Add H3 hex grid in unmapped areas.

[jthiller]

Problem: The mappers overlay helps a lot to chart new territory, but it becomes difficult to recognize where distinct hexes might lie just a few spaces from mapped areas. In other words, the mapping benefit of the mappers overlay only helps if there are already mapped hexes in the area.

Solution: Include outlines of empty hexes across the entire map when the community map is enabled.

• In my experimentation, white hex outlines of 5% opacity felt like enough to hint at hex borders.
• Mappers data is currently represented in hex res 9 - this additional overlay should match.
• Hex res 9 will bring devices to their knees when rendered on a zoomed-out map. The hex borders should only be rendered at closer zoom levels. I didn't determine an ideal zoom level in my testing.
  • Edit: Zoom 12 and up seem appropriate to show the grid. Maybe 13 to be safe.
• Hex overlay appears in conjunction with the mappers data, controlled by the in-app switch.

Figure: crude representation using h3 outlines as an overlay on the cargo app

Long term: My understanding is that this overlay is best rendered using h3 and geojson2h3 on the client side. This sets up Cargo to ingest and draw h3 indexes directly in app. This would allow us to reduce the mappers payload by passing h3 indexes with their associated RSSI instead of the rendered polygons for those regions.