Polygon area calculation using Latitude and Longitude generated from Cartesian space and a world fil

Posted by Heath on Stack Overflow See other posts from Stack Overflow or by Heath
Published on 2010-05-18T21:27:27Z Indexed on 2010/05/18 21:30 UTC
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latitude-longitude

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area

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map

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geocoding

Given a series of GPS coordinate pairs, I need to calculate the area of a polygon (n-gon). This is relatively small (not larger than 50,000 sqft). The geocodes are created by applying an affine transform with data from a world file.

I have tried to use a two step approach by doing converting the geocodes to cartesian coordinates:

double xPos = (lon-lonAnchor)*( Math.toRadians( 6378137 ) )*Math.cos( latAnchor );
double yPos = (lat-latAnchor)*( Math.toRadians( 6378137 ) );

then I use a cross product calculation to determine the area.

The issue is that the results are a bit off in accuracy (around 1%). Is there anything I can look into to improve this?

Thanks.

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