Beginner level projection |
Beginner level projection |
Nov 6 2019, 11:50 PM
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#1
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Junior Member Group: Members Posts: 31 Joined: 31-October 19 Member No.: 8699 |
Hi,
I'm trying to do the mapping just using SPICE for the Junocam images rather than going through ISIS. It might seem like I'm making life difficult for myself but I just wanted to make sure I'm doing the bare minimum amount of processing so it looks as close to a non-spinny-push-frame image as I can. I'm making all the beginner mistakes but I can't seem to figure out what they are so I was hoping someone might give me a hint? First I want to figure out how far Jupiter is because I want to have anything that didn't hit Jupiter get mapped to a sphere that hits Jupiter. This means any lens effects can get mapped in space near where they originated from which should hopefully make the edges of the planet seem less processed: [jupiterPos, jupiterLt] = spice.spkpos('JUPITER', et0, 'JUNO_SPACECRAFT', 'NONE', 'JUNO') jupiterDistance = np.linalg.norm(jupiterPos) Then I go through all the undistorted Junocam pixel vectors and figure Jupiter intercept points in the IAU_JUPITER frame so now I have a point cloud of all the planet mapped pixels: [point, trgepc, srfvec, found ] = spice.sincpt( 'Ellipsoid', 'JUPITER', et, 'IAU_JUPITER', 'LT+S', 'JUNO_SPACECRAFT', 'JUNO_JUNOCAM', v) If it didn't find an intersection then I figure out where that invisible sphere is going to be by extending out the pixel vector by the separation and move that to the IAU_JUPITER frame: direction = np.array(v) pos = direction*jupiterDistance/np.linalg.norm(direction) rotationMatrix = spice.pxform('JUNO_JUNOCAM','IAU_JUPITER',et-jupiterLt) pos = spice.mxv(rotationMatrix, pos) It works terribly! I seem to have a timing error in the frame offsets that seems suspiciously close to the light time between Jupiter and Juno and the sphere that catches all the sincpt misses is completely miles off. I've been staring at the code for a while and not figuring my mistake, I was hoping someone might point out where I've gone wrong. Many thanks Adam |
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Nov 7 2019, 10:53 PM
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#2
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
It works terribly! I seem to have a timing error in the frame offsets that seems suspiciously close to the light time between Jupiter and Juno and the sphere that catches all the sincpt misses is completely miles off. I'm not sure what you're trying to do (not following the "invisible sphere" stuff) and I have the suspicion that you're counting the light time twice, but all that said there are known timing errors of roughly six pixels 1 sigma in the Junocam start time that you need to correct for. We're working on pushing updates to the PDS but it'll probably be a while before that happens. In the meantime, which images are you working with? Also, make sure you are using the reconstructed SPK files. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Nov 7 2019, 11:27 PM
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#3
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Junior Member Group: Members Posts: 31 Joined: 31-October 19 Member No.: 8699 |
I'm not sure what you're trying to do (not following the "invisible sphere" stuff) and I have the suspicion that you're counting the light time twice, but all that said there are known timing errors of roughly six pixels 1 sigma in the Junocam start time that you need to correct for. We're working on pushing updates to the PDS but it'll probably be a while before that happens. In the meantime, which images are you working with? Also, make sure you are using the reconstructed SPK files. Just to explain that sphere thing, my plan is to map every pixel to a point in space and then turn it back to an image from nearst points to vectors coming from the spacecraft's location. So the points not mapped to a planet need to get mapped somewhere nearish so I thought a sphere centered on Juno and intersecting with the middle of Jupiter would be some kind of start. |
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