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
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IMG to PNG GOD Group: Moderator Posts: 2254 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). |
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Sep 28 2010, 12:59 AM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Here is a preliminary version of a Voyager 1 movie showing the rotation of the Great Red Spot and a lot of other interesting cloud motions. It consists of 16 frames but the final version is going to consist of 66 frames (or something close to 66).
jup_vgr1_sharp.avi ( 198.5K ) Number of downloads: 2325 This should be the most interesting part of the movie because this really is what will be the end of the final version so this part is of somewhat higher resolution than the start of the imaging sequence I'm using for the movie. This movie is different from similar Voyager movies because I'm keeping Jupiter's size constant. This is accomplished by reprojecting the source images to simple cylindrical projection and then rendering everything using the same viewing geometry. I also sharpened the images a bit to better reveal various details. One possible problem is that for some features there are slight changes in latitude from frame to frame. This is especially obvious in the polar regions. I suspect this is not a real feature but a consequnce of small errors in the camera angles I had to reverse engineer for all of the source images. Another problem is that I also had to reverse engineer the spacecraft position because the available SPICE kernels only contain Voyager 1's position from 6 February 1979 and onward and these images were obtained in January. The source images where obtained on every Jovian rotation on January 23 to 29, 1979. During that interval Voayger 1's distance from Jupiter dropped from 42 to 36 million km. The images were obtained through orange, green and blue filters. Satellite and shadow transits have been removed using Photoshop. Note: If playing the animation does not work the reason is probably that you don't have an H.264 codec installed. For the animation to work you need to have an H.264 codec installed (if you are using Windows you can find one here for example). As a sample, here is a typical frame from the movie: |
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