Perseverance Imagery, technical discussion of processing, cameras, etc. |
Perseverance Imagery, technical discussion of processing, cameras, etc. |
Nov 19 2022, 07:27 AM
Post
#166
|
|
Senior Member Group: Members Posts: 2431 Joined: 30-January 13 From: Penang, Malaysia. Member No.: 6853 |
....For WATSON, the best I can offer is the attached image from the calibration dataset (see SHERLOC WATSON Camera Pre-delivery Characterization and Calibration Report... Thanks for that information (from me and others) Were you involved in testing the other cameras such as the NavCams pre launch? If so, is there any publicly available information that you could share (such as released calibration reports / calibration targets used for any of the other M20 cameras) |
|
|
Nov 20 2022, 04:45 PM
Post
#167
|
|
Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
I was involved in the data taking for Mastcam-Z but responsibility for calibration rests with a working group of the science team. There is an open literature paper on that: https://link.springer.com/article/10.1007/s11214-021-00795-x
I didn't have anything to do with Navcam. There's supposed to be enough info in the data product SIS to answer any question one might have. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
|
|
|
Nov 21 2022, 03:03 AM
Post
#168
|
|
Senior Member Group: Members Posts: 2431 Joined: 30-January 13 From: Penang, Malaysia. Member No.: 6853 |
I was involved in the data taking for Mastcam-Z but responsibility for calibration rests with a working group of the science team. There is an open literature paper on that: https://link.springer.com/article/10.1007/s11214-021-00795-x I didn't have anything to do with Navcam. There's supposed to be enough info in the data product SIS to answer any question one might have. Many thanks |
|
|
Dec 23 2022, 10:29 PM
Post
#169
|
||
Senior Member Group: Members Posts: 1669 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
Here's what we have so far with a mosaic from the PDS for Sol 539 using the .png images on the web browser index. Individual contrast stretching was needed and the color balance is different between the lower and upper tier of NavCam images. The "RAD" images were used among the choices. The images are more uniform, since for example the vignetting was removed upstream.
A somewhat improved matching between lower and upper tiers is now in place for Sol 539 within the drive movie. Here is a large format version of this frame. -------------------- Steve [ my home page and planetary maps page ]
|
|
|
||
Feb 13 2024, 02:08 PM
Post
#170
|
||
Member Group: Members Posts: 790 Joined: 9-May 21 From: Germany Member No.: 9017 |
If you have not already done so, you should read this post first.
Thorough information about PCA (principal components analysis) you can find here on Wikipedia. Raw material for my image processing is a set of six multispectral images from Mastcam-Z left eye (ZL1...ZL6) or right eye (ZR1...ZR6). Sometimes I use RGB images (ZL0 or ZR0) when no multispectral images are available. I use the pixel values of the six multispectral images (or of the three RGB channels in a RGB image) as variables to calculate the first three principal components. Sky is excluded (masked) from calculation of the principal components, but resulting coefficients are applied to the sky, too. The image below is a visual explanation of numerical processing steps based on PCA results. A very short summary: It is "painting by numbers". |
|
|
||
Feb 14 2024, 11:24 AM
Post
#171
|
|||
Member Group: Members Posts: 349 Joined: 20-June 07 From: Slovenia Member No.: 2461 |
Tau, thank you for all your efforts to explain the procedure.
I can get the three primary components easily, as the following image shows. What I still struggle to understand is how the rotation in RGB color space (steps r2 and r3) and the resulting blend (pc2+pc3) are accomplished. I can get somethng resembling your final product by performing some band gymnastics, but I'm obviously still doing something wrong. I would really any pointers you can give, thank you in advance. |
||
|
|||
Feb 18 2024, 07:19 PM
Post
#172
|
||
Member Group: Members Posts: 790 Joined: 9-May 21 From: Germany Member No.: 9017 |
Here is a schematic sketch of what is meant by the rotation in the RGB color space from the gray axis to a perpendicular plane.
The color axes of PC2 and PC3 are also perpendicular to each other. Usually, only the resulting image PC1+PC2+PC3 in my previous post is created. All other partial images are just illustrations of intermediate numerical calculation steps. The calculated principal components pc1, pc2, pc3 are centered around 0 (coordinate origin). Scaling and translation: PC1 = a1*pc1 + b1, where b1 is about 128 (center of the RGB cubus with values 0...255) PC2 = a2*pc2 + b2, where b2>0 for a more rust-colored Mars PC3 = a3*pc3 + b3, where b3≈0 Vector addition with rotated PC2 and PC3 in RGB space: R = PC1 + 0.707*PC2 - 0.408*PC3 G = PC1 + 0.816*PC3 B = PC1 - 0.707*PC2 - 0.408*PC3 If any of the values of R,G,B is less than 0 or greater than 255, find the point where the perpendicular line from (R,G,B) to the gray axis meets the cubus surface. If the resulting image has unusual colors (e.g. yellow basalts, greenish dust in ZL0 images), replace a2 and/or a3 with their negative values. |
|
|
||
Feb 20 2024, 07:53 AM
Post
#173
|
||
Member Group: Members Posts: 349 Joined: 20-June 07 From: Slovenia Member No.: 2461 |
Tau, big thanks, it appears it had worked. I've noticed that a lot depends on how you scale your bands. There was a lot of trial & error, before I succeeded. Also some wild color permutations. I still have a lot of details to iron out (like flattening the atmosphere), but I finally get the idea. It is a very elegant analysis tool. |
|
|
||
Feb 20 2024, 10:05 PM
Post
#174
|
|
Senior Member Group: Members Posts: 1057 Joined: 17-February 09 Member No.: 4605 |
I really enjoy Tau's false colour renditions and now yours kymani. They take me back to the early days of Spirit and Opportunity where it was, and indeed still is, such a useful tool particularly in the identification of hematite. In false color the vistas of hematite concretions were at times stunning and it provided a pseudo scratch test of fines from Opportunity's grinds. Thank you for your efforts with tools more sophisticated than I was used to.
|
|
|
Feb 22 2024, 07:39 PM
Post
#175
|
|
Member Group: Members Posts: 349 Joined: 20-June 07 From: Slovenia Member No.: 2461 |
Thank you very much The software has really come a long way since MER rovers, but those were more romantic times in exploration of Mars.
I was also intrigued by tau's processing, so I feel over the moon now for learning the procedure. So the credit is all his. But I have several ideas how to apply this newfound knowledge to some datasets. Will be posting first result in short time. |
|
|
Lo-Fi Version | Time is now: 26th September 2024 - 09:01 PM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |