Time-Specific CFR and PVR Transforms – Global Mapper

Time-Specific Coordinate Frame Rotation (CFR) and Time-Specific Position Vector Rotation (PVR) datum transformation methods are time-based transformations valid for only the given time. EPSG transforms of this type have been added to the base datasource.

The Eight Parameter Coordinate Frame Rotation and Position Vector Rotation methods each incorporate three translations, three rotations, a scale correction factor, and a reference epoch parameter. To properly define the parameters, you must know which rotation sense is used for your transformation parameters.

Note: There are two types of rotation sense:

Position Vector Rotation

The rotations are defined as positive clockwise, as may be imagined to be seen by an observer at the origin of the coordinate frame, looking in the positive direction of the axis about which the rotation is taking place.

Coordinate Frame Rotation

Rotation is positive counter-clockwise, as may be imagined to be seen by an observer at the origin of the coordinate frame, looking in the positive direction of the axis about which the rotation is taking place.

Transformations of this type will appear in the transformation picker in the Time-Dependent Transformations folder if the source and target coordinate reference system dates are both set to a specific transformation reference epoch. If one or both dates do not match a transformation's reference epoch the transformation will not appear in the datasource.

If options for time-dependent transformations are disabled in the Geographic Calculator Preferences or no dates are set for the source and target coordinate reference systems in a job, these transformations will appear in the datasource under Datum Transformations folder.