Re: [Talk-GB] Lines of Trees along river banks etc.

2013-08-30 Thread OpenStreetmap HADW
On 29 August 2013 09:42, sk53.osm sk53@gmail.com wrote:

 comparable to the European Environment Agency's Urban Atlas. The slides are
 here. I think there are enough details in the methodology for anyone to

You might have warned me about the size of the document, so I
downloaded it at off peak times!

Unfortunately there seem to be a lot of professional references, which
probably won't make sense to me without further research.  However, my
take on problems with landuse is that they arise from amateur mappers.


 Whereas there are some issues with landuse tags, they will not be fixed by
 inventing another category which will be beset by the same problems over
 time. It's much better to try and persuade people that things like
 landuse=grass for farmland pasture is a bad idea.

In particular, this is like the presentational/semantic debate in
HTML.  Landuse is a semantic concept, but amateur mappers tend to
think in presentational terms, and because landuse=forest was the only
way of representing trees, in the rendered Mapnik rendered image, they
coded the central reservation as a forest.  landcover would be a more
presentational coding, and would allow people to achieve the rendering
they wanted without distorting the deep meaning of the data.

The whole history of HTML has shown that when you give the technology
to the masses, you will end up with presentational markup, so, if you
don't provide an alternative way of getting the rendering, you can
expect landuse to be abused for that, and even if you do, a lot of
people will fail to understand the difference.

(natural also has problems.  There is an area near me currently coded
as natural=trees, but, which on further research turns out to actually
have been landscaped.  Mapnik renders this as solid green, without
tree texturing, so this was not an attempt to control presentation.  A
less sophisticated user would probably coded it as a forest, to get
the texturing, when it is really part of a park.)

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Re: [Talk-GB] Lines of Trees along river banks etc.

2013-08-29 Thread OpenStreetmap HADW
On 28 August 2013 23:15, Dudley Ibbett dudleyibb...@hotmail.com wrote:

 This would perhaps suggest they should be marked as ways with barrier=hedge
 and hedge=line_of_trees or perhaps just the latter.

 An alternative might be to use natural=tree_row which is defined in the wiki
 but the examples seem more to related to trees that have been planted at
 regular intervals and where there isn't generally an overlap in the canopy.
 I have used this a few times but I'm not convinced it is the right way to
 tag this feature given that it seems they are a type of hedgerow.


This sort of micro-woodland feature is a case where it would be nice
if Mapnik supported the proposed landcover key.  I found a whole
forest growing in the central reservation of a short section of dual
carriageway, but had to leave it that way as it no longer rendered
when converted to landcover (in most areas, people wouldn't have
bothered to try to make it render, but  since someone had done so,
they would reasonably object if it stopped rendering.

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Re: [Talk-GB] Lines of Trees along river banks etc.

2013-08-29 Thread sk53.osm
The entire landcover tag discussion on the wiki is a huge distraction,and
not based on any objective criteria, let alone an attempt to see if what we
have works.

I, on the other hand, gave a paper at SotM-Eu in 2011 which showed that use
of existing tags could provide a level of land-use/land-cover mapping
comparable to the European Environment Agency's Urban Atlas. The slides are
here https://sotm-eu.org/slides/38_JerryClough_UrbanAtlas_SK53.pdf. I
think there are enough details in the methodology for anyone to replicate
this for other places. Unfortunately a lot of Europe has imported Corine
data and therefore it is not possible to assess the practicability of OSM
as a general source for land-use/land-cover.

Furthermore the main dataset I used, Nottingham, was based on a snapshot so
that I was not tempted to add tags to correct. I actually ran the data for
several european cities, and for two square degrees of the UK. The main
problem in matching OSM to Urban Atlas was not tagging, but the absence of
mapping of landuse. Other discrepancies were due to change in landuse in
the timeframe since the UA data had been compiled, and faulty
interpretation in the UA data set (faculty buildings at Nottingham
University classed as residential, for instance).

Whereas there are some issues with landuse tags, they will not be fixed by
inventing another category which will be beset by the same problems over
time. It's much better to try and persuade people that things like
landuse=grass for farmland pasture is a bad idea.

Jerry

PS. Can I just echo what Richard said in a recent e-mail: you are taking
the wiki far too seriously. It really is a curates egg.


