OpenStreetMap

SK53 has commented on the following diary entries

Post When Comment
import geonames data 18 days ago

I'd agree with @Zverik. Even for the United Kingdom geonames data is of very variable quality. I wouldn't be surprised if places local to you are incorrectly located or their names are not immediately recognisable to you. Often they are extracted from old US military maps and transcription of names may not follow modern standards; furthermore in many places some names may no longer be used. See what I wrote about geonames in Pakistan a while back.

Nothing is more valuable than the knowledge you yourself have. I know it is frustrating when there are places lacking in detail, but OSM seems to work best with a slow but steady approach to adding data. The Tortoise not the Hare (https://en.wikipedia.org/wiki/The_Tortoise_and_the_Hare).

Alpine Ski World Championship meets OpenStreetMap: Who are the Mapping Champions? about 1 month ago

Hmm, a shame one of the medallists appears to be adding fantasy ski runs in the Engadin area.

Finding dragged nodes about 1 month ago

OSM-GB a project at the University of Nottingham which ran over 2011-2013 provided all these type of error checking for Great Britain, but like every other OSM error checking routine it tended to produce too many false positives. Many of the TO-FIX reported errors may indeed be errors but many are one-or-more of a) trivial; b) unimportant (eg in service roads); or c) require too much time to investigate. Eyeballing a list of contributors in a region is still often the best way to identify changes which need checking.

One kind of check we have relatively little of is dramatic changes in geometry for something which has been stable for a long time. Of course this wouldn't work in the US with TIGER fixup, or with re-drawing NPE waterways in the UK, but it would make it easier to see potentially regressive edits.

Are you joking ?? about 1 month ago

@BushmanK I dont rely on the documentation as this is often misleading and not infrequently an interpretation of one person, or a small group of people. I'd far rather that the wiki described HOW people used tags than saying how they SHOULD use tags. As fo descriptive and prescriptive grammars the former does not preclude tags being wrong: anyone tagging a lake highway=motorway is indubitably wrong.

On the other hand the US interpretation of landuse=forest (and a few other tags leisure=recreation_ground, place=hamlet, highway=residential etc) is very far removed from usage anywhere else. So even if it is consensus tagging in the US it is not on a worldwide basis.

@Circeus: that looks like individual townships of national forest land have also been tagged forest even though the landuse tag has gone from the large polygon (national or state forest).

Are you joking ?? about 1 month ago

The issue is that US mappers have used landuse=forest to map administrative areas owned and managed by the Federal US Forest Service (mainly National Forests). In virtually all the National Forest areas much of the land is actually used for other purposes: for instance in Summit County Colorado many of the main ski resorts are situated within the National Forest.

Unfortunately, although the topic is discussed from time to time on talk-us, no real consensus has been reached to use this tag in ways closer to how the rest of the world uses it. Recent discussions do suggest some viable alternative tagging approaches, but I'm not holding my breath.

Validating Wikidata tags on OpenStreetMap about 1 month ago

Not mentioned is that wikidata co-ordinates will many times represent data added to Wikipedia from sources which are not compatible with the OSM licence.

Equally I presume that there are many objects both in wikidata and OSM (notably imported GNIS nodes) which may agree in location but in fact are wrong.

Some wikidata objects are a very long way from their actual location: see http://www.openstreetmap.org/node/1244940858. Likely because the originator of a wikipedia article copied over information from another article & forgot to change the lat/long information.

The Italian community had a tool for comparing wikipedia and OSM items (sorry dont have a link), but it was based on administrative geography (usually represented in the wikipedia articles & wikidata) and on classes of objects (places, historic buildings ...). There were a number of advantages in my view: one could focus both on topic & area; missing or incorrect data showed up both ways. Fixing things could be done purely by searching for a putative missing object in OSM, adding it to OSM & then potentially fixing wikipedia. In this way the only information I used from wikipedia was a) such and such a place exists; and b) it's located within a given admin geography.

In summary there are multiple reasons why a straight comparison of locations may not only be misleading but may encourage use of undesirable sources for edits which may not improve OSM.

POI standardization: Tractor Supply Co. about 2 months ago

I'd completely forgotten that I'd documented this on the wiki! Mapping in a couple of small country towns I came to realise we'd missed this category, and after a bit of sleuthing I realised that it was not insignificant: say, a couple of hundred in the UK.

Let's collect more information about formats in the US. I'd be rather surprised if there were not something similar in Canada and Argentina. I presume they evolved from the historical general dry goods store. If the TSC category is slightly different from those in the UK then maybe the formal use in Retail Week rural_supplies will cover a broader scope better.

POI standardization: Tractor Supply Co. about 2 months ago

I wonder if there's any overlap between your shop=farm_supply and what we map in the UK (or at least the East Midlands) as shop=country_store.

These sell a range of farm supplies, but usually in smallish sizes so you cant buy enough seed to sow 25 hectares with wheat. I get the impression that most customers are folk with a few acres, probably grazing for horses: small-holders, hobbyist farmers, stables etc. Therefore the pet side is significant.

Mapping natural and planted habitats 3 months ago

Again can only agree. There's many a time when it's the only thing I've been able to do because image resolution not enough to pick out which parts of a woodland are conifers & which not.

Mapping natural and planted habitats 3 months ago

Dont know why I didn't comment before. I think I am very much in agreement with this. It's not just that using a multiple dimensional tagging approach helps inexperienced users, but in many cases even the most experienced user only knows "here be trees".

