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Re: IDL function to get area cover of polygon [message #73280] Wed, 03 November 2010 17:06
JDS is currently offline  JDS
Messages: 94
Registered: March 2009
Member
On Nov 2, 7:44 pm, Seb <g5s...@web.de> wrote:
> Hi,
>
> I have the longitude/latitude coordinates of a polygon, and I am
> looking for a function which calculates the area covered by the
> polygon (e.g. in km^2). I am sure there is a function like this but
> was unable to find it.
>
> Any advice is much appreciated.


I have a function which computes the solid angle of a spherical
polygon in steradians, given ra/dec input:

http://tir.astro.utoledo.edu/idl/spherical_poly_area.pro

JD
Re: IDL function to get area cover of polygon [message #73313 is a reply to message #73280] Wed, 03 November 2010 02:50 Go to previous message
Seb is currently offline  Seb
Messages: 15
Registered: January 2006
Junior Member
On Nov 2, 11:55 pm, Paulo Penteado <pp.pente...@gmail.com> wrote:
> On Nov 2, 9:44 pm, Seb <g5s...@web.de> wrote:
>
>> Hi,
>
>> I have the longitude/latitude coordinates of a polygon, and I am
>> looking for a function which calculates the area covered by the
>> polygon (e.g. in km^2). I am sure there is a function like this but
>> was unable to find it.
>
>> Any advice is much appreciated.
>
>> Cheers,
>> Sebastian
>
> If the polygon is small enough to make the surface curvature
> negligible, you can convert lat/lon to x/y, and use poly_area() or an
> IDLanROI.

Thanks, I will give it a try.
Sebastian
Re: IDL function to get area cover of polygon [message #73330 is a reply to message #73313] Tue, 02 November 2010 16:55 Go to previous message
penteado is currently offline  penteado
Messages: 866
Registered: February 2018
Senior Member
Administrator
On Nov 2, 9:44 pm, Seb <g5s...@web.de> wrote:
> Hi,
>
> I have the longitude/latitude coordinates of a polygon, and I am
> looking for a function which calculates the area covered by the
> polygon (e.g. in km^2). I am sure there is a function like this but
> was unable to find it.
>
> Any advice is much appreciated.
>
> Cheers,
> Sebastian

If the polygon is small enough to make the surface curvature
negligible, you can convert lat/lon to x/y, and use poly_area() or an
IDLanROI.
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