bdiscoe has commented on the following diary entries

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How to track and encourage contribution? 2 months ago

Update! Today, after many months, the #MissingMaps leaderboard ( is live again, and apparently accurate!

The return of the OSM rank table 3 months ago

Thanks, Zverik.

mmd, I'm not sure what you mean by "not that helpful". The table is my attempt to understand who is editing, how much, where and when; this is potentially useful for other people too. If we are trying to understand why some accounts have made 24 million nodes, noting that these include geometrically inefficient waterways clarifies the mystery. If we are trying to understand why an account suddenly stopped editing, then noting that the mapper is no longer with us clarifies the mystery. If we are trying to estimate how long it will take to manually clean up the USA TIGER or NHD imports, then the last modified number nodes/ways by those import accounts gives us a metric of that progress! You may find them "not helpful" to you, but they are certainly helpful to others. It is indeed the result of years of study of publicly-open data by effectively anonymous accounts, so there is nothing "intimidating" about it, surely? There is not even much "opinion" in it, unless you consider a statement like "low-quality imports are bad" to be an "opinion".

Issues with Japan imports 3 months ago

Thanks Viajero and SomeoneElse, i tested it and that is indeed the case:

  • JOSM hides the deprecated "KSJ2:" tags in the GUI, although you can still see them with "View: Advanced Info" (Ctrl+I)
  • If you change anything about the way (say, removed the bad "layer=-1" tag) and upload it, then JOSM automatically removes the deprecated tags as well.

That's a fascinating undocumented JOSM feature. I approve of it, although in this particular case, I'd argue that even more of the tags in this particular import could/should be removed, including: * "note" and "note:ja" which are absurd to have repeated on every single way. * "source_ref" which doesn't tell you anything that "source" doesn't already. * "name:ja" which is an identical copy of "name"; unlike some other countries, Japan's OSM data has no issue of exonyms appearing "name" tags, so this is truly useless.

How to track and encourage contribution? 3 months ago

@SomeoneElse, I took a look at the switch2osm page you mentioned, and I am very surprised that you consider it to be "fairly straightforward" (!!!) to get hundreds of command-line steps working. I mean, I've done a fair bit of Linux development, and I'd schedule several days to get something like that working; for the general mapper, that's clearly a non-starter.

The bigger problem, though, is that even if "install a tile rendering web server" was an easy 2-click thing that ordinary people could do, how would it get updated to reflect what's on the OSM server in real time? The desired outcome is:

  1. Mapper uses an editor (iD or JOSM) to do a bunch of great mapping work.
  2. They upload it.
  3. ???
  4. They immediately see how OSM's rendered map looks much better now, and are motivated an encouraged to do more great work.

How, exactly, does having ones own map server help with that?

OSM Contributor Analysis - Entry 2: Annual Summaries of User Edits almost 2 years ago

This is really useful, thanks! It allowed me to solve some mysteries, for example, there was an account named "lks1" which did a ton of edits in west-central Poland, but then they suddenly disappeared. Using this tool, I was able query that area of Poland, to find that the account is now known as "lks1[konto usunięte]", i.e. lks1[account deleted].

What's up with the Rann of Kutch? almost 2 years ago

Alan, I'm the main guy who probably did the most work on the Rann of Kutch, including carefully putting the wetland tag over all the land area which, judging from Bing imagery, is sometimes underwater (the very definition of wetland). It's a hard problem but I'm proud of what I managed to get done.

As for "Here's what it looks like now", the pictures you show are of mapnik's zoom level 9, and that rendering doesn't even show wetlands at all until zoom level 10. You don't have to do a overpass turbo query to see the wetlands, just zoom in one more step.

As for "doesn't look very well mapped", I think your issue is with the default mapnik rendering. It is pretty well mapped.

As for wetland=saltmarsh, I'm not sure it adds much information over just natural=wetland, but that sounds fine by me as an additional tag, feel free to add it.

