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Venus Full Disk -mariner 10
Malmer
post Sep 13 2005, 04:22 PM
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Hi!

I have just finished compositing this large Venus panorama from Mariner 10.

I have tried to generate natural colors for the planet using orange and UV filters.

Raw frames: FDS 58870-59038
I used 78 frames in that range and then picked out a few other frames to fill in the gaps. There where about 5% missing data.

I did dark subtraction and flatfielding. for flatfields i used the venus images that looked flat enough.

Does anyone have any information on camera linearity and stuff?
I cant seem to find the calibration report; "MVM 73 TV Subsystem Calibration Report". if anyone has it, please let me have a look!

The full panorama is 4000*4000 pixels.

All processing is done in either floats or 16bit.

Take a look!
/mattias


Venus realistic colors

Venus enhanced colors

Venus in UV
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um3k
post Sep 13 2005, 04:43 PM
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QUOTE (Malmer @ Sep 13 2005, 12:22 PM)
Does anyone have any information on camera linearity and stuff?
*

I don't know it for a fact, but I suspect the response is logarithmic.

EDIT: By the way, great pictures!
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Bob Shaw
post Sep 13 2005, 04:47 PM
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Mattius:

Nice planet! I'll take two!

Seriously, nice mosaic...

Bob Shaw


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DarthVader
post Sep 13 2005, 05:23 PM
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very nice indeed. Thanks for the work! smile.gif
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4th rock from th...
post Sep 13 2005, 05:51 PM
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Very nice images. Best Venus I've ever seen!

I like the colors but in my opinion using the Mariner 10 UV filter to create realistic images color isn't a good solution wink.gif You can't see UV!

The best would be to use the Yellow bandpass (730-500um) , as you already did, and
the Blue bandpass (530-425). These two filters cover mostly the visible spectrum, without adding UV information.
It's also possible to replace to Yellow Bandpass filter for the Clear or Minus UV, because Venus is almost featureless at those wavelengts.

Here's an image I've created using the Clear and Blue bandpass filters. Not much details, but this is what you would see if you were there. General color balance is a best guess.

http://www.astrosurf.com/nunes/explor/mari...mosaic_rgb2.jpg


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Guest_spaceffm_*
post Sep 13 2005, 06:21 PM
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@Malmer

Amazing work!
Thank You!
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JRehling
post Sep 13 2005, 06:52 PM
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QUOTE (4th rock from the sun @ Sep 13 2005, 10:51 AM)
Very nice images. Best Venus I've ever seen!

Here's an image I've created using the Clear and Blue bandpass filters. Not much details, but this is what you would see if you were there. General color balance is a  best guess.

http://www.astrosurf.com/nunes/explor/mari...mosaic_rgb2.jpg
*


Great work from the both of you, although I think in terms of trying to capture true color from Mariner's imagery, you're trying to make a silk purse from a sow's ear. (In terms of making great-looking non-true color images, it's a smashing success, though.)

We have tons of true-color imagery of Venus as seen from Earth, and the vaguely dirty-yellow bands corresponding to the features in the reconstituted Mariner images never appear in them.

One guess of mine is that Venus's bands show up pretty well at the blue end of the spectrum just where human S cones are failing to perform (~400nm-420nm), so that a filter with a broader response shows yellowish features pretty distinctly on Venus whereas the human eye doesn't, or just barely, can.

In general, different filter systems can be made to approximate each other pretty well when the spectrum of the body in question is nonpsychopathic. If the "dark stuff" in Venus's clouds has a really sharp dropoff around the edge of human sensitivity, then a camera/filter system that would produce results close to true color when looking at 9 out of 10 objects might go more awry with Venus.

My guess is that a person would have serious trouble seeing the relatively sharp border between yellow and white that shows up in all of these images. I will note, however, two possible alternative explanations. One is that the sharp edges are there for us to see, but are situation so close to polar latitudes that they are hard to observe from Earth. Other other is that good old glass in our telescopes performs some critical violet absorption that hides some things we would see if we were eyeball-to-cloudtop with Venus (although note: looking out of normal high-quality windows doesn't make anything I know of look funnily-colored).

