Dawn data in the PDS |
Dawn data in the PDS |
Nov 27 2012, 01:52 PM
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#61
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Wow! These are awesome mosaics, especially the 36 image mosaic.
This shape is from Dr Robert Gaskell produced after the survey orbit. As i remember, this shape use the old system coordinate before the first change (Claudia as prime meridian) by Dawn Team. I made (year ago) a conversion for cmod file (I choose cmod because i think it is very easy 3d file structures to read) here: http://patzawa.perso.sfr.fr/Download/Astro...que/Mesh/Vesta/ But even with shape i have a problem to build small mosaic Vesta rotates very fast and condition of illumination change as well. This seems to be a very high quality shape model that opens up some very interesting possibilities, even though there are major gaps near the north pole for obvious reasons (the shape model is from 2011). |
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Nov 28 2012, 12:02 PM
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#62
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Member Group: Members Posts: 102 Joined: 29-January 10 From: Poland Member No.: 5205 |
Here is my version of RGB Vesta
Images are taken 26 Jul 2011 R - FC21A0003496_11206015247F7K G - FC21A0003491_11206015148F2K B - FC21A0003497_11206015300F8K -------------------- Adam Hurcewicz from Poland
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Dec 7 2012, 01:27 AM
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#63
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Senior Member Group: Members Posts: 1585 Joined: 14-October 05 From: Vermont Member No.: 530 |
Press release regarding "sinuous" gullies on Vesta:
http://www.nasa.gov/mission_pages/dawn/new...wn20121206.html The release images are nicely accessible here, too: http://dawn.jpl.nasa.gov/multimedia/vesta_dawn_gallery.asp All looks like it could just be dry sloughs to me, but neat nonetheless. |
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Dec 16 2012, 12:13 AM
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#64
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Newbie Group: Members Posts: 17 Joined: 24-August 12 Member No.: 6610 |
New image browsing tool availible at PDS for Vesta data.
is this a beta of Emilys tool ? http://dawn.psi.edu/data/PDS-Vesta/index.html -------------------- Thomas Gold was probably right about a iceball Mars.....
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Jul 18 2013, 10:24 PM
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#65
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Two 8 month old posts from this thread:
You might want to take a look at this regarding shape files.. http://naif.jpl.nasa.gov/pub/naif/DAWN/kernels/dsk/ This shape is from Dr Robert Gaskell produced after the survey orbit. As i remember, this shape use the old system coordinate before the first change (Claudia as prime meridian) by Dawn Team. I made (year ago) a conversion for cmod file (I choose cmod because i think it is very easy 3d file structures to read) here: http://patzawa.perso.sfr.fr/Download/Astro...que/Mesh/Vesta/ But even with shape i have a problem to build small mosaic Vesta rotates very fast and condition of illumination change as well. I'm finally going to take a fairly detailed at the Vesta data and the first step is a shape model that the images will be draped over. I have the files mentioned above. Sarunia's cmod files are probably easier to handle but they are not the highest resolution available. The highest resolution files can be downloaded using the link posted by Doug but they are in a format that I need to convert to something else (possibly cmod). After exploring the data I'm getting the impression that converting them is going to require considerable work, possibly some programming (I have not found a converted version of the hi-res stuff anywhere). Yet the lower resolution versions have been converted to at least cmod. Does anyone know of any utilities that can read/convert this stuff? I haven't found any easy solution but I wouldn't be surprised if I have missed something. |
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Jul 22 2013, 10:38 AM
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#66
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Junior Member Group: Members Posts: 22 Joined: 23-August 11 From: France Member No.: 6134 |
Two 8 month old posts from this thread: I'm finally going to take a fairly detailed at the Vesta data and the first step is a shape model that the images will be draped over. I have the files mentioned above. Sarunia's cmod files are probably easier to handle but they are not the highest resolution available. The highest resolution files can be downloaded using the link posted by Doug but they are in a format that I need to convert to something else (possibly cmod). After exploring the data I'm getting the impression that converting them is going to require considerable work, possibly some programming (I have not found a converted version of the hi-res stuff anywhere). Yet the lower resolution versions have been converted to at least cmod. Does anyone know of any utilities that can read/convert this stuff? I haven't found any easy solution but I wouldn't be surprised if I have missed something. VestaGaskellOldPM_512.cmod added: http://patzawa.perso.sfr.fr/Download/Astro...que/Mesh/Vesta/ No time to test it but i hope that it will be ok For the conversion, I use my own tool but it's very tricky and "unreleasable". When i have time i will try to do. |
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Jul 24 2013, 11:50 PM
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#67
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
VestaGaskellOldPM_512.cmod added: http://patzawa.perso.sfr.fr/Download/Astro...que/Mesh/Vesta/ No time to test it but i hope that it will be ok For the conversion, I use my own tool but it's very tricky and "unreleasable". When i have time i will try to do. Works perfectly - big thanks . I converted this from binary cmod to ASCII cmod using cmodfix (a utility associated with Celestia). It was very easy to then read the ASCII cmod file into my software and now the fun starts. I will be posting results here sometime in August probably. |
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Jul 25 2013, 02:23 AM
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#68
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Member Group: Members Posts: 890 Joined: 18-November 08 Member No.: 4489 |
glad something is working with the new format
i take it you have looked through the alpha "alpha_dsk_c.tar.Z" version of "cspice-N0064" In the folder /src/dskcook_c/ is example code on accessing the new format |
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Jul 25 2013, 10:23 PM
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#69
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Yes, I knew about this example code but I haven't started experimenting with it. Getting the shape model in cmod format from Sarunia speeds things up a lot.
