I dont think the tiffs are good enough for auto-extraction: the resolution is a mix of 1 & 2 m. There is an edge detection routine available in the gdal toolset, but I suspect the merging of buildings in OpenMap Local is due to some similar processing. By the time you fiddle with all the algorithms you can probably get several hundred buildings mapped using JOSM directly.
There are around 2400 building features in the 4 sq km I have processed the Lidar data for : perhaps an hour or so tracing for a week might get most of them in. It will take a lot longer to start properly adding value by putting more attributes on them. The town centre is the area which needs most work: existing traced polygons aren't really very useful, and Newark still needs more shops. Personally I find this a bit more rewarding than the slog of address surveying in the 'burbs. Relevant tiffs here: https://www.dropbox.com/sh/h8s5pgwkccpqh30/AAAr5SjYccxiUMJZfpPNHHgaa?dl=0 . The *.vrt files might not work if they have full directory paths encoded. Jerry On 24 November 2015 at 16:53, Christian Ledermann < christian.lederm...@gmail.com> wrote: > can you send me (a link to) the tiffs, I'd like to have a look at them, > maybe there is a way to auto extract and compare buildings from that data > > On 24 November 2015 at 13:19, SK53 <sk53....@gmail.com> wrote: > > I've finally (after 8 months) got around to looking at the OpenMap Local > > buildings. I needed them for something else which caused me to download > the > > SK data. I'll say more in a blog post, but for now here are two > comparisons > > of OpenMap Local buildings with EA Lidar data (DSM-DTM & Z axis > > accentuated): > > > > Central Newark (note parish church bottom left): > https://flic.kr/p/ARUvRv > > Residential area to E of town centre (note terraces): > > https://flic.kr/p/ARUvQP > > > > I've also put a few comparisons of Nottingham between OSM & OpenMap > > buildings. > > > > Generally I'd say that the OpenMap Local buildings, although better than > > VMD, still have some of the same problems, and particularly that very > > similar buildings (such as the terraced houses) may be shown > differently, or > > that discrete buildings are merged in unpredictable ways. It's also a bit > > disappointing that the main medieval building, the parish church is just > > shown as a box. The Lidar data looks to have more promise as a base line > for > > creating buildings. There may be scope to use the OpenMap Local > buildings on > > a case-by-case basis where these clearly match the Lidar/Aerial imagery, > or > > where the building shape is obviously simplified & can be improved > (parish > > church again). I would advise not touching things like most of the > housing > > and the merged buildings in the central retail areas. My experience with > > working with such data is that splitting & refining such buildings is > often > > a lot more work than drawing them from scratch. > > > > I have Geotiffs for the DTM, DSM, their difference & hillshaded versions > of > > the DSM & difference. However I have failed to get these to load in > JOSM. If > > someone else know the trick do let me know. > > > > Regards, > > > > Jerry > > > > > > > > > > On 20 November 2015 at 13:03, Christian Ledermann > > <christian.lederm...@gmail.com> wrote: > >> > >> Hi, > >> > >> Are there any mappers in and around Newark on Trent? > >> > >> I'd like to import the "OS Open Map - Local - SK" for newark and liked > >> to have some other 'local eyes on it. > >> > >> > >> > >> -- > >> Best Regards, > >> > >> Christian Ledermann > >> > >> Newark-on-Trent - UK > >> Mobile : +44 7474997517 > >> > >> https://uk.linkedin.com/in/christianledermann > >> https://github.com/cleder/ > >> > >> > >> <*)))>{ > >> > >> If you save the living environment, the biodiversity that we have left, > >> you will also automatically save the physical environment, too. But If > >> you only save the physical environment, you will ultimately lose both. > >> > >> 1) Don’t drive species to extinction > >> > >> 2) Don’t destroy a habitat that species rely on. > >> > >> 3) Don’t change the climate in ways that will result in the above. > >> > >> }<(((*> > >> > >> _______________________________________________ > >> Talk-GB mailing list > >> Talk-GB@openstreetmap.org > >> https://lists.openstreetmap.org/listinfo/talk-gb > > > > > > > > -- > Best Regards, > > Christian Ledermann > > Newark-on-Trent - UK > Mobile : +44 7474997517 > > https://uk.linkedin.com/in/christianledermann > https://github.com/cleder/ > > > <*)))>{ > > If you save the living environment, the biodiversity that we have left, > you will also automatically save the physical environment, too. But If > you only save the physical environment, you will ultimately lose both. > > 1) Don’t drive species to extinction > > 2) Don’t destroy a habitat that species rely on. > > 3) Don’t change the climate in ways that will result in the above. > > }<(((*> >
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