Display filtered roads

Directions API
1

TLDR

How can I display a map using a data source like OpenStreetMap (OSM) where instead of displaying route from A to B, I display all roads in a region, then apply filters on attributes like road_class, surface, and road_access? The goal is to visualize the impact of the GraphHopper custom_model on the routes that are affected when “multiply_by”: “0.0” is used. I want to see what roads disappear from road_class X or Y.

CONTEXT

When using the GraphHopper custom_model, I encountered the “max nodes 5,000,000” error. After some trial and error, I realized that the primary issue wasn’t my “multiply_by” applied on curvature, but rather the lack of filtering on attributes like surface, road_class, and road_access, which led to a high node count. Now, I’ve improved my custom_model by restricting many many nodes and now I want to be sure I don’t filter things I would actually like to keep.

2

You can run your own GraphHopper server instance and a separate instance of GraphHopper Maps. You can adjust this code to highlight/display/hide roads based on their attributes: https://github.com/graphhopper/graphhopper-maps/blob/56cdfc78acf88b477457f8846c8715058b5375db/src/layers/UseRoutingGraphLayer.tsx#L78-L105

3

So, by running my own server instance, I could have a maps app display all roads in a region, then filter them by attribute ? I don’t want to simply show route from A to B.

For example, I would want to zoom in a mountain region and filter all road_class that are UNCLASSIFIED and/or TRACK to see which ones affect my custom_model.

4

Yes, this is possible due to the /mvt endpoint of the open source GraphHopper server (which is not offered via the hosted Directions API)

For example, I would want to zoom in a mountain region and filter all road_class that are UNCLASSIFIED and/or TRACK to see which ones affect my custom_model.

Yes, this is possible. Strictly speaking you don’t necessarily need the GraphHopper server for this and there are many other OSM tools you could use to achieve the same.

5

Strictly speaking you don’t necessarily need the GraphHopper
You are right, but this would be a “debug” tool to improve my custom_model, which is a graphhopper thing.

If anyone arrives here after a web search, these are the solutions I found:

  1. Easiest: use overpass-turbo on an area and filter the roads you want. You can use the wizard, or learn the OverpassQL language.

  2. Most complete: implement a POST request towards the overpass API inside your app to display the wanted roads as a layer. You’ll want to use “osmtogeojson” lib to avoid headaches processing the answer from overpass API.