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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Full-frame FWHM

Replied by Jasem Mutlaq on topic Re:Full-frame FWHM

That was an interesting read, but without some code, this could take months to develop with my limited time.
6 years 7 months ago #18888

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Yeah code would be awesome, but it's very hard to actual find, I'll try though. In the mean time, maybe another interesting paper providing formulas (which should be possible to code) is nice?
6 years 7 months ago #18890
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Replied by Eric on topic Re:Full-frame FWHM

Just as a reference, there's a nice talk about full frame guiding on TAIC:
(sorry that should indeed be a link to their website instead).
I think the focusing issue is touched at some point.
6 years 7 months ago #18891

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Ah, look at that, the authors of that last paper wrote an actual Python open-source program about it: github.com/johnmgregoire/PyWaveletPeakID

It's all on 1D data I think they mention, would that be problematic given the 2D nature of an image? I read somewhere that a scan in the x and one in the y direction would then work..
Last edit: 6 years 7 months ago by Vincent Groenewold.
6 years 7 months ago #18892

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Stop me if I'm spamming, but here's an interesting one on 2D wavelet analysis including Matlab code (which I doubt is useful): link.springer.com/content/pdf/10.1007/978-981-10-2537-2_4.pdf
The following user(s) said Thank You: Jim
Last edit: 6 years 7 months ago by Vincent Groenewold.
6 years 7 months ago #18893

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Replied by Eric on topic Re:Full-frame FWHM

I don't clearly see what would be the benefit of this fine-grained star detection. I went through the document and observed that the quality metric is mostly the number of stars detected. While there would statistically be a better coverage over the full frame, isn't detecting one single star over 9-square quadrants enough to drastically improve the focus quality? And as mentioned, selecting stars so that they may not be mistaken with others. We perhaps only need a "usual" source detector for this, and a clever algorithm.

-Eric
6 years 6 months ago #18896

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Yes I agree, but to be able to detect more real stars in an image, requires a good algorithm also for that 1 star. It requires to be able to define the edges of the signal, the peak of it etc. If you get that better, it will automatically result in more stars to be detected. Having a good understanding of that peak shape is what makes a good FWHM measurement possible and hence a good focusing procedure.
Last edit: 6 years 6 months ago by Vincent Groenewold.
6 years 6 months ago #18901

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Replied by Eric on topic Re:Full-frame FWHM

Definitely agree, indeed.
About the full frame option (which I'm curious and eager to test), how does it play with the frame average option?
And about the level at which it should be implemented, does it make sense to build an INDI driver in the same way as the astrometry driver?

-Eric
6 years 6 months ago #18905

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Replied by Michael Fulbright on topic Full-frame FWHM

It would be nice to capture any star detection algorithms into a library that could be reused by other projects. That would encourage more people to contribute.

It is unfortunate sextractor isn't workable for this problem.

My honest preference would be to have a focus utility like FocusMax that is independent of any program. Much like I prefer the idea of PHD2 for guiding. And a separate program to control taking sequences of data (break Ekos out), etc.
6 years 6 months ago #18906

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Replied by Jasem Mutlaq on topic Re:Full-frame FWHM

"Full frame" option is how Ekos did focusing when it was first created, but I found it too slow so I went for subframe a single star. The average still works the same way even with full frame. I don't understand what you mean by INDI driver? This is not related to INDI.
6 years 6 months ago #18909

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Replied by Eric on topic Re:Full-frame FWHM

It's probably as much related to INDI as the astrometry driver is. No so much of a hardware driver as a non-intelligent module with input, configuration and output, that can snoop and be snooped.
What if for instance the astrometry driver was divided into a source extraction driver and an astrometry driver using only .xy inputs? This would allow other drivers to use sources, and for the focuser example to convert those sources into HFR records with the help of the original fits file, etc. Then it's up to the client to orchestrate how those drivers play to achieve the intended operation, that is, controlling the focuser driver until HFR is minimal.
My question is actually does this architecture makes sense? I really like the idea behind the astrometry driver, and I think it would be a good idea to continue that way. That's less Ekos and more INDI, but that's also moving code in lower layers.

-Eric
6 years 6 months ago #18998

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Replied by Jasem Mutlaq on topic Re:Full-frame FWHM

So use astrometry.net for source extraction?
6 years 6 months ago #18999

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