environmentaltools.spatial.global_to_local_coords

environmentaltools.spatial.global_to_local_coords(x_glob, y_glob, alpha, lon_0_glob, lat_0_glob)[source]

Transform global coordinates to local rotated coordinate system.

Converts coordinates from a global reference system to a local coordinate system defined by an origin point and rotation angle. Useful for analyzing data in a local shore-normal/shore-parallel reference frame.

Parameters:

  • x_glob (float or np.ndarray) – Global X coordinates (e.g., UTM easting or longitude)

  • y_glob (float or np.ndarray) – Global Y coordinates (e.g., UTM northing or latitude)

  • alpha (float) – Rotation angle in degrees defining local coordinate system orientation

  • lon_0_glob (float) – Global X coordinate of local system origin

  • lat_0_glob (float) – Global Y coordinate of local system origin

Returns:

  • x_loc (float or np.ndarray) – Local X coordinates (along rotated axis)

  • y_loc (float or np.ndarray) – Local Y coordinates (perpendicular to rotated axis)

Notes

The transformation applies: 1. Translation to move origin to (lon_0_glob, lat_0_glob) 2. Rotation by angle alpha

Examples

>>> x_glob, y_glob = 100.0, 200.0
>>> x_loc, y_loc = global_to_local_coords(x_glob, y_glob, 45, 0, 0)