Voyager 2 Saturn Revisited, Still a lot to be processed and reprocessed Options

[Bjorn Jonsson]

Emily recently mentioned in her blog the availability of calibrated and geometrically corrected Voyager images. Actually I had 'discovered' this dataset several months earlier but then managed to completely forget about it. Now I decided to do something so I downloaded volume 37 and decided to do some quick-and-dirty processing, mainly to check if it was feasible to do a very high resolution map (probably 25 degrees/pixel to match my Cassini map of the southern hemisphere) of Saturn's entire northern hemisphere by colorizing green filtered images using lower resolution color data I processed several years ago - at the resolution I want only green filtered images are available.

This was successful, opening the door to a new 'monster project': A very high resolution full color map of Saturn's entire northern hemisphere.

First a color composite made from wide angle orange, green and blue images:

This one was made from images C4386547_GEOMED.IMG, C4386554_GEOMED.IMG and C4386608_GEOMED.IMG. I adjusted the color to something more realistic than I initially got and removed some reseau marks in Photoshop that were visible, especially near ring edges and Saturn's limb. Some color fringing was also visible on Saturn's disk due to Saturn's rotation while the three images were obtained; I removed this by cloning the color of adjacent areas. The spokes in the rings presented similar problems.

I then colorized a green filtered image obtained at a similar time as the wide angle images above. This was the result:

The image should be fairly realistic and I was happy with the result, especially because I didn't do this very carefully - something better should be possible.

Finally the same image sharpened with an unsharp mask:

Lots of small scale details are visible, especially near the pole.

I will probably post several additional Voyager Saturn images in the next several weeks. As previously mentioned, the plan now is to do a very high resolution map of Saturn's entire northern hemisphere based on these calibrated and rectified images. This means reprojecting the images to simple cylindrical projection. To do this I need to know the viewing geometry. Does anyone know if this information is available somewhere (or if not, if it's likely to ever become available)? I have some SPICE kernels which give me Voyager 2's location relative to Saturn. These are probably fairly accurate. However, the limited instrument pointing information I have is very inaccurate so it's useless to me. I can reverse engineer the viewing geometry/pointing but it's a lot of extra work.

[tedstryk]

My closer Galileo mosaic is also very high resolution, but it is extremely high phase.

[Ian R]

The color isn't perfect, and indeed one or two frames suffer minor alignment issues, but otherwise this movie of Saturn's spokes is best viewed in 1080p:

https://www.youtube.com/watch?v=dgbUaQGd4RE

[Bjorn Jonsson]

Wow.
This is probably the best Voyager Saturn movie I have ever seen.

[ZLD]

Absolutely stunning work Ian!

[ElkGroveDan]

Very impressive Ian.

[Ian R]

Thanks guys! I did this last year, and given I was preoccupied with another project, I gave myself a week to complete this movie, from start to finish. This explains some of the minor flaws I listed above, and there is scope for a revised version, perhaps using reprojected frames to fill the central gap.

[jgoldader]

Ian: just... wow! Riding along with Voyager indeed!

[PDP8E]

Ian, nice work! thanks

[Ian R]

This is how the very same sequence was presented back in the day:

https://youtu.be/b1GDhWQbHfQ?t=5m28s

[ZLD]

This makes it much clearer how impressive your version is! Once again, well done Ian.

[DrShank]

This makes it much clearer how impressive your version is! Once again, well done Ian.

agree! it is beautiful. would it look even better if more of the center were cropped out so the frame edges didn't dance around so much?

[Floyd]

Ian, your work impressively demonstrates how much information was in the Voyager data--and how your skills and modern tools have the ability to unlock that old dataset. Cassini has so improved our image coverage and scientific knowledge of Saturn's moons that watching 1981 clips shows both the joy of first discoveries, but also how far we have come in 34 years.

[jasedm]

Stunning work Ian, thanks for sharing with us!

Noticeable difference to me between Voyager and Cassini is the (relative) paucity of spokes in the rings. They are very prominent in the Voyager data.

[Rob Pinnegar]

Beautiful job Ian -- really nice work.

[Ian R]

With my grateful thanks to Tanya and Emily of The Planetary Society, my new guest blog entry gives the low-down on how I assembled this sequence last year, over the course of just one week:

http://www.planetary.org/blogs/guest-blogs...oach-movie.html