Building heights in Mapbox Streets

AJ Ashton
Wed, 05 Oct 2016 07:00:00 -0400

We’ve pushed an update to Mapbox Streets v7 vector tiles to add heights and subparts to the buildings layer. This will be important very soon when Mapbox GL supports 3D buildings and extrusions. Until then you can start exploring the data with 2D map designs in Mapbox Studio.

Examining the new data fields in Mapbox Studio

The height field stores the height of a building in meters. In many cases, this will be based on the number of stories in a building rather than an actual measurement (with an estimate of 3m per above-ground level). All of this data comes from OpenStreetMap, so coverage will vary for different areas and improve as mappers continue to contribute data. If you’re looking for test areas to explore, New York and Los Angeles have near-complete building height data thanks to imports of open government data.

Building heights visualized in New York

The type field was added to allow designers to distinguish full building footprints from subparts, which have a value of building:part. For full footprints, this field will contain the value of the building tag from OpenStreetMap (with the exception that yes is changed to building).

The National Gallery of Art in Washington, DC. Top: building footprints + parts. Bottom: footprints only.

The other two new fields, min_height and extrude, are specifically aimed at enabling 3D extrusion rendering.

The min_height indicates how many meters off the ground the bottom of a building part is — essential for rendering things like skybridges and cantilevers.

The extrude field contains a true or false that indicates whether a particular geometry should be included in a 3D-extrusion rendering. In some cases, the 3D rendering of a building will be handled entirely by building:part geometries, which means the geometry representing the full footprint should not be extruded.

We’ve updated the Mapbox Streets v7 vector tile documentation to reflect these field additions. Keep an eye out for updates on using this data for 3D rendering in Mapbox GL!

Map data © OpenStreetMap contributors