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mapbox / tilejson-spec

JSON format for describing map tilesets.
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Document maskLevel/fillzoom #27

Open sfkeller opened 7 years ago

sfkeller commented 7 years ago

I'm pretty sure that there are TileJSON files - as well as services and data - around which contain maskLevel. The logic is described here: https://github.com/mapbox/tilelive-vector Should'nt this be part of the spec.?

mapsam commented 6 years ago

Thanks for bringing this up! Looks like maskLevel is now referred to as fillzoom, we’ll revisit when we start researching and drafting up the next versions.

mapsam commented 6 years ago

Let's plan on having fillzoom documented in #36 since this can be a complicated concept and would be great to have a single point of reference for other users.

Right now the most this is documented is in tilelive-vector with:

maskLevel tiles: to avoid requiring many duplicate or empty vector tiles to be generated at high zoom levels, the backend source can specify a 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.

and

fillzoom: tile from the fillzoom of the backend (backfilled from a lower zoom)

I think we can do better, and provide more concrete examples for why you would use this property.

cc @springmeyer @GretaCB