DEM Downloader Module

Download SRTM Digital Elevation Model data for specified geographic areas.

This module provides functions to download SRTM elevation data using either bounding box coordinates or place names, via NASA Earthdata authentication.

SRTM Data

  • Source: NASA Shuttle Radar Topography Mission

  • Coverage: 60N to 56S latitude

  • Resolution: 1 arc-second (~30m) for SRTM1, 3 arc-second (~90m) for SRTM3

  • Format: HGT (Height) files, 1 x 1 tile grid

Usage Examples

Download by bounding box:

from src.terrain.dem_downloader import download_dem_by_bbox

bbox = (42.0, -83.5, 42.5, -83.0)  # Detroit area
files = download_dem_by_bbox(
    bbox=bbox,
    output_dir="data/detroit_dem",
)

Download by place name:

from src.terrain.dem_downloader import download_dem_by_place_name

files = download_dem_by_place_name(
    place_name="Detroit, MI",
    output_dir="data/detroit_dem",
)

API Reference

DEM (Digital Elevation Model) downloader for SRTM elevation data.

This module provides functions to download SRTM elevation data for specified geographic areas using either bounding box coordinates or place names.

SRTM Data:

  • NASA Shuttle Radar Topography Mission

  • Global coverage (60°N to 56°S)

  • 1 arc-second (~30m) resolution (SRTM1)

  • 3 arc-second (~90m) resolution (SRTM3)

  • Data format: HGT (Height) files

  • Tile size: 1° × 1° geographic grid

Usage - Download by bbox:

from src.terrain.dem_downloader import download_dem_by_bbox

bbox = (42.0, -83.5, 42.5, -83.0)  # Detroit area
files = download_dem_by_bbox(
    bbox=bbox,
    output_dir="data/detroit_dem",
    username="your_earthdata_username",
    password="your_earthdata_password"
)

Usage - Download by place name:

from src.terrain.dem_downloader import download_dem_by_place_name

files = download_dem_by_place_name(
    place_name="Detroit, MI",
    output_dir="data/detroit_dem",
    username="your_earthdata_username",
    password="your_earthdata_password"
)

Usage - Visualize bbox:

from src.terrain.dem_downloader import display_bbox_on_map

bbox = (42.0, -83.5, 42.5, -83.0)
display_bbox_on_map(bbox, output_file="bbox_map.html")
# Open bbox_map.html in browser to visualize the area
src.terrain.dem_downloader.get_srtm_tile_name(lat, lon)[source]

Get SRTM tile name for a given latitude/longitude coordinate.

SRTM tiles are 1°×1° and named by their southwest corner coordinates.

Parameters:

  • lat (float) – Latitude in decimal degrees (-90 to +90)

  • lon (float) – Longitude in decimal degrees (-180 to +180)

Returns:

Tile name following SRTM convention (e.g., “N42W084”)

Return type:

str

Examples

>>> get_srtm_tile_name(42.3, -83.0)
'N42W083'
>>> get_srtm_tile_name(42.9, -83.9)
'N42W084'
src.terrain.dem_downloader.calculate_required_srtm_tiles(bbox)[source]

Calculate which SRTM tiles are needed to cover a bounding box.

Parameters:

bbox (Tuple[float, float, float, float]) – Bounding box as (south, west, north, east) in decimal degrees

Returns:

List of SRTM tile names (e.g., [“N42W084”, “N42W083”])

Return type:

List[str]

Examples

>>> calculate_required_srtm_tiles((42.0, -83.5, 42.5, -83.0))
['N42W084', 'N42W083']
src.terrain.dem_downloader.download_dem_by_bbox(bbox, output_dir, username=None, password=None)[source]

Download SRTM elevation data for a bounding box area.

Parameters:

  • bbox (Tuple[float, float, float, float]) – Bounding box as (south, west, north, east) in decimal degrees

  • output_dir (str) – Directory to save downloaded DEM files

  • username (str | None) – NASA Earthdata username (optional for testing)

  • password (str | None) – NASA Earthdata password (optional for testing)

Returns:

List of Path objects pointing to downloaded ZIP files

Return type:

List[Path]

Note

NASADEM downloads tiles as ZIP files (e.g., “NASADEM_HGT_N32W117.zip”). Each ZIP contains the HGT file and metadata.

Examples

>>> bbox = (42.0, -83.5, 42.5, -83.0)  # Detroit
>>> files = download_dem_by_bbox(bbox, "data/dem", "user", "pass")
>>> print(f"Downloaded {len(files)} tiles")
src.terrain.dem_downloader.download_dem_by_place_name(place_name, output_dir, username=None, password=None)[source]

Download SRTM elevation data for a named location.

Parameters:

  • place_name (str) – Place name like “Detroit, MI” or “Mount Rainier”

  • output_dir (str) – Directory to save downloaded DEM files

  • username (str | None) – NASA Earthdata username (optional for testing)

  • password (str | None) – NASA Earthdata password (optional for testing)

Returns:

List of Path objects pointing to downloaded HGT files

Return type:

List[Path]

Examples

>>> files = download_dem_by_place_name("Detroit, MI", "data/dem")
src.terrain.dem_downloader.display_bbox_on_map(bbox, output_file='bbox_map.html')[source]

Create an interactive HTML map showing the bounding box.

Helps users visualize and verify their bounding box selection.

Parameters:

  • bbox (Tuple[float, float, float, float]) – Bounding box as (south, west, north, east) in decimal degrees

  • output_file (str) – Path to output HTML file

Return type:

None

Examples

>>> bbox = (42.0, -83.5, 42.5, -83.0)
>>> display_bbox_on_map(bbox, "detroit_bbox.html")
# Opens detroit_bbox.html in browser

See Also