GeographicTransformation

Used to transform coordinates of geometries between spatial references that have two different geographic coordinate systems. Each geographic transformation has an input and an output spatial reference. The transformation operates on the horizontal (geographic) datums in each spatial reference.

The inverse of the geographic transformation, if any, used to transform in the opposite direction, may be accessed using a member function.

A geographic transformation can be constructed from a single geographic transformation step object, or from a list of geographic transformation steps objects that are chained together. Most transformations between spatial references that do not share the WGS 1984 datum use WGS 1984 as an intermediate datum. Thus, it is common to create a geographic transformation object with two geographic transformation steps: first to transform from the datum in the input spatial reference to WGS 1984, and then from WGS 1984 to the output spatial reference's datum. There are a limited number of transformations directly between two non-WGS84 datums, such as WKID 4461, which is NAD_1983_HARN_To_NAD_1983_NSRS2007_1. These do not need WGS 1984 as an intermediate datum.

In most cases, you do not need to construct your own GeographicTransformation. You can get a list of suitable transformations for a given input and output spatial reference using one of the functions on the transformation catalog class.

A geographic transformation object is immutable.