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Perseverance Imagery, technical discussion of processing, cameras, etc.
phase4
post Feb 26 2021, 07:10 PM
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QUOTE (mcaplinger @ Feb 26 2021, 08:00 PM) *
Pixel size is 7.4e-6 m = 7.4e-3 mm, is that what you were using?


Ah thank you, I used 0.074 mm instead of 0.0074. Things are obviously ok now. biggrin.gif


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fredk
post Feb 26 2021, 07:21 PM
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In a previous post I estimated the horizontal FOV to be 19.5 degrees for an image with a "34" focal length filename field. I said there that that was near the maximum FOV of 19.2 deg, but I mistakenly used vertical FOV, not horizontal. My measured 19.5 deg corresponds very closely to the max horizontal 25.6 scaled from 26 to 34 mm, so everything is consistent with a 34 mm focal length (apart from the statement yesterday as Doug mentioned).

And we seem to have a little bonus of around 1608 horizontal pixels, vs the 1600 photoactive stated in Bell etal.
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MahFL
post Feb 27 2021, 11:19 PM
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Is there a way to tell the zoom used from the MastCamZ file names ?
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mcaplinger
post Feb 27 2021, 11:31 PM
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QUOTE (MahFL @ Feb 27 2021, 03:19 PM) *
Is there a way to tell the zoom used from the MastCamZ file names ?

Yes. See post #25 in this thread.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Greenish
post Mar 1 2021, 04:36 AM
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It appears the JSON data for the Sol 9 images has corrected the CAHVORE formatting issue we saw in the earlier image metadata (i.e. in correct order).
I wonder if it was a different version effect from the cruise software load.
CODE
            "camera": {
                "filter_name": "UNK",
                "camera_vector": "(0.6929857012250769,-0.7042489328574726,-0.1542862873579498)",
                "camera_model_component_list": "(1.10353,-0.008945,-0.729124);(0.884935,-0.17181,0.432865);(2606.49,1675.44,1273.54);(747.819,-326.9,2757.19);(0.885293,-0.171227,0.432363);(1e-06,0.00889,-0.006754);(-0.006127,0.010389,0.004541);2.0;0.0",
                "camera_position": "(1.10353,-0.008945,-0.729124)",
                "instrument": "FRONT_HAZCAM_LEFT_A",
                "camera_model_type": "CAHVORE"


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djellison
post Mar 1 2021, 04:43 AM
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The front hazcams have quite a significant toe-out between them. ~20deg.
page 17
See https://www.ncbi.nlm.nih.gov/pmc/articles/P...Article_765.pdf
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MarkL
post Mar 1 2021, 08:14 PM
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QUOTE (JohnVV @ Feb 26 2021, 12:56 AM) *
just came across a paper on the cameras and mic



Thank you!
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PDP8E
post Mar 1 2021, 11:07 PM
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The cameras used for rover lookdown and lookup are AMS CMV20000

here is the datasheet from AMS

https://ams.com/documents/20143/36005/CMV20...e1-428cb363ab0a

Maybe the lookup camera can be used for stargazing, cloud studies, tau....

My debayer program is still a little wonky green

(are there R and B multiplier 'factors' known for this camera?)

I downsized it to fit in 3MB here
Attached Image


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CLA CLL
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Andreas Plesch
post Mar 2 2021, 03:19 AM
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Since I believe this may not have been mentioned, it is useful to know that the rss API json feed allows for just returning a single record based on id. It has an id query parameter.
So one can browse to find an image, say

CODE
https://mars.nasa.gov/mars2020-raw-images/pub/ods/surface/sol/00002/ids/edr/browse/edl/EDF_0002_0667111022_758ECV_N0010052EDLC00002_0010LUJ01.png


and then use the id (filename without suffix) to get the record:

CODE
https://mars.nasa.gov/rss/api/?feed=raw_images&category=mars2020&feedtype=json&id=EDF_0002_0667111022_758ECV_N0010052EDLC00002_0010LUJ01

For example, this is interesting pointing out that the downlook rover camera does not have any interesting additional data.

