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Large mosaic registration problems

3 Posts
2 Users
Red Giant
Joined: 5 years ago
Posts: 40
Topic starter  

Hi.  I have gathered all the OSC panels for the second half of my full Milky Way mosaic, however they are not registering correctly.   I am using exactly the same settings as I used on my Carina to North America mosaic which worked very well

From the attached images you can see that the Vela region by itself registered ok as did the region from Orion to Taurus, but registering all together fails.

All Vela test fail
Summer Milky Way all panes test 1 1.083 fail
Milky Way Taurus   Orion Successful
Vela 8 pane success


I have tried 2.0.0 betas 4 and 13 and both fail quite badly.  (13 worse than 4)

I reverted to 1.83.2 and it seems to do a better job but still not right with just a few panes not registering and highly distorted.

Can you suggest what might be going wrong ? 

Important Settings as follows :

Analyse stars set to 10,000

Mercator projection 40mm / 4.63um pixel size  

Registration pane changed to somewhere near the middle of the mosaic  (reduces distortion of the finished mosaic)

Pattern recognition : triangles

Scale start : 1 / Finish : 15

Dynamic distortion on / same camera and optics off

Other notes :  Not all panes are exactly the same size.   Most are 4137x2815 +/- 2 pixels but one is 4121x2796 and one is 4137 x 2837.  (from my previous successful Milky Way I found they had to be very similar in size)    Also I think a couple of pane pairs have only about 10% overlap

Any advice would be much appreciated.



Kelvin Hennessy


Universe Admin
Joined: 6 years ago
Posts: 5386

That looks like the dynamic distortion correction going wrong. Could you try to see what happens when you switch that off when you combine both regions? I also think you don't need 10.000 stars, try it with 2000 on the latest beta.

Red Giant
Joined: 5 years ago
Posts: 40
Topic starter  

  @vincent-mod thanks for the advice.   I ended up going back to basics using the settings from the old mosaic tutorial on this site, then gradually added different processing combinations over a couple of days.   Here is a draft version of the processed results.    I still have much work to do on the doubled-up stars in certain areas and different star sizes between some panes - I consider this quite messy.  I will likely capture some more frames with the dual OSC camera rig on pane-pairs where there is small overlap which clearly causes problems.  (as well as capturing Hydrogen Alpha & Oiii panels to blend in sometime in the future )


For anyone who is interested here are my settings:

Roughly 7 x 4 mosaic using dual cameras : ASI294MC Pro & Sigma 40mm F/1.4 at F/2.8 plus CentralDS modified Canon 6D & Sigma 85mm F/1.4 at F/2.8

All images per pane  integrated with calibration frames (flats / dark flats / darks)  and light pollution removed.

All panes then registered & integrated in mosaic mode with the following settings

APP version 2.0.0.beta13

10000_stars analysed

Quadrilaterals Scalestart 5 Scalestop stop 10   Integration reference changed to a panel near the middle

Dynamic distortion on

Same camera and optics on

MBB 20 / LNC 2 iterations 5

Integration Scale 1.0   (1.6GB output TIF file !  )

Saved as 15% BG 3 sigma 2.5% base  Adobe_RGB_1998

Star and starless layers separated  in Photoshop using RC Astro StarXterminator

Noise removal via RC Astro NoiseXterminator

SUmmer Milky Way test run
SUmmer Milky Way test run unedited


Star reduction using RC Astro StarShrink