[Talk-us] natural=* and landuse=* multipolygons at the urban interface

Tod Fitch tod at fitchdesign.com
Tue Aug 15 14:21:34 UTC 2017

Definitely a pain. It took me a long time to alter (I hope improve) the land cover around the Morgan trailhead and San Mateo peak. Trails, etc. were easy to do from my Garmin tracks and satellite imagery but working with the existing land use/cover was so frustrating I nearly decided not to touch it.

Tod Fitch
(n76 on OSM)

> On Aug 15, 2017, at 6:37 AM, Steve Friedl <steve at unixwiz.net> wrote:
> The challenge with the Scrub from Hell is that it’s mostly one huge area (role=outer in 8 segments) and 40 or something role=inner that provide “cutouts” for things other than natural=scrub;  this could be a lake or it could be a city or whatever. This is the largest single object I’ve ever had to work with in OSM.
> I guess I’ll start looking for natural boundaries to split the big area into smaller ones which will make them more manageable (and separate). 
> Some have suggested just removing the scrub entirely,  but this is going to make the Santa Ana mountains look lousy; it’s almost entirely scrub, and that’s where I hike.
> Steve
> From: Nathan Mixter [mailto:nmixter at gmail.com <mailto:nmixter at gmail.com>] 
> Sent: Monday, August 14, 2017 2:12 AM
> To: OSM Volunteer stevea <steveaOSM at softworkers.com <mailto:steveaOSM at softworkers.com>>
> Cc: talk-us <talk-us at openstreetmap.org <mailto:talk-us at openstreetmap.org>>; David Kewley <david.t.kewley at gmail.com <mailto:david.t.kewley at gmail.com>>; Rihards <richlv at nakts.net <mailto:richlv at nakts.net>>; Steve Friedl <steve at unixwiz.net <mailto:steve at unixwiz.net>>
> Subject: Re: [Talk-us] natural=* and landuse=* multipolygons at the urban interface
> Steve is indeed correct. ID isn't really designed as an editor of complex relations since it is browser based. In JOSM, you can select the relation and all the members 
> and easily see how the elements interact. That being said, it is fine to simplify the FMMP relationships by splitting them into smaller parts like you did or even to delete 
> the relationships altogether. Especially in Orange County, it might be easier just to delete it. 
> The FMMP data are designed primarily to focus on farms. The original designation of "farm" has now been changed to "farmland". Unfortunately it doesn't break it 
> down further to separate things like orchards and vineyards. The data are usually pretty good in separating farmland from everything else. But the everything else is where
> it gets vague. The FMMP data are not designed to break down landcover designations like grassland, scrub, meadows or woods.
> In that sense, it really isn't a landcover import.
> Even with true landcover imports like Corine, the distinction between what is classified a certain way is often arbitrary compared with what you would expect to find by 
> looking at imagery.
> Often the FMMP landcovers and landuses will be grouped together as non farm land. Not too helpful for OSM purposes. If there is no actual farmland like in the area 
> around Orange County it makes sense just to delete it entirely since nothing is gained if the area covered is too broad. 
> Nathan
> <<<<<<<<<<<<<<<<<<<<<<<<<<<<<
> Development in Orange County, California pushes into areas currently
> covered by polygons (often large multipolygons) tagged as natural=scrub,
> landuse=meadow, or landuse=[farm|farmland]. These were part of the FMMP
> import http://wiki.openstreetmap.org/wiki/California_Farms. <http://wiki.openstreetmap.org/wiki/California_Farms.>
> Mostly I try to leave those large multipologons alone, because I don't feel
> confident I can handle them properly, and because I'm using iD (due to
> using a Chromebook), where relation handling is rudimentary.
> But I'd like to update the urban-wildland boundary, where new suburban
> developments are pushing into former wildland, farmland, or (historical?)
> "grazing land". See for example the new development (with 2017 imagery
> recently added to Bing) at
> http://www.openstreetmap.org/edit?editor=id#map=16/33.5352/-117.6034. <http://www.openstreetmap.org/edit?editor=id#map=16/33.5352/-117.6034.>
> Editing these huge multipolygons, and reviewing others' edits to them,
> becomes very cumbersome, at least to me. It seems to me probably sensible
> and reasonable at the urban edge to split off small parts of these
> multipolygons, e.g. at roads, to make the smaller bits easier to edit and
> review in the context of the expanding urban edge.
> As one test / demonstration edit (
> http://www.openstreetmap.org/changeset/51090963 <http://www.openstreetmap.org/changeset/51090963>), I carved off a bit of
> natural=scrub from a large outer role of a multipolygon, into its own
> polygon. I manually added new boundary way segments, stitched them together
> into the existing ways, copied tags, and made the split-off piece its own
> polygon, independent of its original parent multipolygon. I did the split
> at an existing highway=residential object (Golden Ridge Lane).
> I know, I should find a way to use JOSM, which I expect makes this much
> easier. :)
> Meanwhile, does this seem a reasonable approach to making the urban
> interface a bit more manageable in the future? I.e. splitting off parts of
