Global geographic elevation data made easy. Elevation provides easy download, cache and access of the global datasets SRTM 30m Global 1 arc second V003 elaborated by NASA and NGA hosted on Amazon S3 and SRTM 90m Digital Elevation Database v4.1 elaborated by CGIAR-CSI.

Note that any download policies of the respective providers apply.

Installation

Install the latest version of Elevation from the Python Package Index:

$ pip install elevation

The following dependencies need to be installed and working:

• GNU make
• curl
• unzip
• gunzip
• GDAL command line tools

The following command runs some basic checks and reports common issues:

$ eio selfcheck
Your system is ready.

GNU make, curl and unzip come pre-installed with most operating systems. The best way to install GDAL command line tools varies across operating systems and distributions, please refer to the GDAL install documentation.

Note that starting from elevation v1.1 only Python 3 is officially supported. To get the last version sporting Python 2 support please use pip install elevation=1.0.6.

Command line usage

Identify the geographic bounds of the area of interest and fetch the DEM with the eio command. For example to clip the SRTM 30m DEM of Rome, around 41.9N 12.5E, to the Rome-30m-DEM.tif file:

$ eio clip -o Rome-30m-DEM.tif --bounds 12.35 41.8 12.65 42

For the SRTM 90m DEM use:

$ eio --product SRTM3 clip -o Rome-90m-DEM.tif --bounds 12.35 41.8 12.65 42

The --bounds option accepts latitude and longitude coordinates (more precisely in geodetic coordinates in the WGS84 reference system EPSG:4326 for those who care) given as left bottom right top similarly to the rio command form rasterio.

If you have installed the packages rasterio and fiona you can clip a DEM on the same extent of any other geospatial data source supported by GDAL and OGR, for example if you have a georeference image MyImage.tif you can clip the corresponding DEM with:

$ eio clip -o MyImage-DEM.tif --reference MyImage.tif  # enable with: $ pip install rasterio

The --reference option can take also verctor data as input:

$ eio clip -o MyShapefile-DEM.tif --reference MyShapefile.shp  # enable with: $ pip install fiona

The first time an area is accessed Elevation downloads the data tiles from the USGS or CGIAR-CSI servers and caches them in GeoTiff compressed formats, subsequent accesses to the same and nearby areas are much faster.

The clip sub-command doesn't allow automatic download of a large amount of DEM tiles, please refer to the upstream providers' websites to learn the preferred procedures for bulk download.

To clean up stale temporary files and fix the cache in the event of a server error use:

$ eio clean

Command line reference

The eio command as the following sub-commands and options:

$ Usage: eio [OPTIONS] COMMAND [ARGS]...

Options:
  --version                Show the version and exit.
  --product [SRTM1|SRTM3]  DEM product choice.  [default: SRTM1]
  --cache_dir DIRECTORY    Root of the DEM cache folder.  [default:
                           /Users/amici/Library/Caches/elevation]
  --help                   Show this message and exit.

Commands:
  clean      Clean up the product cache from temporary files.
  clip       Clip the DEM to given bounds.
  distclean  Remove the product cache entirely.
  info       Show info about the product cache.
  seed       Seed the DEM to given bounds.
  selfcheck  Audit the system for common issues.

The clip sub-command:

$ eio clip --help
Usage: eio clip [OPTIONS]

Options:
  -o, --output PATH     Path to output file. Existing files will be
                        overwritten.  [default: out.tif]
  --bounds FLOAT...     Output bounds in 'left bottom right top' order.
  -m, --margin TEXT     Decimal degree margin added to the bounds. Use '%' for
                        percent margin.  [default: 0]
  -r, --reference TEXT  Use the extent of a reference GDAL/OGR data source as
                        output bounds.
  --help                Show this message and exit.

Defaults can be defined by setting environment variables prefixed with EIO, e.g. EIO_PRODUCT=SRTM3 and EIO_CLIP_MARGIN=10%.

Python API

Every command has a corresponding API function in the elevation module:

>>> import elevation >>> # clip the SRTM1 30m DEM of Rome and save it to Rome-DEM.tif >>> elevation.clip(bounds=(12.35, 41.8, 12.65, 42), output='Rome-DEM.tif') >>> # clean up stale temporary files and fix the cache in the event of a server error >>> elevation.clean()

Project resources

Contributing

Contributions are very welcome. Please see the CONTRIBUTING document for the best way to help. If you encounter any problems, please file an issue along with a detailed description.

Authors:

• B-Open Solutions srl - @bopen -

• Alessandro Amici - @alexamici

License

Elevation is free and open source software distributed under the terms of the Apache License, Version 2.0.