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Jul 27 2013, 09:09 AM
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#70
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
an extremely interesting paper comparing Dawn and HST observations at Vesta: Comparing Dawn, Hubble Space Telescope, and Ground-Based Interpretations of (4) Vesta
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Aug 8 2013, 09:47 PM
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#71
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Does anyone reading this know how accurate the released camera pointing information should be for the Dawn images? I'm getting close to reprojecting the images onto the shape model but I'm getting significant differences between Dawn's images of Vesta and images I render of the shape model using the viewing geometry information.
The differences range from typically 20-30 pixels for the RC3 images from the approach phase to ~250 pixel for the HAMO images. 250 corresponds to an error of more than 1° if the spacecraft position is assumed to be correct - this is a very large difference. I'm aware of the various coordinate systems. The file VESTA_COORDINATES_120918.PDF in the DOCUMENT directory in the PDS data contains information on these. The released data is in the Claudia Double-Prime system. I assumed that the shape model is in the IAU-2000 system, both because of Sarunia's post earlier in this thread and because of the following line in the CMT files that come with the shape model: REF_FRAME_NAME = 'IAU_VESTA' But because of the mismatches I get I also tried rendering the shape model by assuming that it was in some of the other coordinate systems but that did not result in an improvement. It's rather difficult to debug this stuff because I really have nothing I know is 100% correct that I can use as ground truth. I think my code is working correctly and the shape model cannot be this inaccurate (for one thing, if it was it wouldn't have been released). So I'm leaning towards inaccurate pointing information. That's not exactly something new when dealing with spacecraft data but what makes me somewhat suspicious (and is the reason I'm posting this instead of simply 'correcting' the pointing) is the large mismatch I get in the HAMO images, as indicated above. Usually the spacecraft position is very accurate in the SPICE kernels and image labels; I assume that is the case here too. If this is likely to be due to inaccurate pointing I'll simply correct the pointing; otherwise it's back to debugging my code. |
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Aug 8 2013, 10:00 PM
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#72
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
I've sent an email to a friend on the Dawn team pointing him to your post -- let's see if I get a response.
-------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Aug 8 2013, 11:58 PM
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#73
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Junior Member Group: Members Posts: 22 Joined: 23-August 11 From: France Member No.: 6134 |
The shape from Gaskell seems to use the old prime meridian with a pole orientation corrected.
So I modified the vesta related SPICE pck file like this: BODY2000004_POLE_RA = ( 309.031 0.0 0.0 ) BODY2000004_POLE_DEC = ( 42.235 0.0 0.0 ) BODY2000004_PM = ( 292.0 1617.332776 0.0 ) Below the result of a projection with a survey picture (FC21A0005503_11232092641F1F): (On Top left: only the shape shading. Top Right: projection+shape shading. Bottom Left: only the projection result) But frankly i didn't measure the actual precision (but certainly not a 30 pixels difference) and didn't try with an HAMO pictures. In waiting for the Dawn Team answer for more informations. |
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Aug 9 2013, 12:32 AM
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#74
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
The shape from Gaskell seems to use the old prime meridian with a pole orientation corrected. So I modified the vesta related SPICE pck file like this: BODY2000004_POLE_RA = ( 309.031 0.0 0.0 ) BODY2000004_POLE_DEC = ( 42.235 0.0 0.0 ) BODY2000004_PM = ( 292.0 1617.332776 0.0 ) It works!!! It never occurred to me that the shape model might be in a 'hybrid' coordinate system. 'Hacking' the pck file by applying this modification eliminated most of the discrepancies I was getting, at least for the RC3 images. I'll test the HAMO images tomorrow but I'm pretty sure they'll be fine. More tomorrow and possibly some preliminary image processing results. Big thanks. |
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Aug 10 2013, 11:03 PM
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#75
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IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Everything works now. This is a test image where a HAMO image has been draped over the shape model:
Even though everything works I'm still interested in how accurate the relased camera pointing information should be. Some discrepancies remain but they are much smaller than earlier. For the RC3 images I've tested it's almost perfect though, the error is typically 2-4 pixels. In contrast, there are some differences between HAMO images and rendered shape model images, typically 20-30 pixels. That's probably normal. In the image above I made a relatively crude correction to the pointing - I'll do it more accurately once I start mosaicking images. I'm also interested in the accuracy of the spacecraft position; I'm assuming it to be very accurate. And now something different: Typically only image processing successes get posted here but I'm making a rare exception just to show what can happen when you're doing something new. This was supposed to be a simple cylindrical map of Vesta but there was a simple bug that caused it to have a very strange look: |
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