Voyager mosaics and images of Jupiter, A fresh look at some ancient stuff |
Voyager mosaics and images of Jupiter, A fresh look at some ancient stuff |
Aug 20 2010, 05:47 PM
Post
#1
|
||
IMG to PNG GOD Group: Moderator Posts: 2256 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Thanks to modern computers and software the old, 'official' Voyager Jupiter images can be reprocessed into something much better. There is also a lot of Voyager data there that was never processed into color composites and/or mosaics (or at least it has not appeared on the WWW). With proper processing the apparent image quality approaches the quality of the Cassini images but needless to say the wavelength coverage is (vastly) inferior.
I have recently been taking a close look at the high resolution Voyager 1 images, i.e. the images obtained in early March 1979. This is going to result in some new and/or reprocessed mosaics. The first one is now complete and I'm working on another one. The image below is a 12 image mosaic (12 orange + 12 violet + 12 synthetic green images). The images were obtained on March 2, 1979 at a range of 4.3 million km. The first image (C1629045.IMQ) was obtained at 05:09:23 and the last one (C1629131.IMQ) at 05:46:11. The resolution is roughly 43 km/pixel. The raw images were calibrated, reprojected to simple cylindrical projection, mosaicked and then rendered using a typical viewing geometry (there is no such thing as a "correct viewing geometry" because the images were obtained over a 37 minute period with Jupiter rotating). I then fixed the color balance. I still haven't 'standardized' how I process the Voyager color. I wasn't completely satisfied with the color I got using an approach similar to what's described in another thread but I think the color could be improved a bit. The final step was to sharpen the resulting image a bit, mainly to compensate for all of the resampling that the previous processing steps required. This image shows lots of features: The Great Red Spot and one of the three white ovals present during the Voyager flybys, smaller spots, scallopped belt/zone boundaries, gravity waves, a bright equatorial plume and the dusky south polar region. I don't think I'm bragging by saying that this is probably the best Voyager 1 Jupiter mosaic that I know of, mainly because of its size (12 images). I will be posting more Jupiter stuff in this thread in the coming days/weeks, both mosaics and interesting images (and needless to say, others are welcome to post images and mosaics as well). |
|
|
||
Nov 23 2010, 10:08 PM
Post
#2
|
|||
IMG to PNG GOD Group: Moderator Posts: 2256 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
I have just finished a completely new mosaic of the Great Red Spot (GRS), this time based on Voyager 2 images. First an enhanced, sharpened version and then a version that should have approximately natural color and contrast:
This is a 5x3 mosaic of images obtained on July 8, 1979 when Voyager 2 was ~1.45 million km from Jupiter. The resolution of the original images is ~14 km/pixel. The resolution of this mosaic is similar. This is a slightly higher resolution than in the Voyager 1 GRS mosaic I posted earlier in this thread. Each of the 15 frames making up the mosaic is a color composite from orange, green and violet images. This results in more accurate color than in my earlier Voyager 1 GRS mosaic because in that case I had no green images I could use. Thanks to this the color variations in this mosaic seem more interesting. As far as I know this is completely new stuff. Very few and possibly none of the images I used have appeared earlier in official image releases, at least not in color. There is a fairly well known Voyager 2 mosaic of the GRS but that one is composed from images obtained three Jovian rotations earlier at a range of 2.6 million km (see http://photojournal.jpl.nasa.gov/catalog/PIA00065 ). Thanks to modern computers and software the quality of this new mosaic is higher. As usual the mosaic was created by reprojecting the source data to simple cylindrical projection and then rendering the resulting map using a 'typical' viewing geometry (there is no single correct geometry because the source images were obtained over a period of ~70 minutes). Thanks among other things to improvements I've made to some of the processing steps required to create these mosaics the geometric accuracy of this mosaic is higher than for the earlier Voyager 1 mosaic. This new mosaic contains lots of interesting stuff, including small scale details and interesting color variations. Cloud shadows are visible, in particular at (3040,2040) and nearby. The color variations seem more interesting here than in the Voyager 1 mosaic, probably because the color is more accurate. There is an interesting brownish/orange 'band' near (1180,615) for example. Also the color changes from brownish to whitish near (900,1300) without any obvious changes to the 'texture' of the image (the wind is northnortheasterly at this location). I could name at least 10 additional features that look interesting to me and where I wish I knew what was happening. The Voyager 1 images of Jupiter (and not the least the GRS) are probably better known than the Voyager 2 images, mainly because Voyager 1 arrived earlier. So yet again in a way I feel like I'm looking at images from a new Jupiter flyby. The GRS region looks more 'Galileo-like' to me in the Voyager 2 images than it does in the Voyager 1 images. |
||
|
|||
Lo-Fi Version | Time is now: 31st October 2024 - 11:46 PM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |