Hi all, been getting to grips with Star Tools over the last few days - really great program!
I've been working on a mosaic of the Milky Way/Rho Ophiuchi (9 panels, 3x3 grid. 135mm, ~15-30 min exposure on each, more on Rho Ophiuchi).
I've stacked in DSS, then stitched all the panels together in ICE, and now when processing in ST I am seeing subtle lines where the seams are. They're not too noticeable in most cases, but I've marked the most obvious ones. How can I best fix these?
https://imgur.com/a/fsUyEAG
Also, I don't really know what I'm doing re: colouring. How is it looking so far? Any major tweaks needed?
Many thanks!
Fixing 'seams' on mosaic
Re: Fixing 'seams' on mosaic
Hi delta 9857,
The seams usually occur due to local differences in Normalization/Calibration.
The preferred method would be to fix as much as possible using proper flat calibration. I use APP (AstroPixelProcessor) as stacker and it really excels for mosaics. Unfortunately it is not free like DSS. You may just throw in all lights and APP will build a huge picture, stacking all lights, registered correctly. You will end up with one big stack You may process further in ST. There are some features (Multi-Band Blending and Local Normalization correction which will remove those seams.
Ideally, these features should not be used for ST processing, as these would interfere with ST's tracking engine, making the background noise processed non-linear locally, but I found with proper quality and number of the subs & calibration frames, good flat calibration and sufficient Integration time, noise level is kept reasonably and seams are minimal, so ST does not have a long way to go processing this data. Make sure not to shoot Your lights under changing conditions (moon, sky background).
As said, this is a borderline compromise and not an ideal processing, but might work for You
Clear Skies,
Jochen
The seams usually occur due to local differences in Normalization/Calibration.
The preferred method would be to fix as much as possible using proper flat calibration. I use APP (AstroPixelProcessor) as stacker and it really excels for mosaics. Unfortunately it is not free like DSS. You may just throw in all lights and APP will build a huge picture, stacking all lights, registered correctly. You will end up with one big stack You may process further in ST. There are some features (Multi-Band Blending and Local Normalization correction which will remove those seams.
Ideally, these features should not be used for ST processing, as these would interfere with ST's tracking engine, making the background noise processed non-linear locally, but I found with proper quality and number of the subs & calibration frames, good flat calibration and sufficient Integration time, noise level is kept reasonably and seams are minimal, so ST does not have a long way to go processing this data. Make sure not to shoot Your lights under changing conditions (moon, sky background).
As said, this is a borderline compromise and not an ideal processing, but might work for You
Clear Skies,
Jochen
Re: Fixing 'seams' on mosaic
When I did a widefield mosaic I stacked in DSS then processed each panel in startools with the same settings then stitched in ICE.
Re: Fixing 'seams' on mosaic
Thanks to both of you! I've download the trial of APP so I'll give that a try, and I'll try processing each one individually in ST as well.