Voyager and Galileo Images of Ganymede, The Ganymede images and mosaics thread |
Voyager and Galileo Images of Ganymede, The Ganymede images and mosaics thread |
May 18 2007, 09:43 PM
Post
#31
|
|||
IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
I've been processing some of the high resolution Galileo Ganymede images recently. As far as I know the two mosaics below have not appeared at the official websites (at least not in this form) so in a sense they are 'new'.
The first one was obtained during the G1 flyby in 1996. It covers a part of Memphis Facula which is centered at roughly 15°N, 132°W. The images were obtained at a distance of approximately 5000 km from Ganymede's center. The second one was obtained during the G28 flyby in May 2000. It is centered near 14.5°S, 319.7°W. The images making up the mosaic were obtained at a distance of roughly 4500 km from Ganymede's center. I will probably post more Ganymede mosaics later this month or next month. |
||
|
|||
May 23 2016, 09:19 PM
Post
#32
|
||
IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Here is a new global mosaic of Ganymede from Voyager 1 images:
There are versions of this mosaic earlier in this thread that aren't as carefully processed and also they are not completely global. This is the biggest global mosaic of Ganymede I've seen, a 17 frame mosaic. The source images were obtained by Voyager 1 on March 5, 1979 over a period of about 2 hours. During these 2 hours Voyager 1's distance from Ganymede dropped from 305,000 to 180,000 km. As usual I reprojected the original images to simple cylindrical projection, did all of the color and mosaicking work there and then rendered the resulting map with 3D software using a typical viewing geometry. Most of the 17 cylindrical maps that I created and then mosaicked are in GBV or OBV color. From this I created synthetic R, G and B color, resulting in approximately true color (the color difference between the equatorial and polar areas should probably be more pronounced though). Somewhat unexpectedly, when making the R, G and B color it didn't seem to make any difference if the source images were OBV or GBV. In a few small areas only one or two colors were available. I colorized these areas by taking the color from nearby areas. A significant problem when making this mosaic is that some of the source images are smeared. This happened because the intense radiation in Jupiter's magnetosphere affected Voyager 1's computers and clock. As a result some of the images were taken when the instrument scan platform was moving. It's difficult to make a full color global mosaic without using some of these smeared images. Following very useful information from machi it turned out that these images can be successfully deconvolved, making it possible to use them. Discussion on this can be found here: http://www.unmannedspaceflight.com/index.php?showtopic=8091 This is very useful because in addition to the Ganymede images some of Voyager 1's images of Io and Callisto are smeared as well. |
|
|
||
May 25 2016, 10:03 PM
Post
#33
|
|
Junior Member Group: Members Posts: 74 Joined: 9-October 10 From: Victoria, BC Member No.: 5483 |
|
|
|
Lo-Fi Version | Time is now: 27th September 2024 - 02:37 AM |
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. |