voxcity.downloader.gee

Module for interacting with Google Earth Engine API and downloading geospatial data.

This module provides functionality to initialize Earth Engine, create regions of interest, download various types of satellite imagery and terrain data, and save them as GeoTIFF files. It supports multiple data sources including DEMs, land cover maps, and building footprints.

The module offers the following main functionalities: 1. Earth Engine initialization and region of interest (ROI) management 2. Digital Elevation Model (DEM) data access from multiple sources 3. Land cover data retrieval from ESA WorldCover, Dynamic World, and ESRI 4. Building footprint and height data extraction 5. GeoTIFF export with customizable parameters

Dependencies:

  • ee: Google Earth Engine Python API

  • geemap: Python package for interactive mapping with Earth Engine

Note: Most functions require Earth Engine authentication to be set up beforehand.

Functions

initialize_earth_engine(**initialize_kwargs)

Initialize the Earth Engine API if not already initialized.

get_roi(input_coords)

Create an Earth Engine region of interest polygon from coordinates.

get_center_point(roi)

Get the centroid coordinates of a region of interest.

get_ee_image_collection(collection_name, roi)

Get the first image from an Earth Engine ImageCollection filtered by region.

get_ee_image(collection_name, roi)

Get an Earth Engine Image clipped to a region.

save_geotiff(image, filename[, resolution, scale, ...])

Save an Earth Engine image as a GeoTIFF file.

get_dem_image(roi_buffered, source)

Get a digital elevation model (DEM) image for a region.

save_geotiff_esa_land_cover(roi, geotiff_path)

Save ESA WorldCover land cover data as a colored GeoTIFF.

save_geotiff_dynamic_world_v1(roi, geotiff_path[, date])

Save Dynamic World land cover data as a colored GeoTIFF.

save_geotiff_esri_landcover(roi, geotiff_path[, year])

Save ESRI Land Cover data as a colored GeoTIFF.

save_geotiff_open_buildings_temporal(aoi, geotiff_path)

Save Open Buildings temporal data as a GeoTIFF.

save_geotiff_dsm_minus_dtm(roi, geotiff_path, ...)

Get the height difference between DSM and DTM from terrain data.

Module Contents

voxcity.downloader.gee.initialize_earth_engine(**initialize_kwargs)[source]

Initialize the Earth Engine API if not already initialized.

Uses a public-behavior check to determine whether Earth Engine is already initialized by attempting to access asset roots. If that call fails, it will initialize Earth Engine using the provided keyword arguments.

Arguments are passed through to ee.Initialize to support contexts such as specifying a project or service account credentials.

voxcity.downloader.gee.get_roi(input_coords)[source]

Create an Earth Engine region of interest polygon from coordinates.

Parameters:

input_coords – List of coordinate pairs defining the polygon vertices in (lon, lat) format. The coordinates should form a valid polygon (non-self-intersecting).

Returns:

Earth Engine polygon geometry representing the ROI

Return type:

ee.Geometry.Polygon

Note

The function automatically closes the polygon by connecting the last vertex to the first vertex if they are not the same.

voxcity.downloader.gee.get_center_point(roi)[source]

Get the centroid coordinates of a region of interest.

Parameters:

roi – Earth Engine geometry object representing the region of interest

Returns:

(longitude, latitude) coordinates of the centroid

Return type:

tuple

Note

The centroid is calculated using Earth Engine’s geometric centroid algorithm, which may not always fall within the geometry for complex shapes.

voxcity.downloader.gee.get_ee_image_collection(collection_name, roi)[source]

Get the first image from an Earth Engine ImageCollection filtered by region.

Parameters:

  • collection_name – Name of the Earth Engine ImageCollection (e.g., ‘LANDSAT/LC08/C02/T1_TOA’)

  • roi – Earth Engine geometry to filter by

Returns:

First image from collection clipped to ROI, with any masked pixels unmasked

Return type:

ee.Image

Note

The function sorts images by time (earliest first) and unmasks any masked pixels in the final image. This is useful for ensuring complete coverage of the ROI.

voxcity.downloader.gee.get_ee_image(collection_name, roi)[source]

Get an Earth Engine Image clipped to a region.

