curryer.compute.elevation

Elevation computations and DEM management.

References

GMTED2010

https://pubs.usgs.gov/of/2011/1073/pdf/of2011-1073.pdf

UNAVCO Geoid Height Calculator

https://www.unavco.org/software/geodetic-utilities/geoid-height-calculator/geoid-height-calculator.html

@author: Brandon Stone

Attributes

logger
VDATUMS
VDATUM_TO_EPSG

Classes

Elevation	High-level class for accessing elevation data from individual files.
ElevationRegion	High-level class for accessing elevation data from an optimized

Module Contents

curryer.compute.elevation.logger

curryer.compute.elevation.VDATUMS

curryer.compute.elevation.VDATUM_TO_EPSG

class curryer.compute.elevation.Elevation(data_dir: str | pathlib.Path = None, meters=False, degrees=True)

High-level class for accessing elevation data from individual files.

LON_STEP = 30

LAT_STEP = 20

LON_MID = 0

LAT_MID = 10

data_dir = None

meters = False

degrees = True

egm96_to_wgs84

static check_for_geoid_data()

Ensure that third-party geoid data is available.

latlon_to_pixel(lon: float, lat: float, transform: affine.Affine)

Convert lon/lat to raster row/col indices using the given Affine transform.

Parameters:

• lon (float) – Longitude coordinate in degrees.

• lat (float) – Latitude coordinate in degrees.

• transform (affine.Affine) – Affine transformation object for coordinate conversion.

Returns:

Row and column indices (row, col) in the raster.

Return type:

tuple of int

Notes

This assumes pixel-center coordinates, so we don’t need to add 0.5 offset since our coordinates already represent pixel centers.

locate_files(pattern: str = '*_gmted_*.tif') → list[pathlib.Path]

Locate DEM files on the filesystem (cached).

Parameters:

pattern (str, optional) – File name pattern to filter DEM files with.

Returns:

List of found DEM files. Cached after first execution.

Return type:

list[Path]

describe_files() → pandas.DataFrame

Compute the metadata for the available DEM files (cached).

Returns:

Metadata for the individual DEM files. Cached after first execution.

Return type:

pd.DataFrame

lookup_file(lon: float, lat: float, arcsec: float = None, stat: str = 'mea', wrap_lon=False, degrees: bool | None = None) → pandas.Series | None

Find the DEM file for a given lon/lat point.

Parameters:

• lon (float) – Longitude in degrees or radians, see degrees.

• lat (float) – Latitude in degrees or radians, see degrees.

• arcsec (float, optional) – Select the DEM resolution. Default is the highest available.

• stat (str, optional) – Select the type of DEM file. Default is “mea” (mean).

• wrap_lon (bool, optional) – Allow longitude values less than -180 and greater than 180, wrapping them around the globe (e.g., 190 = -170). Default is False.

• degrees (None or bool, optional) – Assume in/out lon/lat are in degrees. If not specified or None (default), uses the instance value of degrees (default is True).

Returns:

Matching DEM metadata entry or None if no match was found.

Return type:

pd.Series or None

load_file(filepath: pathlib.Path) → xarray.DataArray

Load data from a DEM file (cached).

Parameters:

filepath (Path) – Path to the DEM file to load.

Returns:

Loaded elevation data. Cached for each unique file path.

Return type:

xr.DataArray

get_geoid_height(lon: numpy.ndarray | float, lat: numpy.ndarray | float, degrees: bool | None = None) → numpy.ndarray | float

Query the geoid height for a given lon/lat(s).

Parameters:

• lon (np.ndarray or float) – Longitude in degrees or radians, see degrees.

• lat (np.ndarray or float) – Latitude in degrees or radians, see degrees.

• degrees (None or bool, optional) – Assume in/out lon/lat are in degrees. If not specified or None (default), uses the instance value of degrees (default is True).

Returns:

Geoid height above the ellipsoid. Default is kilometers unless init variable meters was True.

