On Thursday, February 23, 2012 2:13:18 PM UTC-5, Paulo Penteado wrote:
> On Feb 23, 7:34 am, Craig Markwardt <craig.markwa...@gmail.com> wrote:
>>> I'm thinking of making polygons with a large number of edges, instead
>>> of rectangles, with every data point at the edge of a FITS file as a
>>> vertex. That would minimize the projection error, right?
>>
>> That helps. Special care is probably need around the poles though.
>
> Not only the poles. Also at the longitude boundary. Working with
> polygons in spherical geometry is, in my experience, a pain. Just
> because there is not enough library support for it.
I
On Thursday, February 23, 2012 2:13:18 PM UTC-5, Paulo Penteado wrote:
> On Feb 23, 7:34 am, Craig Markwardt <craig.markwa...@gmail.com> wrote:
>>> I'm thinking of making polygons with a large number of edges, instead
>>> of rectangles, with every data point at the edge of a FITS file as a
>>> vertex. That would minimize the projection error, right?
>>
>> That helps. Special care is probably need around the poles though.
>
> Not only the poles. Also at the longitude boundary. Working with
> polygons in spherical geometry is, in my experience, a pain. Just
> because there is not enough library support for it.
On Thursday, February 23, 2012 2:13:18 PM UTC-5, Paulo Penteado wrote:
> On Feb 23, 7:34 am, Craig Markwardt <craig.markwa...@gmail.com> wrote:
>>> I'm thinking of making polygons with a large number of edges, instead
>>> of rectangles, with every data point at the edge of a FITS file as a
>>> vertex. That would minimize the projection error, right?
>>
>> That helps. Special care is probably need around the poles though.
>
> Not only the poles. Also at the longitude boundary. Working with
> polygons in spherical geometry is, in my experience, a pain. Just
> because there is not enough library support for it.
I
On Thursday, February 23, 2012 2:13:18 PM UTC-5, Paulo Penteado wrote:
> On Feb 23, 7:34 am, Craig Markwardt <craig.markwa...@gmail.com> wrote:
>>> I'm thinking of making polygons with a large number of edges, instead
>>> of rectangles, with every data point at the edge of a FITS file as a
>>> vertex. That would minimize the projection error, right?
>>
>> That helps. Special care is probably need around the poles though.
>
> Not only the poles. Also at the longitude boundary. Working with
> polygons in spherical geometry is, in my experience, a pain. Just
> because there is not enough library support for it.
On Thursday, February 23, 2012 2:13:18 PM UTC-5, Paulo Penteado wrote:
> On Feb 23, 7:34 am, Craig Markwardt <craig.markwa...@gmail.com> wrote:
>>> I'm thinking of making polygons with a large number of edges, instead
>>> of rectangles, with every data point at the edge of a FITS file as a
>>> vertex. That would minimize the projection error, right?
>>
>> That helps. Special care is probably need around the poles though.
>
> Not only the poles. Also at the longitude boundary. Working with
> polygons in spherical geometry is, in my experience, a pain. Just
> because there is not enough library support for it.
I have a few routines for spherical polygons available:
http://tir.astro.utoledo.edu/jdsmith/code/idl.php
JD
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