Registering Images of Different Scale and Doing Drizzle

K

klanes

Well-known member
I downloaded some images from Telescope Live and I want to combine them with images from my system. The images are of radically different FOV's and pixel scale. One set is 4.75" IFOV and my data is 1.45". Some data is 2.02". I can't get StarAlignment to work because of the scale and FOV differences although there might be a technique that I am missing here. So I have solved this problem with either Image Solver and AlignByCoordinates and also using FFTRegistration however I can't see how to generate drizzle data. I would like to drizzle the 4.75" by 3x which I am thinking will give me a more compatible IFOV with my 1.45" data. My idea it to use the dark site data to normalize my 1.45" data which is Bortle 5. Is there a way to do this? I am also thinking I would drizzle the 1.35" data 1:1 to get a set of drizzle files so I can then integrate all the images together.

Thanks
Kurt
 
Hello @klanes

Much of what you're trying to do depends on the outcome of StarAlignment (Using AlignByCoordinates is a good idea but you can't generate drizzle data with it).
Can you share one image of each setup (although I'm not sure it's ok with data from Telescope Live)?
Have you tried to use a preview in the larger fov image matching the reference image fov before using StarAlignment?
 
Thanks Nico. I asked permission to see I I can upload a Telescope Live image.

I am not sure how to use the preview. Do I need to create one in every one of the large images?

Kurt
 
klanes said:
Thanks Nico. I asked permission to see I I can upload a Telescope Live image.

I am not sure how to use the preview. Do I need to create one in every one of the large images?

Kurt
Click to expand...

The idea, as a first step, is to see if you can use a preview to align only two images.
If it works then it means that, by reducing the field of view of the wider images, you can align them to the smaller ones. I don't know how to create previews in batch but I think the same result can be achieved by cropping.
 
klanes said:
One set is 4.75" IFOV
Click to expand...
FYI: IFOV is a term widely used in the security / sensor imaging domain, but I have hardly ever seen it used in the astrophotography community, where the term "Image Scale" is almost universally used.
 
I designed spy satellites for a living so I guess I expected IFOV to be understood but will use Image Scale in the future. I didn't say GSD :) or NIIRS.

Nico. I grock how to crop a batch. I probably need to leave some edge margin.

Kurt
 
I was able to crop the large image and get Star Alignment to work. FFTRegistration sometime does goofy stuff. It worked on on data set but made funny little postage stamp sided images scattered over the frame sequence on another.

Kurt
 
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