Document maskLevel/fillzoom
sfkeller opened this issue · 2 comments
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.?
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.
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.