Return type:

np.ndarray or float

get_dem_height(lon: float, lat: float, filepath: pathlib.Path, degrees: bool | None = None) → float

Query the DEM height above the geoid for a given lon/lat.

Parameters:

• lon (float) – Longitude in degrees or radians, see degrees.

• lat (float) – Latitude in degrees or radians, see degrees.

• filepath (Path) – DEM file to query data from.

• degrees (None or bool, optional) – Assume in/out lon/lat are in degrees. If not specified or None (default), uses the instance value of degrees (default is True).

Returns:

DEM height above the geoid. Default is kilometers unless init variable meters was True.

Return type:

float

query(lon, lat, orthometric=False)

Query the surface (DEM + geoid) height above the ellipsoid a given lon/lat.

Parameters:

• lon (float) – Longitude in degrees or radians, see init degrees.

• lat (float) – Latitude in degrees or radians, see init degrees.

• orthometric (bool, optional) – Exclude the geoid height as part of the surface height. Default is False.

Returns:

Surface (DEM and geoid (unless orthometric=True) height above the ellipsoid. Default is kilometers unless init variable meters was True.

Return type:

float

local_minmax(lon, lat, pad, orthometric=False) → tuple[float, float]

Compute the elevation min/max around a buffered point.

Parameters:

• lon (float) – Longitude in degrees or radians, see init degrees.

• lat (float) – Latitude in degrees or radians, see init degrees.

• pad (float) – Padding to add to the point, in meters or kilometers, see init meters.

• orthometric (bool, optional) – Exclude the geoid heights from the result.

Returns:

Min and max elevation around the specified padding point.

Return type:

(float, float)

local_region(min_lon: float, max_lon: float, min_lat: float, max_lat: float, orthometric=False)

Create a regional subset, supporting SIGNIFICANTLY faster queries.

Parameters:

• min_lon (float) – Minimum longitude extent of the region, see init degrees.

• max_lon (float) – Maximum longitude extent of the region, see init degrees.

• min_lat (float) – Minimum latitude extent of the region, see init degrees.

• max_lat (float) – Maximum latitude extent of the region, see init degrees.

• orthometric (bool, optional) – Exclude the geoid heights from the result.

Returns:

Elevation subset that only supports queries within its region, but SIGNIFICANTLY faster within the region!

Return type:

ElevationRegion

class curryer.compute.elevation.ElevationRegion(data: numpy.ndarray, ulx: float, uly: float, dx: float, dy: float, orthometric=None, meters: bool | None = None, degrees: bool | None = None)

High-level class for accessing elevation data from an optimized pre-cached dataset.

data

ulx

uly

dx

dy

orthometric = None

meters = None

degrees = None

lrx

lry

classmethod from_xarray(hts: xarray.DataArray, **kwargs)

Create a region from an xarray data array.

Parameters:

• hts (xr.DataArray) – Elevation data with lon/lat coordinates (x/y).

• kwargs (dict) – See init arguments.

Returns:

Elevation region from an xarray data array.

Return type:

ElevationRegion

query(lon: numpy.ndarray | float, lat: numpy.ndarray | float, orthometric=None) → numpy.ndarray | float

Query the surface (DEM + geoid) height above the ellipsoid a given lon/lat.

Parameters:

• lon (np.ndarray or float) – Longitude in degrees or radians, see init degrees.

• lat (np.ndarray or float) – Latitude in degrees or radians, see init degrees.

• orthometric (bool, optional) – Included for backwards compatibility with the slower Elevation implementation. Ignored if not specified, otherwise it must match the value used to create this region.

Returns:

Surface (DEM and geoid (unless orthometric=True)) height above the ellipsoid. Default is kilometers unless init variable meters was True.

Return type:

np.ndarray or float

local_minmax(lon=None, lat=None, pad=None) → tuple[float, float]

Compute local min/max elevation. Simply assumes the region is the same as the locality, returning its min/max.

Parameters:

• lon – Ignored.

• lat – Ignored.

• pad – Ignored.

Returns:

Min and max elevation for the region.

Return type:

float, float