I have a dataset of items I'm interested in mapping over a greater metropolitan area, with multi-item cluster markers at a zoomed-out scale and single-item point markers when zoomed in. Users would be able to click a marker to view information about the associated item, or see a list of items.
About half of the items I have exact addresses for. Of the ones that I don't have exact addresses for, half I know down to the neighborhood (5-10 block area) locations for, and half I know down to the city (about a 3 mile squared area) locations for.
As people using the map zoom to the point where they're able to see specific markers on the map (vs a combined cluster indicator when they're further out), what's the best way to indicate the presence of other items in the area they're viewing?
Bonus problem challenge: some items (perhaps 50 at a time) share the same exact location, to the point where I'll want to display a cluster marker even at the most-zoomed in level.