Map Clustering Is Not My Favorite • Hacker News Board

Re: Map Clustering Is Not My Favorite

#21

Post by smeej » Wed, Jun 17, 2026, 1:29 PM UTC

I still don't understand how the dots help when multiple dots need to be at the exact same coordinates at the lowest zoom level. How do you open a list of them?

I'm working on a project (using Protimaps and MapLibre, even, so this is very timely for me) where users create groups at physical locations. If 12 groups choose the local public library's schedulable meeting room as their meeting space, how would anyone click to see the list of groups that use that one room? Wouldn't I just end up with what looks like one very dark dot?

Re: Map Clustering Is Not My Favorite

#22

Post by gregsadetsky » Wed, Jun 17, 2026, 1:46 PM UTC

smeej wrote: post #21

I still don't understand how the dots help when multiple dots need to be at the exact same coordinates at the lowest zoom level. How do you open a list of them? I'm working on a project (using Protimaps and MapLibre, even, so this is very timely for me) where users create groups at physical locations. If 12 groups choose the local public library's schedulable meeting room as their meeting space, how would anyone clic…

(op here)

I typically deal with dots at the same place as a single dot and, when clicked, open an infowindow/infopanel that will let people see all of the points’ data.

ie you do need to deal with this issue (by default, no mapping library will do it for you) - and most clustering librairies (or at least their default settings) will also not solve this for you.

The ui for what happens when a point (or even a cluster) is clicked but that point contains more than one point’s worth of data is its own separate problem basically

Re: Map Clustering Is Not My Favorite

#23

Post by cwmma » Wed, Jun 17, 2026, 1:54 PM UTC

As somebody who makes maps for a living, I think clusters are overrated (I have had, on multiple occasions, had to talk people out of it). The leaflet extension that gives you a preview of the area covered by the cluster and allows you to click to zoom to the extent of cluster I do feel is a good setup for situations where just putting all the dots down isn't going to give you good information. That being said doesn't work great on mobile.

Also pour one out to google fusion tables which back in the day was the amazing way to get tons of dots onto a map.

Re: Map Clustering Is Not My Favorite

#24

Post by apwheele » Wed, Jun 17, 2026, 1:55 PM UTC

smeej wrote: post #21

I still don't understand how the dots help when multiple dots need to be at the exact same coordinates at the lowest zoom level. How do you open a list of them? I'm working on a project (using Protimaps and MapLibre, even, so this is very timely for me) where users create groups at physical locations. If 12 groups choose the local public library's schedulable meeting room as their meeting space, how would anyone clic…

Checkout how leaflet does this, it is the "spiderfy" part of markercluster. So you click down into the number bubble, and at the lowest zoom explodes out into multiple point markers.

Re: Map Clustering Is Not My Favorite

#25

Post by francisofascii » Wed, Jun 17, 2026, 1:57 PM UTC

The map in hotels.com does a good job of clustering. For example, searching for hotels in a high density area like NYC. Airbnb, conversely, does not seem to have any clustering. Properties vanish and reappear at various zoom levels.

Re: Map Clustering Is Not My Favorite

#26

Post by smeej » Wed, Jun 17, 2026, 2:07 PM UTC

apwheele wrote: post #24

smeej wrote: post #21

I still don't understand how the dots help when multiple dots need to be at the exact same coordinates at the lowest zoom level. How do you open a list of them? I'm working on a project (using Protimaps and MapLibre, even, so this is very timely for me) where users create groups at physical locations. If 12 groups choose the local public library's schedulable meeting room as their meeting space, how would anyone clic…

Checkout how leaflet does this, it is the "spiderfy" part of markercluster. So you click down into the number bubble, and at the lowest zoom explodes out into multiple point markers.

I think for my purposes, people would rather see a list of the groups meeting at that place than click individual identical markers arranged around the point to see what's there.

I can see why this would be helpful in other use cases though!

Re: Map Clustering Is Not My Favorite

#27

Post by smeej » Wed, Jun 17, 2026, 2:10 PM UTC

gregsadetsky wrote: post #22

smeej wrote: post #21

I still don't understand how the dots help when multiple dots need to be at the exact same coordinates at the lowest zoom level. How do you open a list of them? I'm working on a project (using Protimaps and MapLibre, even, so this is very timely for me) where users create groups at physical locations. If 12 groups choose the local public library's schedulable meeting room as their meeting space, how would anyone clic…

(op here) I typically deal with dots at the same place as a single dot and, when clicked, open an infowindow/infopanel that will let people see all of the points’ data. ie you do need to deal with this issue (by default, no mapping library will do it for you) - and most clustering librairies (or at least their default settings) will also not solve this for you. The ui for what happens when a point (or even a cluster)…

Does it end up a darker or at least fully opaque dot to show it's not the same as the individual dots elsewhere? Like from your example in the article, I might make that dot maroon (or some other color entirely) instead of red so people understand "there are multiple things here."

This has been my first adventure dealing with maps with user-generated points and I'm discovering how much goes on behind the scenes that I never noticed!

Re: Map Clustering Is Not My Favorite

#28

Post by mjmsmith » Wed, Jun 17, 2026, 2:25 PM UTC

well_ackshually wrote: post #10

>You don’t have to cluster anymore. You can just be. Try to get Google Maps or Apple Maps running on a phone with more than 200 Markers/Annotations, then come back to me with that. Their performance is fucking dreadful. Google Maps released a new renderer that just OOMs if you're rendering a Polyline with 5k segments. Decimate it or face consequences. As far as I know, MapBox is about the only one that has tolerable…

My iOS app using MapKit is smooth with ~4k annotations on an iPhone 14. My experience is that it doesn't really start to choke until you get closer to ~10k.

Re: Map Clustering Is Not My Favorite

#29

Post by gregsadetsky » Wed, Jun 17, 2026, 2:28 PM UTC

smeej wrote: post #27

gregsadetsky wrote: post #22

Earlier quoted context omitted.

(op here) I typically deal with dots at the same place as a single dot and, when clicked, open an infowindow/infopanel that will let people see all of the points’ data. ie you do need to deal with this issue (by default, no mapping library will do it for you) - and most clustering librairies (or at least their default settings) will also not solve this for you. The ui for what happens when a point (or even a cluster)…

Does it end up a darker or at least fully opaque dot to show it's not the same as the individual dots elsewhere? Like from your example in the article, I might make that dot maroon (or some other color entirely) instead of red so people understand "there are multiple things here." This has been my first adventure dealing with maps with user-generated points and I'm discovering how much goes on behind the scenes that…

It’s not easy for sure and I’m not a designer or ui/ux expert - just been around maps for a while

I agree with you that the point itself could show that it’s special - or - rely on users tapping/clicking it and then show all the info

In a sense, maybe conveying that the point has more than one data point attached to it isn’t critical - as long as you can see everything inside when clicking it!

Feel free to email me, would love to jam/chat about this!

Re: Map Clustering Is Not My Favorite

#30

Post by heltale » Wed, Jun 17, 2026, 2:30 PM UTC

This is one of the major gripes that real estate sales agents have.

I’ve consistently heard complaints from customers that they don’t like it. At this point, map technology has come far enough that we could visualize thousands of points using Cesium on consumer-grade hardware so I don’t think it’s a performance issue either.

When it comes to overlapping dots, we generally solve this by displacing the dots minimally so that they’re all still in the same building or same area but visibly different locations.