subject:"\[OSM\-talk\] Landuse areas etc. abutting highways"

Thanks to those who responded to this thread. Advice gratefully received.

There seems to be a clear majority preference for option (b) - the more 
detailed approach that avoids superimposing boundaries of areas (and their 
nodes) on an adjacent way (and its nodes). I fully understand the two caveats:

1. It is only worth being precise if there is precise data available.
2. There are a few exceptions where, for example, the character of the adjacent 
area has access features more like that of a normal linear way - the pedestrian 
area is a good example.

I am persuaded that the advantages of forward compatibility and a higher 
standard of mapping justify my small efforts (where I have good GPS data) in 
separating out superimposed areas/ways and using option (b). I am particularly 
pleased to receive support for splitting single large landuse areas (e.g. 
=residential or =farm) that cross large numbers of ways.

It is a minor irritant and I didn't want to do the work - or mess with other 
people's mapping - without a bit of a 'reality check' with more experienced 
folk in the community.

Thanks again

Mike Harris
 

 -Original Message-
 From: Martin Koppenhoefer [mailto:dieterdre...@gmail.com] 
 Sent: 05 October 2009 15:52
 To: Marc Schütz
 Cc: talk@openstreetmap.org
 Subject: Re: [OSM-talk] Landuse areas etc. abutting highways
 
 2009/10/5 Marc Schütz schue...@gmx.net:
  2009/10/5 Marc Schütz schue...@gmx.net:
   But a) could be used as acceptable temporary solution until 
   someone with better information (like having aerial 
 photography) 
   remaps it as
   b)
  
   Yes, this is basically what I wanted to say. Leave it to the 
   mappers
  whether they want to use a way or an area for a road.
 
  it will be much harder to add this detail, if all areas 
 are merged though.
 
  Not really. JOSM supports disconnecting ways since a long 
 time now. But anyway: doing things wrong just to make editing 
 easier is not a good thing.
 
 +1. That's why adjacent landuses (see topic) shouldn't be extented to
 the center of the road.
 
   But with option (b) and a linear way you would have a 
 gap next to 
   the
  road. In the case of landuse, this is not a problem in 
 practice, but 
  if there is a place, there you need to insert artificial ways that 
  are not there in reality, just to get the connectivity 
 between the two objects:
   http://osm.org/go/0JUKytHID--
 
  which objects are you referring to? parkings usually have 
 those ways 
  (for crossing the sidewalk) so they won't be artificial, and 
  pedestrian areas are the exception I mentioned above.
 
  Look at the google sat image:
  
 http://maps.google.com/maps?f=qsource=s_qhl=degeocode=q=bayreuths
  
 ll=37.0625,-95.677068sspn=59.856937,107.138672ie=UTF8hq=hnear=Bayr
  
 euth,+Bayern,+Deutschlandll=49.946316,11.577148spn=0.000754,0.001635
  t=kz=20
 
 That's the mentioned pedestrian area. I agree with you here.
 
  Mapping it the way it is done there does not really make 
 sense: Either the exact geometry is important for you, then 
 you should convert both the plaza and the road to areas. Or 
 it isn't, but then there shouldn't be a problem with 
 extending the plaza so that it borders to the road.
 
 +1. but that's still pedestrian areas / highway areas. In these cases
 the areas _do_ connect to the road.
 
 cheers,
 Martin
 
 
 


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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-06 Thread James Livingston

On 05/10/2009, at 8:18 PM, Marc Schütz wrote:
 IMO (a) is the correct way to do this.
  ...
 For a road, we can either choose to map it as a linear object (this  
 is the common case), or we can map its geometry more exactly by  
 using an area. In both cases, however, the object in our database  
 represents the entire road (i.e. not only the middle line). Because  
 in reality, there is no gap between the road and the areas next to  
 it, there shouldn't be one in the database either.

I agree with this, for things like landuse (which is what is mentioned  
in the topic) where the road is represented by a way. A residential  
area or farming area abuts the road reserve, so the polygon should  
abut the road's area or way.

If you're actually mapping the road and not the road reserve, so  
putting things like footpaths as separate ways, you obviously wouldn't  
want to have the landuse cover those, but for just a single way it  
makes sense.
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Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/6 James Livingston doc...@mac.com:
 On 05/10/2009, at 8:18 PM, Marc Schütz wrote:
 IMO (a) is the correct way to do this.
  ...
 For a road, we can either choose to map it as a linear object (this
 is the common case), or we can map its geometry more exactly by
 using an area. In both cases, however, the object in our database
 represents the entire road (i.e. not only the middle line). Because
 in reality, there is no gap between the road and the areas next to
 it, there shouldn't be one in the database either.

 I agree with this, for things like landuse (which is what is mentioned
 in the topic) where the road is represented by a way. A residential
 area or farming area abuts the road reserve, so the polygon should
 abut the road's area or way.

 If you're actually mapping the road and not the road reserve, so

Does anyone actually map the road reserves?

Some people are marking the landuse hard up against roads, but this
isn't correct since the property boundary never touches any roads, at
least none that I'm aware of, and foot paths etc use the same land use
area as roads.

