Vector tile => raster tile backend for tilelive
Implements the tilelive API for rendering mapnik vector tiles to raster images.
tilelive.load(). This is fallback source that will be used if no source is found as part of the Mapnik XML parameters.
bz/bx/byand generally represent the same or lower zoom level. This allows for features like overzooming, maskLevel tiles, and scale factor adjustment.
maxzoomof the backend is requested, Vector will attempt to render the tile using the parent of the request at
maskLevel. If a vector tile is not initially found at some
z > maskLevel, Vector will issue an additional request to the backend using the parent tile of of the request at
maskLevel. This allows a lower zoom level to "backfill" high zoom levels.
scale: 4decrements by 2, and so on.
The Backend and Vector sources set the
x-vector-backend-object header to indicate the type of backend source tile loaded. Possible values:
|empty||backend returned no tile|
|fillzoom||tile from the fillzoom of the backend (backfilled from a lower zoom)|
|overzoom||tile from the maxzoom of the backend (overzoomed)|
There are two additional constructors provided for slightly different workflows for loading vector sources.
Load a vector source from a
uri (filepath or HTTP url) to a tm2-generated tm2z style package.
Load a vector source with autogenerated data inspection ("xray") styles.
xml is not required -- only the
uri to a vector source backend is necessary.