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.

2 Answers 2


Instead of a circle, how about highlighting the neighbourhood or the post office for a given zip code area. Another alternative (depending on the context), the (main) train station for the area.

Clustered items can be presented by a “mulitple items version” of the default marker icon and all sub-elements listed in a bubble or somewhere outside the map.

  • Highlighting neighborhood or the post office is good idea, here's an example of showing groups on the map: livelovely.com/search When you zoom in, the size of "neighborhood" changes. You might want to consider something similar.
    – Janko
    Mar 26, 2013 at 9:48

I think it is common practice to represent a non-exact location using a circle with a radius that indicates the level of certainty you have about its location. Without making this circle seem intrusive, it can be a very light shade or an outline with a central label not unlike a map marker for an exact location (but with a different styling).

Once you have a variable or large number of items for your cluster markers, I suggest presenting that information somewhere else off the map where it will be easier to do the layout and display the content.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.