Venus Express should give us the real skinny on this.
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Bob Shaw
post Sep 13 2005, 07:01 PM
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I don't think there'll ever be much naked-eye viewing of Venus from up close - that sucker is B R I G H T ! It'll be a matter of tinted glass windows on manned spacecraft, or some electronic process, or even plain ol' sunglasses. Perhaps a camera obscura would give the best unmediated view...


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tedstryk
post Sep 13 2005, 09:14 PM
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SPECTACULAR!!!!!


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tedstryk
post Sep 13 2005, 09:15 PM
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QUOTE (Bob Shaw @ Sep 13 2005, 07:01 PM)
I don't think there'll ever be much naked-eye viewing of Venus from up close - that sucker is B R I G H T ! It'll be a matter of tinted glass windows on manned spacecraft, or some electronic process, or even plain ol' sunglasses. Perhaps a camera obscura would give the best unmediated view...
*



Of course, a dark tinted window would do the trick...


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Malmer
post Sep 13 2005, 09:21 PM
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I agree on the fact that using UV filtered images to create visible light is a bit dubious at best. looking at the blue and orange filter images gives a more realistic look. I do however think that since venus is so bland in orange and blue that the eye might pick up whatever detail that the deep blues might contain? (guessing here)

I think that if I where to make an even blander version of the first image it would be close enough to reality.

But really... how fun would it be to painstakingly stitch together 80 raw frames if the result is a perfectly smooth sphere smile.gif

Venus Express and Messenger might clear things up.

Mattias
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tedstryk
post Sep 13 2005, 09:50 PM
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QUOTE (Malmer @ Sep 13 2005, 09:21 PM)
Venus Express and Messenger might clear things up.

Mattias
*


My hope is with Messenger. I don't know if VMC has RGB capability (if it does, then it might deliver in this area as well). A big problem with Mariner is that 8-bit imagery doesn't pick up everything the eye would.


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4th rock from th...
post Sep 13 2005, 11:11 PM
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QUOTE (Malmer @ Sep 13 2005, 10:21 PM)
....
I do however think that since venus is so bland in orange and blue that the eye might pick up whatever detail that the deep blues might contain? (guessing here)
...
But really... how fun would it be to painstakingly stitch together 80 raw frames if the result is a perfectly smooth sphere smile.gif
...


Well, I've never seen any color on Venus through a telescope, but the polar areas do look brighter. But I never saw any dark bands or areas! Just a white disk with some light patches and bright poles with absolutely no color.

So the dark UV markings might be just an interpretation of the data. Those areas could be as bright in the UV as they are in the visible. The bright UV areas are really much brighter, and they "leak" into the extreme blue. You don't see the color variation, but do see a bright are. (off course, I might be wrong tongue.gif )

Anyway, lets wait for the next probes to arrive and see what the planet look like.


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edstrick
post Sep 14 2005, 08:24 AM
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Malmer: "I have just finished compositing this large Venus panorama from Mariner 10."

WHOOOO!... A pic I've wanted to do for 25 years plus. *CONGRATULATIONS*

There is some limited full-disk imagery using the blue filter and some tests I did about 1981 indicated that that darkish band in the south polar haze is distinctly different in color from the low latitude dark markings.

Have you considered trying to generate color from the Mercury flyby-1 approach images. There is an actual rotation/zoom sequence from some 8 days out of a small crescent to the data where the planet fills the narrow-angle field of view before they started systematic mosaicing. NOBODY's ever done that.
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edstrick
post Sep 14 2005, 09:07 AM
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D'oh. "There is some limited full-disk imagery using the blue filter and some tests I did about 1981 indicated that that darkish band in the south polar haze is distinctly different in color from the low latitude dark markings."


JRheling: "Here's an image I've created using the Clear and Blue bandpass filters. Not much details, but this is what you would see if you were there. General color balance is a best guess."

That's the one I was talking about.
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