Author Topic: Do Mosaics really have to be this difficult  (Read 2878 times)

Offline kkoppert

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Do Mosaics really have to be this difficult
« on: 2013 March 15 00:42:57 »
I come from a background of lunar photography where I created a lunar mosaic from 20-50 seperate panels. You ran Microsoft ICE and dragged the xx frames into ICE and saved the results ICE fixed up te differences and seams did not appear. I try to do something similar with shots of a star cluster (IC2602) in PixInsight. First I use StarAlignment to align the frames. First problem, it appears PI can only do this two frames at a time. Then I merge the frames using GradientMergeMosaic and it creates aweful artifact around bright stars near the boundaries of frames. Reading the forum it appears there is too much difference in brightness between the parts and I am supposed to adjust the histograms, but GMM is to be used on linear data (say what, err umm, reboot brain). Further advice resembles black magic but since I can't find any eye of newt or the entrails of a cat I give up and use ICE. OK I had to use histogramTransformation and 16 bit data but it works like a charm and does all the parts at once.

Is there any less crude method of doing this in PI other than StarAlignment, GradientMergeMosaic and black magic?

Offline f11

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Re: Do Mosaics really have to be this difficult
« Reply #1 on: 2013 March 18 15:48:57 »
Did you ever figure out how to do a lunar mosaic within PI?  I'm trying to do the same thing, and can't seem to figure out how...

I keep thinking there MUST be a way to copy previews or whole images into a new image in a way that allows me to rearrange the pieces, but I can only get them into the Clipboard (Win7)... from there, the clipboard data can only be pasted to a new image - no way (I can find) to copy several previews or images into one image.

I also had high hopes for PreviewAggregator - at least all the previews get added to one image - but they aren't moveable and I can't seem to figure out how to pre-order them so they land and overlap the way I want.

Yet - there SHOULD be a way to use the GMM tool by indicating where each mosaic piece overlaps with another... the function for specifying overlap appears to be there, but...

I have five crummy panels I want to stitch together to depict last night's waxing gibbous moon - for once even my focus is pretty good... but if I can't find a way, I guess I'll have to resort to "that other software" to finish it off.

To be fair, a lunar mosaic might be pushing the design boundaries of PI pretty far.  Juan DID say he doesn't want to spend much time adding features into PI that have to compete with those of other photo-editing software that may cost less than PI, or even be distributed free.  It could be argued that a lunar mosaic is more about photo-editing than astronomy.

Rod

Offline kkoppert

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Re: Do Mosaics really have to be this difficult
« Reply #2 on: 2013 March 21 23:37:43 »
Actually I've never tried doing a lunar mosaic with PI, quite frankly Microsoft ICE is too easy.

Offline f11

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Re: Do Mosaics really have to be this difficult
« Reply #3 on: 2013 March 22 00:02:03 »
I guess I'll have to give it a try.

I did finally get my mosaic done, but half in PI and half in "another program".  Kinda disappointing, but the part that PI looked after was critical to the end result.  I tried doing it ALL in the other program, but the merging was a disaster because of differences in brightness and contrast in each panel.  A combo of STF and HTF before converting to TIFF format did the trick.

Since the merge was handled as transformed (repositioned and rotated) layers, I guess this capability won't be added to PI for quite a while based on Juan's comment.  Ah well, PI can't do EVERYTHING - although it already does damn NEAR everything. :)

Rod