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urbica / galton

Lightweight Node.js isochrone map server
https://galton.urbica.co
MIT License
271 stars 36 forks source link

Incorrect isochrones? #204

Closed heyarne closed 6 years ago

heyarne commented 6 years ago

I have set up galton in a docker container as described in the readme. The OSM extract I'm using is brandenburg-latest. Set up went flawless – however the isochrones that are generated seem very unnatural and cut off.

An example can be found in this gist: click me

It's the result of the command http :4000 lat==52.5219184 lng==13.4132147 (using httpie), setting Berlin Alexanderplatz as center.

For another query there was a null element in the feature-array. Is that intentional? I've had some GeoJSON tool stumble over that because they were expecting every element in the array to be a Feature. You can see the other file in the Gist which is not rendered for the example output of http :4000 lat==52 lng==13 which shows this behavior.

stepankuzmin commented 6 years ago

Thanks for the issue, @heyarne! The cut off of the isochrone is caused by the radius limit (6 km by default). You can expand area by increasing radius option.

There are should not be any null features. Could you please provide the query that produced this?

heyarne commented 6 years ago

Yes. The query is encoded into the filename, but also written towards the end of my article where maybe it's easy to miss:

the [...] output of http :4000 lat==52 lng==13

So it's a request to localhost:4000 and the parameters given are lat=52&lng=13.

I did not give any further parameters. For the other problem I will try increasing the radius, thanks for the hint!

heyarne commented 6 years ago

One possible explanation might be that the null element shows up because the isochrones cross the line of the dataset I used for setup.

Increasing the radius gave me 3 beautiful isochrones on my other query, thanks a lot for the quick help!