Review tile sizes and performance of map tiles

[danrademacher]

Max Tile Size

• 500kb is the recommended tile size

We have tiles of 8MB and even 18MB!

• See San Jose https://vtiles.openhistoricalmap.org/#8.46/37.2451/-121.9371
  • Overly detailed boundaries?
• See Europe https://vtiles.openhistoricalmap.org/#4.49/51.46/10.92
  • These are villages but it's often hard to distinguish them from large cities to get hierarchy of cities in different zooms.

Have we been overly generous adding stuff to vtiles? How can we find the largest tiles?

• Check the cache in the S3 bucket
• Look at this thread on OSM slack for vitles inspection tools. https://osmus.slack.com/archives/C01G3D28DAB/p1686525845672629
• Try this one from Stamen https://stamen.github.io/map-tools/tilestats/

[danrademacher]

Stamen tool with ohm tiles

https://stamen.github.io/map-tools/tilestats/?tiles=https://vtiles.openhistoricalmap.org/maps/osm/%7Bz%7D/%7Bx%7D/%7By%7D.pbf#11.66/37.3023/-121.8144

Next need to focus that on a few known problem areas

[danrademacher]

OK, actually that link is San Jose:

These are some massive tiles!

total tiles: 4 min size: 2270.83kb avg size: 4366.51kb max size: 6905.41kb

And this is the main driver:

land_ohm    1254.97k    1927.48k    4317.01 5594

In Europe, place_points and transport_lines are the main driver: https://stamen.github.io/map-tools/tilestats/?tiles=https://vtiles.openhistoricalmap.org/maps/osm/{z}/{x}/{y}.pbf#4.49/51.46/10.92

transport_lines 39.84m  11562.29    135.78  774.33
place_points    88.9m   4852.31 259.82  10324.95

[1ec5]

• See San Jose https://vtiles.openhistoricalmap.org/#8.46/37.2451/-121.9371
• Overly detailed boundaries?

At zoom level 8, we can probably afford to do more aggressive simplification on features like boundaries: #702. Another big gain would come from replacing boundary polygons with boundary edge polylines: #701.