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31 May 2021: APP 1.083-beta2 has been released ! APP 1.083 stable will follow soon afterwards. It includes a completely new Star Reducer Tool, New File Saver Module, Improved Comet registration and much more, check the release notes here!
9-panel Mosaic Difficulties
I have frequent problems trying to register mosaic panels with PixInsight, so I am trying APP. It is registering the panels beautifully, but I'm having a strange problem with integration: the center-most panel is always different from the others (despite them all being processed with identical settings). It's like a square smog bank in the middle of the mosaic.
At first I thought this might be a peculiarity with the subject (M31), or with 9 panels being used, but when I built a mosaic using one raw sub from each panel, it worked beautifully.
I believe I am using all the proper mosaic settings based on the excellent tutorial from Mabula, but it still is not working right. Any ideas what I may be doing wrong?
What are the settings that you have used exactly? Those for tabs 4, 5 and 6 are most important here.
scale stop: 10 (also tried 15)
Dynamic distortion correction ON
Same camera/optics OFF
Registration mode mosaic
registration model projective
All other settings are default
5: All default
2nd degree LNC, 10 iterations
MBB set to 10% (also tried 15)
Frame 5 (the center) was chosen as the reference.
All other settings are default.
Each panel consists of 55 subs, stacked separately in APP with all the appropriate calibration frames. The center frame looks fine on its own, it's only after the integration that it seems to be mangled.
@mountainair Thanks that's very useful info. I forgot to ask about tab 3, sorry.
If you haven't changed the setting in tab 3 then try setting the number of stars to 2500 or 3000. Sometimes an even higher number is needed!
set scale start to 5, scale stop to 12 or higher
That should all be fine
Please try that (leave all other settings as you had them) and let us know if that worked.
@wvreeven Excellent, thank you. I will kick off another attempt with these settings in a few minutes.
Note, in step 3 for mosaics with lots of stars I always try around 5,000. I think it was consistently picking up close to that in each panel.
@wvreeven This seems to have worked! Now which one of those variables helped, I wonder?
I had already tried scale stop 15, so I don't think it was changing from 10 to 12.
I had tried quadrilaterals and pentagons, and all the panels registered OK (I'm assuming the weird thing in the middle wasn't a registration issue, because I wasn't missing any panels elsewhere). So, I don't think it was the triangles setting.
I suspect it was the normalization mode change from regular to advanced. If I get time I'll test that, but right now I have an image to process.
Thank you, @wvreeven!!
Glad that it helped! It must have been the combination of triangles and using the advanced mode but that latter change probably had the biggest influence.