[Routing] generalized routing format

[Robert (Jamie) Munro]

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flo Detig wrote:
> Marcus Wolschon wrote:
>> I think it would be better to discuss basic
>> storage and indexes first before going on
>> about special optimizations.
>>   
> I agree with that.
> Is there some lowest common denominator for a generalized routing format?
> Something everyone could use / need who works on routing osm data?
> There is a nice visual description by Michael Josenhans in the wiki
> http://wiki.openstreetmap.org/index.php/OSM_Routing_Data_Layer
> As a first step merge the intermediate nodes of degree two?
> Is this simple enough to fit everyone?
> Does it make sense to add this to the database (maybe in pgrouting 
> compatible format)?
> Or just some kind of transformation script that outputs osm-xml again?
> Anyone interested?

Personally, I don't think OSM should be trying to do this in the
abstract. I think that as people develop routing applications, they
should develop their own formats and converters from OSM XML format,
optimised to how their particular applications work. As routing
applications evolve, they could copy ideas and formats from each other.
I don't think we should try to invent a format that is targeted at a
particular market.

It may be worth repackaging OSM XML and changesets as a binary format
that is more compact, but routing applications would still need to index
it before they could use it.

Certianly I don't think that OSM centrally should be splitting the data
into "routing layers". Competing routing algorithms should be making
that kind of decision. It will break if you choose something like "avoid
motorways" because the motorway layer would just become completely
inapplicable. What if someone wants to make a system that lets you route
over public transport? All the data is in OSM, but all the assumptions
about how to index a routing format would be completely invalid.

Robert (Jamie) Munro
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