Parameters:

  • collection_name – Name of the Earth Engine Image asset

  • roi – Earth Engine geometry to clip to

Returns:

Image clipped to ROI with masked pixels unmasked to 0

Return type:

ee.Image

Note

Unlike get_ee_image_collection(), this function works with single image assets rather than image collections. It’s useful for static datasets like DEMs. Masked pixels are replaced with 0 via unmask() so that downstream consumers receive numeric values instead of dataset-specific nodata sentinels (e.g. 255).

voxcity.downloader.gee.save_geotiff(image, filename, resolution=1, scale=None, region=None, crs=None)[source]

Save an Earth Engine image as a GeoTIFF file.

This function provides flexible options for exporting Earth Engine images to GeoTIFF format. It handles different export scenarios based on the provided parameters.

Parameters:

  • image – Earth Engine image to save

  • filename – Output filename for the GeoTIFF

  • resolution – Output resolution in degrees (default: 1), used when scale is not provided

  • scale – Output scale in meters (overrides resolution if provided)

  • region – Region to export (required if scale is provided)

  • crs – Coordinate reference system (e.g., ‘EPSG:4326’)

Note

  • If scale and region are provided, uses ee_export_image()

  • Otherwise, uses ee_to_geotiff() with resolution parameter

  • The function automatically converts output to Cloud Optimized GeoTIFF (COG) format when using ee_to_geotiff()

voxcity.downloader.gee.get_dem_image(roi_buffered, source)[source]

Get a digital elevation model (DEM) image for a region.

This function provides access to various global and regional Digital Elevation Model (DEM) datasets through Earth Engine. Each source has different coverage areas and resolutions.

Parameters:

  • roi_buffered – Earth Engine geometry with buffer - should be larger than the actual area of interest to ensure smooth interpolation at edges

  • source – DEM source, one of: - ‘NASA’: SRTM 30m global DEM - ‘COPERNICUS’: Copernicus 30m global DEM - ‘DeltaDTM’: Deltares global DTM - ‘FABDEM’: Forest And Buildings removed MERIT DEM - ‘England 1m DTM’: UK Environment Agency 1m terrain model - ‘DEM France 5m’: IGN RGE ALTI 5m France coverage - ‘DEM France 1m’: IGN RGE ALTI 1m France coverage - ‘AUSTRALIA 5M DEM’: Geoscience Australia 5m DEM - ‘USGS 3DEP 1m’: USGS 3D Elevation Program 1m DEM

Returns:

DEM image clipped to region

Return type:

ee.Image

Note

Some sources may have limited coverage or require special access permissions. The function will raise an error if the selected source is not available for the specified region.

voxcity.downloader.gee.save_geotiff_esa_land_cover(roi, geotiff_path)[source]

Save ESA WorldCover land cover data as a colored GeoTIFF.

Downloads and exports the ESA WorldCover 10m resolution global land cover map. The output is a colored GeoTIFF where each land cover class is represented by a unique color as defined in the color_map.

Parameters:

  • roi – Earth Engine geometry defining region of interest

  • geotiff_path – Output path for GeoTIFF file

Land cover classes and their corresponding colors:

  • Trees (10): Dark green

  • Shrubland (20): Orange

  • Grassland (30): Yellow

  • Cropland (40): Purple

  • Built-up (50): Red

  • Barren/sparse vegetation (60): Gray

  • Snow and ice (70): White

  • Open water (80): Blue

  • Herbaceous wetland (90): Teal

  • Mangroves (95): Light green

  • Moss and lichen (100): Beige

Note

The output GeoTIFF is exported at 10m resolution, which is the native resolution of the ESA WorldCover dataset.

voxcity.downloader.gee.save_geotiff_dynamic_world_v1(roi, geotiff_path, date=None)[source]

Save Dynamic World land cover data as a colored GeoTIFF.

