[AstroPy] [SciPy-user] FITS images with header-supplied axes?

Bridgman, William T. William.T.Bridgman at nasa.gov
Tue Apr 1 13:51:46 EDT 2008

I agree there is some lack of coordination on some of these  
projects.  Such is the nature of Open Source.

I think there is also an issue where some of the projects are  
overkill for what individuals might need for production-pipeline/ 
research/educational uses.  Hence many of us start from scratch to  
keep the work compact.  It's only later that we discover others  
working in similar directions.

I obtained a copy of pywcs many months ago, trying to get  
heliographic coordinate systems installed.  Other priorities  
intervened and by the time I got back to it, migration to numpy and  
changes in pyFITS seemed to break the previous version.  I didn't get  
a chance to make any revisions operational.

Would there be any interest in members of the list publishing a short  
description of what types of modules they are designing in their own  
work?  It might be worthwhile for coordination & possible  
collaborations.  My requirements for work projects are quite  
different from my recreational & educational python projects.


On Apr 1, 2008, at 10:41 AM, humufr at yahoo.fr wrote:
> 				Hello,
> I just want to discuss about a problem that our python astronomer  
> have and the
> answer from Perry is a very good example of it. There are too many  
> projects
> which are doing exactly the same thing and essentially because  
> nothing is
> centralized or worst, in the case of pywcs, not advertised.
> For example Perry told us about pywcs developped by STSCI (it was  
> the first
> time I saw any reference to this project) but Adam spoke about
> astlib ( http://astlib.sourceforge.net/ ) which are different  
> package with
> exactly the same goal and I did myself something similar (even if  
> it was fast
> and dirtier).
> I think it's time to try to identified the most important task that  
> the
> astronomer are needing and try to centralized all the effort at the  
> same
> place. The astropy mail list is probably a good start as the
> astropy.scipy.org website.
> Perhaps we can start to identified the need and desiderata. We will  
> have too
> many but that some most important or urgent must be identified. As  
> example,
> we clearly needed the pywcs and thanks to STSCI we have it now. We  
> also need
> a package to plot our data, images etc. Matplotlib is very good but  
> does have
> a major problem (at least for my point of view), it's slow, very  
> slow for big
> array or can't even produce the image if the image is too big. ( If I
> remember a precedent discussion, the problem is mainly due to Agg.)
> After we need to know, if possible, for which project if someone is  
> doing
> something, who and how to contact him/her. So interested people can
> eventually help him/her to do it. It's seems that STSCI is doing  
> most of the
> work but I'm pretty sure that other people are willingly to help  
> them to
> extend python to be the ideal tool for astronomer.
> Just my 2 cents,
> Nicolas
> Le Sunday 30 March 2008 10:54:04 Perry Greenfield, vous avez écrit :
>> On Mar 28, 2008, at 8:28 PM, Keflavich wrote:
>>> Is there any plotting routine in scipy / matplotlib that can plot a
>>> fits image with correct WCS coordinates on the axes?  I know pyfits
>>> can load fits files, astLib has routines to interpret header
>> coordinates, and I think you can make the axes different using
>>> matplotlib transforms, but is there anything that puts all three
>>> together currently available?
>>> Thanks,
>>> Adam
>> Well, we (STScI) recently wrapped WCSLIB to obtain a mapping function
>> between pixel and sky coordinates for python (you can find it as  
>> pywcs in
>> astrolib on scipy; that may have been what you were referring to).
>> But I'm not sure you understand what you are asking for with  
>> regard to
>> matplotlib. The new transforms stuff should make it much easier to  
>> display
>> the sky coordinates in the interactive display. The axis labeling  
>> is a
>> different matter. Suppose your image (let's say it's 1Kx1K for the  
>> sake of
>> discussion) is rotated 45 degrees with regard to north (either  
>> way, it
>> doesn't really matter). What would you expect to see for axis  
>> labels? I
>> don't think it is at all obvious how people would want labeling to  
>> be done
>> along the edges of the image. I can imagine someone wanting axes  
>> or grids
>> superimposed on the image itself, but that's not quite the same  
>> thing. Do
>> you want the image rotated so that it is resampled on to RA and  
>> Dec and
>> displayed that way?
>> In any event, no we haven't yet done anything to try to integrate  
>> all three
>> things. Among other things we wanted to make sure that the api for  
>> the wcs
>> info was suitable before doing a lot with it (and in the meantime,  
>> Mike is
>> working on rewriting drizzle which is taking a lot of his time).
>> Perry
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Dr. William T."Tom" Bridgman               Scientific Visualization  
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Email: William.T.Bridgman at nasa.gov         Code 610.3
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