[OSM-talk] Abandon all ways: a polemic

Raphaël Jacquot sxpert at sxpert.org
Tue Mar 20 17:01:19 GMT 2007


[redirecting to list :D]

Laurence Penney wrote:
> Raphaël Jacquot wrote:
>> the definition of a way is typically in the GIS world
>>
>> * goes from one intersection to another intersection *
>  >
>> whoever says "the common definitions from the GIS world don't apply to
>> us because <blah>" is mistaken.
>>
>> they represent topology at the most lower level, that is you can use
>> that way to go from a point to another point without intesecting with
>> another way.
>>
>> now, this definition implies that this may be different from a street.
> 
> That would be lovely! If ways represented topological edges (one 
> intersection to the next) then they would certainly represent something 
> useful, notably for route-finding.
 >
> Please forgive me if this is what the whole "ways as node sequences" is 
> all about. It's a good plan, equivalent to the segments-only approach 
> except there's an arbitrariness in that a way of 10 nodes can be 
> represented as any number of ways between 1 and 9; and also some ways 
> will need splitting if they go beyond a topological edge.

that's how I see it, and that's why people are talking about "superways" 
that should really be called "streets" :D

> I'd simply prefer to have a model where those two problems above simply 
> cannot exist. The post-processing in the segments-only approach would be 
> to compress the attribute data, and to cache the topological edges; 
> neither of these would change data as far as a human tagger could see.
> 
>> a street is composed of a number of ways, and ways composing that street
>> may have different navigation rules applied to them.
>>
>> for instance, a street may be 2-way for most of it's lenght, except for
>> a little bit in the middle where it's either one way, forbidden except
>> to non motorized vehicle, access requires permission which is handled by
>> some device (automatic or manual bollards) or whatever else us, stupid
>> humans can think of to piss off other humans.
>>
>> now. I'd like a proper explanation of why you feel a way shouldn't have
>> a arbitrary number of nodes in it's composition.
> 
> When I say arbitrary, I am talking about ways that are longer than 
> topological edges, such as ways in the db now that represent major 
> roads: the same way passes minor roads, yet stops & restarts for no 
> apparent reason (perhaps editing convenience).

ah, yeah. that's people being lazy and the tool not being nazi enough I 
guess.

personally, all the ways I create have one begin, one end, and are linear.

> 
> -- Laurence
> 
> 





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