Approaches to how points are drawn when zoomed out

[jokroese]

Commonly in a digital map, when zoomed out, the map clusters points together to make it easier to read. However, for aesthetic and political reasons, there's a drive for QtM to avoid clustering.

This has implications on the technical side, from the feasibility (#5) to the performance aspects (#8). I created this issue as a place to discuss what approach we should take.

As I see it, the options available are:

1. Show all pins. Currently, this is blocked by MapLibre failing to render more than 32768 points #5. Showing all pins is also has potentially detrimental performance implications as the number of points in QtM keeps growing. However, we still don't know if this would be a performance bottleneck so this requires testing.
2. Cluster points. Whilst this is the default for digital maps, I'm against this as it most strongly goes against the importance of showing that every individual moment in QtM is important.
3. Drop points. We can do this through using PMTiles, choosing to drop a certain number of pins when zoomed out. We can also make this related to the density of pins, allowing us to just drop pins from denser places while keeping all of them in more rural, less-densely-pinned areas.

[jokroese]

Bringing together some conversations around this from other issues.

From @nielsbom:

What attributes of "having all points rendered on the map" are (most) important?

• Is it the visual aspect?
• Is it a feeling we want to evoke when visitors view the map?
• Do the creators of the map want to have a feeling of "completeness"?

From Lucas:

What attributes of "having all points rendered on the map" are (most) important?

the visual impact of the scale and distribution of pins is most important. my biggest concern from day one, has been that clustering pulls the outliers into the mean, which means rural and less active areas on QTM were getting erased at high scale. But, as the site grows to have users in more places with lower bandwidth, I am open to a display model that is more accessible, even if it means losing a few of the outliers.

From me:

losing a few of the outliers

We can display pins (or leave them out) based on how densely they are spaced. That means we don't have to lose any outliers, just dropping pins from within dense areas like cities.

[jokroese]

We decided to show all pins. Maplibre does some tiling of this to improve performance. To improve it further, we can generate PMTiles at build time.