Dawn approaches Ceres, From opnav images to first orbit |
Dawn approaches Ceres, From opnav images to first orbit |
Jan 12 2015, 12:10 AM
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Solar System Cartographer Group: Members Posts: 10184 Joined: 5-April 05 From: Canada Member No.: 227 |
On Tuesday (two days from now, for visitors from the future), the first optical navigation image will be taken... hopefully we'll have it in our hands soon after that. So it's time for a new topic. Over the next few months we'll have progressively closer images and full orbit characterization sequences, no doubt including multispectral image sets.
A new world... This is a bit of reprocessing I have been doing with the Hubble images from a few years ago. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jan 24 2015, 04:42 PM
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#2
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Senior Member Group: Members Posts: 4251 Joined: 17-January 05 Member No.: 152 |
When you view an animated gif of the released set your brain can pull real structure out of the noise, and you end up seeing more structure than in any single frame. This makes me wonder about producing a super-res from this set. It would be a lot of work. You'd have to create a rotation model and transform each image into some fixed projection, before doing the stacking with each frame aligned in longitude. Of course you'd get maximal improvement near the central region of the central frame, and less improvement towards the edges. Still, it would be interesting to see what could be done.
Or you could wait for the next release... |
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Jan 25 2015, 01:34 PM
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#3
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
...This makes me wonder about producing a super-res from this set. It would be a lot of work. You'd have to create a rotation model and transform each image into some fixed projection... I originally wasn't going to spend any time doing this since there isn't a long time until the next images arrive but I found that I simply couldn't resist checking if more details could be revealed, also this was an interesting image processing experiment. I used the last 9 images from the set, reprojected them to simple cylindrical projection and then aligned and stacked the maps. This was followed by rendering an ellipsoid using the map as a texture map. I was rather disappointed with the result and I'm not sure which 'new' details are real, maybe some but maybe none. Below are two versions, the left one sharpened with an unsharp mask and the right one processed with a high pass filter followed by a contrast stretch: I'm more happy with the version at left. The most interesting feature is the one below center that stretches from the left limb and more than half the way to the right limb. This looks like a possible 'depression' (reminds me a bit of Tethys' Ithaca Chasma!?) but an albedo feature (or something else) can't be ruled out. One important caveat is that the images in the rotation movie have been processed and enlarged - I'd me more confident in these results if I was using the original, raw images. It should be mentioned that the original 20 images were obtained over a period of ~1 hour at a range of 383,000 km and the subspacecraft latitude is 28.2 degrees south. |
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