Some of the most important elements in the OpenStreetMap database are relations. It’s used to define administrative boundaries, restrictions on the road network (which has a relevant impact on routes), elements made by multiple geometries, etc. Relations are also some of the most difficult elements to monitor and track modifications, as some of them don’t affect the way the data is rendered on the map.

This week we added the possibility to visualize relations on OSMCha! To avoid increasing the number of elements rendered on the map, the visualization of relations works in a bit different way…

By default, we show the bounding box of all relations that were created, modified or deleted by a changeset. When you click on a relation, it will hide all other ways and nodes and add to the map the elements that are (or were) members of that relation.

We have a new panel on the bottom right corner of the page that lists the members of the relation and the role of each of them. Clicking on a item of that list will highlight that member geometry on the map.

If you click on a second relation on the map, it will hide the first relation members and show the members of that second one. Clicking on a part of the map that doesn’t have any element, it will reset the visualization to the default view.

One important advice: if the relation bounding box is bigger than the changeset bounding box, only the relation members that intersect with the changeset BBox will be available for visualization. It is a technical limitation that will affect mainly the roads and administrative boundaries, but I believe that, even on those cases, it will be useful to analyse the changeset impact on the integrity of that relation part.

Let us know if you have some new idea to make the relations visualization yet better.