Creating Detailed Isochrones with "Holes"

Hi All,

I have successfully set up a Dockerised version of OpenRouteService v8.1.0 and must say it’s been a great tool so far - it has imported the entire Great Britain OSM model and is able to do Isochrones and Matrix Analysis.

Something that we have noted is missing are the gaps within the Isochrone polygon where there would be no access - quite key for rural or mountainous areas. We have this problem even if we set smoothing to 0, but is there something we can enable in the “ors-config.yml” file instead?

Thanks,

Barney

Hey,

isochrone calculation, in simplified terms, works in two steps.

First, all streets on the routable street network that are reachable in the given time or distance, are calculated.

Second, an isochrone area is created from these points.
This is where the issue lies. The area creation algorithm doesn’t know anything about any area not covered by a street.
Thus, it does its best to create an area that it deems “reachable”, from a given “linear” street network of reachable streets.

How we, as humans, interpret this, is rather subjective as well. What constitutes “no access”? Is a forest inside an isochrone with no streets going across it “inaccessible”? What about an open field? Or a swamp?

If you have a specific example, feel free to provide a screenshot, so we can see what’s going on.

Best regards