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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-06 Thread David Earl

On 06/10/2009 14:09, John Smith wrote:
 Some people are marking the landuse hard up against roads, but this
 isn't correct since the property boundary never touches any roads, at
 least none that I'm aware of, and foot paths etc use the same land use
 area as roads.

I keep adjacent areas separate, a small number of metres away from the 
way for the road, which essentially reflects a model of reality without 
being over pedantic about the exact distance. This includes grass in the 
middle of islands and the like. Because road widths are exaggerated in 
the renderers that means areas neatly abut them when drawn, which is 
just the way it should be IMO. If the road moves (due to inaccurate 
mapping) it does mean the area has to be moved too, which is somewhat 
inconvenient. On the other hand selecting an area which shares edges 
with ways is a pain, so there is also some loss of convenience (not to 
mention lack of reality) in sharing edges.

David


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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-06 Thread Dave F.

Marc Schütz wrote:
 IMO (a) is the correct way to do this.

 We are trying to represent reality in our database.

I'm not sure that's true. A map is a representation of reality, not 
reality itself. With the tools available to us at the moment attaining 
reality is a lot of work For instance the majority of mappers don't draw 
an area for, lets say, an 1800mm wide pavement/sidewalk, they would use 
a linear way to represent it.

 In order to achieve this, certain abstractions are necessary.

 For a road, we can either choose to map it as a linear object (this is the 
 common case), or we can map its geometry more exactly by using an area. In 
 both cases, however, the object in our database represents the entire road 
 (i.e. not only the middle line).

I Disagree
In the database a linear way /does /represent the centreline of the 
road. It's up to the renderer to decide how 'real world' it looks by 
deciding how thick to render that line.
If a) was used in this case the abutting area would overlap with the 
road render as it would be attached to the centre of the way.

  Because in reality, there is no gap between the road and the areas next to 
 it, there shouldn't be one in the database either.
   

If you want to do real world with no gaps then whole road 
(highway,footpaths,verges, barriers etc) needs to be mapped.
Leaving a gap as in b) implies that the whole highway does have some 
width, it's just not been mapped yet.


 In other words, we should keep the topology intact, even if we choose to 
 simplify the geometry.
   
With option a) I think the topology is deformed inaccurately as it 
attached to the centreline of the simplified highway geometry.


Cheers
Dave F.
 Regards, Marc

   


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Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/6 David Earl da...@frankieandshadow.com:
 On 06/10/2009 14:09, John Smith wrote:

 Some people are marking the landuse hard up against roads, but this
 isn't correct since the property boundary never touches any roads, at
 least none that I'm aware of, and foot paths etc use the same land use
 area as roads.

 I keep adjacent areas separate, a small number of metres away from the way
 for the road, which essentially reflects a model of reality without being
 over pedantic about the exact distance. This includes grass in the middle of
 islands and the like. Because road widths are exaggerated in the renderers
 that means areas neatly abut them when drawn, which is just the way it
 should be IMO. If the road moves (due to inaccurate mapping) it does mean
 the area has to be moved too, which is somewhat inconvenient. On the other
 hand selecting an area which shares edges with ways is a pain, so there is
 also some loss of convenience (not to mention lack of reality) in sharing
 edges.

We now have property boundaries for about 1/4 of Australia, so this
makes it perfectly obvious the property boundaries, and the road
usually runs down the middle however that isn't always the case.

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Re: [OSM-talk] Landuse areas etc. abutting highways

On Tue, Oct 6, 2009 at 9:39 AM, Dave F. dave...@madasafish.com wrote:

 Marc Schütz wrote:
  IMO (a) is the correct way to do this.
 
  We are trying to represent reality in our database.

 I'm not sure that's true. A map is a representation of reality, not
 reality itself.


True, but the database is not the map.  The database is used to create a
map.


 With the tools available to us at the moment attaining
 reality is a lot of work For instance the majority of mappers don't draw
 an area for, lets say, an 1800mm wide pavement/sidewalk, they would use
 a linear way to represent it.


Personally I'd say that's because the way doesn't represent the sidewalk, it
represents a path of travel which happens to coincide with a sidewalk.  But
I think I'm in the minority there.
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Re: [OSM-talk] Landuse areas etc. abutting highways

On Tue, Oct 6, 2009 at 10:04 AM, Anthony o...@inbox.org wrote:

 On Tue, Oct 6, 2009 at 9:39 AM, Dave F. dave...@madasafish.com wrote:

 With the tools available to us at the moment attaining
 reality is a lot of work For instance the majority of mappers don't draw
 an area for, lets say, an 1800mm wide pavement/sidewalk, they would use
 a linear way to represent it.


 Personally I'd say that's because the way doesn't represent the sidewalk,
 it represents a path of travel which happens to coincide with a sidewalk.
 But I think I'm in the minority there.


By the way, so long as the linear way has a width tagged, it can be treated
as an area subject to certain constraints (must be constant width).

Most sidewalks pretty much meet that criterion, and roads sort of meet it
(not at intersections, though).
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Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/7 Anthony o...@inbox.org:
 Most sidewalks pretty much meet that criterion, and roads sort of meet it
 (not at intersections, though).

There is a landuse area around roads that isn't part of surrounding
property boundaries.

