MATLAB: How to calculate polyarea in metres using latitude and longitude coordinates

convhullgpslatitudelongitudemappingMapping Toolboxpolyarea

I would like to know how I can calculate polyarea in metres from known latitude and longitude GPS coordinates. I have time data for 18 individuals and would like to know the area provided by the outermost individuals. I am currently using convhull to identify the outermost players and then using this to index into polyarea function. While this gives me an area, the result is in degrees at latitude and longitude are in degrees (e.g. I get an answer of 8.745314499722379e-07). I cannot simply use the distdim function as this provides a conversion for distances (e.g. converting the above area to metres using distdim = 0.0972m). Is there a way to overcome this or calculate the area in metres?

Best Answer

"the result is in degrees at latitude and longitude are in degrees"
No, the result would be in degrees squared. But you would have the problem that degrees in one direction are not the same size as degrees in a different direction.
You cannot use polyarea for this because you are not working with a planar surface where Euclidean distances apply. You need to calculate surface area on the oblate ellipsoid or whatever world model you are using.
You can use areaint() for that: areaint() is specifically designed to take lat/long readings and calculate surface area on sphere or oblate sphereoid.
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