[edit:] If the filename for the image has trailing digits as in https://mars.nasa.gov/mars2020-raw-images/p...2_06_0LLJ01.png, for some cameras (not sure which ones) it is necessary to omit the trailing digits (here "01") for the json id: https://mars.nasa.gov/rss/api/?feed=raw_ima...AZ00102_07_0LLJ

EDF_0002_0667111022_758ECV_N0010052EDLC00002_0010LUJ01 (for EDL) vs.
FLE_0009_0667754529_115ECM_N0030000FHAZ00102_07_0LLJ (for FHAZ)



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Greenish
post Mar 2 2021, 03:23 AM
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Good info from Emily Lakdawalla on twitter:
QUOTE
@elakdawalla 8:54 PM · Mar 1, 2021
- I just got off WebEx with Justin Maki, who leads of the Perseverance engineering camera team. I've learned a lot and gotten a lot of confused questions sorted out. I'll try to bang out a blog entry with lots of techy detail about raw images tomorrow.
- The TL;DR: of the interview was: a lot of the things that are weird and confusing in the raw image metadata from sols 1-4 have to do with the rover being on the cruise flight software at the time.
- For example, the cruise flight software did not "know" how to automatically create image thumbnails. So they had to instruct the rover computer with separate commands to make thumbnails for each image, which is why sequence IDs don't match up between thumbnail and full-res.
- Many of the more confusing issues were solved by the flight software update. They're going to continue to tweak parameters over the next week or two, testing to see what modes they like best for returning their data, but before long they'll settle into some routines.
- It's SO FUN to see this process working out in real time. They *could* hold all the images back until they're happy with their tweaking, but they're not. They're just shunting the images out, never mind the temporarily wonky metadata.
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JohnVV
post Mar 2 2021, 03:26 AM
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QUOTE
My debayer program is still a little wonky green


have you tried the debayer in G'Mic
https://gmic.eu/
CODE
gmic input.png bayer2rgb -o output.png

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fredk
post Mar 2 2021, 06:02 PM
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Yeah, gmic gives the same wonky green/yellow cast. The particular deBayering interpolation algorithm shouldn't determine the overall hue (but may affect pixel-scale chroma details). What a deBayering by itself gives is known as "raw colour", and won't generally look right because the relative sensitivities of the RGB channels differ from those of the eye. DeBayered images released have similar casts, eg:
https://mars.nasa.gov/mars2020-raw-images/p...0_01_295J02.png

A simple relative scaling between RGB channels, ie a whitebalance, should help a lot with these images.
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fredk
post Mar 2 2021, 07:48 PM
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QUOTE (fredk @ Mar 2 2021, 07:02 PM) *
A simple relative scaling between RGB channels, ie a whitebalance, should help a lot with these images.

If the black level isn't maintained during the autostretch which is done on the public engineering cam frames, then such a simple fixed RGB scaling won't work for all frames and we're left with trial and error. So it could be that different tiles of a full frame navcam would need different colour adjustment.
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lingyuk
post Mar 3 2021, 07:58 AM
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So, as I understand it - Perseverance has the ability compress frames into .MP4 files? And the landing videos posted by NASA on youtube were uploads of those MP4 files? And the rover will later send all of the full resolution frames (1000s of them) of the landing?

My question is: are those MP4 files available anywhere to download? Has NASA made them available?

Because Youtube compresses videos a lot, and the original files would have a lot more detail. Thanks!
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MarkL
post Mar 3 2021, 05:54 PM
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QUOTE (lingyuk @ Mar 3 2021, 08:58 AM) *
My question is: are those MP4 files available anywhere to download? Has NASA made them available?

Great question. JPL ws able to get video footage very quickly and there are still a lot of individual frames to be published so these must have been videos created by the cameras and uplinked on Sol 1.

Where are the raw video files do you suppose?

Can we get our hands on them?
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