Investigate impact of new Uploads API costs

[mcbeth]

Mapbox just announced charging for the uploads. They say there's a generous free tier, but I've not dug in to it yet.

[mmertsock]

tl;dr I think we have no concerns:

We should stay well within the free limits by limiting tilesets to a max zoom of 16 (up to 10,000 sq km per month free). Tilesets with max zoom of 17–22 start incurring costs after 10 sq km of processing/hosting. All of our tilesets currently have a max zoom of 15.

There's also mention of up to 50 GB of free monthly upload bandwidth, which is no problem. We also continue to be well within the existing per-tile and per-user free tiers for the mobile and web SDKs.

[mmertsock]

Direct link: https://www.mapbox.com/pricing/

[mmertsock]

Inspecting a little closer: the rectangular bounds of our tilesets covers 4584 sq km. So we can certainly upload a tileset twice a month with no fees. Their pricing calculator states that four 4584 sq km tilesets processed in a month would cost $2.25. However, that should be a worst case scenario; I believe the effective area is significantly less than 4584 sq km because we have large empty areas within those bounds: this page says "the area is the sum of all tiles that intersect with each feature in your data, at the precision level chosen by the Uploads API."

The https://account.mapbox.com page has a summary of the current monthly usage, so we can check that page after doing one or two tileset uploads to see how the math works out.

We could configure our tilesets to have a max zoom of 13 instead of 15 to stay within a cheaper pricing tier that should have no risk at all of incurring costs. There's a good chance this would still be sufficient precision for our needs but I haven't verified that. https://docs.mapbox.com/help/troubleshooting/manage-tileset-costs/

We don't need to worry about accidentally creating a tileset with a max zoom greater than 17 (and thus triggering the expensive pricing tier): https://docs.mapbox.com/accounts/overview/pricing/#tilesets says you need to contact Mapbox to enable these higher zoom levels.