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INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

For those with focus issues

2 months 1 week ago
hy
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For those with focus issues #51253
Magnus,

Sorry, looked at your log and something is clearly broken (I mean likely software) for your setup.
I'll look further. Which moonlight focuser are you using?

It didn't look to me like you had any successful focus runs with Linear. Is that correct?

Hy

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2 months 1 week ago
mlarsson
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For those with focus issues #51254
Hi!

No problem, just glad if I can on the one hand, understand something, on the other, contribute to your great work!!! :) Maybe I missed some settings?

I'm doing polynomial now, works great with full field :)

I have a MyFocuser Pro (1st version), that I built myself with an arduino board. It controls a Baader Diamond focuser on my Skywatcher 100 ED Pro, f 7.6.

Magnus


C8, Losmandy G11, Canon 1000D astromodified.

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2 months 1 week ago
hy
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For those with focus issues #51255
Magnus,

I may not have much time later today to look into it, but a quick initial look shows that:

Now I'm not sure if it's sortware or hardware.

it is asking the focuser to move to a certain position to start, and the focuser doesn't get there, and the Linear algorithm doesn't
reset to the new position that the focuser is insisting on.

For instance, in the first attempt.
Starts at 10760
Linear wants to start its sweep at 11160, but does this by planning to go out to 11660, then back in 500 to 11160 (It doesn't violate max position, but it is ignoring max travel)
So it requests that the moonlight go to 11660. Indi copies that. But the focuser reports getting to 10916.
*** Do you have some kind of backlash removal active or something like that that could be confusing it?
The Linear focus seems to ignore this discrepancy and then moves back in by 500 which gets it to 10416 (instead of 11660) and now things are messed up and Linear isn't recovering well.

2nd focus session:

Starts at 11000
Plans to go out to 11900 and back to 11400.
But only gets to 11134 and then goes back to 10634.
Same finish as above.

I'm not sure why your focuser is not going out to the position requested in the first outward movement.
It seems to work fine for the inward movements, but not the outward movements.

Does it all work well in polynomial?

Can you manually command it to move out to these positions and back in?

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2 months 1 week ago
mlarsson
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For those with focus issues #51256
Hi!

No backlash removal that I know of... to the best of my knowledge, there is none in the MyFocuser Pro ver 1. And no mechanical stuff like that.

I can try tomorrow to see if I manually can move it to those positons. Right now it is imaging...

Polynomial works fine, and tonight even better than usual (if because we have real clear skies, or because I use full field with annulus set properly, I do not know.

I'll try tomorrow.

Magnus


C8, Losmandy G11, Canon 1000D astromodified.

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2 months 1 week ago
mlarsson
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For those with focus issues #51267
Hi!

So, I have no problems in moving to those positions and positions beyond them (in the 12000 range) manually.

Magnus


C8, Losmandy G11, Canon 1000D astromodified.

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2 months 1 week ago
ChrisRowland
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For those with focus issues #51273
Some focus problems are caused by outliers - hot pixels and extended sources such as galaxies. Would these be more effectively removed by changing the full field HFR determination to use the median rather than the average HFR value. This will cause extreme values to be ignored quite naturally.

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2 months 1 week ago
gilesco
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For those with focus issues #51275

ChrisRowland wrote: Some focus problems are caused by outliers - hot pixels and extended sources such as galaxies. Would these be more effectively removed by changing the full field HFR determination to use the median rather than the average HFR value. This will cause extreme values to be ignored quite naturally.


Or even better discard the 5% smallest and biggest outliers and take the mean of the remaining detections.

__
I blog my progress: www.coochey.net

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2 months 1 week ago
DerPit
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For those with focus issues #51277
With 50+ stars you might as well do a winzorized sigma clipping. Or maybe even linear clipping. For only one 'pixel' the computational overhead is not noticeable.

openSUSE Tumbleweed KStars git INDI git
GPDX+EQMOD, CEM60EC, ASI1600+EFW+EAF+ASI290 mini

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2 months 1 week ago
ChrisRowland
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For those with focus issues #51278

gilesco wrote:

ChrisRowland wrote: Some focus problems are caused by outliers - hot pixels and extended sources such as galaxies. Would these be more effectively removed by changing the full field HFR determination to use the median rather than the average HFR value. This will cause extreme values to be ignored quite naturally.


Or even better discard the 5% smallest and biggest outliers and take the mean of the remaining detections.


Better? Why? How does an arbitrary change to the data make it better?

In actual fact the current code has an undocumented feature where the full set of HFRs is averaged, the standard deviation is determined, values that are more than two standard deviations from the original mean are removed and a new 'average' is determined.
This is statistically dubious, not only does this reduce the mean but the amount by which it is reduced will depend on the data. Maybe extended objects will be included sometimes but not in others.

The median is at least a valid way to determine a central value.

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2 months 1 week ago
ChrisRowland
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For those with focus issues #51279

DerPit wrote: With 50+ stars you might as well do a winzorized sigma clipping. Or maybe even linear clipping. For only one 'pixel' the computational overhead is not noticeable.


What benefit does this have, other than be more complex?

From a look at the code the HFR array is already sorted so getting the median is easy.

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2 months 1 week ago
gilesco
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For those with focus issues #51280

ChrisRowland wrote:

gilesco wrote:

ChrisRowland wrote: Some focus problems are caused by outliers - hot pixels and extended sources such as galaxies. Would these be more effectively removed by changing the full field HFR determination to use the median rather than the average HFR value. This will cause extreme values to be ignored quite naturally.


Or even better discard the 5% smallest and biggest outliers and take the mean of the remaining detections.


Better? Why? How does an arbitrary change to the data make it better?

In actual fact the current code has an undocumented feature where the full set of HFRs is averaged, the standard deviation is determined, values that are more than two standard deviations from the original mean are removed and a new 'average' is determined.
This is statistically dubious, not only does this reduce the mean but the amount by which it is reduced will depend on the data. Maybe extended objects will be included sometimes but not in others.

The median is at least a valid way to determine a central value.


If that is what is in the code then I would leave it as it is, in a binomial distribution 2 standard deviations within the mean would equate to 95% of samples, with those outside being discarded, so pretty much it is already discarding outliers then.

I'm not sure whether using an actual median value would be better in all cases, perhaps it would be nice to have the option to configure it either way.

__
I blog my progress: www.coochey.net

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2 months 1 week ago
TallFurryMan
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For those with focus issues #51282
I wonder if the HFR of stars on a field is always a Poisson distribution. There are probably not enough of them in a focus frame to determine that and use that statistical property.

I am trying to introduce PSF in the CCD simulator to better test the different focus algorithms. SExtractor support will be there too relatively soon. We also need to display an interface for the SEP settings.

We also need to better document the features in the tooltips that appear in the UI.

Anyone has unused work days to spare? ;)

-Eric

HEQ5-Pro - Atik 314E - Orion ED80T - DMK21 on Orion 50mm
DIY 3D-printed Moonlite and FWheel RGB/LPR
KStars and indiserver on two Atom 1.6GHz 1GB RAM Linux, VPN remote access

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