I want to second the recommendation to manually provide a good guess for
the field-of-view. And at least initially to not include it as an
optimisation parameter. In Photos > Optimize > Geometric select "Custom
parameters", then an additional "Optimizer" tab appears, and and there
with lens parameters you check b, d, e.
If things are ok, you may check v as well. But given that telescopes are
strongly tele, this can lead to unwanted funny behaviour. The v
parameter may wrongly deputise for higher distortion parameters that the
hugin lens model lacks.
Better not use the parameters a and c. They are mathematically flawed.
If there were more than one good distortion parameter in hugin, b that
is, alignment errors could be even in the 1/10th to 1/100th pixel range.
Caveat: noise-filtering cameras might spoil your star positions
(blackfield correction is ok). On a good image (I have not tested with
stars), the hugin "Finetune" should be good to 1/5 to 1/10 pixels per
individual Control Point.
On 16.12.20 00:28, [email protected] wrote:
I've used Hugin to stitch a variety of astro photos; overlapping star
fields are excellent for determining your lens parameters, as there
are guaranteed to be no (detectable) parallax errors. The challenge
is to select enough star pairs in overlapping images - the automatic
control point detection can't always tell which star is which so I
generally end up adding and fine-tuning control points manually
(current Hugin versions might be better, it's been a few years since I
last tried this). But with 20 or so control points between each image
pair, and optimizing everything except translation (I use the Expert
interface) I've routinely gotten the errors down to one pixel or less.
But it does help to start with something close to the correct FoV -
telescopes in general don't tell the camera their focal length (or
anything else) so the EXIF data doesn't give Hugin enough information...
On Tuesday, December 15, 2020 at 4:51:23 PM UTC-5 dkloi wrote:
You should enable the advanced or expert modes where you have the
option to control what parameters are optimised. You may want to
optimised individual parameters, or certain subsets. If you know
your effective horizontal field of view for each image, you can
enter that value and disable its optimisation whilst allowing
other lens parameters to be optimised. It would help if you could
post examples or the source images so that we can see what is
going on.
On Monday, 14 December 2020 at 15:05:01 UTC [email protected] wrote:
Hi Daniel,
I've been trying to use HUGIN to stitch mosaics of the
Rosette nebula and ended up with a distorted image. Part of
the nebula was missing and kind of squeezed together new the
middle. The preview image showed that some of the segments
were turned slightly. I have come to the conclusion that my
problem is the fact that HUGIN corrects for all kind of
effects such as curvature or perspective, etc which are common
in terrestrial imaging using different lenses. However images
shot with a telescope of objects in the night sky are for all
practical purpose FLAT.
It sure seem like HUGIN is a very powerful program, but does
it have a simple flat stitch function that will allow the
stitching of images without turning or skewing the segments? I
see that there are all kinds of different options to use for
stitching unfortunately I not familiar with any of them.
Your suggestion would be greatly appreciated.
Thanks
Nor
On Thursday, December 3, 2020 at 7:26:27 AM UTC-5 nor s wrote:
Hi Daniel,
Wow you sure have that process down pat. I will have a
closer look at your steps and see how they will work on my
stuff.
Cheers
Nor
On 12/3/2020 6:56 AM, 'dkloi' via hugin and other free
panoramic software wrote:
Stitch looks good. You can see in the stitch tab that the
FOV is now a more reasonable 4 deg x 5 deg. The
optimisation process seems to have come up with a more
proper value for the lens HFOV.
I have made available example Hugin pano projects at:
http://www.dkloi.co.uk/?p=1490
http://www.dkloi.co.uk/?p=1501
http://www.dkloi.co.uk/?p=1518
They are for complete panospheres but many of the the
basic concepts are unchanged for a partial pano and may
be useful for gaining familiarity with Hugin.
On Wednesday, 2 December 2020 at 18:16:46 UTC
[email protected] wrote:
HI
I've been playing around with Hugin 2019.2 and
finally got it to work today. Yes the finished size
is rather large since each segment is 3020x1985 which
roughly translates to 6040x7940 as the completed 2x4
mosaic. I've attached a finished mosaic and the
screen capture of the stitcher tab that I finally used.
Not really being familiar with this program I was
just poking and hoping that something would work.
ONce I have it all figured out I'll put together a
work flow.
Thanks for the reply.
Cheers
Nor
On 12/2/2020 10:24 AM, 'dkloi' via hugin and other
free panoramic software wrote:
Welcome to the group. It would help if you could
provide the images. You should be able to stitch
astronomical images together. I note on the log file:
Number of active images: 3
Output exposure value: 0.0
Canvas size: 6040x7940
ROI: (0, 0) - (6040, 7940)
FOV: 360x473
Projection: Equirectangular(2)
The FOV is a bit big (473 deg vertically), this is
probably causing the problem. The FOV of you images
are probably too large, this can be manually set (by
specifying the focal length and crop factor) but
this may have been optimised to the wrong values,
leading to the problem.
Once we can see the photos and your Hugin project
file, we can tell you more.
On Wednesday, 2 December 2020 at 06:13:03 UTC
[email protected] wrote:
Hi,
A little about me. I've been doing
astrophotography for many years and occasionally
want to image an object that is larger than the
field of view of my equipment. The obvious way
of doing that is to image the object in
sections and then stitch them together to form
one complete image. In the past I have been
using photoshop to manually match the segments
and back grounds. A difficult problem at times.
An acquaintance put me on to Hugin so I loaded
up version 2012 and gave it a try on
the, Pleiades. To my pleasant surprise it did a
very good job of combining the 2x3 image grid
into a single picture.
Later When I tried to open Hugin again, it
requested the lens info twice and then quit. I
tried it several more time even after rebooting
the PC but still no luck. I decided to un
install2012 and get the latest from the website
2019.2 for 64bit WIndows10 PC.
When I first started the new version it
complained about open GL not available. After
rerunning it I got no more errors and loaded my
8 images 2x4 grid mosaic. Each image is
3020x1985 with an overlap of about 10%. I
selected the points automatically but noticed
there were no points is some of the images on
the top and bottom edge so I added them.
Finally when I click the STITCH button it fails.
The log is attached.
Any help would be appreciated. If I'm using the
wrong program to stitch these mosaics together
perhaps someone can recommend one that would
work better.
Thanks
Nor
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