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Re: Already written function to find if a point is within a rectangle? [message #79400 is a reply to message #79338]

Wed, 22 February 2012 19:25

Jacare Omoplata
Messages: 6
Registered: February 2012

Junior Member

>>> So I need a way to find out if a point ( position of a star ) is
>>> within a rectangle ( image boundary ). The rectangle edges are not
>>> strictly horizontal or vertical.
>
>> You talk about coordinates in RA and dec. So are the images really
>> rectangular? It seems to me that the real problem is that you need to
>> deal with spherical geometry.
>
> Not only that, but an "image boundary" will be projection-dependent
> [*]. For small images it probably won't matter much, but there will
> always be an edge case that gets you later.
>

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?

Thanks

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[Message index]

		Re: Already written function to find if a point is within a rectangle? By: Craig Markwardt on Mon, 20 February 2012 19:22
		Re: Already written function to find if a point is within a rectangle? By: Jacare Omoplata on Mon, 20 February 2012 15:47
		Re: Already written function to find if a point is within a rectangle? By: Jacare Omoplata on Mon, 20 February 2012 15:37
		Re: Already written function to find if a point is within a rectangle? By: penteado on Mon, 20 February 2012 14:56
		Re: Already written function to find if a point is within a rectangle? By: David Fanning on Mon, 20 February 2012 14:09
		Re: Already written function to find if a point is within a rectangle? By: Jacare Omoplata on Wed, 22 February 2012 19:25

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