Use the NE min zoom to cull places at low zooms.

[zerebubuth]

We were already using the NE min zoom as the min_zoom property, but had failed to actually act on that by removing items outside of the zoom range.

Overall file size reduction (NOTE: most of the very low zoom labels come from the earth layer - things like continent labels):

Tile	Previous places size (bytes)	New places layer size (bytes)	Percentage improvement
0/0/0	518,111	0	100%
1/0/0	139,980	0	100%
1/0/1	42,043	0	100%
1/1/0	266,788	0	100%
1/1/1	83,228	0	100%
2/0/0	-	-	-
2/0/1	33,015	14,536	56%
2/0/2	20,091	1,979	90%
2/0/3	-	-	-
2/1/0	4,326	4,091	5%
2/1/1	178,337	44,582	75%
2/1/2	58,487	20,020	66%
2/1/3	-	-	-
2/2/0	2,145	0	100%
2/2/1	410,712	110,756	73%
2/2/2	83,789	32,137	62%
2/2/3	-	-	-
2/3/0	827		100%
2/3/1	155,139	44,066	72%
2/3/2	44,228	21,546	51%
2/3/3	-	-	-

Zoom 0

It's all continent and ocean labels, no places visible.

Zoom 1

It's all continent and ocean labels, no places visible.

Zoom 2

I was expecting some places to be visible at this zoom level, as some are present in the tiles. Perhaps the label collision prevents any from appearing?

Zoom 3

Looks like a pretty good selection of capitals, major cities and country labels.

Zoom 4

Nice overview of US states and major cities. Do we have the same state data for Canada - given that we show the state borders, it might be nice to label them too? Perhaps a ☔ issue?

[zerebubuth]

Connects to #1687.

Note that tile 2/2/1 is still pretty huge - 110,756 bytes. However most (69%) of this is properties, which will get better once we implement #1643.

[nvkelso]

Here's what I see in Natural Earth for these zooms:

[nvkelso]

Also, your zoom 2 looks pretty weird!?

[nvkelso]

The likely reason you're not seeing Canada region labels at zoom 3 is they are set to 3.5 and Tangram only does the evaluation at zoom 3 (and 3.5 !< 3 so it filters them out). Or your PR / existing code filters them.

Looks like this PR is doing the right thing (nominal zoom + 1), so might be in the setting of min_zoom, please ensure that's taken from Natural Earth's min_label value. (NE's min_zoom is for polygon or line visibility, while min_label is for when it separately gets labeled.)

[zerebubuth]

Yup, zoom 2 was messed up because I was using the Go version of tapalcatl, which doesn't understand the "max zoom packing" feature/hack that we added to tapalcatl-py. Moving to the latter, I now see:

Which is has a bunch of cities on it. 🎉

(Although no space for London? What's up with that? 🙀)