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Why has Cassini not done a high-rez mosaic of Titan?
stephenv2
post Jan 27 2009, 07:27 PM
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I've not be able to find a good answer to this question. High resolution visible light images of all the major moons of Saturn seem to exist but I don't see anything much over 500 pixels and not very usuable. I desperately need one for my film. I realize that the hazy world may make it seems there is not much science value in this but I'm not 100% convinced of that. Plus, I suspect a really high resolution image (say a 16-image one) would be well worth the cost from a PR viewpoint and perhaps it would reveal some interesting info as well.

I have not found any real orbital/mission reason it could not be done before Cassini is finished. Anyone have any insight?


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volcanopele
post Jan 27 2009, 07:36 PM
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The biggest problem with creating a high-resolution visible color mosaic of Titan is the blandness of Titan's atmosphere. It would be difficult to piece the images together properly if there are no real features to set as control points. And as you point out, the science basis for using all that data volume is pretty limited.

Now, I can definitely see taking more single frame visible color images. I wonder if there is enough data volume available to splice them into out cloud monitoring observations.


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stephenv2
post Jan 27 2009, 08:11 PM
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QUOTE (volcanopele @ Jan 27 2009, 02:36 PM) *
The biggest problem with creating a high-resolution visible color mosaic of Titan is the blandness of Titan's atmosphere. It would be difficult to piece the images together properly if there are no real features to set as control points.


Sure, a little challenging but certainly not a reason not to do it. I would enjoy putting that mosaic together myself. I think the real issue is per the mission planning. I mean Titan is the moon we landed on - yet we don't have good photograph. Does this have anything to do with the general public's general ignorance of Huygens? This reminds of Apollo 8 and lack of planned photographs of earth. Fortunately, astronaunts with cameras were aboard and took perhaps some of the most important pictures in history.

I know if Cassini were manned we'd have a ton of nice photos of Titan. I think it's important that we get a least one before Cassini leaves.


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ugordan
post Jan 27 2009, 08:20 PM
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You're not missing out on much. At low phase angles, Titan is just a fuzzball as almost all haze structure in visible light is invisible. You could get away with just massively enlarging a smaller image and filtering it a bit - like this one. Compare to this shot of the south pole at native resolution - no structure visible either, at the very least it's lost in 8bit color banding.

For high phase, crescent views, things are a bit different and you would be actually able to see more details with a higher resolution shot as opposed to a distant snapshot. Even then, mostly over the north pole (in this Titan season).


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volcanopele
post Jan 27 2009, 08:32 PM
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Looks about right, ugordan smile.gif


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stephenv2
post Jan 27 2009, 08:33 PM
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QUOTE (ugordan @ Jan 27 2009, 03:20 PM) *
You're not missing out on much. At low phase angles, Titan is just a fuzzball as almost all haze structure in visible light is invisible. You could get away with just massively enlarging a smaller image and filtering it a bit - like this one. Compare to this shot of the south pole at native resolution - no structure visible either, at the very least it's lost in 8bit color banding.

For high phase, crescent views, things are a bit different and you would be actually able to see more details with a higher resolution shot as opposed to a distant snapshot.


I do agree about high phase, though I would prefer a full body shot. But, for the film, even slight enlargements produce artifacts that wreak havoc - I learned this from my 2 minute filmout test projected on 90ft wide IMAX screen that I did in September. The enlargement you sent would simply be usable as the color artifact on rim of Titan would look awful on filmout. It's precisely the 8-bit banding issue that native high resolution is so useful to me. It greatly minimizes 8-bit artifacts and I like to keep things at 50% in an 8k frame (roughly 8000 x 6000 pixels). The 3D motion I use puts even more demands and for images that I want to fill 50% of the screen, 100 Megapixel images are ideal.

Enlargements of images beyond even 125% using the best algorithms and filters available still look bad in IMAX.

While the body of Titan is a fuzzball, the real value of the large mosaic would be the great detail of the atmosphere layers in a global view. Would be beautiful and might reveal a little science.


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djellison
post Jan 27 2009, 08:36 PM
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QUOTE (stephenv2 @ Jan 27 2009, 08:11 PM) *
we don't have good photograph.


We have the best photographs worth taking.

And please - manned spaceflight, and the manned v unmanned issue, both banned subjects at UMSF. Please read the Forum Guidelines.
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stephenv2
post Jan 27 2009, 08:44 PM
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Full inline quote removed - Admin

Per the manned/unmanned, I was not clear, my error. I was not trying to argue about manned vs. unmanned, I was raising for comparison the mission planning science focus vs. the value of great images to support further unmanned spaceflight.

That's the very reason I'm making this film - to hopefully raise awareness among non space image fans of the paramount importance of unmanned spaceflight and exploration.