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Re: [OSM-talk] Landuse areas etc. abutting highways

On Tue, Oct 6, 2009 at 10:21 AM, John Smith deltafoxtrot...@gmail.comwrote:

 2009/10/7 Anthony o...@inbox.org:
  Most sidewalks pretty much meet that criterion, and roads sort of meet it
  (not at intersections, though).

 There is a landuse area around roads that isn't part of surrounding
 property boundaries.


I'm quite aware of that, and that's why I think there should be a
landuse=right_of_way, completely separate from the highway.

I wonder, how do others define highway, if not as a path of travel?  It
contains such things as roads, sidewalks, and dirt paths, and presumably
also includes paths of travel which are completely unbuilt (the unpaved
grass on the side of the road gets a highway tag, right?).
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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-06 Thread Chris Morley

Mike Harris wrote:
 Thanks to those who responded to this thread. Advice gratefully received.
 
 There seems to be a clear majority preference for option (b)
 - the more detailed approach that avoids superimposing boundaries
 of areas (and their nodes) on an adjacent way (and its nodes). 
 I fully understand the two caveats:
 
 1. It is only worth being precise if there is precise data available.
 2. There are a few exceptions where, for example, the character of the
 adjacent area has access features more like that of a normal linear way
 - the pedestrian area is a good example.
 
 I am persuaded that the advantages of forward compatibility and a higher
 standard of mapping justify my small efforts (where I have good GPS data)
  in separating out superimposed areas/ways and using option (b).
  I am particularly pleased to receive support for splitting single large
  landuse areas (e.g. =residential or =farm) that cross large numbers 
of ways.

Let me encourage you to use option a), based on the reasoning of 
Frederik Ramm.

In detailed mapping, everything is an area way which share nodes with 
its adjacent areas. When roads etc. are linear features, it means they 
have *indeterminate* width and the only non-arbitrary representation 
of this in an editor is for the width to be zero, with adjacent areas 
on both sides sharing the nodes - option a). This makes it consistent 
with the detailed modelling approach. I would look at the linear road 
etc. as being, not a centre-line, but an indeterminately wide 
structure comprising the road surface, sidewalks, verges etc. up to a 
boundary (which in the British countryside would often be a hedge.) By 
mapping with option a) you are saying that the golf course, say, comes 
up to the road's boundary hedge but that you haven't specified exactly 
where that is. If you do know, you are into a detailed mapping 
approach. If a linear road is still used then it would now be 
interpreted as a centre-line, as is sometimes done with rivers.

Since I map in the same are as you, I suspect that in most cases you 
do not have enough information to use the detailed mapping approach. 
Even with arial photography we have available, poor resolution and 
interference from tree cover and shadows often does not allow the 
separation between the hedges to be very reliable.

Editor support for ways sharing nodes is certainly poor, but as with 
inadequate renderers, we should improve them rather than adding 
artificial data (arbitrarily positioned structures) into the database.

Landuse areas which cross a large number of ways are very common. 
Surely you don't intend to divide say, Delamere Forest, into a large 
number of separated areas separated by the paths and tracks? When you 
do need to do it, separating an area into two at a road is certainly 
laborious and maybe somebody should build a JOSM plugin to do it.

Chris

 
 -Original Message-
 From: Martin Koppenhoefer [mailto:dieterdre...@gmail.com] 
 Sent: 05 October 2009 15:52
 To: Marc Schütz
 Cc: talk@openstreetmap.org
 Subject: Re: [OSM-talk] Landuse areas etc. abutting highways

 2009/10/5 Marc Schütz schue...@gmx.net:
 2009/10/5 Marc Schütz schue...@gmx.net:
 But a) could be used as acceptable temporary solution until 
 someone with better information (like having aerial 
 photography) 
 remaps it as
 b)
 Yes, this is basically what I wanted to say. Leave it to the 
 mappers
 whether they want to use a way or an area for a road.

 it will be much harder to add this detail, if all areas 
 are merged though.
 Not really. JOSM supports disconnecting ways since a long 
 time now. But anyway: doing things wrong just to make editing 
 easier is not a good thing.

 +1. That's why adjacent landuses (see topic) shouldn't be extented to
 the center of the road.

 But with option (b) and a linear way you would have a 
 gap next to 
 the
 road. In the case of landuse, this is not a problem in 
 practice, but 
 if there is a place, there you need to insert artificial ways that 
 are not there in reality, just to get the connectivity 
 between the two objects:
 http://osm.org/go/0JUKytHID--
 which objects are you referring to? parkings usually have 
 those ways 
 (for crossing the sidewalk) so they won't be artificial, and 
 pedestrian areas are the exception I mentioned above.
 Look at the google sat image:

 http://maps.google.com/maps?f=qsource=s_qhl=degeocode=q=bayreuths
 ll=37.0625,-95.677068sspn=59.856937,107.138672ie=UTF8hq=hnear=Bayr
 euth,+Bayern,+Deutschlandll=49.946316,11.577148spn=0.000754,0.001635
 t=kz=20
 That's the mentioned pedestrian area. I agree with you here.

