Transformations

Module for performing reference systems transformations.

Transformer

A class for performing coordinate transformations between two different EPSG projections.

Parameters:

Name	Type	Description	Default
epsg_from	int	EPSG code of the source projection.	required
epsg_to	int	EPSG code of the target projection.	required
transform3d	bool	Flag indicating whether to perform 3D transformations. Defaults to False.	required
geoid_path	Union[str, Path]	Path to a raster file containing geoid undulation data. Required if transform3d is True. Defaults to None.	None

Raises:

Type	Description
AssertionError	If epsg_from and epsg_to are the same or not of integer type.

Attributes:

Name	Type	Description
epsg_from	int	EPSG code of the source projection.
epsg_to	int	EPSG code of the target projection.
crs_from	CRS	CRS object of the source projection.
crs_to	CRS	CRS object of the target projection.
_transformer	Transformer	Transformer object for performing the coordinate transformation.
transform3d	bool	Flag indicating whether to perform 3D transformations.
geoid_path	Union[str, Path]	Path to a raster file containing geoid undulation data.

Methods:

Name

Description

transform

float, lon: float, ellh: float = None) -> Tuple[float, float] or Tuple[float, float, float]: Transforms a given set of latitude, longitude, and, optionally, ellipsoidal height coordinates from the source projection to the target projection. Args: lat (float): Latitude coordinate in decimal degrees. lon (float): Longitude coordinate in decimal degrees. ellh (float, optional): Ellipsoidal height coordinate in meters. Required if transform3d is True. Returns: A tuple containing the transformed x, y, and z (if transform3d` is True) coordinates. Raises: ValueError: If transform3d is True but geoid_path is not provided.

__init__(epsg_from, epsg_to, transfrom3d=False, geoid_path=None)

Initializes a Transformer object for coordinate transformations.

Parameters:

Name	Type	Description	Default
epsg_from	int	EPSG code of the input coordinate reference system (CRS).	required
epsg_to	int	EPSG code of the output CRS.	required
transform3d	bool	Indicates whether the transform should include a height component. Defaults to False.	required
geoid_path	Union[str, Path]	Path to a geoid undulation raster file for height correction. Defaults to None.	None

Raises:

Type	Description
AssertionError	Raised if epsg_from and epsg_to are the same integer value.

transform(lat, lon, ellh=None)

Transforms a given set of latitude, longitude, and, optionally, ellipsoidal height coordinates from the source projection to the target projection.

Parameters:

Name	Type	Description	Default
lat	float	Latitude coordinate in decimal degrees.	required
lon	float	Longitude coordinate in decimal degrees.	required
ellh	float	Ellipsoidal height coordinate in meters. Required if transform3d is True.	None

Returns:

Type	Description
Tuple[float, float, float]	A tuple containing the transformed x, y, and z (if transform3d is True) coordinates.

Raises:

Type	Description
ValueError	If transform3d is True but geoid_path is not provided.
AssertionError	If ellh is not provided for 3D transformations.

bilinear_interpolate(im, x, y)

Performs bilinear interpolation on a 2D array (single channel image given x, y arrays of unstructured query points. Args: im (np.ndarray): Single channel image. x (np.ndarray): nx1 array of x coordinates of query points. y (np.ndarray): nx1 array of y coordinates of query points.

Returns:

Type	Description
ndarray	np.ndarray: nx1 array of the interpolated color.

get_geoid_undulation(geoid_path)

Returns the geoid undulation and its affine transformation matrix from a geoid raster file.

Parameters:

Name	Type	Description	Default
geoid_path	Union[str, Path]	Path to the geoid raster file.	required

Returns:

Type	Description
Tuple[ndarray, Affine]	Tuple[np.ndarray, Affine]: A tuple containing the geoid undulation as a NumPy array and its affine transformation matrix as a Rasterio Affine object.

Raises:

Type	Description
ImportError	Raised if rasterio is not installed in the system.

rc2xy(tform, row, col)

Converts row, column coordinates to x, y coordinates using an affine transformation, as stored in the rasterio dataset (i.e., the transformation that maps pixel coordinates to world coordinates)

Parameters:

Name	Type	Description	Default
tform	Affine	The affine transformation matrix.	required
row	float	The row coordinate.	required
col	float	The column coordinate.	required

Returns:

Type	Description
Tuple[float, float]	Tuple[float, float]: The x, y coordinates.

xy2rc(tform, x, y)

Converts x, y coordinates to row, column coordinates using an affine transformation, as stored in the rasterio dataset (i.e., the transformation that maps pixel coordinates to world coordinates)

Parameters:

Name	Type	Description	Default
tform	Affine	The affine transformation matrix.	required
x	float	The x coordinate.	required
y	float	The y coordinate.	required

Returns:

Type	Description
Tuple[float, float]	Tuple[float, float]: The row, column coordinates.