On Mon, Feb 11, 2013 at 3:56 PM, Ákos Maróy <a...@maroy.hu> wrote:
>
> another interesting thing I found is that when doing this conversion:
>
> ReferencedEnvelope coverage = new ReferencedEnvelope(
> -179.9999, 179.9999, -89.9999, 89.9999,
> DefaultGeographicCRS.WGS84);
> CoordinateRererenceSystem crs = CRS.decode("EPSG:900913");
> ReferencedEnvelope re = coverage.transform(crs, false);
>
>
> the result is:
>
> ReferencedEnvelope[-2.0037497210840166E7 : 2.0037497210840166E7,
> -8.898594657792848E7 : 8.89859465782924E7]
>
>
> where the vertical extent is unrealistically large in both directions.
> so much so, that when performing the following:
>
>
Nothing unrealistic about it, the google projection derives from
cylindrical mercator which
diverges at the poles, where the y coordinate becomes infinite.
> GeodeticCalculator gc = new GeodeticCalculator(crs);
> gc.setStartingPosition(new DirectPosition2D(crs,
> re.getMinimum(0), re.getMinimum(1)));
> gc.setDirection(0, mapBounds.getHeight());
>
>
> one gets the following exception IllegalArgumentException:
>
> The distance 177,971,893.156 is out of range (0 to 20,003,930.459 m)
>
>
>
> indeed, shouldn't the above result be:
>
> ReferencedEnvelope[-2.0037497210840166E7 : 2.0037497210840166E7,
> -2.0037497210840166E7 : 2.0037497210840166E7]
>
>
> instead?
>
Only if you limit yourself to 85 degrees if memory serves me well, which is
the north/south
limit in google/bing/yahoo maps.
Beyond that the deformation introduced by the projection is massive, and
the math really stops
to make any sense.
Cheers
Andrea
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