[OSM-talk] Advanced relationships

[Nic Roets]

On 6/13/07, Robert (Jamie) Munro <rjmunro at arjam.net> wrote:
> Example uses:
> * Turn restrictions between segments

Currently we can do pretty sofiticated stuff with oneway=yes and ways
crossing each other with or without an intersecting node. Any examples
of a particular requirement that you want to address ?

> * Place is in place between nodes (with a value if it has a special
> significance, e.g. it's the capital)
> * 3 ways: Road A, Railway B, Bridge C; two relationships A "is on" C, B
> "is on" C where a road and railway share a bridge.

On some blog I've seen a similar requirement, but I can't see why it
would be important to indicate this. Is it purely cosmetic (i.e.
rendering) ? If yes, we should be considering full blown 3D virtual
reality. Now that will look nice, but it will also slow the mapping
pace to a real crawl.

> * Way "is border" of country, county or city node. Every county border

I still don't know how to survey that information. Sometimes it's
obvious where a county or a suburb ends, e.g. 2 signs either side of a
big road. In that case it will also be obvious where the border is for
anyone who look at the map.

We need to become more like WikiMedia, namely it must be easy for
anyone to add or change stuff. But if there are relationships all
over, it simply wouldn't be the case.

I still think my idea for improving ways is a simple extention that is
easy to implement : Currently a way consists of a set of tags and an
array (or list) of segments. I want ways to be an array (or list) of
"segmentTags". Each segmentTag is either segment or a tag. A tag is
applicable to all segments below it unless the tag appears more than
once, in which case the last assignment holds. This way it will be
easy to change the name, layer or highway halfway through a "way".
When you select a way with an editor, the editor can have little
balloons to show you which tags are changed at which nodes.