On Thu, Aug 29, 2013 at 8:25 AM, OpenStreetmap HADW osmh...@gmail.comwrote:

 On 28 August 2013 23:15, Dudley Ibbett dudleyibb...@hotmail.com wrote:
 
  This would perhaps suggest they should be marked as ways with
 barrier=hedge
  and hedge=line_of_trees or perhaps just the latter.
 
  An alternative might be to use natural=tree_row which is defined in the
 wiki
  but the examples seem more to related to trees that have been planted at
  regular intervals and where there isn't generally an overlap in the
 canopy.
  I have used this a few times but I'm not convinced it is the right way to
  tag this feature given that it seems they are a type of hedgerow.
 

 This sort of micro-woodland feature is a case where it would be nice
 if Mapnik supported the proposed landcover key.  I found a whole
 forest growing in the central reservation of a short section of dual
 carriageway, but had to leave it that way as it no longer rendered
 when converted to landcover (in most areas, people wouldn't have
 bothered to try to make it render, but  since someone had done so,
 they would reasonably object if it stopped rendering.

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Re: [Talk-GB] Lines of Trees along river banks etc.

2013-08-29 Thread Dudley Ibbett
Many thanks for the information.  I'm afraid my knowledge of the detail you 
provide is quite limited.  I'll stick to natural=row_of_trees.  As you suggest 
it is likely to require the way to be marked on both sides.  I hadn't thought 
about using scrub on a way.  For some reason the JOSM preset is restricted to 
an area but it seems you can directly tag a way as scrub.

Regards

Dudley

Date: Thu, 29 Aug 2013 06:30:23 +0100
Subject: Re: [Talk-GB] Lines of Trees along river banks etc.
From: sk53@gmail.com
To: dudleyibb...@hotmail.com
CC: talk-gb@openstreetmap.org

I don't think these are hedgerows at all. They are really relict river gallery 
woodland (usually Salicion albae, NVC W6) and I would expect are mainly Willows 
with the odd Poplar and Alder.


A photo example (and a location) might help.

Typical components along the Trent (Notts  Derbys) and Thames (Berks  Bucks)  
will be: 
planted trees, usually hybrid Poplar and White Willow, but some real oddities
Crack Willow and Alder as standard trees
pollarded trees, mainly Crack Willowshrubby trees, predominantly Osier and Grey 
Willow, but some Almond  Purple Willow
occasionally dense scrub with Hawthorn and Elder
The willows nearly always are self-set. Any willow twig broken off in a flood 
is capable of regenerating (for Crack Willow and Native Black Poplar this is 
the usual means of propagation), provided there is enough moisture. This means 
that river banks are naturally always getting new additions, and that clearance 
of willow scrub is a never ending task. However, the zone where this happens is 
quite narrow, depending of height of flood waters and maintaining the relevant 
moisture levels.


I don't know much about palatability of willows to livestock, but suspect they 
are not very tasty. When fields have grazing next to a river, usually cattle 
will have made a few gaps to get at the water, but my impression is that they 
don't graze on willows, although sheep probably do.

It may be useful to show that a water body is tree-lined. I personally use 
tree_lined=yes on tree-lined roads (more as a place holder), but there is also 
natural=row_of_trees. You might want left and right. For the scrub willow 
thickets I think natural=scrub is the right tag, even if you choose to put it 
on a way (these will be NVC W1-W3, with W1 being the commonest).

Regards,
Jerry



On Wed, Aug 28, 2013 at 11:15 PM, Dudley Ibbett dudleyibb...@hotmail.com 
wrote:




Hi

I was wondering if anyone has been mapping these?   Quite often I come across 
streams and rivers where there are dense lines of trees along the river banks.  
Occasional I find lines of trees which seem to be remnant hedgerows where the 
shrubs have been removed.


Looking on line it would seem that these are a hedgerow type.  

http://www.hedgelink.org.uk/images/bap/key%20to%20hedgerow%20types%20bigger.jpg


https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69285/pb11951-hedgerow-survey-handbook-070314.pdf


This would perhaps suggest they should be marked as ways with barrier=hedge and 
hedge=line_of_trees or perhaps just the latter.

An alternative might be to use natural=tree_row which is defined in the wiki 
but the examples seem more to related to trees that have been planted at 
regular intervals and where there isn't generally an overlap in the canopy.  I 
have used this a few times but I'm not convinced it is the right way to tag 
this feature given that it seems they are a type of hedgerow.


