[Talk-GB] Southwark update

[SK53 on OSM]

On 03/03/2011 03:21, Jason Cunningham wrote:
> Well done to all those who finished off the road network in Southwark. 
> I was drawn into OSM when searching for a mapping solution in the far 
> south of Southwark, and it's brilliant to see how things have come along.
>
> Tom, I've noticed you've added a large number of trees with species 
> details supplied by Southwark Council. Some of the trees appear a bit 
> random
> eg http://osm.org/go/euuuYWULe--
> Whats the story behind this? I wondering if they're from Southwarks 
> TPO list? or  list of plum trees?
> Noticed Southwark are one of the better councils for providing maps on 
> their website showing important info (hopefully they can start using 
> OSM as the base map)
>
> cheers
>
> Jason
>
Tom posted a picture on Flickr a while ago and I asked him the same 
question: http://www.flickr.com/photos/tomchance/5415845316/.

The best place to get a sense of completeness is Peckham Rye Common & 
Park <http://osm.org/go/euuudw2m>: I confess to having corrected 
<http://www.openstreetmap.org/browse/changeset/7439566> a typo on a 
couple of the trees.

I find this an exciting development: a place where I can point to and 
put pressure on other councils to make their tree databases available. 
My particular interests lie with good specimen trees and relatively 
unusual ones which are hosts to particular insects (e.g., Gleditsia, 
Holm Oak).

I have two minor reservations, which the Southwark data set shows:

1) Overlaying individual trees on an existing closed way showing 
woodland (see Peckham Rye Park). My suspicsion is that although this is 
closed canopy it's not really a wood (its nigh on impossible to keep 
accurate records of trees in woodland as the Lady Park Wood experience 
has shown). Of course this can be handled by post-processing in the 
renderer, but I think it needs a little thought as to how such things 
are mapped.

2) Tagging the botanical name. There is little point in pushing 
individual trees into OSM without this. There are three (perhaps more) 
schemes : name:botanical=*, species=* and taxon=*, each with various 
merits and demerits. The former is the most popular (a JOSM preset I 
think), but although comprehensible, it does horrible things to the 
meaning of the name tag, as name is usually used to things, not types of 
things. (I am not named /Homo sapiens/ under any nomenclature, nor am I 
going to tag phone boxs name=K5). Species is fine until we start using 
it for varieties like /Prunus cerasifolia/ 'Pissardi' (called by Alan 
Mitchell, "Pissards 'orrible Plum") and /Prunus cerasifolia/ 'Nigra'. Or 
for things like /Prunus /'Kanzan', which is such a mix of genetics 
no-one knows where it came from & therefore it does not have a specific 
name. That is why I have preferred taxon, the generic term which covers 
any scientific name whether for a species, a variety, a cultivar, genus 
or aggregate. I labour this point because experience tells me that this 
type of pedantry is important for maintaining credibility with 
naturalists: ultimately it is naturalists and tree enthusiasts who might 
maintain this data.

If my local council is anything to go by there will be plenty of 
mis-identified trees, or ones which it hasn't been possible to identify 
(typically Victorian oddities), plus new planting which has been badly 
sourced and thus isn't what it purports to be.

Thanks again to Tom for seeing this through.

Jerry

P.S. just seen Tom's comment about trees obscuring street names too.


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