* Generator: [DEM Net Elevation API](https://elevationapi.com)
* Digital Elevation Model: [SRTM_GL3 OpenTopography](https://opentopography.org/)
* Imagery: [Esri World Imagery](https://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer)
* Data: [OpenStreetMap](http://www.openstreetmap.org)