[GraphHopper] RFC: Improve tower/pillar node marking

[Peter]

Hi Andreas,

thanks for your post and introduction :) !

The node stuff is documented here a bit:
https://github.com/graphhopper/graphhopper/blob/master/docs/core/low-level-api.md

Maybe the bigger problem what you mean is the OSM parsing? This is
indeed too complex and should be changed:
https://github.com/graphhopper/graphhopper/issues/220

So I think any refactoring effort should go into this new 'mapdb'-stuff
but as the import has to be fast (only a bit slower is okay) and memory
efficient the refactoring won't be easy. But maybe you like this
challenge ;)

Kind Regards,
Peter

On 06.05.2015 11:35, Andreas Wolf wrote:
> Hi,
>
> after struggling a few days with the concept of tower/pillar nodes, or
> rather how they are defined during reading the OSM file, I think I
> have finally understood how it works…
>
> As I think I’m not the only one who did not get this at the first
> grasp, I want to improve the code to better express what is really
> done (that is – in my understanding – count how often each node was
> seen and if it is encountered at least twice, mark it as a tower node).
>
> For that, I want to create two new classes/interfaces: a NodeMap, that
> encapsulates the source (OSM)->internal ID mapping, and a NodeTypeMap
> that uses the NodeMap to get the node type. The latter can probably be
> thrown away after preprocessing, I did not think that through till the
> end.
>
> What do you think of that approach? Is it a good idea? Or am I missing
> a part of the bigger picture that makes this unfeasible?
>
>
> Regards
> Andreas
>
> PS: This being my first mail to this list, I should probably shortly
> introduce myself: I’m studying Electrical Engineering and Information
> Technology at KIT (fka University of Karlsruhe). Currently I’m writing
> my diploma thesis, using GraphHopper as a tool to generate driving cycle
> s.
>
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