> large multipolygons (so long as they don't have names or other unique
> identifiers that matter, just generic tags things like natural=scrub), to
> make future editing easier?
> I know for the above example of a new residential area, I could make a
> landuse=residential island, and make it an inner role in the surrounding
> landuse=meadow multipolygon. But at some point as the urban sprawl expands,
> it seems to me it makes more sense to stop pretending the area is dominated
> by the natural features, and make it clear it's dominated by e.g.
> landuse=residential, with possibly interspersed natural features like scrub.
> What would the group suggest?
> Is my test edit reasonable, or should it be reverted?
> Thanks,
> David
> P.S. As an aside (not my main point today), the FMMP-based distinction in
> this area between scrub and meadow seems awfully arbitrary. I could be
> mistaken, but I don't believe the "meadow" is actually used today for
> grazing nor feed harvesting, and in the aerial photography, it appears
> indistinguishable from the adjacent "scrub". It appears (and I'm nearly
> certain from driving by) that there's both substantial grass and
> substantial woody plant cover, in similar ratios in both "meadow" and
> "scrub".
> I don't believe there's any current agricultural use of that land, at least
> not near where I'm giving examples today. There might be some
> large-acreage, semi-wildland grazing or feed harvesting activity remaining
> in Orange County, but I've not noticed any.
> As documented in the FMMP wiki page
> http://wiki.openstreetmap.org/wiki/California_Farms, <http://wiki.openstreetmap.org/wiki/California_Farms,> the FMMP designation
> "Grazing Land" was mapped to landuse=meadow.
> But the FMMP designation of "Grazing Land" explicitly does not mean that
> there *is* grazing activity there, just that it is "...land on which the
> existing vegetation, whether grown naturally or through management, is
> suitable for grazing or browsing of livestock." (See for example
> http://www.conservation.ca.gov/dlrp/fmmp/Documents/soil_criteria.pdf. <http://www.conservation.ca.gov/dlrp/fmmp/Documents/soil_criteria.pdf.>) So
> wildlands that will never again see livestock, or harvesting for livestock
> feed, can still be designated Grazing Land by FMMP. Those areas map better
> to natural=grassland or natural=scrub, I think.
> So landuse=meadow seems less useful than natural=scrub or natural=grassland
> for many of these areas. Even though this is a secondary point today, I'd
> welcome comments on this as well.
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> On Sun, Aug 13, 2017 at 9:29 PM, OSM Volunteer stevea <steveaOSM at softworkers.com <mailto:steveaOSM at softworkers.com>> wrote:
>> David, I would contact Nathan Mixter directly (in OSM, nmixter, import account Eureka gold) and ask him what he thinks, as he is (largely speaking) the original importer of these (and many other, very large) imports, many of which, unfortunately generated consternation or reversion.  You might ask him what his plans are to "upkeep" the data he has imported.
>> Nathan is a friend of mine I met in OSM (on a personal and "let's go hiking/camping/backpacking together" level) and I have helped him on both improving the Santa Cruz County (my home) and Monterey County (next door to both of us) landuse imports that he initiated.  Together, we did the single-county FMMP import of Monterey County (only, I didn't help with other counties) over many months (instead of the days Nathan thought it might take) as I wanted to convey the care, vetting, quality assurance and teamwork that such an endeavor truly requires to get it right (or much closer to right, as I still think Monterey County's landuse from this import is "pretty good," if I say so myself).  I/we documented what we did if you click around the links in our wiki, already introduced in this thread.
>> In short, these landuse polygons are indeed very large, unwieldy or virtually "just kill me now" highly difficult to edit using iD (PLEASE use JOSM to edit complex polygons like these!).  I declare that they aren't anything "sacred," especially as new human urban development simply outdates more and more edges of these data as obsolete.  Subtle differences between scrub and meadow, while I admire your diligence in determining "what is best" for a given area, are not hard-and-firm.  I'd characterize these FMMP imports as "2010-12 data, roughly applied to OSM to avoid large blank areas in California" (except Monterey County, were I was very careful to apply the lipstick carefully so there was no piggy ugliness about it).  So, should these FMMP import (multi)polygons need to be changed, edited, modernized and especially trimmed down to more manageable size, please, get a read from Nathan if you can, then take the controls of JOSM firmly in your hands and go for it!  Especially as those bulldozers build those suburbs.
>> Nathan, you might please chime in either on-list or via email to this distro; thank you.  If you wish, I additionally invite anybody to contact me off-list to ask about this topic should you care to know further details, though Nathan is the primary importer of these data.
>> SteveA
>> California
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