Grandine: Vector Tiles, Summary June 2017
Continuation of the documentation of my Prototype Fund related work. Previous summaries: March, April, May
Before I use too many words to describe the obvious, just have a look:
It is now possible to render all tiles from a dataset and write them to disk. At the moment the
tiler tool supports reading from GeoJSON is supported and all features will be written to the same layer in the tiles.
tiler parses all geometries inside the given GeoJSON file, determines which tiles need to be generated, and per tile is walks through the geometries, cuts them to the tile boundaries, if inside, and writes out a vector tile. All of this happens at the moment single-threaded and doesn’t use any spatial index, so there is room for improvement, but nonetheless it is able to process all primary roads in Saxony in seconds (as seen in the second clip).
For points and line strings it already work fine, polygons have problems with winding order; this is to be fixed.
Next steps ahead: Simplifing lines, generating tiles directly from OSM data, mapping and normalizing features from geospatial data to tile layers/attributes.