Transforming

This module provides functions for transforming coordinates between different geodetic datums. It includes methods for performing Helmert transformations, functions for various common geodetic transformations and support for NTv2 2D grid-based transformations.

Helmert Transformations

geodepy.transform.conform7(x, y, z, trans, vcv=None)[source]

Performs a Helmert 7 Parameter Conformal Transformation using Cartesian point co-ordinates and a predefined transformation object.

Parameters:

  • x – Cartesian X (m)

  • y – Cartesian Y (m)

  • z – Cartesian Z (m)

  • trans – Transformation Object (note: this function ignores all time-dependent variables)

  • vcv – Optional 3*3 numpy array in Cartesian units to propagate tf uncertainty

Returns:

Transformed X, Y, Z Cartesian Co-ordinates, vcv matrix

geodepy.transform.conform14(x, y, z, to_epoch, trans, vcv=None)[source]

Performs a Helmert 14 Parameter Conformal Transformation using Cartesian point co-ordinates and a predefined transformation object. The transformation parameters are projected from the transformation objects reference epoch to a specified epoch.

Parameters:

  • x – Cartesian X (m)

  • y – Cartesian Y (m)

  • z – Cartesian Z (m)

  • to_epoch – Epoch co-ordinate transformation is performed at (datetime.date Object)

  • trans – Transformation Object

  • vcv – Optional 3*3 numpy array in Cartesian units to propagate tf uncertainty

Returns:

Cartesian X, Y, Z co-ordinates and vcv matrix transformed using Transformation parameters at desired epoch

geodepy.transform.plate_motion_transformation(x, y, z, from_epoch, to_epoch, plate_motion, vcv=None)[source]

Preforms plate motion transformations using a helmert 14 conformal transformation.

Parameters:

  • x – Cartesian X (m)

  • y – Cartesian Y (m)

  • z – Cartesian Z (m)

  • from_epoch – Epoch the co-ordinate transformation is from (datetime.date Object)

  • to_epoch – Epoch the co-ordinate transformation is to (datetime.date Object)

  • plate_motion – Plate motion model for transformation

  • vcv – Optional 3*3 numpy array in Cartesian units to propagate tf uncertainty

Returns:

Cartesian X, Y, Z co-ordinates and vcv matrix transformed using plate motion to desired epoch

Common Geodetic Transformations

geodepy.transform.transform_mga94_to_mga2020(zone, east, north, ell_ht=False, vcv=None)[source]

Performs conformal transformation of Map Grid of Australia 1994 to Map Grid of Australia 2020 Coordinates using the GDA2020 Tech Manual v1.2 7 parameter similarity transformation parameters

Parameters:

  • zone – Zone Number - 1 to 60

  • east – Easting (m, within 3330km of Central Meridian)

  • north – Northing (m, 0 to 10,000,000m)

  • ell_ht – Ellipsoid Height (m) (optional)

  • vcv – Optional 3*3 numpy array in local enu units to propagate tf uncertainty

Returns:

MGA2020 Zone, Easting, Northing, Ellipsoid Height (if none provided, returns 0), and vcv matrix

geodepy.transform.transform_mga2020_to_mga94(zone, east, north, ell_ht=False, vcv=None)[source]

Performs conformal transformation of Map Grid of Australia 2020 to Map Grid of Australia 1994 Coordinates using the reverse form of the GDA2020 Tech Manual v1.2 7 parameter similarity transformation parameters

Parameters:

  • zone – Zone Number - 1 to 60

  • east – Easting (m, within 3330km of Central Meridian)

  • north – Northing (m, 0 to 10,000,000m)

  • ell_ht – Ellipsoid Height (m) (optional)

  • vcv – Optional 3*3 numpy array in local enu units to propagate tf uncertainty

Returns:

MGA1994 Zone, Easting, Northing, Ellipsoid Height (if none provided, returns 0), and vcv matrix

geodepy.transform.transform_atrf2014_to_gda2020(x, y, z, epoch_from, vcv=None)[source]

Transforms Cartesian (x, y, z) Coordinates in terms of the Australian Terrestrial Reference Frame (ATRF) at a specified epoch to coordinates in terms of Geocentric Datum of Australia 2020 (GDA2020 - reference epoch 2020.0)

Parameters:

  • x – ATRF Cartesian X Coordinate (m)

  • y – ATRF Cartesian Y Coordinate (m)

  • z – ATRF Cartesian Z Coordinate (m)

  • epoch_from – ATRF Coordinate Epoch (datetime.date Object)

  • vcv – Optional 3*3 numpy array in Cartesian units to propagate tf uncertainty

Returns:

Cartesian X, Y, Z Coordinates and vcv matrix in terms of GDA2020

geodepy.transform.transform_gda2020_to_atrf2014(x, y, z, epoch_to, vcv=None)[source]

Transforms Cartesian (x, y, z) Coordinates in terms of Geocentric Datum of Australia 2020 (GDA2020 - reference epoch 2020.0) to coordinates in terms of the Australian Terrestrial Reference Frame (ATRF) at a specified epoch

Parameters:

  • x – GDA2020 Cartesian X Coordinate (m)

  • y – GDA2020 Cartesian Y Coordinate (m)

  • z – GDA2020 Cartesian Z Coordinate (m)

  • epoch_to – ATRF Coordinate Epoch (datetime.date Object)

  • vcv – Optional 3*3 numpy array in Cartesian units to propagate tf uncertainty

Returns:

Cartesian X, Y, Z Coordinates and vcv matrix in terms of ATRF at the specified Epoch

NTv2 Transformations

geodepy.transform.ntv2_2d(ntv2_grid, lat, lon, forward_tf=True, method='bicubic')[source]

Performs a 2D transformation based on ntv2 grid shifts.

Parameters:

  • ntv2_grid – Ntv2Grid object (create with read_ntv2_file() function in geodepy.ntv2reader module)

  • lat – latitude in decimal degrees

  • lon – longitude in decimal degrees

  • forward_tf – True/False: - True applies the shifts in the direction given in the grid. - False applies the shifts in the opposite direction of the grid

  • method – Interpolation strategy - either ‘bicubic’ or ‘bilinear’

Returns:

Transformed latitude and longitude