Mosaic seems to be ...
 
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Mosaic seems to be adding artifacts  

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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 7, 2021 20:37  

Before anything I have verified that stacking both panels seperately does not produce the artifacts, this only seems ot be happening when I use the Mosaic Funcion in APP, you can see here some of the artifacts.  The artifacts get worse the higher the LNC Degree and/or iterations of LNC

image
image
image
image

Last image above here is the same region with just the single panel stacked and STF applied as above

image

As I said, if I stack both the panels seperately there is no issue, but then I cannot perform the mosaic stack, and believe me the mosaic stack method is far more reliable (aside from the artifacts) than any other method I have found.

But I would really like to find out why the artifacts are appearing.

All settings are default except for

4. Register
Scale Start = 1
Scale End = 10
Use Dynamic Distortion Correction
Registration mode = Mosaic

6. Integrate
LNC Degree = Tried 1 or 2
LNC Iterations = Tried 1, 2 and 3 with above
Enable MBB 20% (Frames overlap by 20%)

Everything else is defailt

Anyone else experienced these kinds of artifacts with Mosaic Mode?

Simon

 

 

 

 

 

 


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 7, 2021 20:44  

Mmm interesting, these look like hot-pixels. However, if you already stacked the panels that should be gone. Would you be able to share the data (just the minimum which produces the issue) to our server?

Go to https://upload.astropixelprocessor.com and use upload1 as username and upload1 as password.

Create a directory named “stastro-mosaicartefacts” and upload in there. Thank you!

 


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 7, 2021 21:26  

@vincent-mod I do not have specific frames that cause this, and it happens in both panels during the mosaic, but none of the panels when processed seperately, I am going to re-run with Mosaic but without LNC and see what happens, I have Over 160 frames each are 62mpx


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 7, 2021 21:42  

@vincent-mod  Also if it was hot pixels, I would expect all the artifacts to show up in a similar pattern, which they do not, would you agree?


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 8, 2021 19:57  

@vincent-mod I fixed it by adding Sigma Rejection, sigma rejection gets rid of the artifacts

Note to self....Use Sigma rejection on Mosaics 🙂


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 9, 2021 10:57  

Interesting, I thought the panels would already have had rejection applied as you didn't see the issue on those? Otherwise I'd advise to use it also for regular data.


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 9, 2021 17:16  

@vincent-mod Yeah I have never had to use any rejection method in the past, this is the first time with creating a mosaic in APP, for normal frames I never use rejection method


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 9, 2021 17:34  

Could indicate that your camera has developed some hot pixels maybe. The automatic setting in tab 6 will always use rejection based on the number of frames. It shouldn't affect your data in a negative way really, as the kappa values are pretty mild.


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 9, 2021 17:58  

@vincent-mod I would agree but if that was the case then they would show up when stacking the single panels


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 9, 2021 18:56  

I agree, that is indeed puzzling. I think more data/investigation will tell us what's going on. 🙂


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 9, 2021 19:57  

@vincent-mod too much data to upload, it's around 27GB in total 😀


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 9, 2021 20:32  

I meant, for you to take more data so it may become clearer. 😉


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 10, 2021 09:29  

@vincent-mod So I created some new darks last night, and processed without any Rejection Algorithm and the artifacts are there in exactly the same place, so it cannot be due to hot pixels


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 10, 2021 09:45  

Well it could still be as darks are not necessarily getting rid of 100% of them, as that would usually cause more data damage. This is where the rejection algorithms do the final touch basically.


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 10, 2021 10:32  

@vincent-mod  Still doesn't explain why I do not see them in normal stacks, when I do not use any rejection algorithm at all (And have not done since I started using APP), I even processed with the new Darks and still no artifacts, it only seems to be happening in Mosaic mode


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 10, 2021 10:54  

Yes, that remains odd. Do you want to upload the panels? Would be interesting if I can replicate that.


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 10, 2021 12:08  

@vincent-mod Do you have enough capacity? 😀


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3694
February 10, 2021 12:11  

🙂 We do, but wouldn't just say, 2 panels also show the issue? Just the already integrated panels I mean.


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 10, 2021 12:24  

@vincent-mod OK I'll upload the following

1. Mosaic Integration
2. Panel 1 Integration
3. Panel 2 Integration

Would that be OK?


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(@stastro)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 37
February 10, 2021 12:26  

Also is there a way to perform the Mosaic on the two separate stacks?  So basically if I take the two separate stacks, can I perform a Mosaic function in APP somehow?


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