Add an option to exclude tiles that are entirely covered by a polygon

[e-n-f]

No description provided.

[jingsam]

How to render this excluded tiles which are entirely covered by a polygon? using mapbox-gl's overzoom feature?

I think it would be better to create a images table that store blob and hashes, then create a tiles view to reference. On these way, many duplicated tiles can be omitted.

[e-n-f]

The particular ticket that this was in response to intended to fill the holes by overzooming. The table of hashed blobs may be a better way to do it though.

[andrewharvey]

So I tested out this branch and it did work in reducing a tileset of around 30M tiles (which is the maximum tile count Mapbox will accept uploads) to around 21M tiles.

Still testing to see if there are any downsides or side affects when submitting tilesets to Mapbox with missing ocean or land tiles.

[e-n-f]

It might be more effective to only drop tiles in sets of 4, to be clearer that all 4 should inherit from the same parent tile, but I am not sure whether this is actually effective in rendering.

[jingsam]

clients may experice too may 404 errors. What if map initial zoom is 8, but parent tile only exsist in zoom 7. so these tiles would be never be loaded.

[andrewharvey]

What if map initial zoom is 8, but parent tile only exsist in zoom 7. so these tiles would be never be loaded.

I'm pretty sure that GL JS will trace up the tile pyramid until it gets a tile response. So it might take a bit longer to load since there are more requests but it should eventually get a tile and overzoom it.

The other option is too break the MBTiles into different regions upload each to Mapbox then ask for the composited tiles, which also has a performance cost for having to composite, given this is only an issue a high zooms in the middle of nothing, I think it's preferable than asking Mapbox servers to composite every tile request.