 Mapping it the way it is done there does not really make 
 sense: Either the exact geometry is important for you, then 
 you should convert both the plaza and the road to areas. Or 
 it isn't, but then there shouldn't be a problem with 
 extending the plaza so that it borders to the road.

 +1. but that's still pedestrian areas / highway areas

Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-06 Thread Dave F.

Anthony wrote:
 On Tue, Oct 6, 2009 at 9:39 AM, Dave F. dave...@madasafish.com 
 mailto:dave...@madasafish.com wrote:

 Marc Schütz wrote:
  IMO (a) is the correct way to do this.
 
  We are trying to represent reality in our database.

 I'm not sure that's true. A map is a representation of reality, not
 reality itself.


 True, but the database is not the map.  The database is used to create 
 a map.
Which is what I said in the second part of my post.


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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-06 Thread Dave F.

Anthony wrote:
 On Tue, Oct 6, 2009 at 10:04 AM, Anthony o...@inbox.org 
 mailto:o...@inbox.org wrote:

 On Tue, Oct 6, 2009 at 9:39 AM, Dave F. dave...@madasafish.com
 mailto:dave...@madasafish.com wrote:

 With the tools available to us at the moment attaining
 reality is a lot of work For instance the majority of mappers
 don't draw
 an area for, lets say, an 1800mm wide pavement/sidewalk, they
 would use
 a linear way to represent it.


 Personally I'd say that's because the way doesn't represent the
 sidewalk, it represents a path of travel which happens to coincide
 with a sidewalk.  But I think I'm in the minority there.


 By the way, so long as the linear way has a width tagged, it can be 
 treated as an area subject to certain constraints (must be constant 
 width).
Which is what I said in the second part of my post.
The abutting render would not be attached to the edge of that width 
render but the centreline of it.

 Most sidewalks pretty much meet that criterion, and roads sort of meet 
 it (not at intersections, though).


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Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/7 Anthony o...@inbox.org:
 On Tue, Oct 6, 2009 at 10:21 AM, John Smith deltafoxtrot...@gmail.com
 wrote:

 2009/10/7 Anthony o...@inbox.org:
  Most sidewalks pretty much meet that criterion, and roads sort of meet
  it
  (not at intersections, though).

 There is a landuse area around roads that isn't part of surrounding
 property boundaries.

 I'm quite aware of that, and that's why I think there should be a
 landuse=right_of_way, completely separate from the highway.

 I wonder, how do others define highway, if not as a path of travel?  It
 contains such things as roads, sidewalks, and dirt paths, and presumably
 also includes paths of travel which are completely unbuilt (the unpaved
 grass on the side of the road gets a highway tag, right?).


landuse=road_reserve ?

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Re: [OSM-talk] Landuse areas etc. abutting highways

On Tue, Oct 6, 2009 at 10:56 AM, John Smith deltafoxtrot...@gmail.comwrote:

 2009/10/7 Anthony o...@inbox.org:
  On Tue, Oct 6, 2009 at 10:21 AM, John Smith deltafoxtrot...@gmail.com
  wrote:
 
  2009/10/7 Anthony o...@inbox.org:
   Most sidewalks pretty much meet that criterion, and roads sort of meet
   it
   (not at intersections, though).
 
  There is a landuse area around roads that isn't part of surrounding
  property boundaries.
 
  I'm quite aware of that, and that's why I think there should be a
  landuse=right_of_way, completely separate from the highway.
 
  I wonder, how do others define highway, if not as a path of travel?
 It
  contains such things as roads, sidewalks, and dirt paths, and presumably
  also includes paths of travel which are completely unbuilt (the unpaved
  grass on the side of the road gets a highway tag, right?).
 

 landuse=road_reserve ?


I'm not sure they're always used for roads, but good enough!  I'm planning
on implementing this, probably in the next few weeks (though it may be a few
months, and I may have a small scale run within a week or two).  Should I
use landuse=road_reserve, landuse=right_of_way, or not bother tagging those
areas at all?

On Tue, Oct 6, 2009 at 10:45 AM, Chris Morley c.mor...@gaseq.co.uk wrote:

 Landuse areas which cross a large number of ways are very common.
 Surely you don't intend to divide say, Delamere Forest, into a large
 number of separated areas separated by the paths and tracks?


In that case, you shouldn't, because the paths and tracks are part of the
forest.  Likewise, you wouldn't split the landuse at a service highway which
goes through a landuse=commercial.  But that's not an example of landuse
abutting a highway, it's an example of a highway cutting through a
landuse.  Landuse and highway are really independent concepts, aren't
they?  The main counterexample where you *would* have a landuse abutting a
highway is in the case of pedestrian areas, which are tagged as
highway in addition to being tagged as landuse, right?

Whether or not a highway should cut through a landuse=residential or
landuse=farm is probably jurisdiction dependent.  Where I live there are
specific areas of land set aside for roads and other specific areas of land
set aside for houses.  Seems to me like a clear case for separate landuse
areas, no?

If you don't have the data to separate out the two, that's fine.  I don't
mind highway ways cutting through landuse areas so much.  But that's not
the same as using the highway way as the border to your landuse area.
The only way I can see doing that is when the landuse area is *also* a
highway area.
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Re: [OSM-talk] Landuse areas etc. abutting highways

On Tue, Oct 6, 2009 at 12:29 PM, Anthony o...@inbox.org wrote:

 The only way I can see doing that is when the landuse area is *also* a
 highway area.


