[GraphHopper] Creating round trips for mountain bikers

[Peter]

Hi Marian,

the following two requirements:

- overall distance should be within a certain range

- the ideal round trip (start and finish on the same spot) is circle-like...

sound more like an optimization problem rather than a routing problem
(what Graphhopper is about). But you could still use GraphHopper to
produce something like this. E.g. have a look at komoot.de/suggest where
they utilize GraphHopper to achieve similar. You could e.g. use 4 or
more points in a certain radius to produce such routes. The difference
to routing is that an optimization problem requires completely different
algorithms but the tool chain like the OSM import and graph storage etc
could still be reused.

Another maybe also interesting misuse of GraphHopper could be to
influence the 'Weighting' in a way that it puts a penalty on a center
point and its neighborhood so that it looks like a hill and GraphHopper
routes around it e.g. when going from north to south. Then you would
only need two queries and it will produce fairly circle-like tours I
think. Still the problem with the maximum time range remains but it also
should be easy to guess.

> - the more ascend (meters to climb), the better - maybe to a limit

See Bike2WeightFlagEncoder where we increase or decrease the speed
depending on the ascend/descend. You could now use this code and set the
priority as it is done in BikeFlagEncoder.

> - paths are preferred over roads, but roads are okay to some degree

See MountainBikeFlagEncoder

Kind Regards,
Peter.

> Hi,
>
> as someone who knows rather little about what it takes to do routing as graphhopper does it, I’d like to ask a question out of interest: What would it take to programmatically create route suggestions for mountain bikers?
>
> Here are some constraints I can think of:
>
> - start and end point are the given and may be the same point
> - overall distance should be within a certain range
> - the more ascend (meters to climb), the better - maybe to a limit
> - paths are preferred over roads, but roads are okay to some degree
> - the ideal round trip (start and finish on the same spot) is circle-like, not „flat“ (i. e. A to B, then back to A). In other words: The area enclosed by the route should be big.
>
> Does GraphHopper provide the tools to achieve this?
>
> Thanks!
>
> Marian
>