Downloads and exports Google’s Dynamic World near real-time land cover classification. The data is available globally at 10m resolution from 2015 onwards, updated every 2-5 days.

Parameters:

  • roi – Earth Engine geometry defining region of interest

  • geotiff_path – Output path for GeoTIFF file

  • date – Optional date string (YYYY-MM-DD) to get data for specific time. If None, uses the most recent available image.

Land cover classes and their colors:

  • water: Blue (#419bdf)

  • trees: Dark green (#397d49)

  • grass: Light green (#88b053)

  • flooded_vegetation: Purple (#7a87c6)

  • crops: Orange (#e49635)

  • shrub_and_scrub: Tan (#dfc35a)

  • built: Red (#c4281b)

  • bare: Gray (#a59b8f)

  • snow_and_ice: Light purple (#b39fe1)

Note

If a specific date is provided but no image is available, the function will use the closest available date and print a message indicating the actual date used.

voxcity.downloader.gee.save_geotiff_esri_landcover(roi, geotiff_path, year=None)[source]

Save ESRI Land Cover data as a colored GeoTIFF.

Downloads and exports ESRI’s 10m resolution global land cover classification. This dataset is updated annually and provides consistent global coverage.

Parameters:

  • roi – Earth Engine geometry defining region of interest

  • geotiff_path – Output path for GeoTIFF file

  • year – Optional year (YYYY) to get data for specific time. If None, uses the most recent available year.

Land cover classes and colors:

  • Water (#1A5BAB): Water bodies

  • Trees (#358221): Tree cover

  • Flooded Vegetation (#87D19E): Vegetation in water-logged areas

  • Crops (#FFDB5C): Agricultural areas

  • Built Area (#ED022A): Urban and built-up areas

  • Bare Ground (#EDE9E4): Exposed soil and rock

  • Snow/Ice (#F2FAFF): Permanent snow and ice

  • Clouds (#C8C8C8): Cloud cover

  • Rangeland (#C6AD8D): Natural vegetation

Note

The function will print the year of the data actually used, which may differ from the requested year if data is not available for that time.

voxcity.downloader.gee.save_geotiff_open_buildings_temporal(aoi, geotiff_path)[source]

Save Open Buildings temporal data as a GeoTIFF.

Downloads and exports building height data from Google’s Open Buildings dataset. This dataset provides building footprints and heights derived from satellite imagery.

Parameters:

  • aoi – Earth Engine geometry defining area of interest

  • geotiff_path – Output path for GeoTIFF file

Note

  • The output GeoTIFF contains building heights in meters

  • The dataset is updated periodically and may not cover all regions

  • Resolution is fixed at 4 meters per pixel

  • Areas without buildings will have no-data values

voxcity.downloader.gee.save_geotiff_dsm_minus_dtm(roi, geotiff_path, meshsize, source)[source]

Get the height difference between DSM and DTM from terrain data.

Calculates the difference between Digital Surface Model (DSM) and Digital Terrain Model (DTM) to estimate heights of buildings, vegetation, and other above-ground features.

Parameters:

  • roi – Earth Engine geometry defining area of interest

  • geotiff_path – Output path for GeoTIFF file

  • meshsize – Size of each grid cell in meters - determines output resolution

  • source – Source of terrain data, one of: - ‘England 1m DSM - DTM’: UK Environment Agency 1m resolution - ‘Netherlands 0.5m DSM - DTM’: AHN4 0.5m resolution

Note

  • A 100m buffer is automatically added around the ROI to ensure smooth interpolation at edges

  • The output represents height above ground level in meters

  • Negative values may indicate data artifacts or actual below-ground features

  • The function requires both DSM and DTM data to be available for the region