Re: [hugin-ptx] Digest for hugin-ptx@googlegroups.com - 1 update in 1 topic
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Kurt Hillig
Jul 22, 2018, 7:31:05 AM7/22/18
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FWIW I’ve used Hugin to create night sky panoramas, and I’ve always had to manually define the control points. One star looks pretty much like another, and cpfind can’t easily tell them apart. Even after manually setting points and running one iteration of alignment it still has problems...
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"David W. Jones" <gnome...@gmail.com>: Jul 20 10:11PM -1000
On 07/18/2018 06:22 PM, clepsydrae wrote:
> No -- since the reason for the stack is that I intend to do a gmic
> median_image for the purpose of noise reduction I didn't want to do any
> per-image NR. Would it help for CP-creation?
Possibly. Others can explain about how cpfind works, but I think it
works on areas rather than specific points. Otherwise, how is it
supposed to determine that Bright Spot A in upper left isn't the same as
Bright Spot B in lower right?
> adjustment effectively removed a lot of noise.) I.e. it seems like the
> only way cpfind is finding anything at all is by matching subtle
> variations in the darker areas.
Don't know. I haven't worked with starfield images like yours. Perhaps
setting a few manual control points in Hugin would help get the process
started?
> I confess cluelessness, but it seems like cpfind is not designed to look
> for little bright points in a dark field. but rather to match more
> textural image areas.
Well, it does pick control points on edges of things or where edges
intersect, at least on my ordinary photos.
> stars, defined as less than X pixels in diameter and with a certain
> degree of contrast to the background (or even just a brightness
> threshold as you describe).
That would make sense to me!
> since it seems like it "should" be among the most simple kinds of
> alignment to do, that maybe it's a good suggestion? Or maybe it just
> belongs in a different CP tool altogether.
Something worth mentioning to them. They may know of others using cpfind
in similar situations as yours, people who could give you some ideas.
Somebody has to prepare all those astronomical photos for publication!
> (Or maybe someone knows some magic I can pass to cpfind on the command
> line to make it work!)
Don't know. IIRC, you were having it run with the --fullscale option?
Does it do any better without that?
--
David W. Jones
gnome...@gmail.com
wandering the landscape of god
http://dancingtreefrog.com
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