Dawn data in the PDS |
Dawn data in the PDS |
Feb 15 2012, 12:55 AM
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Administrator Group: Admin Posts: 5172 Joined: 4-August 05 From: Pasadena, CA, USA, Earth Member No.: 454 |
Hey folks, Christmas came just a little bit late this year...
http://dawnpub.igpp.ucla.edu QUOTE DAWN DATA RELEASE: LEVEL 1A DATA FROM APPROACH AND SURVEY It is a LOT of data. Just the Vesta Approach includes about 2000 FC images! Wow!!!The Dawn project has created a public website that is available to serve the cruise and Vesta data sets that have been delivered to the Planetary Data System (PDS) while the data are still under review. Data are available from all three Dawn instruments, the Framing Camera (FC), the Visual and Infrared Mapping Spectrometer (VIR), and the Gamma Ray and Neutron Detector (GRaND). The data that are currently available are raw data, in engineering units, sometimes referred to as EDRs by the PDS or as NASA level-1a data. Additional data sets will be added when they are submitted to the PDS. The Dawn website is located at: http://dawnpub.igpp.ucla.edu Users of these data should exercise caution. Invariably there will be errors or omissions in the documentation. Please report any problems... I think that the first thing I'm going to work on is that approach sequence/movie that I wish I'd had in real time. The rotation of Vesta through the image sequences makes color composition very hard, but I am sure there are people here who are up to it. I hope someone here can come up with a pretty color global shot that I can put into a comparison montage! -------------------- My website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
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Aug 8 2013, 09:47 PM
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IMG to PNG GOD Group: Moderator Posts: 2256 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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