mercator, robinsen projections

*To*: mathgroup at smc.vnet.net*Subject*: [mg56104] mercator, robinsen projections*From*: Edward Peschko <esp5 at pge.com>*Date*: Fri, 15 Apr 2005 04:48:08 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

hey all, I was wondering if people had some pointers on how to translate Mercator Latitude/Longitude points to Robinsen (or other projections.) Example: suppose I had a robinsen graph of the world, which is on a flat, 2D graph. I'd like to 'pick points' off of this axis, and turn them into equivalent points on a mercator graph. And I'd like to go vice versa. Is there a simple, mathematica function or package that will do this, eg: Mercator[.1,.1] which takes the linear representation of Mercator ( x == 0 => corresponds to zero meridian, x == -1 => corresponds to -180 longitude, y == 0 => corresponds to equator, y == -infinity => corresponds to the south pole ) and turns it into a latitude/longitude representation? Ultimately, I'd like to be able to say something like: Robinson_Coords[ Mercator_LatLong[.1,.1] ]; to convert from the flat, Mercator version of a map to the Robinson coordinates, and Mercator_Coords[ Robinson_LatLong[.1,.1] ] to go the other way around. There's got to be a projections package out there somewhere, or is this a particular wheel I need to reinvent? Thanks much, Ed