purkinje_effect</a>. Perhaps something like that works for Venus. Pretty neat that you've been able to see such features. It seems to me Venus is bright enough so it would work more with cones rather than rods. While color may not show up with a small crescent, I can speculate that if one can see features from Earth, then orbiting in a spacecraft it would look large enough to have a chance at seeing a slight hue. -------------------- Steve [ my home page and planetary maps page ]
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Oct 17 2010, 09:20 PM
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#59
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Junior Member Group: Members Posts: 74 Joined: 9-October 10 From: Victoria, BC Member No.: 5483 |
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Oct 18 2010, 02:53 AM
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#60
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Member Group: Members Posts: 890 Joined: 18-November 08 Member No.: 4489 |
QUOTE Has anyone actually tried to make a true-colour map of Venus' surface directly from the Magellan radar data? true color - not possible now a "better" than that old red/orange and yellow/white http://photojournal.jpl.nasa.gov/jpegMod/PIA00481_modest.jpg http://photojournal.jpl.nasa.gov/jpegMod/PIA00104_modest.jpg the color i settled on http://www.unmannedspaceflight.com/index.p...st&p=164503 now as to clouds They change SO fast that there is no "real" up to date data -- artist concept -- that i use a 100% artistic map for it a link to a artistic thread http://www.shatters.net/forum/viewtopic.php?f=5&t=16019 ( the last post is the above image) the color is adjusted so that some of the clouds can be seen and it looks like "bright smog" basically it is darker than if "you" were in orbit looking down at it |
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