Vector Tiles: Unterschied zwischen den Versionen

Version vom 6. Dezember 2015, 17:50 Uhr

Vector tiles are roughly-square shaped "tiles" containing vector geometries and metadata – like road names, place names, house numbers – in a compact, structured format. Web Mercator is the projection of reference, and the Google tile scheme is the tile extent convention of reference. Together, they provide a 1-to-1 relationship between a specific geographical area, at a specific level of detail, and a path such as https://example.com/17/65535/43602.mvt

Vector tiles are typically preprocessed for a certain purpose and for several zoom levels (typically 1 to 14). Preprocessing means that expensive filtering (database queries), vector geometry clipping and cartographic generalization operations are performed in advance.

Vector tiles are rendered by either a client, like a web browser (Mapbox GL JS), a mobile app (Mapbox iOS SDK, Mapbox Android SDK), or a desktop GIS (Vector Tiles Reader QGIS Plugin). They can also be rendered on the fly on a server and delivered as common raster image tiles (WMTS).

Vector tiles have some advantages over fully rendered raster image tiles:

• Styling: As vectors, tiles can be styled when requested and on-the-fly, allowing for many map styles on global data
• Size: Vector tiles are small, enabling global high resolution maps, fast map loads
• Caching: As with raster tiles, the tiling allows efficient caching
• Decentralization: Rendering takes place in distributed (GPU) processors.

On the other hand, it's important to note that vector tiles are rather specific vector data targeted to visualization and thus not comparable to generic geospatial (vector) data formats.

More info

• Vector tiles specification: https://github.com/mapbox/vector-tile-spec
• Vector tiles on Wikipedia: https://en.wikipedia.org/wiki/Vector_tiles Wikipedia
• The MBTiles is an efficient format for storing millions of vector tiles in a single SQLite database file.

Vector Tiles Providers

• MapBox Map Styles
• MapZen Vector Tiles
• osm2vectortiles.org by Geometa Lab & Klokan Technologies

Tools

• For software around vector tiles see https://github.com/mapbox/awesome-vector-tiles
• QMapboxGL - a Qt-enabled viewport for vector tiles using Mapbox GL for rendering: [1]
• Vector Tiles Reader QGIS Plugin

Discussion

• Vector tiles means high coupling of server and client (vs low coupling of raster tiles/WMS/WMTS)
• Vector tiles gives performance gain for production (without database) but makes it harder to get "right" structure for specific use case on client side
• Vector tiles allows 3D view / tilt map view on client
• Vector tiles allow labels that may be moved into bbox and oriented

See e.g. Vector Tiles Reader QGIS Plugin.