Using StarAlignment making a mosaic

[Jameedon]

I'm using StarAlignment to register the 8 panels of my mosaic so I can then use GradientMergeMosaic for a seamless merge.  I've seen in a couple different tutorials that the working mode used in StarAlignment is Register/Union - Separate and once that is selected you then add all your files in the Target Images section but when I set the working mode to Register/Union - Seperate, the add files button is greyed out and won't let me add my files.  Does anyone know why I can't add files in the StarAlignment tool when I set the mode the Register/Union - Separate?

[chris.bailey]

Unless I am also missing something you can only use Register/Union-Seperate on pairs of open images at a time so if your images are M1-M8 you will register M2 to M1 and then gradient merge the result. Then register M3 to the M1M2 image and merge the result again. With 8 panels to do it becomes a bit laborious but does allow you to tweak the merge settings as you go to minimise artefacts. It is sometimes beneficial to clone out very bright stars at the image edges on the overlap.

The Mosaic by co-ordinate script is probably the tool of choice when you have more than a few panes to combine. It does rely on each pane being run through the Image Plate Solve script first but then creates the registered panels in one sweep. As these are the dimensions of the final mosaic the files can be quite large. These are then input to the Gradient Merge Mosaic tool. I have found this to work very well indeed even on quite wide field of view mosaic panels.

Another option is to generate an artificial star field using Star Generator and then using Register/Union - Seperate on each pane using the star field as a reference. Getting the star field to cover the area of the mosaic and having sufficient stars can be a bit trial and error and distortion correction is a must but it can work well.

Chris

[georg.viehoever]

Hi,

please study the documentation http://pixinsight.com/doc/tools/GradientMergeMosaic/GradientMergeMosaic.html and Steves Video http://www.youtube.com/watch?v=H2r3ZYqCaP8 .
The video explains the trick that you are currently missing: Creating Super Mosaic version (starting at 2:40), then register the individual panes (8:00), then do GMM on those panes (9:00).

Georg

[chris.bailey]

Thanks Georg, that is a neat trick and gives another alternative.

Chris

[Jameedon]

Ok, I must of misunderstood something along the line to think I needed to use Register/Union - Separate.  But now there's a new issue that I'm having trouble with.  I used StarAlignment in Register/Union - Mosaic mode to put together the 7 panels but now when I switch the Working Mode over to Register/Match Images and use that mosaic as the Reference Image and add the 7 images to the Target Images section, 2 of those images aren't being registered.  I've tried Registration Mode as 2-D Surface Spline and Projective Transformation, and in 2-D Spline mode I've tried increasing Spline Smoothness.  I have Distortion Correction and Frame Adaptation both checked and I've tried a bunch of different settings in the Star Matching section.

What settings should I be messing with to get StarAlignment to be able to register all of the images to the mosaic?

[georg.viehoever]

You should try detection and noise parameters. Usually, images dont register because star detection finds too many noisy or hot pixels. Try Noise Scales and Log(sensitivity). Star Alignment also has a number of diagnostic Working Modes (detected stars, matched stars) that can help to tune the parameters.
Georg

[pfile]

you can also define a preview over the part of the reference mosaic image that overlaps the frame you are currently trying to register. that limits SA to relevant stars…

rob