Pixinsight Geometry issue

[Marky1973]

I have been slowly working through Warren Keller's great "Inside PI" book and slowly getting to grips with the basics. I've been working on some old TIFF files from my Atik 414EX, which aren't great, but have been used before (via the BatchPreProcessing script) and stacked into a fairly ropey LRGB image.

So I have been through the early stages of cleaning up the subframes, dynamic cropping, calibrating, registering and stacking as per the book and have come to the point where I have a Luminance Master and a Chrominance Master. However, when I come to recombine these images into the LRGB image, I get a warning that the Geometry is Invalid and the image will not be combined. All the subs were registered to a Luminance Reference frame as per the instructions, so I presumed they would all fit together nicely.

Of course, there is the possibility that I did something wrong in the process and I'm going back to square one anyway - not going to get too deeply into the advanced stuff until I have mastered the basics, so a bit more practice can't hurt! But, barring the fact that, perhaps, I didn't register the images correctly, are there any other instances where this error might crop up, something that I should look for when going through again?

The RGB subs are few in number and the B channel was affected by light cloud (some of the brighter stars are bloated) which might be an issue but I guess they would not have registered and stacked in the first place? And this wasn't a problem for the original effort with the BPP Script.

I did see a similar thread when I was looking quickly this morning, but that was relating to DSLR images.

Any thoughts, or shall I just work through it again and see what happens?

[Barry-Wilson]

If you apply different crops to each stack you will change the geometry of the stacks such that they cannot be combined even though they have been aligned to the same sub-frame.  The way to prevent this is to create a New Instance of the Dynamic Crop before you apply it to a stack after you have set the crop by dragging the triangle onto the desktop.

If you forget to do this, you can re-align the cropped stacks with their differing geometry by using the Dynamic Alignment Process after which you will be able to combine the stacks as one will be aligned to the new geometry.

HTH

Barry

[Marky1973]

Hi Barry, thanks for that. I did use Dynamic Crop and used a new instance that was applied to the RGB stacks, but still had that problem - will check out the DA process as well though as that may save my bacon (and haven't come across that one yet)!

Cheers

Mark