Create a basemap for Overture Maps

[Drabble]

To follow up on the simple Overture Maps example for Overture Maps data to a MVT Rest service we could now start working on a full Overture basemap.

Some questions to answer:

• How much data is there to download and how long does it take?
• What are the storage requirements for the PostGIS database?
• How many simplifications should we do so that the map loads fast?
• How do we map the styles from the OSM basemap to Overture?
  • Maybe we can use the Overture categories mapping.

Here is a proposition for the roadmap:

1. [ ] Copy the example into a folder called basemap-overture.
2. [ ] Improve the style for the administrative boundaries which are already used in the overture example.
3. [ ] Add support in order for all the sub-themes https://docs.overturemaps.org/schema/reference/. It means creating spatial indexes, mapping styles from the OSM basemap and creating materialized views for simplifications.
   1. [ ] Administrative Boundary
   2. [ ] Locality
   3. [ ] Locality Area
   4. [ ] Infrastructure
   5. [ ] Land
   6. [ ] Land Cover
   7. [ ] Land Use
   8. [ ] Water
   9. [ ] Building
   10. [ ] Building Part
   11. [ ] Boundary
   12. [ ] Division
   13. [ ] Division Area
   14. [ ] Place
   15. [ ] Connector
   16. [ ] Segment

[bchapuis]

@Drabble The roadmap is great, and I think it is a good idea to proceed step by step. I would simply name the folder overturemaps as we already have basemap and daylight without prefix. Also, depending on the size of the data, we may need some beefy hardware to do this. We can synchronize in private if you need some resources for this.