[Proj] Problem with merc projection

Oscar van Vlijmen ovv at hetnet.nl
Sun Dec 30 04:37:48 EST 2007

> From: Antonio Volpicelli
> Date: Wed, 26 Dec 2007 22:27:45 +0100
> Subject: [Proj] Problem with merc projection

> I am using the Mike Adair proj4js and merc.js code .
> The trasformation using cs2cs gives me different result if I use the
> Mike code.
> When I transform lon/lat to X/Y the Mike code give me a latitude lower
> then the cs2cs of about 0.200 degrees.
>> cs2cs +proj=latlong +to +proj=merc
> 10.6846908 41.26904150
> 1189414.34      5023915.99 0.00
> with the Mike code
> 1189414.34   5052106.58

PROJ (and CS2CS) works as expected.
PROJ does an ellipsoidal Mercator projection with in this case default
lon0=0; x0=0; y0=0; k0=1.0; WGS84 ellipsoid.
Apparently the 'Mike' code does a spherical Mercator, taking the semi-major
WGS84 axis as the radius.

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