Author Topic: Mosaic construction using star alignment & gradient merge mosaic tools  (Read 5762 times)

Offline tstephens

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One of the challenges to PixInsight is that available tutorials use a range of versions of PixInsight but not the current v1.8. I am attempting to make a mosaic of M31 and have been following Harry's tutorial using the Star Alignment tool. I am, however, stuck constructing a mosaic and attempting to follow the video on the topic. The video uses the Register/Union Separate mode of Star Alignment tool. When I make that setting in the current version, the “Add View” or “Add Files” buttons are greyed out so that you cannot select them. How can I construct a mosaic if I cannot add files? The look of the tool in version 1.8 is very different. :-[
« Last Edit: 2013 November 02 12:09:41 by tstephens »

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #1 on: 2013 November 02 09:13:39 »
A follow-up question is, how do you use this tool/process if you are integrating four images?

Offline pfile

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Re: Mosaic construction using the star alignment tool
« Reply #2 on: 2013 November 02 09:38:12 »
add view should still work but the entire files pane should be greyed out. mosaic construction is kind of an interactive, iterative process. you should be able to select a view as a reference image.

after you make the first mosaic out of two images, then you make the reference image the newly created image and apply the process to the next pane. then make the reference the 2nd mosaic and apply to the next pane…

rob

Offline Zocky

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Re: Mosaic construction using the star alignment tool
« Reply #3 on: 2013 November 02 09:42:00 »
A follow-up question is, how do you use this tool/process if you are integrating four images?
Maybe this topic can help you.
http://pixinsight.com/forum/index.php?topic=3369.0
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Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #4 on: 2013 November 02 09:59:58 »
I am moving along by starting in "Resister/Match Images" and then switching to "Register/Union Separate" since all "Add" buttons become deselected with that option. Since my files are already selected, I can now perform the task. Very cumbersome since I have to save everything. Combine the first to images into the first mosaic and then start over.

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #5 on: 2013 November 02 10:14:59 »
Just integrated the fourth images and got a very strange result. Using "Overlay" mode for all images the fourth image cannot be seen with a stretch that clearly shows the first three integrated images and there is background in areas of the overall template that show background where there was no image. All the images were carefully prepared with background correction so that they should have integrated well. Still not understanding the process well.

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #6 on: 2013 November 02 10:35:14 »
Attempted to do the mosaic in two halves. Combined the left two images and the right two images. Looks good. Now combine the two halves and again I get the artifact in the top of the right half with a circular dark area creeping in from the top blanking out that fourth image. I cannot get a screen stretch with the fully integrated mosaic. What am I doing wrong (or what is PixInsight doing wrong)? :-\

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #7 on: 2013 November 02 10:38:27 »
It seems like PixInsight is now assuming the black background of the left image is actually part of a real image and is integrating that into the top of the right image. It does not do this on the bottom because the left and right halves mate exactly. How do I keep PixInsight from integrating part of the background template into the integrated image?

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #8 on: 2013 November 02 10:45:06 »
Thought I had the answer "Increase the Black Point". Now I get dark dimples around several areas of the outer image boundary?

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #9 on: 2013 November 02 10:47:05 »
Increased the "Black point" and now I get a psychedelic image?

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #10 on: 2013 November 02 10:55:49 »
Got it! I needed to go down in the Black Point setting so it is just above the PixInsight fill-in background (0.0039-0.0052). Now I have a nice clean integrated mosaic. :D

Offline tstephens

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Re: Mosaic construction using the star alignment tool
« Reply #11 on: 2013 November 02 10:58:37 »
Not quite clean. When stretched properly, I still have dimples around the edges.

Offline tstephens

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Going beyond this stage, it seems like none of the PixInsight functions work accurately with the large integrated file. I get blank screens when I should not. Color calibration seems totally off. I need to restart tomorrow but there are questions about whether large integrated mosaics can work in PixInsight.

Offline pfile

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check out deepskycolors.com if you think that large mosaics can not be done in PI.

are you using a 32-bit version of PI?

rob

Offline Zocky

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Tstephens did you check this topic: http://pixinsight.com/forum/index.php?topic=3369.0
It is excellent tutorial that covers how to build, large panel number mosaic. 
Skywatcher ED 80/600 with FF/FR x0.85; HEQ5-pro mount
SBIG ST-8300M, FW5 with Baader LRGB Ha7nm filters
https://www.flickr.com/photos/zoran-novak/