Large Mosaic Errors
 
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Large Mosaic Errors


(@mountainair)
White Dwarf Customer
Joined: 2 years ago
Posts: 19
Topic starter  

Hello, I recently stitched together a 6-panel mosaic with APP and it came out well (as others have).  However I may have gotten a bit over-ambitious with a 9-panel mosaic consisting of ~70 x 123MB frames each.  The result, after nearly two weeks of processing (I needed 7TB of temporary work space, which I didn't have on SSD so I had to use a -- gasp! -- spinning hard disk).

The result looks like some panels didn't register correctly, the blending went crazy between most panels (but strangely, also within a panel), and there are even joints that look like there's some kind of spatial anomaly.  Crescent also appears twice.

I'm not sure what may have gone wrong.  I'm running the latest beta on Apple M1 Max, 32GB RAM.  From the defaults in the APP beta, I changed Analyze Stars to 1000 (there are tons of them in this super-wide-field shot), Registration Mode to Mosaic, Scale Stop set to 10, Use Dynamic Distortion Correction and Same Camera and Optics are on, Normalize is set to Advanced, LNC is 1st degree 3 iterations, MBB is enabled at 10%, and each of my panels should have 20% overlap minus dithering.

I would try stitching the panels together via other means, but it looks like APP didn't save the individual stacked panels.

I'm about to blink through >600 frames to see if any of them were significantly off-target, but as these were 70-minute durations on a good mount, I don't see how (and I did blink them all initially).

Any ideas what may have gone wrong?  See attached photo.  

I do have an 8TB SSD array now, but I still wouldn't want to try processing this again unless I have a decent idea as to what to change.

Screen Shot 2022 07 19 at 9.37.34 AM

 


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(@mountainair)
White Dwarf Customer
Joined: 2 years ago
Posts: 19
Topic starter  

It appears the last 10 frames of Panel 5, which I took 3 days later, appear to be off by slightly over 2.5° north.  Crescent isn't even visible in those subs like it is in the rest of panel 5.  But APP should register that by star alignment, not filename.  So I get more signal where I didn't want it, and less where I did.  It shouldn't have caused this, correct?

Unrelated question, is there any way to "re-load" the last session in APP?  I've been keeping it open so I can troubleshoot, but I tried command-tab to another application and accidentally hit command-q to quit!


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(@wvreeven)
Galaxy Customer
Joined: 4 years ago
Posts: 2091
 

@mountainair Hi!

In case of large mosaics like this, it saves a LOT of time by processing the individual panels first. Then load each panel integration result as light (no calibration data!) and create the mosaic from those.

Regarding creating mosaics, make sure to use these settings:

Tab3: set the number of stars to at least 2000 and preferrably higher
Tab4: set scale start to 5 and scale stop to 12 or higher. Set registration mode to mosaic.
Tab5: set mode to advanced.
Tab6: enable MBB and set to 15 or higher

Regarding reloading the last session in APP: this will be part of APP 2.0.0 final. We are still in the beta phase so this isn't possible yet.

 

Wouter


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(@mountainair)
White Dwarf Customer
Joined: 2 years ago
Posts: 19
Topic starter  

Great, thanks Wouter.  I will try that.

In addition to being able to save/reload a "project" file list for later re-processing, it would be great if I could also have it save the individual panels as it's doing the mosaic.  Then if something goes awry I can reload the stacked panels as separate light frames as you suggest.

Your assistance is much appreciated!


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