| Re: good mapping tutorial? [message #82438] |
Mon, 10 December 2012 21:10 |
Jeremy Bailin
Messages: 618
Registered: April 2008
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Senior Member |
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Ah, if Mollweide is a valid projection for FITS files, that makes my
life considerably easier! And puts off learning about the IDL map
projection routines for another year. ;-)
-Jeremy.
On 12/10/12 10:47 PM, wlandsman wrote:
> It's not clear to me what you are seeking. First you mention the IDL map projection routines, which are the large part of IDL that astronomers rarely touch, because they have the wrong signs in their axes ;-) i.e. for looking down at the Earth rather than up toward the sky. But then it seems that you do not really want to create a map but rather write a FITS file.
>
> You might want to look at the example FITS files for different projections (including Mollweide) provided by Mark Calabretta ( http://www.atnf.csiro.au/people/mcalabre/WCS/example_data.ht ml ). This should show you the proper WCS (world coordinate system) FITS keywords to use, You can view these files with ATV (http://www.physics.uci.edu/~barth/atv/ ) or ds9 to see if the projection is displayed correctly. --Wayne
>
>
>
> On Monday, December 10, 2012 11:15:32 PM UTC-5, Jeremy Bailin wrote:
>> Dealing with the map projection routines in IDL is something I've never
>>
>> really had to do, but I find myself wanting to right now and I am
>>
>> searching in vain for a good tutorial on the basics. Can anyone point me
>>
>> towards something appropriate?
>>
>>
>>
>> (in particular, what I'd like to do right now is take an all-sky image
>>
>> that I've managed to harangue into a Mollweide projection and write out
>>
>> a piece of it into a FITS file in one of the native projections that
>>
>> FITS files deal with... but I'm sure that I will be much the wiser if I
>>
>> can find a tutorial that will include more than just this)
>>
>>
>>
>> -Jeremy.
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| Re: good mapping tutorial? [message #82439 is a reply to message #82438] |
Mon, 10 December 2012 20:47  |
wlandsman
Messages: 743
Registered: June 2000
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Senior Member |
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It's not clear to me what you are seeking. First you mention the IDL map projection routines, which are the large part of IDL that astronomers rarely touch, because they have the wrong signs in their axes ;-) i.e. for looking down at the Earth rather than up toward the sky. But then it seems that you do not really want to create a map but rather write a FITS file.
You might want to look at the example FITS files for different projections (including Mollweide) provided by Mark Calabretta ( http://www.atnf.csiro.au/people/mcalabre/WCS/example_data.ht ml ). This should show you the proper WCS (world coordinate system) FITS keywords to use, You can view these files with ATV (http://www.physics.uci.edu/~barth/atv/ ) or ds9 to see if the projection is displayed correctly. --Wayne
On Monday, December 10, 2012 11:15:32 PM UTC-5, Jeremy Bailin wrote:
> Dealing with the map projection routines in IDL is something I've never
>
> really had to do, but I find myself wanting to right now and I am
>
> searching in vain for a good tutorial on the basics. Can anyone point me
>
> towards something appropriate?
>
>
>
> (in particular, what I'd like to do right now is take an all-sky image
>
> that I've managed to harangue into a Mollweide projection and write out
>
> a piece of it into a FITS file in one of the native projections that
>
> FITS files deal with... but I'm sure that I will be much the wiser if I
>
> can find a tutorial that will include more than just this)
>
>
>
> -Jeremy.
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