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Astrophoto alignment

asked 2015-10-31 16:27:59 -0600

Suspense gravatar image

updated 2015-11-01 17:39:55 -0600

I'm looking for a way to align astrophotos with OpenCV in Java. These photos will typically have a dark background, random scattering of stars, and a subject like a galaxy or nebula. They will also have high levels of noise. I could come up with an algorithm myself, but there must be something I can use that already exists.

Right now I'm successfully using Video.findTransformEcc() to align images that are already very close. However, I also have photos like the following examples I'd like to align. Can anyone give suggestions?

EDIT for more information: My goal is to sample pixels from each image in the stack based on its location in the sky, rather than its location in each image. This will let me analyze the variance in that location to filter out noise and bring out faint details. I'll go with whatever technique works best, whether that be alignment or stitching or something else.

Also, I'm not interested in finding existing software for this. I'm aware of several existing software packages for this exact use-case. My goal here is to learn how to do it myself.

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answered 2015-11-01 09:36:14 -0600

Eduardo gravatar image

I took the liberty to use your photos if you don't mind.

I would use the stitching module to do what you want.

But if what you want to achieve is only to align the photos, I would suggest you to use directly stitching softwares like Microsoft ICE or Hugin that are dedicated to stitch multiple photos into panoramas.

For example, with Microsoft ICE:

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That's a good way to do it. I think another way is thershold image and sort blob as function of star intensities (that's a simple descriptor ) after match star and use homography

LBerger gravatar imageLBerger ( 2015-11-01 11:33:29 -0600 )edit

Thanks for the suggestions, Eduardo. But I'm not interested in using existing software. My purpose is learning ways to do this myself. See my edit for more information.

Suspense gravatar imageSuspense ( 2015-11-01 17:40:27 -0600 )edit

LBerger, that sounds like the kind of thing I'm looking for. How reliable will the sorting and matching steps be considering that these photos can be very noisy?

Suspense gravatar imageSuspense ( 2015-11-01 17:44:06 -0600 )edit

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Asked: 2015-10-31 16:27:59 -0600

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Last updated: Nov 01 '15