python-geo-dem

A Python library that simplifies the process of obtaining altitude data for a set of lat/long points

Downloading Geographic Data

Before you begin using the geographic libraries, you must download the required altitude data files. The library is capable of handling DEM altitude files obtained via GLOBE, a research project run by the NOAA. To download a global set of data, simply run the command

python download_data.py

Note that the full GLOBE data will take approximately 1.8GB

Determining Altitude

Assuming a full set of data has been downloaded to the default directory via the download_data.py command, usage is very straightforward.

To get the altitude (in meters) at a given longitude/latitude point:

from geodem.utils import altitude_at_geographic_coordinates
altitude = altitude_at_geographic_coordinates(lon=-122, 50)
print altitude # => 951

To get the altitude for a given range

from geodem.utils import altitude_at_geographic_coordinates
altitudes = altitude_at_geographic_range(lon1=-122, lat1=50, lon2=-122 - 0.01, lat2=50 - 0.01)
print altitudes # => [(938, 681, 951), (1163, 728, 727)]

Methods - Advanced Usage

geodem.utils.get_dem(dem_paths, lon, lat)

Given a particular longitude and latitude, loops though a list of dem paths until it finds a file that contains data for that point

Example:

dem_files='a10g,b10g,c10g,d10g,e10g,f10g,g10g,h10g,i10g,j10g,k10g,l10g,m10g,n10g,o10g,p10g'
dem_paths = [os.path.join('store', dem_file) for dem_file in dem_files.split(',')]
dem_path = get_dem(dem_paths, lon=-122, lat=50) # => store/10g

geodem.utils.load_dataset(dem_paths, lon, lat)

Simple convenience method to wrap the initialization of a dem file into a dataset