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INDI Library v1.9.7 Released (29 Jul 2022)

Bi-monthly INDI Library released with new drivers and bug fixes.

Cool paper on focusing?

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Link here . It’s from the RAS… is there a function like this in Ekos? Seems like a winner since it doesn’t rely on star detection. I guess they’ve been using it in APT for the last year. 

 
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5 months 4 days ago #81346

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Replied by Kevin Ross on topic Cool paper on focusing?

I don't use APT, so I haven't tried out the new algorithm. But I skimmed through the paper, and it does look quite interesting. They have a Github with code here: github.com/bschulz81/hyperbolicfitdll
5 months 3 days ago #81350

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Replied by Ron DeBry on topic Cool paper on focusing?

There's a CN thread about it, much about publishing, but some talk about their algorithm. 
CN thread
5 months 3 days ago #81351

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This is indeed interesting and was previously brought up by Bob Majewski IIRC. We were missing open source code, but since now we have one, it would be interesting to try out. Bob wanted to use it for guiding so that we can detect shifts in the image overall irrespective of star detection.
Jasem Mutlaq
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5 months 3 days ago #81360

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Replied by Doug S on topic Cool paper on focusing?

The paper and CN comments are interesting. Some cautionary thoughts:

Having a new focus algorithm in Ekos wouldn't necessarily hurt anything, but it may not help much either. The old saying "out of the pan, into the fire" comes to mind.
The paper acknowledges some new algorithm weaknesses, and these are different pains, but on par with existing algorithm weaknesses.
1. Any saturated stars in the image will cause an inverted fitting problem. Until this has been addressed, fast imaging systems (e.g < f/4?) will likely be particularly sensitive to the issue.
2. A quote from the author (CN post): "Starting from nothing is a problem for any algorithm. IMO, a rough focus position is needed to get autofocusing started". This is the same problem ekos currently has (all algorithms), and one of the primary reasons why temperature and altitude focus compensation was implemented (although never integrated).
3. Improperly set step size is a problem. The authors suggest 1/2 CFZ for a step size. I've previously stated that CFZ size is critical (the setting should have been automated). I concur with the 1/2 CFZ size suggestion.
4. The number of images needed is stated from 8-17. That probably excludes any use for guiding assistance (only noted because Jasem raised that question).

In the end, star detection becomes non-problematic, but avoiding star saturation becomes problematic. The same "avoid donuts" starting condition problem prevails, and setting step_size appropriately is equally important.

IMO, integration of temperature based focus compensation (even if using the current config file vs unimplemented GUI) would answer the donuts problem while seriously reducing time consuming focus runs (as focus is updated between exposures...thus tracking longer before another focus run is needed).

See: indilib.org/forum/ekos/7626-temperature-...us-compensation.html

CS... Doug
RASA11, Celestron CGX-L, ASI183mc Pro, 60mm guider + ASI290mm mini, ASI EAF focuser, PPB, Rpi4-4Gb+SSD, Powered USB3 hub, hardwire Ethernet.
Last edit: 5 months 3 days ago by Doug S.
5 months 3 days ago #81373

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