And then, only if you're sure that's what you want to do.  If you have two
pedestrian areas separated by a highway, and you use the highway as a shared
border between them, you're telling routers that pedestrians are allowed to
cross the road at any section (not only at crosswalks).  If that's what you
want to say, fine.  If not, then you need the gap.

It seems like something more useful for bicycle ways than pedestrian ways.
But I'm sure there's a counterexample to that, just like everything else.
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Re: [OSM-talk] Landuse areas etc. abutting highways

Chris

Despite the well-argued views of a minority, I am persuaded by the equally 
well-argued views of the (considerable) majority who favour option (b).

That is not to say that there isn't room for using a bit of common sense! I 
wouldn't divide up Delamere Forest into individual areas bounded by paths etc. 
- the paths in a sense form part of the forest landuse - but I would probably 
divide a residential area with, say, a major road going through it and would 
certainly divide landuse=farm either side of a road, for example, if I knew 
that it was a different farm on either side.

Like everything else in OSM, it all a question of judgement!

I asked the original question from a neutral standpoint but - in the light of 
the responses have now developed a preference for option (b) - with exceptions.

Of course, nothing is ever final ...

Mike Harris
 

 -Original Message-
 From: Chris Morley [mailto:c.mor...@gaseq.co.uk] 
 Sent: 06 October 2009 15:46
 To: talk@openstreetmap.org
 Subject: Re: [OSM-talk] Landuse areas etc. abutting highways
 
 Mike Harris wrote:
  Thanks to those who responded to this thread. Advice 
 gratefully received.
  
  There seems to be a clear majority preference for option (b)
  - the more detailed approach that avoids superimposing 
 boundaries of 
  areas (and their nodes) on an adjacent way (and its nodes).
  I fully understand the two caveats:
  
  1. It is only worth being precise if there is precise data 
 available.
  2. There are a few exceptions where, for example, the 
 character of the 
  adjacent area has access features more like that of a normal linear 
  way
  - the pedestrian area is a good example.
  
  I am persuaded that the advantages of forward compatibility and a 
  higher standard of mapping justify my small efforts (where 
 I have good 
  GPS data)
   in separating out superimposed areas/ways and using option (b).
   I am particularly pleased to receive support for splitting 
 single large   landuse areas (e.g. =residential or =farm) 
 that cross large numbers of ways.
 
 Let me encourage you to use option a), based on the reasoning 
 of Frederik Ramm.
 
 In detailed mapping, everything is an area way which share 
 nodes with its adjacent areas. When roads etc. are linear 
 features, it means they have *indeterminate* width and the 
 only non-arbitrary representation of this in an editor is for 
 the width to be zero, with adjacent areas on both sides 
 sharing the nodes - option a). This makes it consistent with 
 the detailed modelling approach. I would look at the linear 
 road etc. as being, not a centre-line, but an indeterminately 
 wide structure comprising the road surface, sidewalks, verges 
 etc. up to a boundary (which in the British countryside would 
 often be a hedge.) By mapping with option a) you are saying 
 that the golf course, say, comes up to the road's boundary 
 hedge but that you haven't specified exactly where that is. 
 If you do know, you are into a detailed mapping approach. If 
 a linear road is still used then it would now be interpreted 
 as a centre-line, as is sometimes done with rivers.
 
 Since I map in the same are as you, I suspect that in most 
 cases you do not have enough information to use the detailed 
 mapping approach. 
 Even with arial photography we have available, poor 
 resolution and interference from tree cover and shadows often 
 does not allow the separation between the hedges to be very reliable.
 
 Editor support for ways sharing nodes is certainly poor, but 
 as with inadequate renderers, we should improve them rather 
 than adding artificial data (arbitrarily positioned 
 structures) into the database.
 
 Landuse areas which cross a large number of ways are very common. 
 Surely you don't intend to divide say, Delamere Forest, into 
 a large number of separated areas separated by the paths and 
 tracks? When you do need to do it, separating an area into 
 two at a road is certainly laborious and maybe somebody 
 should build a JOSM plugin to do it.
 
 Chris
 
  
  -Original Message-
  From: Martin Koppenhoefer [mailto:dieterdre...@gmail.com]
  Sent: 05 October 2009 15:52
  To: Marc Schütz
  Cc: talk@openstreetmap.org
  Subject: Re: [OSM-talk] Landuse areas etc. abutting highways
 
  2009/10/5 Marc Schütz schue...@gmx.net:
  2009/10/5 Marc Schütz schue...@gmx.net:
  But a) could be used as acceptable temporary solution until 
  someone with better information (like having aerial
  photography)
  remaps it as
  b)
  Yes, this is basically what I wanted to say. Leave it to the 
  mappers
  whether they want to use a way or an area for a road.
 
  it will be much harder to add this detail, if all areas
  are merged though.
  Not really. JOSM supports disconnecting ways since a long
  time now. But anyway: doing things wrong just to make 
 editing easier 
  is not a good thing.
 
  +1. That's why adjacent landuses (see topic) shouldn't be 
 extented to
  the center of the road

Re: [OSM-talk] Landuse areas etc. abutting highways

Yes - I think Anthony makes the case very well and gives a clearer response
to Chris than I did!
 
I think the distinction between landuse=forest (where the tracks - and even
roads - are normally regarded as part of the forest) and some of the other
landuse= is sensible. I also agree that there is a different set of criteria
that apply between the abutment and the cut-across cases.
 
As for a new landuse=road_something, that seems helpful for micro-mapping,
especially in urban areas. I would counsel against using
landuse=right_of_way, however, because the term right of way has specific
legal implications in some jurisdictions and might not apply in all cases
(e.g. a private or unadopted residential road).
 
In the UK, at least, the highway in law usually extends for the whole area
between the adjacent land areas - i.e. it includes the carriageway upon
which vehicles travel as well as the verges, which might be grass, dirt,
paved footways (with or without cycleways), etc. Thus this area would
normally completely fill the real-world 'gap' between adjacent landuse
areas, e.g landuse=residential, commercial, farm, forest, etc.
 
[Chris: a nice rural example near you would be the several green lanes in
and around Great Barrow; some are private and others are footpaths,
bridleways or even restricted byways. Most of the area was owned by the
Marquess of Cholmondeley but when he sold most of it to individual farming
landowners in 1919 he retained ownership of many of the green lanes - and to
the best of my knowledge he is still the landowner of these between the
fences/hedges that separate them on either side from the adjacent farmland.]
 
This suggests that the area tag might even be landuse=highway!
 
Mike Harris
 


  _  

From: Anthony [mailto:o...@inbox.org] 
Sent: 06 October 2009 17:30
To: John Smith; c.mor...@gaseq.co.uk
Cc: talk@openstreetmap.org
Subject: Re: [OSM-talk] Landuse areas etc. abutting highways


On Tue, Oct 6, 2009 at 10:56 AM, John Smith deltafoxtrot...@gmail.com
wrote:


2009/10/7 Anthony o...@inbox.org:
 On Tue, Oct 6, 2009 at 10:21 AM, John Smith deltafoxtrot...@gmail.com
 wrote:

 2009/10/7 Anthony o...@inbox.org:
  Most sidewalks pretty much meet that criterion, and roads sort of meet
  it
  (not at intersections, though).

 There is a landuse area around roads that isn't part of surrounding
 property boundaries.

 I'm quite aware of that, and that's why I think there should be a
 landuse=right_of_way, completely separate from the highway.

 I wonder, how do others define highway, if not as a path of travel?
It
 contains such things as roads, sidewalks, and dirt paths, and presumably
 also includes paths of travel which are completely unbuilt (the unpaved
 grass on the side of the road gets a highway tag, right?).



landuse=road_reserve ?



I'm not sure they're always used for roads, but good enough!  I'm planning
on implementing this, probably in the next few weeks (though it may be a few
months, and I may have a small scale run within a week or two).  Should I
use landuse=road_reserve, landuse=right_of_way, or not bother tagging those
areas at all?


On Tue, Oct 6, 2009 at 10:45 AM, Chris Morley c.mor...@gaseq.co.uk wrote:


Landuse areas which cross a large number of ways are very common.
Surely you don't intend to divide say, Delamere Forest, into a large
number of separated areas separated by the paths and tracks?



In that case, you shouldn't, because the paths and tracks are part of the
forest.  Likewise, you wouldn't split the landuse at a service highway which
goes through a landuse=commercial.  But that's not an example of landuse
abutting a highway, it's an example of a highway cutting through a
landuse.  Landuse and highway are really independent concepts, aren't
they?  The main counterexample where you *would* have a landuse abutting a
highway is in the case of pedestrian areas, which are tagged as
highway in addition to being tagged as landuse, right?

Whether or not a highway should cut through a landuse=residential or
landuse=farm is probably jurisdiction dependent.  Where I live there are
specific areas of land set aside for roads and other specific areas of land
set aside for houses.  Seems to me like a clear case for separate landuse
areas, no?

If you don't have the data to separate out the two, that's fine.  I don't
mind highway ways cutting through landuse areas so much.  But that's not
the same as using the highway way as the border to your landuse area.
The only way I can see doing that is when the landuse area is *also* a
highway area.


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Re: [OSM-talk] Landuse areas etc. abutting highways

On Tue, Oct 6, 2009 at 1:04 PM, Mike Harris mik...@googlemail.com wrote:

 This suggests that the area tag might even be landuse=highway!


Hey, I could go for that.  I've already clearly separated the meaning of the
term highway when dealing with OSM from the meaning of the term highway
that I'd use in non-OSM situations.

landuse=highway an area of land set aside for public use in transportation

Should I add it to the wiki as a proposal?
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Re: [OSM-talk] Landuse areas etc. abutting highways

Why not - it seems as good as any other idea - of course someone is going to
object (;) but ...

Mike Harris
 

 -Original Message-
 From: dipie...@gmail.com [mailto:dipie...@gmail.com] On 
 Behalf Of Anthony
 Sent: 06 October 2009 19:03
 To: Mike Harris
 Cc: talk@openstreetmap.org
 Subject: Re: [OSM-talk] Landuse areas etc. abutting highways
 
 On Tue, Oct 6, 2009 at 1:04 PM, Mike Harris 
 mik...@googlemail.com wrote:
 
   This suggests that the area tag might even be landuse=highway!
 
 
 Hey, I could go for that.  I've already clearly separated the 
 meaning of the term highway when dealing with OSM from the 
 meaning of the term highway that I'd use in non-OSM situations.
 
 landuse=highway an area of land set aside for public use in 
 transportation
 
 Should I add it to the wiki as a proposal?
 
 


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Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/4 Dave F. dave...@madasafish.com:
 I'd go for b) for all the reasons mentioned above

+1

another issue is the size. If you try to do statistics based on the
areas of certain landuse, you would want them to be their real size
(as precise as possible) and not size= area size - (roadlength of
adjacent roads * width * 0,5) as the latter is far more complicated to
get.

cheers,
Martin

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Re: [OSM-talk] Landuse areas etc. abutting highways

I see on exeption though: areas that are pedestrian areas
(highway=pedestrian, area=yes). In this case I'd like to connect the
pedestrian area (if there is no other limit like a wall, fence, hedge,
etc.) to the linear highway (for routing and rendering issues),
especially, when the pedestrian area is paved.

cheers,
Martin

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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-05 Thread Lester Caine

Martin Koppenhoefer wrote:
 I see on exeption though: areas that are pedestrian areas
 (highway=pedestrian, area=yes). In this case I'd like to connect the
 pedestrian area (if there is no other limit like a wall, fence, hedge,
 etc.) to the linear highway (for routing and rendering issues),
 especially, when the pedestrian area is paved.

This is an area of micromapping that DOES need to have some 'guidelines' 
so that it can actually be rendered, and routing software can route for 
pedestrians.

Footpaths around here can take many paths, following the field 
boundaries rather than the road - with a wide grass verge, being absent 
altogether with high hedges lining the sides of a single track road, 
with fields on the other side, or present in either side of a road but 
with wide verges ( which may or may not be usable to walk on - these can 
be steeply banked to prevent 'traveler' camping ), with fields beyond.

At a macro level - foot=yes against the vehicle route may be 'nominally' 
correct, but the real route may require some more detail to add safe 
pedestrian instructions such as - 'cross to footpath on other side of 
road'. The field boundaries, and ramblers paths that they follow instead 
of the roadway need to be consistently tagged?

-- 
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Contact - http://lsces.co.uk/wiki/?page=contact
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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-05 Thread Marc Schütz

 I'm seeking advice as to best practice in the following type of situation:
  
 As an increasingly common example, now that people are getting around to
 mapping areas such as leisure=, natural= and landuse= ...
  
 Consider the case of landuse=farm on one side of a highway (say a
 secondary road) and leisure=golf_course on the other side of the highway. The
 easiest way to map this - and the one usually adopted it seems - is to make 
 the
 boundaries of the farm and the golf course both coterminous with the
 highway so that the three lines are superimposed in the editors (not quite 
 sure
 how the various renderers handle this) and the representation of the highway
 has zero width.
  
 There are, however, potential problems with this (quite apart from the
 slightly clumsy editing when several ways are superimposed) where detailed
 mapping would ideally show that in real life the golf course and the farm do
 not in fact have a common boundary but both are, for example, separated by
 hedges (which may or may not be mapped) from the road.
  
 It is clearly possible to map the farm and the golf course as separated
 areas with the road mapped as a line drawn between them - i.e. the mapping
 has three separate parallel lines. This assists with mapping more clearly
 features such as junctions of paths with the road (and stiles on paths at such
 junctions). But is this unduly messy or does it create rendering issues
 (e.g. if the lines are not absolutely parallel and just far enough apart to
 render with random gaps between, say, the golf course and the road.
  
 The situation is even trickier where, say, a farm has been mapped as a
 single area (same land use) with, say, a road crossing it - whereas in
 practice, this is two separate farms - one on each side of the road - that 
 may at
 some stage need to be named separately. Then we have to go back and split
 the area, etc.
  
 This seems to be a quite a generic issue and I am wondering how people see
 the pros and cons of (a) the simple approach with coterminous lines giving
 a notional zero width to the highway, vs. (b) the more precise approach of
 mapping the areas either side of the highway as areas that are separate
 both from each other and from the highway.
  
 In practice, almost all mapping seems to use approach (a) - but would
 approach (b) be easier for subsequent editing and addition of detail, and
 rather clearer as it avoids superimposed ways and potential editing errors?
  
 Views?

IMO (a) is the correct way to do this.

We are trying to represent reality in our database. In order to achieve this, 
certain abstractions are necessary.

For a road, we can either choose to map it as a linear object (this is the 
common case), or we can map its geometry more exactly by using an area. In both 
cases, however, the object in our database represents the entire road (i.e. not 
only the middle line). Because in reality, there is no gap between the road and 
the areas next to it, there shouldn't be one in the database either.

In other words, we should keep the topology intact, even if we choose to 
simplify the geometry.

Regards, Marc

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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-05 Thread MP

  For a road, we can either choose to map it as a linear object (this is the 
 common case), or we can map its geometry more exactly by using an area. In 
 both cases, however, the object in our database represents the entire road 
 (i.e. not only the middle line). Because in reality, there is no gap between 
 the road and the areas next to it, there shouldn't be one in the database 
 either.

  In other words, we should keep the topology intact, even if we choose to 
 simplify the geometry.

This would be hard to do properly render in the renderers, as they
will render the road with non-zero width and to render things
correctly, they should push the boundaries of touching landuses so
they will touch the rendered road borders.

It is IMHO easier to learn renderers to support proper width tag and
add that tag to the street between.

With proper micro-mapping, even the street between could be mapped as
an area, but that could be perhaps a bit too much of detail.

But a) could be used as acceptable temporary solution until someone
with better information (like having aerial photography) remaps it as
b)

Martin

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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-05 Thread Marc Schütz

   For a road, we can either choose to map it as a linear object (this is
 the common case), or we can map its geometry more exactly by using an area.
 In both cases, however, the object in our database represents the entire
 road (i.e. not only the middle line). Because in reality, there is no gap
 between the road and the areas next to it, there shouldn't be one in the
 database either.
 
   In other words, we should keep the topology intact, even if we choose
 to simplify the geometry.
 
 This would be hard to do properly render in the renderers, as they
 will render the road with non-zero width and to render things
 correctly, they should push the boundaries of touching landuses so
 they will touch the rendered road borders.
 
 It is IMHO easier to learn renderers to support proper width tag and
 add that tag to the street between.
 
 With proper micro-mapping, even the street between could be mapped as
 an area, but that could be perhaps a bit too much of detail.
 
 But a) could be used as acceptable temporary solution until someone
 with better information (like having aerial photography) remaps it as
 b)

Yes, this is basically what I wanted to say. Leave it to the mappers whether 
they want to use a way or an area for a road.

But with option (b) and a linear way you would have a gap next to the road. In 
the case of landuse, this is not a problem in practice, but if there is a 
place, there you need to insert artificial ways that are not there in reality, 
just to get the connectivity between the two objects:
http://osm.org/go/0JUKytHID--

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Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/5 Marc Schütz schue...@gmx.net:
 But a) could be used as acceptable temporary solution until someone
 with better information (like having aerial photography) remaps it as
 b)

 Yes, this is basically what I wanted to say. Leave it to the mappers whether 
 they want to use a way or an area for a road.

it will be much harder to add this detail, if all areas are merged though.

 But with option (b) and a linear way you would have a gap next to the road. 
 In the case of landuse, this is not a problem in practice, but if there is a 
 place, there you need to insert artificial ways that are not there in 
 reality, just to get the connectivity between the two objects:
 http://osm.org/go/0JUKytHID--

which objects are you referring to? parkings usually have those ways
(for crossing the sidewalk) so they won't be artificial, and
pedestrian areas are the exception I mentioned above.

cheers,
Martin

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Re: [OSM-talk] Landuse areas etc. abutting highways

2009-10-05 Thread Marc Schütz

Original-Nachricht
Datum: Mon, 5 Oct 2009 15:28:54 +0200
Von: Martin Koppenhoefer dieterdre...@gmail.com
An: Marc Schütz schue...@gmx.net
CC: MP singular...@gmail.com, talk@openstreetmap.org
Betreff: Re: [OSM-talk] Landuse areas etc. abutting highways

2009/10/5 Marc Schütz schue...@gmx.net:
But a) could be used as acceptable temporary solution until someone
with better information (like having aerial photography) remaps it as
b)

Yes, this is basically what I wanted to say. Leave it to the mappers
whether they want to use a way or an area for a road.

it will be much harder to add this detail, if all areas are merged though.

Not really. JOSM supports disconnecting ways since a long time now. But anyway:
doing things wrong just to make editing easier is not a good thing.

But with option (b) and a linear way you would have a gap next to the
road. In the case of landuse, this is not a problem in practice, but if there
is a place, there you need to insert artificial ways that are not there in
reality, just to get the connectivity between the two objects:
http://osm.org/go/0JUKytHID--

which objects are you referring to? parkings usually have those ways
(for crossing the sidewalk) so they won't be artificial, and
pedestrian areas are the exception I mentioned above.

Look at the google sat image:
http://maps.google.com/maps?f=qsource=s_qhl=degeocode=q=bayreuthsll=37.0625,-95.677068sspn=59.856937,107.138672ie=UTF8hq=hnear=Bayreuth,+Bayern,+Deutschlandll=49.946316,11.577148spn=0.000754,0.001635t=kz=20

As you can see, there are no ways between the road and the plaza on the left
side. But there are in the database (e.g. the one at the end of
Alexanderstraße). This is an ugly hack to reenable routing, which was broken by
letting the plaza end before the street.

(And I don't even want to start about the situation on the other side of the
road.)

Mapping it the way it is done there does not really make sense: Either the
exact geometry is important for you, then you should convert both the plaza and
the road to areas. Or it isn't, but then there shouldn't be a problem with
extending the plaza so that it borders to the road.

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Re: [OSM-talk] Landuse areas etc. abutting highways