Data sources and licences
GeoDrafter is built on open data and open-source software. This page lists every source, what it is used for and its licence.
OpenFreeMap
The background map on every tool. Your browser loads the map tiles for the area you look at directly from OpenFreeMap.
Licence: Free to use, also commercially. Map data © OpenStreetMap contributors (ODbL), vector tiles from OpenMapTiles.
Attribution: OpenFreeMap © OpenMapTiles Data from OpenStreetMap
MapLibre GL JS
Draws the interactive map in your browser. The library is served from geodrafter.com.
Licence: Open source (BSD-3-Clause).
Attribution: MapLibre
GeographicLib (geographiclib-geodesic)
Every distance, circle, area and bearing is calculated on the WGS84 ellipsoid with Charles Karney's geodesic algorithms, accurate to about 15 nanometres.
Licence: Open source (MIT), by Charles Karney.
Attribution: GeographicLib
GeoNames (via all-the-cities)
The place search: a list of about 24,000 towns and cities with at least 15,000 inhabitants, searched in your browser (nothing you type is sent anywhere).
Licence: Creative Commons Attribution 4.0 (CC BY 4.0). Packaged by the all-the-cities npm package (MIT).
Attribution: Place names © GeoNames, CC BY 4.0
Terrain Tiles (Mapzen / Tilezen on AWS Open Data)
The elevation finder. Your browser downloads the elevation tile for the place you click (a PNG image of about 256 × 256 heights) directly from Amazon Web Services and reads the height from it.
Licence: Open data; each source dataset has its own terms, listed below as required by the Tilezen attribution document (github.com/tilezen/joerd/blob/master/docs/attribution.md).
Attribution: Elevation: Terrain Tiles (Mapzen), USGS 3DEP, SRTM, GMTED2010, NOAA ETOPO1 and others
- 3DEP (formerly NED): 3DEP data courtesy of the U.S. Geological Survey
- SRTM: SRTM data courtesy of the U.S. Geological Survey
- GMTED2010: GMTED2010 data courtesy of the U.S. Geological Survey
- ETOPO1: NOAA National Centers for Environmental Information, U.S. Department of Commerce
- New Zealand: LINZ 8m DEM, Crown copyright, Land Information New Zealand and the New Zealand Government, 2011 (CC BY 3.0 NZ)
- United Kingdom: LIDAR Composite DTM, © Environment Agency copyright and/or database right 2015, Open Government Licence v3
- Austria: © offene Daten Österreichs – Digitales Geländemodell (DGM) Österreich (CC BY 3.0 AT)
- Norway: © Kartverket (CC BY 4.0)
- ArcticDEM: DEM(s) created from DigitalGlobe, Inc., imagery and funded under National Science Foundation awards 1043681, 1559691 and 1542736
- Europe: EU-DEM, produced using Copernicus data and information funded by the European Union
- Canada: CDEM, contains information licensed under the Open Government Licence – Canada
- Mexico: Source: INEGI, Continental relief, 2016
- Australia: © Commonwealth of Australia (Geoscience Australia) 2017, DEM of Australia 5 metre grid (CC BY 4.0)
EPSG Geodetic Parameter Dataset (via epsg.io and epsg-index)
The list of about 6,600 coordinate systems in the coordinate converter, with their names, areas of use and how accurate their datum shift is. It is downloaded to your browser when you use an EPSG code.
Licence: EPSG Dataset terms of use (IOGP); the dataset is free to use and is acknowledged here as its terms ask. The definitions are taken from the epsg-index npm package (ISC), built from epsg.io.
Attribution: Coordinate system definitions from the EPSG Geodetic Parameter Dataset (IOGP)
Proj4js
Converts between latitude/longitude, UTM and projected coordinate systems in your browser. The library is served from geodrafter.com.
Licence: Open source (MIT).
Attribution: Proj4js
Open Location Code (Plus Codes)
The Plus Code shown in the lat long finder, which can be typed into Google Maps instead of an address.
Licence: Open specification and reference code by Google (Apache License 2.0). GeoDrafter computes the codes in your browser with its own implementation of the specification.
Attribution: Plus Codes (Open Location Code, Google, Apache 2.0)
Accuracy of the data
The calculations themselves are exact to far better than a millimetre. What limits a result is the input: where you click on the map, how precisely a place is located in the place list (usually the town centre), and, for elevation, the resolution of the elevation model. Each tool page explains its own limits under "How accurate is it?".