-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 David MENTRE wrote: | | The code you give is to translate a (lat, zoom) to x coordinate, you | have a more direct formula applying the Mercator projection to the lat | value: | http://wiki.openstreetmap.org/index.php/Mercator | | In the above page, it helps to know that r_minor and r_major are Earth | Equatorial and Polar radii[1]. | | The original post helps to understand why taking into account the | variation of radius was necessary:
| http://osdir.com/ml/gis.openstreetmap.devel/2006-12/msg00016.html I don't understand. Why was it necessary? AFAICS, taking into account the variation of radius is *not* necessary, but can be done if you want to make the maths much harder for yourself. Last time I looked, the Google, Microsoft, Yahoo and OSM default slippy maps do not take the variation of radius into account, they just assume the earth is a sphere. Robert (Jamie) Munro -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkg28RAACgkQz+aYVHdncI3lAwCfeR0Bbe+xYxMWFwaV9K0XjTYa klcAoJUeLoOV4DlKn3FxoGLHisbVYLPA =Sq8Y -----END PGP SIGNATURE----- _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/dev
