Axis swap

New in version 5.0.0.

Change the order and sign of 2,3 or 4 axes.

Alias axisswap
Domain 2D, 3D or 4D
Input type Any
Output type Any

Each of the possible four axes are numbered with 1–4, such that the first input axis is 1, the second is 2 and so on. The output ordering is controlled by a list of the input axes re-ordered to the new mapping.


Reversing the order of the axes:

+proj=axisswap +order=4,3,2,1

Swapping the first two axes (x and y):

+proj=axisswap +order=2,1,3,4

The direction, or sign, of an axis can be changed by adding a minus in front of the axis-number:

+proj=axisswap +order=1,-2,3,4

It is only necessary to specify the axes that are affected by the swap operation:

+proj=axisswap +order=2,1



Ordered comma-separated list of axis, e.g. +order=2,1,3,4. Adding a minus in front of an axis number results in a change of direction for that axis, e.g. southward instead of northward.