Polygon getArea method about phpgeo HOT 4 CLOSED

Hi!

I'm still looking for an polygon area calculation algorithm which satisfies the following requirements:

• works for concave and convex polygons
• supports ellipsoids (e. g. “WGS-84”) and does not just use simple spherical coordinates
• (optional) works for polygons which cross the -180°/+180° longitude boundary (once or more than once)
• (not needed) area calculation for self-intersecting polygons

Unfortunately I didn't find such an algorithm yet. The current implementation was not implemented by me (was merged via a pull request some time ago).

Marcus

from phpgeo.

Thanks @mjaschen !

Got it !
I implemented my own algorithm before finding your library, but I think It only verify the first point of your list. Otherwise I would have been happy to contribute :)

Do you know why the area is 'wrong' ? Is it only because the current implementation uses a spherical model instead of an ellipsoid one ?

from phpgeo.

I don't remember what exactly was wrong with the algorithm, but IIRC some test calculations lead to wrong results so I added the warning.

You're invited to create a pull request with your algorithm! (It's not a big problem if the support for ellipsoids is missing - we'll annotate the method documentation then).

Thanks!

from phpgeo.

I have implemented a new method and after some testing, the results look good.

I have created the pull request #31.

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