3d model
* Generator: [DEM Net Elevation API](https://elevationapi.com)
* Mesh reduction: [geometry3Sharp (GradientSpace, Ryan Schmidt) BSL 1.0 License](https://github.com/gradientspace/geometry3Sharp/blob/master/LICENSE)
* Digital Elevation Model: [AW3D30 OpenTopography](https://opentopography.org/)
* Imagery: [MapBox Satellite Street](https://www.mapbox.com)