Other dimensions:

  • Canopy height
  • Species mix
  • Ground layer: is this a bluebell wood or a marsh
  • Field layer: is it bracken, heather, bilberry, bruchholz, brash, bramble
  • Shrub layer: does it exist, what is it composed of, density etc
  • Tree spacing
  • Dominant species (when appropriate)
  • in management: plantation (i.e. regularly spaced in rows for easier harvesting), coppicing with standards, selective removal etc
Railway Crossings challenge for MapRoulette 5 months ago

With respect to Postgis queries: gridding the data is always a good strategy for reducing in-memory processing requirements. For analysing European & US road networks I've experimented with grid sizes anywhere from 7.5 minutes to 10 degrees. I would imagine for this task you'd probably be fine with something of the order of 1 degree.

Another route for your data would have been Overpass querying for highways sharing a node with a railway. Max Erickson is usually my goto guy for how to do this kind of thing.

If you used Osmosis to populate a snapshot schema then you just need a plain SQL query on using ways, and way_nodes. You want all nodes in the way_node table which belong to at least 2 ways, something along the lines of the following (untested) (SELECT DISTINCT node_id FROM way_nodes wn JOIN ways w ON wn.way_id = w.id WHERE (w.tags?'highway OR w.tags?'railway') GROUP BY node_id HAVING COUNT(DISTINCT way_id) > 1) and COUNT(DISTINCT COALESCE(w.tags->'highway', w.tags->'railway') > 1). I'd actually do this as separate queries to reduce the number of table scans on the big initial hit on way_nodes.

Tagged and Untagged Nodes 5 months ago

Only a million lonely nodes seems quite small by older standards. When Cadastre first came out I was cleaning up a hundred thousand or so at a time. Matt (zere) used to have a duplicated node map too which was a big problem particularly with TIGER, NHD & landuse imports in the US (more or less until ogr2osm fixed most of those isseus).

State of the Map : Some BoF sessions 5 months ago

I found it relatively easy to retrieve the significant trees in the Czech Republic, but quite a lot harder to query things related to their attributes. The SPARQL manual runs to 200 pages which is rather daunting

State of the Map : Some BoF sessions 5 months ago

I recently tried playing with the wikidata for historic/significant trees in the Czech Republic. It seems that the learning curve to get the most out of SPARQL is rather steep: https://twitter.com/AlbinPCLarsson/status/780038828526563328

Tools I wish I had: smarter paved vs unpaved road defaults. 6 months ago

I now have fairly complete urban shapefiles derived from OSM for the whole world. I have not yet processed them to identify false positives, and in some undermapped areas some urban areas will be missing. However, I believe that a) these are more accurate than Natural Earth; b) have fewer false positives; and c) can be readily split along existing OSM boundary lines to add as a means of incorporating into a country extract. More soon/

Some comments about the OpenStreetMap Awards 6 months ago

Thanks to @imagico for discussing this topic. I had more reservations at the outset, but clearly this was an innovation which need to be tried out.

I would like to make some other suggestions for future occasions:

  • Current members of the OSMF board & the selection committee should be ineligible. This may be hard on people who have made substantial contributions to OSM as a whole, but I think it improves how the process appears.

  • Previous winners should also be ineligible. Many of the nominees were the 'usual suspects' for good and obvious reasons. However, I would like the awards to find the unsung OSM heros (of all genders). Winnowing out previous winners ought to make the field more open.

  • Regional awards. Another way to broaden the nomination pool might be to make the process 2 stage with continent-wide regional awards, with the regional winners forming the pool for the global awards. This would have two effects: decent chances of recognition in very active mapping communities without overwhelming participation from other areas; potentially more familiarity of nominees within area. I see no reason to restrict voting for regional nominees to the region which would make everything more complicated. This concept presumes a decent pool for regional nominees (easy in Europe in North America, but less easy in other regions which leads me to:

  • Nominations. Any open nomination process is always subject to a degree of bias: largely through self-selection in participation. Perhaps the role of the selection committee should be in working on creating a broader range & diversity of nominees: in particular from outside the relatively small pool of people who regular engage in the various forms of OSM communication. The committees role would then be to facilitate a broader pool of nominees: NOT to interfere otherwise with nominations. There are many members of the community whose contributions are not well-known by the broader community.

An awareness of the gifts & talents that these people bring to OpenStreetMap is only latent. Let's make them known!

The Great Canadian Mailbox Heist 6 months ago

We have had along saga about this in the UK, and we are just now beginning to lose post boxes.

Edward Betts obtained a list of post boxes from the Royal Mail back when it was a government body and subject to FOI requests. Then Matthew Somerville of OpenSociety (dracos) built a tool comparing that data to OSM. More recently Robert Whittaker created Post hoc for tracking the mapping of post boxes.

@Jedrzej Pelka : my solitary contribution to Polish post boxes!

Post box 7 months ago

Dont forget royal_cypher !

Sarah Mildred Long Bridge Closed permanently (ME/NH) 7 months ago

I walked across the next bridge seaward, the (old) Memorial Bridge almost exactly 17 years ago. A few days later crossed from MN-WA on the Stillwater Lift Bridge.

There are very few lift bridges in the UK, so have always found them rather intriguing when in North America.

Adding house numbers of one town from cadastre to OSM and survey verification 7 months ago

This sort of careful comparison of official data and what is on the ground is very useful. The fact that there are errors in the official cadastral data is not surprising (I once bought a house which had the parcel mapped incorrectly), but a good estimate of the extent of the error really helps in evaluating just how useful any given import is likely to be.

Equally really good OSM data does require revisits to check things and collect data which one has missed. This is the only way we can try to have data which is even better than the official sources.