-----Original Message----- Martin Hodder wrote:
> I was wondering if anyone has any heard of this projection? I am > thinking it may be a general reference to something like Behrmann > or Miller systems. > If it is a know projection does anyone know where I can get the > parameters to read it into Mapinfo? The Equidistant Cylindrical projection, also known as Plate Caree', plots a point's distance from the Equator on the Y axis. On the X axis, it plots the distance between where the point's meridian intersects the Equator and the Equator's intersection with some central meridian. The projection is useful only for maps of areas near the Equator, or centered on the Equator (such as the entire world). For map scales that show the entire world, this is the same as multiplying the latitude and longitude (in radians) by a constant factor (the radius of the Earth). For smaller areas, the elliptical shape of the earth comes into play, but you can approximate this by multiplying the latitude by the semiminor axis of the ellipsoid you're using. To get this projection in MapInfo, you apply an affine transformation to Latitude/Longitude. Find the semimajor axis and semiminor axis of the datum you choose and For WGS 84, the semimajor axis is 6378137 m (111319.49 meters per degree) the semiminor axis is 6356752.314 m (110946.26 meters per degree). Coordsys Clause: Coordsys Earth Projection 1, 104 Affine units "m", 111319.49,0,0,0, 110946.26,0 MAPINFOW.PRJ: "Plate Caree' (WGS 84)", 1001, 104, 7, 111319.49,0,0,0,110946.26,0 You can shift the central meridian from the Meridian of Greenwich by replacing the middle 0 of the three consecutive zeroes with a constant value of the meter shift between the two meridians. To center the projection on 60 degrees east longitude, this value would be -60*111319.49 = -6679169.4 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 13568
