Author Topic: Weighting expression in new subframe selector process vs script  (Read 951 times)

Offline cmassa

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I've been using the SFS script with a weighting expression that comes from an Excel spreadsheet which I believe is based on expressions by David Ault.

Since I installed the newest PI version, I've tried to use these expressions in the new SFS process but it doesn't seem to work and I've had to continue using the script. Here's a sample weighting expression which comes from the spreadsheet:

35*((1/(FWHM^2))-0.0176103417091248)/0.0781904499199779 + 7*(1-(Eccentricity-0.27988)/0.22451) + 18*(SNRWeight-2.19309)/2.96143 + 40

When the above expression is put into the SFS process and I activate it, the weighting does not change. If I put in a much more simple expression that I found on the forum, then it will work but the weighting comes out to be small numbers (0 to 2). In the SFS script, the above weighting expression will result in weighting between 0 and 100 (Well, I guess that 40 is actually the lowest).

Is there something about the above expression that makes it not work?

Thanks for any advice,
Chris
iOptron CEM60, Celestron Advanced VX mounts
Celestron 8" EdgeHD SCT, Astrotech AT65EDQ
Atik 383L+ mono, EFW2 Filter wheel, Baader filters,Canon T2i/550D, self modded with Baader IR
Astrotech 50mm guides scope
ZWO ASI120MC - guiding and planetary imager
My images: http://www.astrobin.com/users/cmassa

Offline cmassa

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  • Posts: 48
Re: Weighting expression in new subframe selector process vs script
« Reply #1 on: 2019 February 02 10:16:08 »
Well, after some more digging I guess I figured it out. I changed it to:

35*(1-(FWHM - FWHMMin) / (FWHMMax - FWHMMin)) + 7*(1-(Eccentricity - EccentricityMin) / (EccentricityMax - EccentricityMin)) + 18*((SNRWeight - SNRWeightMin) / (SNRWeightMax - SNRWeightMin)) + 40

And it worked. I copied another expression from the forum and changed the numbers a bit. I'm still not sure why the original expression which had some of the calculations already done wouldn't work. Is there one of the functions that doesn't work in the new process?

Chris
iOptron CEM60, Celestron Advanced VX mounts
Celestron 8" EdgeHD SCT, Astrotech AT65EDQ
Atik 383L+ mono, EFW2 Filter wheel, Baader filters,Canon T2i/550D, self modded with Baader IR
Astrotech 50mm guides scope
ZWO ASI120MC - guiding and planetary imager
My images: http://www.astrobin.com/users/cmassa

Offline cmassa

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  • Posts: 48
Re: Weighting expression in new subframe selector process vs script
« Reply #2 on: 2019 February 02 10:32:41 »
After a little more playing with it, it seems that the function (FWHM^2) doesn't work in the new process. I'm far from a mathematician but I assume that means FWHM squared. If I change it to (FWHM*FWHM), then the expression works.

Chris
 
iOptron CEM60, Celestron Advanced VX mounts
Celestron 8" EdgeHD SCT, Astrotech AT65EDQ
Atik 383L+ mono, EFW2 Filter wheel, Baader filters,Canon T2i/550D, self modded with Baader IR
Astrotech 50mm guides scope
ZWO ASI120MC - guiding and planetary imager
My images: http://www.astrobin.com/users/cmassa

Offline msmythers

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Re: Weighting expression in new subframe selector process vs script
« Reply #3 on: 2019 February 02 14:19:57 »
Chris

Take a look at this posting. It might have some be of some help.

https://pixinsight.com/forum/index.php?topic=13129.msg79783#msg79783



Mike