[OSM-dev] Ways with 40k nodes, was: osmosis pgsql schema

Matt Amos zerebubuth at gmail.com
Fri Oct 31 15:35:12 GMT 2008


On Fri, Oct 31, 2008 at 3:19 PM, Stefan de Konink <stefan at konink.de> wrote:
> Matt Amos wrote:
>> would you represent a Y-shaped road as three relations, then? one for
>> the left fork, one for the right stem as a way-relation, then another
>> to group them together?
>
> Yes, but with role='independent'. Otherwise the idx of the subtrees would
> create a pyramid shape.

i don't understand what you mean by a pyramid shape. the relations
would be returned in the same order, regardless of the role tag,
right? and you're not merging subtrees...?

>> when you say "no need for a specific way renderer" - there is still a
>> need, as (in your example) you wouldn't want to render a bunch of
>> camping nodes as a linear feature. you'll also want to render
>> buildings filled. in other words: there isn't a single, specific way
>> renderer anyway because tag inspection is required.
>
> ... snip...
>
> In the first version of the RelationOSM thing I created the same thing in
> the relationship code, when the api 0.5 was used. If the tag way=true was
> present, it would be rendered as <way><nds/></way>.

exactly; you do tag inspection. doesn't that require an extra join to
distinguish ways from relations of nodes?

cheers,

matt




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