I have had a few issues with the Mercator functions. I had to use parseFloat on the values I passed into it.
Linda Rawson On Dec 17, 2007 11:31 AM, cmose <[EMAIL PROTECTED]> wrote: > > Hmnn after giving this a go I seem to be getting wildly inaccurate > results, > at least I believe I am. For instance, I used a polygon over an area I > know > to be roughly 400k square kilometers. Using the getArea on the polygon > (after converting points to sphericalmercator) I'm getting a result of > 748,912,714 sq. km... > > Anyone have any pointers or ideas of where I might be going wrong here? > Thanks! > > Josh Livni-4 wrote: > > > > > > I've not played with the getArea function, but since area calculations > > in the base coordinate system (geographic/dec. degrees, or however it's > > best described) make no sense, I think the only way you can do this with > > the current codebase would be to use the forwardMercator equations found > > in OpenLayers.Layer.SphericalMercator. > > > > After reprojecting your geometry to spherical-mercator, an area > > calculation would make more sense, and be in meters (though still be off > > by I'm guessing a few percent, depending on the size of your geometry > > and it's location). > > > > I think the trunk and next version of OL may include additional methods > > of getting to use SphericalMercator, and perhaps even other projections, > > but I'm not too clued in on the details. > > > > -Josh > > > > > > cmose wrote: > >> Hopefully I'm not making a fool of myself but my assumption is that the > >> getArea function on Geometry/subclasses returns square degrees (that > >> seems > >> to be the case to my eye). How exactly would I go about calculating > >> square > >> miles from this or is that even possible? If not, how do I go about > >> calculating the square miles contained in a shape drawn on the map? > >> > >> Thanks! > >> > > _______________________________________________ > > Users mailing list > > [email protected] > > http://openlayers.org/mailman/listinfo/users > > > > > > -- > View this message in context: > http://www.nabble.com/Square-miles-from-Square-degrees--tp14357316p14373973.html > Sent from the OpenLayers Users mailing list archive at > Nabble.com<http://nabble.com/> > . > > _______________________________________________ > Users mailing list > [email protected] > http://openlayers.org/mailman/listinfo/users >
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