spatial

Functions for reading, writing and processing spatial data

Extends the GRACE/GRACE-FO gravity_toolkit.spatial module adding raster support

Source code

General Methods

class model_harmonics.spatial.raster(projection=None, **kwargs)[source]

Inheritance of spatial class for reading and writing raster data

Attributes:

data: np.ndarray: spatial grid data
mask: np.ndarray: spatial grid mask
x: np.ndarray: x-coordinate array
y: np.ndarray: y-coordinate array
lon: np.ndarray: grid longitudes
lat: np.ndarray: grid latitudes
fill_value: float or NoneType, default None: invalid value for spatial grid data
attributes: dict: attributes of spatial variables
extent: list, default [None,None,None,None]: spatial grid bounds [minimum x, maximum x, minimum y, maximum y]
spacing: list, default [None,None]: grid step size [x, y]
shape: tuple: dimensions of spatial object
ndim: int: number of dimensions of spatial object
filename: str: input or output filename

from_geotiff(filename, **kwargs)[source]

Read data from a geotiff file

Parameters:

filename: str: full path of input geotiff file
compression: str or NoneType, default None: file compression type
bounds: list or NoneType, default bounds: extent of the file to read: [minimum x, maximum x, minimum y, maximum y]

to_geotiff(filename, **kwargs)[source]

Write a spatial object to a geotiff file

Parameters:

filename: str

full path of output geotiff file

driver: str, default ‘cog’

GDAL driver

'GTiff': GeoTIFF

'cog': Cloud Optimized GeoTIFF

dtype: obj, default osgeo.gdal.GDT_Float64

GDAL data type

options: list, default [‘COMPRESS=LZW’]

GDAL driver creation options

get_latlon(srs_proj4=None, srs_wkt=None, srs_epsg=None)[source]

Get the latitude and longitude of grid cells

Parameters:

srs_proj4: str or NoneType, default None: PROJ4 projection string
srs_wkt: str or NoneType, default None: Well-Known Text (WKT) projection string
srs_epsg: int or NoneType, default None: EPSG projection code

Returns:

longitude: np.ndarray: longitude coordinates of grid cells
latitude: np.ndarray: latitude coordinates of grid cells

property spacing: Step size of raster object [x, y]

property extent: Bounds of raster object [minimum x, maximum x, minimum y, maximum y]

copy()[source]: Copy a raster object to a new raster object

expand_dims()[source]: Add a singleton dimension to a spatial object if non-existent

flip(axis=0)[source]

Reverse the order of data and dimensions along an axis

Parameters:

axis: int, default 0: axis to reorder

class model_harmonics.spatial.mosaic(**kwargs)[source]

Utility for creating spatial mosaics

update_spacing(x, y)[source]: update the step size of mosaic

update_bounds(x, y)[source]: update the bounds of mosaic

image_coordinates(x, y)[source]: get the image coordinates

property dimensions: Dimensions of the mosaic

property shape: Shape of the mosaic

property x: X-coordinates of the mosaic

property y: Y-coordinates of the mosaic

model_harmonics.spatial.geocentric_latitude(lon: ndarray, lat: ndarray, a_axis: float = 637813700.0, flat: float = 0.0033528106647474805)[source]

Converts from geodetic latitude to geocentric latitude for an ellipsoid [23]

Parameters:

lon: np.ndarray,: longitude (degrees east)
lat: np.ndarray,: geodetic latitude (degrees north)
a_axis: float, default 6378137.0: semimajor axis of the ellipsoid
flat: float, default 1.0/298.257223563: ellipsoidal flattening

Returns:

geocentric_latitude: np.ndarray: latitude intersecting the center of the Earth (degrees north)

model_harmonics.spatial.scale_factors(lat: ndarray, flat: float = 0.0033528106647474805, reference_latitude: float = 70.0, metric: str = 'area')[source]

Calculates scaling factors to account for polar stereographic distortion including special case of at the exact pole [23]

Parameters:

lat: np.ndarray

latitude (degrees north)

flat: float, default 1.0/298.257223563

ellipsoidal flattening

reference_latitude: float, default 70.0

reference latitude (true scale latitude)

metric: str, default ‘area’

metric to calculate scaling factors

'distance': scale factors for distance

'area': scale factors for area

Returns:

scale: np.ndarray: scaling factors at input latitudes

model_harmonics.spatial.get_latlon(x, y, srs_proj4=None, srs_wkt=None, srs_epsg=None)[source]

Get the latitude and longitude of grid cells

Parameters:

srs_proj4: str or NoneType, default None: PROJ4 projection string
srs_wkt: str or NoneType, default None: Well-Known Text (WKT) projection string
srs_epsg: int or NoneType, default None: EPSG projection code

Returns:

longitude: np.ndarray: longitude coordinates of grid cells
latitude: np.ndarray: latitude coordinates of grid cells