GPeleX: Add elevation data to GPX files

Run it in your browser here!

Add elevation data to GPX trackpoints using local DEM (Digital Elevation Maps) files or online SRTM (Shuttle Radar Topography Mission) elevation data.

Useful for GPX tracks and routes that are missing elevation, e.g., as exported by some sport watches. The added elevation (approximately) follows the ground level.

SRTM data is captured from space and, thus, relatively coarse and affected by buildings and vegetation. National databases can, depending on location, provide higher resolution and more accurate DEM data but require manual downloads. Higher quality data covering multiple countries is available from, for example, https://viewfinderpanoramas.org/dem3.html.

Usage

Python CLI

Easiest way to run is to download the gpelex.py file and use uv:

uv run gpelex.py input.gpx --dem elevation.tif --output output.gpx

Or without manually downloading:

uv run https://raw.githubusercontent.com/Aggrathon/gpelex/main/gpelex.py --help

Alternatively, create a Python (>=3.11) environment with rasterio and scipy for local DEM files or srtm.py for online SRTM data.

Arguments:

Flag	Description
INPUT	Path to the input GPX file
-o, --output FILE	Output GPX path (defaults to <input>_with_elevation.gpx)
-d, --dem FILE ...	One or more DEM files (.tif, .zip, .tar.gz, etc.)
-f, --force	Overwrite existing elevation data
-v, --verbose	Verbose output (use -vv for per-point details)

If no --dem files are provided, the tool fetches elevation from the SRTM API (30 m resolution).

Browser

Open https://aggrathon.github.io/gpelex in a browser. Select a GPX file and one or more elevation map files (.tif, .zip, .tar.gz), then click Add elevation (after Pyodide has loaded all dependencies). All processing runs locally in your browser — nothing is uploaded.

Alternatively, download gpelex.py and index.html and serve it yourself (requires at least a basic server such as uvx python -m http.server since bare html files are not allowed to read local files).

Testing

uvx --with-requirements gpelex.py pytest test_gpelex.py

Project Structure

File	Description
gpelex.py	Main script — CLI entry point and library
index.html	Browser-based UI running via Pyodide
test_gpelex.py	Pytest test suite