[Proj] Re: Distance measured in Mercator projection
strebe at aol.com
strebe at aol.com
Wed Jul 9 16:21:00 EDT 2008
If you assume a spherical earth, the length of a meter on the Mercator equatorial aspect is
1m / cos (phi)
where phi is the latitude and "cos" is the cosine function. Be careful to set the calculator to degrees or else to convert the latitude to radians. The calculation is more complicated on an ellipsoidal earth.
Regards,
-- daan Strebe
-----Original Message-----
From: Shannon Scott <sscott at locationinc.com>
To: Proj at lists.maptools.org
Sent: Wed, 9 Jul 2008 10:52 am
Subject: [Proj] Distance measured in Mercator projection
Hello,?
Please forgive my ignorance, I know very little about map projections.
I apologize if this list is not the appropriate place to post this question.?
If I understand correctly, in the Mercator projection, 1 unit of space
is equal to 1 meter at the equator.?
As you move away from the equator, the longitudinal lines are stretched
to make the lat and long intersect at 90 degree angles.?
How would I calculate the length in meters of 1 unit of space in the
Mercator projection at a specific latitude??
Any advice of pointers are appreciated.?
Thank you.?
Shannon?
?
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