Drizzle integration error  

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(@kees_scherer)
White Dwarf Customer
Joined:1 year  ago
Posts: 23
July 17, 2018 13:01  

Module: Integrator. APP v 1.062 Linux Mint Cinnamon 18.3 64 bits.

When i use the same settings, but with integrate Mode No drizzle i do not get this error. See screenshot att. When the text is hard to read itś because ...well, the other topic.

APP drizzle error


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:1 year  ago
Posts: 1634
July 19, 2018 23:17  

Hi Kees @kees_scherer,

Thank you for sharing this issue.

Luckily, I am able to extract vital information from your screenshot, thanks 😉

I think I know why the error occurs.

First of all, as shown in the integration console output, it happens when the Signal-to-Noise calculation is done at the end of integration.

Let's look at the Drizzle settings, you have set it at scale 2x with droplets of 0.5 pixels.

The culprit here will be the amount of images that you have supplied to integrate. Only 16.

One of the requirements for drizzle is lots of data. I wouldn't really recommend to use drizzle with an image count below 40.

The other requirements are:

  • under-sampled data
  • well dithered

Do you meet those 2 requirements with the dataset?

What happens probably happens is, since you only use 0.5 pixel droplets with scale 2x and only 16 images, is that in the final drizzle integrated data, there actually will be lots of pixels with inferieur quality of data or even 0 values. This then probably leads to a problem with noise calculation, where I expect the source of the error message.

Perhaps I can have a look at the 16 images to really find the cause and gracefully solve this?

Mabula

 

 

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@kees_scherer)
White Dwarf Customer
Joined:1 year  ago
Posts: 23
July 20, 2018 08:06  

Thank you for the answer Mabula! I understand now what the problem is and i normally use 2x drizzle only when i have lots of subs. This was a WIP testrun. A clear error message would be helpfull though 😉


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(@kees_scherer)
White Dwarf Customer
Joined:1 year  ago
Posts: 23
July 21, 2018 09:33  

With 48 light frames the 2x drizzle integration runs fine!

2xdrizzle 48lights


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:1 year  ago
Posts: 1634
July 25, 2018 15:11  
Posted by: Kees Scherer

Thank you for the answer Mabula! I understand now what the problem is and i normally use 2x drizzle only when i have lots of subs. This was a WIP testrun. A clear error message would be helpfull though 😉

Thank you Kees @kees_scherer,

Indeed, i have added a fix for this, so it is caught properly, on my ToDo list 😉

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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(@mabula-haverkamp-administrator)
Quasar Admin
Joined:1 year  ago
Posts: 1634
July 25, 2018 15:14  
Posted by: Kees Scherer

With 48 light frames the 2x drizzle integration runs fine!

2xdrizzle 48lights

Excellent Kees @kees_scherer,

That's re-assuring to know 😉

I suspect that with only 16 frames, some pixels in the integration don't receive any drizzle drops.... I know of a way to solve this, so a Drizzle integration with a small dataset can still be created. I'll work on that.

Mabula

Main developer of Astro Pixel Processor and owner of Aries Productions


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