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DSO Mosaic Workflow and Software

johnb

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johnb

johnb

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Hi

Advice on workflow and software appreciated. Im guessing

Take image in the normal way with Darks, Flats etc and process with DSS, then move the Scope ensuring overlap and take 2nd image and again use DSS, so now I have Image1.tif and image2.tif

Mosaic with something like MS ICE (although that does not see to handle Ti files)

After joing them then into Photoshop and process in the normal way ?

John B

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ollypenrice

ollypenrice

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Hi John,

On capture, yes, but leave plenty of overlap, especially on first attempts.

Image combining is likely to be more involved than just asking ICE to do it, though.

Firstly ICE will probably struggle to do a block of 4 panels because of field curvature effects, though I don't know. It should handle a pair, though. I use Registar as a first step, asking it only to register the images, not calibrate or combine them. I guess you will skip this stage, at least to see if it works without, so...

Secondly open both images in Ps and take the one with the best looking sky background. Increase its canvas size to make room for the second one to go on the canvas in the right place. Copy and paste it on and move it into position. Without Registar it will not be a perfect fit. No matter, get it close.

You will almost certainly see differences where the images join. Try to adjust the pasted image to get it as close as possible. You can sample the colours and measure the levels for the same bit of sky in both images. The quick way is to use levels (inc the grey point) and curves to get them close, along with colour balance set to shadows. In all probability there will be pesky gradients that don't agree across the images. I even get that here without LP. I just use a well feathered lasso to bully the awkward bits into submission.

Thirdly, now that it is close, give ICE a try.

If it won't play, fork out for Registar!

I don't combine in ICE, I do it in Ps and split the channels, doing each one separately.

I feather the edge in a random curved line, too, each colour in a different place. This really will give a seamless result.

PixInsight has a routine but I will need a fortnight's holiday to work out how to do it!

The key to mosaics is good flat fielding and background neutralization. These are easy in Pixinsight so these days that is my first step. If you don't have PI you can still do mosaics though.

Olly

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martin_h

martin_h

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I do most of the above, but I mosaic them in PS using File - Automate - Photomerge, then tick Interactive Layout. When all done click ok and it will open it up on a page with each pane overlayed but in a different layer.

Works for me - so far!

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Psychobilly

Psychobilly

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I think you will be pleasantly suprised if you try ICE...

The version I have works fine with the Canon Raws from all my Canon cameras (350/1000/500D) and the Nikon D200...

The latest update works better than the previous one...

I Just ran a load of old files through it (20 panes) .. stitched them in no time...

Cyg%20Mosaic%2020%20Pane%20ICE.jpg

This was old data before I was taking flats and hadn't had the gradients sorted or the panes calibrated it was just to show you how ICE handles the projection over a fairly large area of the sky...

Just a very quick and dirty stretch

Cygnus%20Mosaic%2020%20panes%20Microsoft%20ICE%20Stitch%20Small.jpg

here's a Registar version for "geometry" comparison

Cygnus_Mosaic_EFS.jpg

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ollypenrice

ollypenrice

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Oh wow, yes, so I was wrong about the multi panel difficulty. Ever the pessimist!

I would still try to get them all as close as possible by hand because I wouldn't want ICE making decisions on my behalf about where to make compromises in order to merge. However, that's amazing.

Olly

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Psychobilly

Psychobilly

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Totally agree Olly Calibrating frames with Registar and then further balancing as neccesary before stitching is the best way forward... especially if you use you map to widefield technique..

I Never got back to this project... It was all being shot through the Megrez 72 FFIII ...

Peter...

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