Re: [Talk-GB] Lines of Trees along river banks etc.
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.) ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Lines of Trees along river banks etc.
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. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Lines of Trees along river banks etc.
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. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Lines of Trees along river banks etc.
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 ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Lines of Trees along river banks etc.
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 ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Lines of Trees along river banks etc.
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 ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb