Overzooming in tile-join

There has been some recent confusion in https://github.com/mapbox/tippecanoe/issues/692 and https://github.com/mapbox/tippecanoe/issues/688 about tile-join behavior when joining tilesets with different zoom ranges. It might be good to have an explicit --overzoom option to overzoom tiles from tilesets with a lower maxzoom when joining them to a tileset with a higher maxzoom.

I brought this up in another thread yesterday and was going to create a new issue, but saw this here.

Currently, joined tilesets using tile-join are not overzoom enabled except for joined tilesets which share a common maximum-zoom.

If I have a tileset that has no need for overzooming beyond a set max-zoom, this isn't a problem. But for other tilesets which I would like to render only to a certain zoom, but remain capable of overzooming, I have to either keep them as isolated source tilesets, or create each tileset to the highest max-zoom of the batch.

A way to add a flag which would preserve overzooming capabilities for each tileset added (despite their processed max-zoom) would be a great addition to tile-join

I just stumbled upon this exact issue today.

I have a few tile sets with differing maximum zoom levels. Some of them seem to disappear and won't overzoom.

Is there a way around this yet?

@leearmstrong I believe the only workaround at this time is to process each of your tilesets to a common max-zoom. Then, when you tile-join them, overzoom will be enabled across the separate layers/tilesets.

Any possible progress on the horizon @e-n-f?

tile-join allowing for an --overzoom flag would really be helpful. Having tile-join require every tileset have the same --maximum-zoom is really limiting in how one must organize there data, and considering Mapbox only allows for a maximum of 15 tilesets in a Map-style, it would really allow me to add both data and detail!

As discussed above, the best solution is what @kdanaher suggests. This will obviously you to "group" your data by zoom level... so at least for myself, when trying to be efficient with my final the number of tilesets for work. I group the tilesets with tile-join based on zoom levels such as low-zoom.mbtiles intermediate_zoom.mbtiles high_zoom.mbtiles, rather than grouping the data by the type of data (such as parks.mbtiles, conservation_area.mbtiles`).