But I do respectfully disagree that we have the best photographs worth taking. I have a long list of photographs I would like to see that don't exist.


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djellison
post Jan 27 2009, 09:52 PM
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QUOTE (stephenv2 @ Jan 27 2009, 08:44 PM) *
I have a long list of photographs I would like to see that don't exist.


Who doesn't.
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imipak
post Jan 27 2009, 09:53 PM
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It depends whose "best" are referred to, I think. The set of images that are "best" by the criteria of scientific value[1] are unlikely to be a perfect union with the set of images are "best" at looking good at IMAX resolution.

[1] unquantifiable, anyway

stephenv2 - there are surely high res colour images of sections of Titan's limb and atmospheric hazes. Depending on the extent you're willing to cheat (or extrapolate from such images) perhaps it'd be possible to generate a [partially] artificial image /based on/ the highest resolution image of the full disk, plus some carefully selected limb shots?


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Phil Stooke
post Jan 27 2009, 11:00 PM
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Uh - 'they' have done lots of high resolution mosaics. But they are of the surface, not the hazy atmosphere, which would be a waste of time.

Phil


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stephenv2
post Jan 28 2009, 01:17 AM
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QUOTE (imipak @ Jan 27 2009, 04:53 PM) *
there are surely high res colour images of sections of Titan's limb and atmospheric hazes.


I've downloaded every image of Titan and there is nothing like that suitable that I'm aware of. In order to do it, it would have to be one image in a potential mosaic to get enough of the limb to work with. Plus, It would end up a cheat as to my eye Titan is not perfectly uniform, fuzzy or not. It would end up being too much of cheat for my purposes anyway.

But perhaps some images that could be used this way will still be taken. I will be working on film until at least late 2010, so there's still time.


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stephenv2
post Jan 28 2009, 01:23 AM
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QUOTE (Phil Stooke @ Jan 27 2009, 06:00 PM) *
Uh - 'they' have done lots of high resolution mosaics. But they are of the surface, not the hazy atmosphere, which would be a waste of time.


And I'm using them including using Mike Malaska's great work which gets me from visual to radar data. But that's actually precisely my problem. My script calls for me to approach Titan, go down through the atmosphere to the Huygens landing site - a very key part of my film. Unfortunately, today, it's not possible unless I do CGI which my film entirely based on only using real images. It's the only planet or moon in the film I don't have a suitable image of, ironically.

I'm sorry you think it would be a waste of time. This is not really about my film but the value to world that a great high resolution photograph of Titan would have. I tend to think it may land on magazine covers, posters, newspapers and more.


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titanicrivers
post Jan 28 2009, 02:26 AM
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QUOTE (stephenv2 @ Jan 27 2009, 07:23 PM) *
And I'm using them including using Mike Malaska's great work which gets me from visual to radar data. But that's actually precisely my problem. My script calls for me to approach Titan, go down through the atmosphere to the Huygens landing site - a very key part of my film. Unfortunately, today, it's not possible unless I do CGI which my film entirely based on only using real images. It's the only planet or moon in the film I don't have a suitable image of, ironically.


Don't know if this will help but ....
There's a web site that you should visit for images: http://photojournal.jpl.nasa.gov/index.html
Click on planet Saturn then select Titan.
Type in the following PIA numbers in the search box:
PIA10008 this is a 185 meg of the north polar lakes
PIA08391 this is a must shot of orange and blue titan atmosphere with Saturn ring in background
PIA08117 this is the descent movie with bells and whistles that you might make into your journey throught the atmosphere to the Huygens landing site. While not very hi res there is no denying of the power of the gradual appearance of the alien landscape of Titan and rapid sequence to the surface with a view from the surface.
PIA08112 Hi res fisheye color views of the Huygens landing site at different heights
PIA06241 a movie of alien clouds moving over the visible south pole of Titan
PIA02145 and 02146 infrared views of Titans topography including a mountain range and a blue cloud band
I can imagine an approach showing Saturn and the orange Titan in full light and then a shot of Titan with sun behind it in eclipse; then a zoom in on PIA08391 to the descent movie to the surface. Go to the north polar hood shot PIA062366 then the infrared view PIA09171 of the giant north polar cloud then wow them with the higher res view of the north polar lakes PIA10008 that have formed under that giant cloud.
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stephenv2
post Jan 28 2009, 05:48 AM
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QUOTE (titanicrivers @ Jan 27 2009, 09:26 PM) *
Don't know if this will help but ....
There's a web site that you should visit for images: http://photojournal.jpl.nasa.gov/index.html


I appreciate the info, but I actually have just about every single Cassini image including all the ones you mention here (as well as every Hubble image) etc. I agree that these are excellent choices.

I will end up using hundreds of thousands of images in the whole film. My problem is not images, it's resolution due to the requirement for IMAX filmout.


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