[AstroPy] Some Feedbacks about Astropy
Adam Ginsburg
adam.g.ginsburg at gmail.com
Thu Jul 3 03:18:19 EDT 2014
I agree with Tom's points, but I'd also like to clarify that the
variety of replies were not all to the same question.
The scipy.map_coordinates+astropy.wcs, pyAST, and montage utilities
that I, Ray, and Sophie mentioned solve the problem of image
regridding and reprojection, which as Tom points out belongs in
astropy-core eventually.
The montage approach uses a wrapper to an underlying C program called
montage that needs to be installed independently. The scipy approach
is more purely python, but it requires interpolation and is not flux
conserving (montage is). The pyAST approach wraps another underlying
C library and implements its own resampling that can be flux
conserving depending on certain flags chosen (but Dave Berry, correct
me if I've gotten something wrong here):
http://dsberry.github.io/starlink/node1.html#Resample
http://www.starlink.rl.ac.uk/docs/sun210.htx/node371.html
These routines could probably live in something called
astropy.reprojection or something similar.
The second class of problems addressed is image registration, which I
think is being treated in ccdproc, SRPAstro, and the methods that Ray
mentioned. I think these are each niche codes with a different role;
image registration based on star matching is very different from that
based on FFTs and extended emission matching. For a summary of the
codes available for extended emission registration, have a look at
http://image-registration.readthedocs.org/en/latest/#programs-implementing-these-methods-in-various-languages.
I hope this is useful clarification, but please correct me if I
misrepresented anyone's code here.
On Thu, Jul 3, 2014 at 8:10 AM, Thomas Robitaille
<thomas.robitaille at gmail.com> wrote:
> Paul Kuin wrote:
>> Reading all this, I think that part of the success of the IDL Astro
>> library is due to having one head, Wayne Landsman, put it all together.
>> This reads like a conversation on the tower of Babel. Everyone their own
>> method. Someone should take the time to check and compare all the
>> different implementations. Some funding for such work would be very
>> useful and save on duplication. I think this is a task that the IAU
>> could(should?) be involved in.
>
> Reducing duplication is precisely the goal of the Astropy project - in
> fact, we have a rule that 'affiliated' packages should not duplicate
> functionality from the core, and also avoid duplication amongst one
> another. See the original vision document:
>
> http://docs.astropy.org/en/stable/development/vision.html
>
> If you are interested in getting involved, you can join the astropy-dev
> mailing list. As part of the Astropy project, there have already been a
> number of successes in merging existing packages to provide a core
> implementation (for example the cosmology routines).
>
> On the more specific topic of re-projection - this is clearly a highly
> requested feature, and I think it should be targeted as something that
> should have an implementation in the core astropy package that then gets
> used by all other packages.
>
> As a side note, the fact there was more than one reply to the original
> question is a testimony to the strength of the development community in
> Python - people are clearly not just waiting for one person to just
> write it all. Yes, we need to all make an effort to not duplicate things
> needlessly, but on the other hand, having two different ways of
> approaching the same problem is not always bad.
>
> Cheers,
> Tom
>
>> Paul
>>
>>
>> On Wed, Jul 2, 2014 at 6:15 AM, Guang Yang <yg1991 at mail.ustc.edu.cn
>> <mailto:yg1991 at mail.ustc.edu.cn>> wrote:
>>
>> Thank all of you for giving those advices. I think I won't bother to
>> switch between python and IDL in my next project. ^^
>>
>> Best wishes,
>> Guang
>>
>>
>> -----Original email-----
>> *From:* "Sofia Lianou" <slianou at uwo.ca <mailto:slianou at uwo.ca>>
>> *Sent Time:* Jul 2, 2014 5:14:53 AM
>> *To:* "Astronomical Python mailing list" <astropy at scipy.org
>> <mailto:astropy at scipy.org>>, "Adam Ginsburg"
>> <adam.g.ginsburg at gmail.com <mailto:adam.g.ginsburg at gmail.com>>
>> *Cc:* "Pauline Barmby" <pbarmby at uwo.ca <mailto:pbarmby at uwo.ca>>
>>
>> *Subject:* Re: [AstroPy] Some Feedbacks about Astropy
>>
>> Hello,
>>
>> This is something that imagecube is doing, too, and the package
>> is hosted here:
>> http://sophiathl.github.io/imagecube/
>>
>> Beta release to follow soon, along with proper documentation.
>>
>> Cheers,
>> Sophia, Pauline, and Jeff
>>
>> On 07/01/14, *Adam Ginsburg * <adam.g.ginsburg at gmail.com
>> <mailto:adam.g.ginsburg at gmail.com>> wrote:
>>> > 1. I find no tools to align two images, i.e. to uniform
>>> their astrometry, pixel scale, image size and etc.
>>> hastrom.pro <http://hastrom.pro>
>>> (http://idlastro.gsfc.nasa.gov/ftp/pro/astrom/hastrom.pro) is
>>> a good example to perform such a task.
>>>
>>> I've written a tool to do that:
>>> https://github.com/keflavich/FITS_tools/blob/master/FITS_tools/hcongrid.py
>>> ...I think it does what hastrom does, not hcongrid, which means I
>>> should change the name.
>>>
>>> Otherwise, you can use the montage wrapper:
>>> http://www.astropy.org/montage-wrapper/
>>>
>>>
>>> --
>>> Adam Ginsburg
>>> Fellow, European Southern Observatory
>>> http://www.adamgginsburg.com/
>>> _______________________________________________
>>> AstroPy mailing list
>>> AstroPy at scipy.org <mailto:AstroPy at scipy.org>
>>> http://mail.scipy.org/mailman/listinfo/astropy
>>
>>
>>
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>>
>>
>>
>> --
>>
>> * * * * * * * * http://www.mssl.ucl.ac.uk/~npmk/ * * * *
>> Dr. N.P.M. Kuin (n.kuin at ucl.ac.uk <mailto:n.kuin at ucl.ac.uk>)
>> phone +44-(0)1483 (prefix) -204927 (work)
>> mobile +44(0)7806985366 skype ID: npkuin
>> Mullard Space Science Laboratory – University College London –
>> Holmbury St Mary – Dorking – Surrey RH5 6NT– U.K.
>>
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--
Adam Ginsburg
Fellow, European Southern Observatory
http://www.adamgginsburg.com/
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