This may be something for the tagging email group but these a quite common 
features in the UK so I thought it would be good to ask here first.

Many Thanks

Dudley




 
  

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Re: [Talk-GB] Lines of Trees along river banks etc.

2013-08-28 Thread Dudley Ibbett
Hi

I was wondering if anyone has been mapping these?   Quite often I come across 
streams and rivers where there are dense lines of trees along the river banks.  
Occasional I find lines of trees which seem to be remnant hedgerows where the 
shrubs have been removed.

Looking on line it would seem that these are a hedgerow type.  

http://www.hedgelink.org.uk/images/bap/key%20to%20hedgerow%20types%20bigger.jpg

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69285/pb11951-hedgerow-survey-handbook-070314.pdf

This would perhaps suggest they should be marked as ways with barrier=hedge and 
hedge=line_of_trees or perhaps just the latter.

An alternative might be to use natural=tree_row which is defined in the wiki 
but the examples seem more to related to trees that have been planted at 
regular intervals and where there isn't generally an overlap in the canopy.  I 
have used this a few times but I'm not convinced it is the right way to tag 
this feature given that it seems they are a type of hedgerow.

This may be something for the tagging email group but these a quite common 
features in the UK so I thought it would be good to ask here first.

Many Thanks

Dudley



 
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Re: [Talk-GB] Lines of Trees along river banks etc.

2013-08-28 Thread sk53.osm
I don't think these are hedgerows at all. They are really relict river
gallery woodland (usually *Salicion albae,*
NVChttp://en.wikipedia.org/wiki/Woodland_and_scrub_communities_in_the_British_National_Vegetation_Classification_systemW6)
and I would expect are mainly Willows with the odd Poplar and Alder.

A photo example (and a location) might help.

Typical components along the Trent (Notts  Derbys) and Thames (Berks 
Bucks)  will be:

   - planted trees, usually hybrid Poplar and White Willow, but some real
   oddities
   - Crack Willow and Alder as standard trees
   - pollarded trees, mainly Crack Willow
   - shrubby trees, predominantly Osier and Grey Willow, but some Almond 
   Purple Willow
   - occasionally dense scrub with Hawthorn and Elder

The willows nearly always are self-set. Any willow twig broken off in a
flood is capable of regenerating (for Crack Willow and Native Black Poplar
this is the usual means of propagation), provided there is enough moisture.
This means that river banks are naturally always getting new additions, and
that clearance of willow scrub is a never ending task. However, the zone
where this happens is quite narrow, depending of height of flood waters and
maintaining the relevant moisture levels.

I don't know much about palatability of willows to livestock, but suspect
they are not very tasty. When fields have grazing next to a river, usually
cattle will have made a few gaps to get at the water, but my impression is
that they don't graze on willows, although sheep probably do.

It may be useful to show that a water body is tree-lined. I personally use
tree_lined=yes on tree-lined roads (more as a place holder), but there is
also natural=row_of_trees. You might want left and right. For the scrub
willow thickets I think natural=scrub is the right tag, even if you choose
to put it on a way (these will be NVC W1-W3, with W1 being the commonest).

Regards,

Jerry


On Wed, Aug 28, 2013 at 11:15 PM, Dudley Ibbett dudleyibb...@hotmail.comwrote:

 Hi

 I was wondering if anyone has been mapping these?   Quite often I come
 across streams and rivers where there are dense lines of trees along the
 river banks.  Occasional I find lines of trees which seem to be remnant
 hedgerows where the shrubs have been removed.

 Looking on line it would seem that these are a hedgerow type.


 http://www.hedgelink.org.uk/images/bap/key%20to%20hedgerow%20types%20bigger.jpg


 https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/69285/pb11951-hedgerow-survey-handbook-070314.pdf

 This would perhaps suggest they should be marked as ways with
 barrier=hedge and hedge=line_of_trees or perhaps just the latter.

 An alternative might be to use natural=tree_row which is defined in the
 wiki but the examples seem more to related to trees that have been planted
 at regular intervals and where there isn't generally an overlap in the
 canopy.  I have used this a few times but I'm not convinced it is the right
 way to tag this feature given that it seems they are a type of hedgerow.

 This may be something for the tagging email group but these a quite common
 features in the UK so I thought it would be good to ask here first.

 Many Thanks

 Dudley





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