[OSM-newbies] Ungluing in Potlatch

[Mike Harris]

See below ...

Mike Harris
 

> -----Original Message-----
> From: Steve Bennett [mailto:stevagewp at gmail.com] 
> Sent: 12 January 2010 11:39
> To: newbies at openstreetmap.org
> Subject: Re: [OSM-newbies] Ungluing in Potlatch
> 
> On Tue, Jan 12, 2010 at 6:49 PM, Mike Harris 
> <mikh43 at googlemail.com> wrote:
> > ... And when there is a hedge or fence alongside the road 
> with a stile 
> > or gate through the hedge giving access to the footpath? 
> The stile is 
> > neither in the road, or at the footpath / road junction 
> node, nor in 
> > the field adjacent to the road ... I don't think it is such a 
> > clear-cut situation as you (rather vigorously IMHO (;>) imply ...
> 
> I can't quite picture what you mean. There is a footpath 
> perpendicular to the road, which crosses a hedge which is 
> parallel and next to the road? If so, wouldn't you have two 
> parallel ways, one tagged barrier=hedge, one highway=road, 
> crossed by a highway=footway, with a barrier=stile at the 
> junction of the hedge and the footway? And meanwhile, have a 
> landuse=farm polygon sharing a way with the road, or with the 
> hedge, as you prefer?

Yes - that's it and it is fair comment to suggest that the landuse polygon
could share a way with the hedge (but not with the road as the hedge would
be the boundary of the farm and, technically, the area between the hedge and
the road (or the midline of the road as represented in OSM by the way
representing the road) is likely to be part of the 'highway' and in the
ownership of the highway authority - including any sidewalks, cycle tracks,
grass verges, hard shoulders, etc.). Unfortunately, I have never encountered
a case where this has been done. It is still fairly rare to map hedge and
fences and the more usual situation is for me to want to add a footpath (and
its stile) to an existing road. If the road already shares its way with the
landuse polygon, unless I have made a note of the nature of the landuse
boundary feature (which might be a hedge, a fence or simply non-existent if
it is an 'open field' as is more common in continental Europe and -
increasingly - in the 'prairie' parts of England), I would either need to
dump the stile inside the landuse polygon (implying that the stile is in the
field - which it is not) or separate the common way into two - one for the
landuse polygon on which I can place a node for the stile where the footpath
crosses it - and the other for the midline of the road.

There is a less good reason for raising a flag here - it is quite difficult
to see where a footpath (or even a track or road) runs when it shares a
boundary with, say, a wood. I realise that this is getting dangerously close
to 'mapping for the renderer' so I won't push the point - but it does tend
to create difficulties both when viewing and when editing maps.

I realise that this is all about micro-mapping (and also note your point
about the landuse tags) but as I primarily walk and often find myself adding
footpaths and the like to (excellent) outline maps probably done by cyclists
(as they show only roads and other ways that can be cycled). One of my
objectives - for reasons that do not matter here - is to record in my local
area the public rights of way and their 'furniture' (stiles, gates, etc.).
So I do encounter this problem quite often where someone has been
industrious enough to "fill the white space" by adding land use information
- but often done at a less detailed scale.

I am not suggesting that there is a 'right' or 'wrong' or asking that
mappers desist from forcing ways to be shared with polygons, etc. I am
prepared to do my own editing!  I just wanted to flag that the original
questioner is not necessarily wasting his/her time!
 
> 
> As you pointed out, at the micro level, you'll probably want 
> something more precise than setting the boundary of the 
> landuse polygon to be a road way, but it's a pretty good 
> approximation for higher levels.
> 
> What's interesting is that the landuse tags (and possibly 
> others) seem to have subtly different meanings depending on 
> the level of detail. A big block of landuse=residential would 
> mean "this area is mostly houses". Whereas a smaller block 
> with a detailed outline would mean "this is one house". It's 
> hard to know how much extraneous stuff you can include in the 
> area you're demarcating.
> 
> Steve
> 
> 
>