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Chang'e-4 farside landing mission
Phil Stooke
post Jan 23 2020, 09:55 PM
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Thanks, Doug. This is Pan 30, 1 April 2019, in circular form (after a bit of cleaning up):

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Comparison with the map shows it was taken at the same location as the end of day 4. Sunset was on 12 April but the rover was already at that location on 1 April after just one drive (I think) in the first 3 days after sunrise. Using arguments like these I am refining dates on the maps.

Phil


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Phil Stooke
post Feb 1 2020, 07:38 PM
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https://twitter.com/Yeqzids/status/1223647437300158464

This tweet (from one of our past students at Western) links to a big collection of PNG versions of the Chang'e 4 and Yutu 2 images, lots of goodies to play with.

Phil



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Phil Stooke
post Feb 1 2020, 07:54 PM
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https://www.hou.usra.edu/meetings/lpsc2020/pdf/2153.pdf

And this LPSC abstract (thanks to Andrew Jones for pointing it out to me) has a map of Yutu 2's travels with those site or panorama numbers I was trying to map earlier. I think this makes it clear they are some kind of observation number, not just full panoramas but also local mosaics (like the impact glass crater) and maybe other things. Some sites have lots of observations, accounting for the apparently missing numbers Doug mentioned.

Phil


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Phil Stooke
post Feb 15 2020, 09:38 PM
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A new paper in JGR-planets:

Lin, H., Xu, R., Yang, W., Lin, Y., Wei, Y., Hu, S., He, Z., Qiao, L. and Wan, W., In situ photometric experiment of lunar regolith with visible and near‐infrared imaging spectrometer onboard the Yutu‐2 lunar rover. Journal of Geophysical Research: Planets, p.e2019JE006076.

explains something about the multiple observations at one target in particular. From 29 March to 1 April the rover performed a photometric experiment with its VNIS, calibrating it under different viewing angles as the rover turned in place.

Phil



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Huguet
post Feb 17 2020, 06:00 PM
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Thanks Phil for the twitter link to the PCAM and TCAM images, i'm just having great fun working with then.

The Rover are taking blocks of images on a very nice pattern, on each stop position. This allow to create 3d models of position shots similar to laser Blocks. Then its just a matter of triangulating the "simulated laser blocks" and geting a very nice detailed terrain and objects models of Moon, Lander and Rover.



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John Moore
post Feb 17 2020, 09:19 PM
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While understanding parts of your graphic entirely, Huguet, which is excellent by the way, I do hope you will expand upon it in final description -- using the laser blocks.

I had a stab at what feature on the aerial view related to the 3D version...so forgive me if incorrect.

Looks like, the OUTER blocks begin from a western position from 48 to 61 east in the top-half of the image in a clockwise direction, and the bottom-half from a western position from 34 to 47 in a counter-clockwise direction.

The INNER blocks are different, in that they begin from a northern position - starting from 34 to 47 anti-clockwise, and from 48 to 61 clockwise.

John Moore

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Huguet
post Feb 18 2020, 12:31 AM
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Hi Jonh,

The only mapping sensor they send with the rover was the PCAM cameras, usualy they could get stereo pairs on the rover direction all the time, but this would limit the mapping area and could generate more black zones without mapping. The best way to map a terrain, by ground view, would be with laser blocks. Its very simple, you just need to change the laser position and take a 360o (or a bubble) cloud of points. Every cloud or block has a internal perfect geometry, we just need to find 3 common points beetween two blocks to triangulate one with the other, and continue this process with the other blocks.

They used this aproach with chang-e'4 rover. Simulating the laser blocks with angular photos with the stereo pcam cameras, inclinating the pcam support or using the rover rotation to expand the distance beetween the images, increasing the acuracy of each 3d block and avoiding black areas.

Within the 5 GB of pics provided of the PCAM cameras, we have lots of group of images to generate 3D blocks. All we need to do is the photogrammetry to generate 3d models of each group of pics, and deal with this 3d models as we would deal with laser blocks, finding 3 common points beetween then and triangulating. This will generate a model with a resolution of more or less 1 point / cm2 of the path of the rover, including the lander model. This full cloud will need to be geo-referenced, we can make this using some know moon points like the center of some craters.

I will isolate the blocks pics ids, the 3d blocks, a full cloud later and post here as RCS (Autocad), LAZ (Globalmapper) or PTS (Text File).

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John Moore
post Feb 18 2020, 01:51 AM
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Thanks again, Huguet...looks like 2D DEMs to 3D bubble DEMs...using laser block technology.

Perhaps, a 'Laser Block' DEM data resource, in the near future?

John Moore
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