Geographic
Represents a step in the process of transforming between datums. Each geographic transformation step can be constructed from a well-known ID (WKID) that represents a geographic transformation. Because the Projection Engine supports thousands of transformations, WKIDs are not presented in the SDK as enumerations. Instead, they are documented in the developers guide.
The list of supported WKIDs includes a transformation from every supported datum to WGS 1984. Additionally, there is more limited list of transformations directly between two non-WGS84 datums, such as 4461, which is NAD_1983_HARN_To_NAD_1983_NSRS2007_1.
Transformations with more than one step typically go via WGS84, with one forward and one inverse geographic transformation chained together to get the required geographic coordinates.
A geographic transformation step object is immutable.
Since
200.1.0
See also
Constructors
Creates a new GeographicTransformationStep instance from a well-known ID. Occasionally, WKIDs may change, and older codes may be deprecated in favor of a new code. Both old (deprecated) and new (latest) WKIDs continue to work for instantiation, as long as they are supported by the Projection Engine. The GeographicTransformationStep.wkid property returns the new (latest) WKID code.
Creates a new GeographicTransformationStep instance from a well-known text string.
Properties
True if this geographic transformation step instance is an inverted transformation. Transformations have a specific direction that is indicated by the GeographicTransformationStep.wkText value. An inverted transformation is used to transform geometries in the opposite direction to that indicated by the well-known text. GeographicTransformation has DatumTransformation.inputSpatialReference and DatumTransformation.outputSpatialReference properties that respect the inverse value of the contained transformation(s).
True if any files needed by the Projection Engine for this transformation step are missing from the local file system. GeographicTransformationStep.projectionEngineFilenames indicates the required files.
A list of the Projection Engine files required to support this geographic transformation step. Datum transformations can be mathematically defined (equation-based transformations), or may rely on external supporting files (grid-based transformations). For a grid-based transformation step, this returns a list of the files required to use this transformation, prefixed by an expected subpath of the file(s) underneath TransformationCatalog.projectionEngineDirectory. For an equation-based transformation, this returns an empty list.
The well-known text of this geographic transformation step instance. This value does not respect the GeographicTransformationStep.isInverse property.