[Proj] Calculate map resolution / LCC

Achim Hasenmueller achim.hasenmueller at gmail.com
Tue Apr 2 04:53:07 EST 2013

Hi all,

I have not been able to figure out how to calculate the map resolution of a
map in Lambert Conformant Conical (LCC). The maps are 1:500 000 and cover
about 7° longitude and 3-5° latitude.

Here's what I have:

- ellipsoid WGS84
- standard parallels 40/52N
- orthogonal meridian (roughly center of map, I use that as lon_0)
- k factor for a given latitude (roughly center of map, I use that as lat_0)
- a list of calibration points, basically the pixel coordinates of each 30'
intersection of latitude/longitude

The projection string I've come up with for one of the maps looks like this:

+proj=lcc +k_0=1.007 +lat_0=46 +lon_0=10.5 +lat_1=40 +lat_2=52 +x_0=0
+y_0=0 +datum=WGS84 +units=m +no_defs

How would one go about determining the vertical and horizontal resolution?

What is the relationship between the pixel values and the map grid

Unfortunately I'm a rookie and just started trying to grasp the theory of
map projections. I use the GeographiLib by Charley Karney.


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