General grid shift

Added in version 9.2.0.

Translation of geodetic coordinates using a grid shift.

Alias	gridshift
Domain	2D and 3D
Input type	Geodetic or projected coordinates (horizontal), meters (vertical)
Output type	Geodetic or projected coordinates (horizontal), meters (vertical)

The transformation may apply horizontal geodetic or projected offsetting and/or vertical (ellipsoidal or orthometric height) offsetting, depending on the type of the grid(s).

This is a generalization of the Horizontal grid shift and Vertical grid shift methods, that may be used in particular for US NADCON5 grids that contain both horizontal geodetic and ellipsoidal height offsets.

Note

Support for grids referenced in a projected CRS has been added in PROJ 9.4.0

Example

Transformation of a point from NAD83(NSRS2007) to NAD83(2011) on conterminous USA using a NADCON5 grid that contains horizontal and ellipsoidal height offsets.

+proj=gridshift +grids=us_noaa_nadcon5_nad83_2007_nad83_2011_conus.tif

Parameters

Required

+grids=<list>

Comma-separated list of grids to load. If a grid is prefixed by an @ the grid is considered optional and PROJ will the not complain if the grid is not available.

Grids must be in GeoTIFF format (Geodetic TIFF grids (GTG)) and have an explicit TYPE metadata item whose value is HORIZONTAL_OFFSET, GEOGRAPHIC_3D_OFFSET, ELLIPSOIDAL_HEIGHT_OFFSET VERTICAL_OFFSET_GEOGRAPHIC_TO_VERTICAL or VERTICAL_OFFSET_VERTICAL_TO_VERTICAL.

Optional

+interpolation=bilinear/biquadratic

Default is bilinear, unless the grid contains a interpolation_method metadata item specifying the method. Biquadratic is typically used for NADCON5 grids, and is defined in NOAA Technical Memorandum NOS NGS 84 - Biquadratic Interpolation

+no_z_transform

If specified, vertical coordinate transformation will be skipped.