Proj4String +axis parameter

Feb 27, 2011 at 12:35 AM

In the proj 4.8 library there is a +axis parameter. This parameter may be used to change the axis orientation (such as when x axis goes from east to west instead of west to east)

According to proj 4 documentation:

'e' - easting
'w' - westing - an x/longitude with the opposite sign to normal.
'n' - northing
's' - southing - a y/latitude with the opposite sign to the normal.
'u' - up - normal z
'd' - down - a z/elevation with the opposite sign to the normal.

So, a normal coordinate system is defined as "+axis=enu". This is the
default and it may be omitted in the normal case. Some variations:

"end" - Normal in x/y but the Z is a depth rather elevation.
"neu" - reversed x/y axes, for instance +proj=latlong +axis=neu would truely
be a latitude/longitude coordinate system.
"wsu" - A coordinate system with the sign of x and y negated as is used
for transverse mercator south orientated.

In the Esri string, these parameters are also supported as "Y_Scale" (1.0 or -1.0), "X_Scale" (1.0 or -1.0) and "XY_Plane_Rotation" (90.0 if x/y axis are reversed)

If the group agrees, may I add "Axis" as a new property of DotSpatial.Projections.ProjectionInfo?