RA DEC mosaic software help

Banter, questions, and polite arguments over the best programming language
Posts: 2
Joined: Tue Jul 29, 2014 4:07 pm

RA DEC mosaic software help

Post by JoeG » Tue Jul 29, 2014 5:14 pm

I'm jumping in the deep end here so please point me in the right direction if I'm lost.
I'm a filmmaker and have used FITS data several times before. Please see some examples below.

I can expand if need be, but to be brief I need to get RA DEC data to lay out FITS tiles automatically in photoshop or something similar.
I have looked into Montage software but it only produces a flattened FITS file or jpeg, both not what I need.
My current project is taking FITS data that needs to be correctly laid out in the corrected mosaic arrangement but not flattened into a jpeg/tiff
I need something equivalent to a photoshop layers file or image sequence with all the fits image data stacked in their correct position and orientation. I'm talking about dozens to hundreds of files. I can then make my movie with them.
Ideally a way to import fits already converted into tiffs with their ra dec header intact and then stacked as a PSD file or tiff sequence.
Is there something like this already? Or is there a simple way to mosaic RA DEC images without flattening them in one layer?

thanks a lot


User avatar
Guardian of the Codes
Posts: 1143
Joined: Wed Aug 04, 2004 4:18 pm
Location: Washington, DC

Re: RA DEC mosaic software help

Post by owlice » Wed Jul 30, 2014 4:19 pm


I posed your question to the Montage team and received the answer below; I hope this helps.



There is enough information from the Montage processing to do this if you know where to look, though of course there will be some massaging involved.

The reprojection part of Montage involves getting all the images to the same projection. In the case of FITS WCS that means the headers will all be exactly the same except for relative pixel offsets in X and Y; exactly what he needs to lay the images out relative to each other.

A side note: You can't bypass the reprojection since the image-to-image differences are almost never simple shift/rotate in nature.

So after reprojecting and building a metadata table (mImgtbl in Montage) you can place the images relative to each other just based on relative CRPIX1 (X) and CRPIX2 (Y) offsets from that table (with appropriate attention to the sign of the offset).

At this time, Montage only outputs JPEGs but so long as you don't crop, shrink or otherwise transform them, the equivalent PNG or TIFF images could be placed relative to each other based on the same CRPIX offsets.

I can give more details if this seems like the right general direction.

- John
Code-seeking owl at your service

Posts: 2
Joined: Tue Jul 29, 2014 4:07 pm

Re: RA DEC mosaic software help

Post by JoeG » Wed Jul 30, 2014 7:34 pm

HI Thanks Alice and John
That is very helpful. I will have a go with your info and come back to you if I need more help.

Post Reply