Author Topic: Continuing problems with Mosaics.  (Read 2057 times)

Offline Robert Q. Kimball

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Continuing problems with Mosaics.
« on: 2016 October 04 13:08:10 »
Hello,

I am fairly experienced with PixInsight but continue to have problems with building a mosaic from four panels.  Earlier a participant, pfile, gave me some great advice, but I still can't get my a mosaic from my data.  I have watched "Creating a Seamless Supermosaic, by Steve Allan" on YouTube many time and completely understand it.  I just can't get it to work. 

First, all of my four panel can be registered in pairs, ( ie. 1+2, 2+4,4+3, and 3+1)  there is no problem with star registration.

Here is what happen. Each time I add a panel to the mosaic, the added panel is "redder" than the first panel.  by the time I add the fourth panel the image is very, very red.  Each added panel seems to have a more blurry noise background.

Here are links to the four panels.  Any help would be appreciated. 

https://www.dropbox.com/s/2g33nlxlo8axb69/Heart_Panel_1_DBE.xisf?dl=0
https://www.dropbox.com/s/14gy55gg4t895p0/Heart_Panel_2_DBE.xisf?dl=0
https://www.dropbox.com/s/bobrfc8tlfvyoty/Heart_Panel_3_DBE.xisf?dl=0
https://www.dropbox.com/s/8x710o300nnx7ro/Heart_Panel_4_DBE.xisf?dl=0

Bob

Offline pfile

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Re: Continuing problems with Mosaics.
« Reply #1 on: 2016 October 04 14:24:25 »
i successfully made a mosaic from the data. i first used the dnaLinearFit script to match the brightness of each frame. 1 as reference to 3 and 2, then 3 to 4.

i then used staralignment in mosaic mode to build the mosaic; 3 as reference to 1, then the combined as reference to 4, then the combined as reference to 2. it turned out that the dnaLinearFit was not perfect, so i turned on 'frame adaptation' in star alignment and did it all again.

p.s. there is some problem with panel 4 - horizontal streaks in the stars. there must have been a bad frame in the integration.

rob

[the xisf is uploading, i'll edit the post when it's done.]

https://drive.google.com/file/d/0B6cW4ae2KyMJNXVrNUdzX0NEdEU/view?usp=sharing

« Last Edit: 2016 October 04 14:38:39 by pfile »

Offline Robert Q. Kimball

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Re: Continuing problems with Mosaics.
« Reply #2 on: 2016 October 04 15:50:12 »
pfile,

Thank you again.  I'll see if I can duplicate your effort.  I'll figure out dnaLinearFit!  Now I owe you two beers in Las Cruces!

Bob

Offline Robert Q. Kimball

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Re: Continuing problems with Mosaics.
« Reply #3 on: 2016 October 04 16:04:44 »
Feeling like an idiot.  How do I get dnaLinearFit?

Bob

Offline pfile

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Re: Continuing problems with Mosaics.
« Reply #4 on: 2016 October 04 16:12:27 »
its a script written by david ault:

http://trappedphotons.com/blog/?p=994

middle of the page, under "intensity matching"

dnaLinearFit might not be necessary - did you use frame adaptation when you made your attempt? i didn't try skipping the dnaLinearFit step so i'm not sure if it helped SA get a better result when doing frame adaptation.

rob


Offline gvanhau

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Re: Continuing problems with Mosaics.
« Reply #5 on: 2016 October 06 11:09:53 »
Hello Bob
A different aproach would be:
Generate a star field the size of your whole mosaic, then register all the tiles to if.
finally use gradient merge mosaic to combine the registerd tiles.

Regards
Geert
Geert Vanhauwaert

Offline Robert Q. Kimball

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Re: Continuing problems with Mosaics.
« Reply #6 on: 2016 October 06 12:21:47 »
Hello Experts!

I still can't get a good mosaic from my panels.

I have put together matrix images before without any problems.  I think my problem has to do with my use of SGPro as my capture program.    When I use Artemis my debayer matrix was BGGR.  I was surprised that when I switched to SGPro the matrix changed to GRBG.  Whether this has any relationship to my mosaic issue I don't know.

I have tried to simplify my issue with new, better data.  I appreciate the help I've already received for Rob (pfile) and others.

Here are two panels each the integration of 4 X 10 min images with an Atik 3833L OSC camera.  I have carefully used DBE, Background Neutralization and Color Calibration to get them very similar in intensity.

https://www.dropbox.com/s/9d4im49ruamhmgm/Panel_1_DBE.xisf?dl=0
https://www.dropbox.com/s/rg6n6irxecj7tpv/Panel_2_DBE.xisf?dl=0

Then I did a Star Alignment using Mosaic/Union.  If you look closely at the resulting mosaic, the two images are very different in "background texture".  This didn't happen when I did the same type of combination with images captured using Atik's capture program Artemis.

https://www.dropbox.com/s/ol2lcmf4030lfmg/Mosaic.xisf?dl=0

The more panels I add the "creamier" the background gets.

I have also tried the Gradient Merge tool on this data and got terrible results.

Any help is welcome.

Bob


Offline chris.bailey

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Re: Continuing problems with Mosaics.
« Reply #7 on: 2016 October 07 00:42:28 »
Strange, I get very different results from using using the parameters below, the result is pretty much seamless??

I find Star Alignment - Union/Mosaic with Frame Adaptation and Distortion Correction works pretty well for two panel mosaics. Its when you get to 4 and above that more complex methods are called for.

Chris

Offline Robert Q. Kimball

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Re: Continuing problems with Mosaics.
« Reply #8 on: 2016 October 07 18:00:26 »
Thanks for your reply.  It does look a lot better with 2-D Spline.  I hadn't tried that.

Bob