HOT mapping initiatives over time almost 2 years ago

MapLesotho is going strong, lots of commits continuously since it began, including open HOTOSM tasks seeing heavy editing until last week. Not sure why the chart shows MapLesotho ending in Jan 2016?

"Urban India" mappers? about 2 years ago

Wow! Thanks Muralidhar, that explains it. I am delighted to learn about Zippr and its mapping efforts, thank you and your very impressive team!

That said, I would recommend that your dedicated cartographers (like saikumar) put at least a brief sentence on their account page linking to Zipper, just like Mapbox mappers (like ramyaragupathy) link to Mapbox.

About Huts over 2 years ago

@MKnight Indeed Shift-Y, I've corrected it above. Apparently my fingers know it perfectly, but my higher brain not always :)

@SomeoneElse The only "benefit" to going along with community practice is that people are happier, I don't have to respond to dozens of messages on HOT tasking manager telling me my 1-node huts are "wrong" and "please read the instructions". Most of OSM is based on rough consensus and there's a limit to how much energy I want to put into arguing about tagging or other practices; it's "pick your battles" and otherwise just go along.

About Huts over 2 years ago

It's almost always "too many" poorly placed nodes, but just now I found a rare example of "too few":

too few

I'm guessing this newbie apparently considered nodes and ways so precious that they attempt to cover multiple huts with a single minimalist blob :) and yet they still manage to create bad overlaps and self-intersections. I want to applaud their urge to model efficiently... but I'm still stuck slogging thru cleaning this up :)

Japan in OSM - The whole picture over 2 years ago

The link is broken ("@Rub21 made a script") to Where is this script?

Cleaning up NHD in North Carolina over 2 years ago

@gormo Thanks for pitching in on SC. Your cautious approach, to avoid deleting waterways is generally good OSM practice. That said, sometimes its very obvious that a pond/stream has been destroyed and replaced with a shopping center or golf course. I have no issue with removing/updating the clearly non-existent waterways; you could do that (or place notes).

@SK53 I feel very comfortable with the waterway tags. I understand the ditch/canal distinction the same as stream/river, only with artificial waterways. In either case, the crossover is around 3 meters of visible water / potential water area. Both ditch/canal and stream/river have some intermediate-sized ones that could go either way. I understand "drain" as a ditch which is so skinny that it has little or no visible/potentially visible water. Practically every artificial waterway in NHD is a ditch or drain; there are really very few canals, even ones with "Canal" in their name like the Denver "High Line Canal" which is definitely a ditch by OSM's definition.

In other parts of the world (like Sudan and India) they have vast expanses of canal-sized irrigation waterways; I haven't come across much of that in the USA at all.

I too spent some time on the Colorado Basin, especially in the Grand Valley, starting around the town of Mack and working my way south-east; I got only part way to Grand Junction, fixing the NHD (mostly changing "canal" to ditch/drain and applying intermittent=yes to nearly every stream). That task is unfinished :|

Cleaning up NHD in North Carolina over 2 years ago

@imagico you wrote about "projection distortion" and "scale independent". AFAICT, JOSM already does this correctly. In fact while I was writing my Osmium-based simplification test code, I spent hours looking at the (many!) ways to approximate displacements, but finally just adapted the code directly from JOSM itself ( translating from Java to C++. (See all the geodetic stuff in there about EARTH_RAD and "Aviaton Formulary v1.3")

As for river/stream classification, among all of NHD's many issues, I haven't seen much trouble with that (the classification usually roughly matches the imagery, at least), but I have seen some NHD in western Colorado where all the ditches/drains came in as "canal", that was clearly wrong.

@SK53 I apologize for "decimation" as jargon, not so much from GIS, more from computer graphics (my background). At least I managed to avoid calling them LODs :)

A Mapper in the Spotlight: Dave Swarthout (USA/Thailand) over 2 years ago

Hi AlaskaDave, you mentioned the Susitna River and that got me interested in it... first I looked at the "Little" Susitna, I saw you had done some work on that... I made a relation for the whole course:

For the "Big" Susitna, I found the relation you had already begun ( so I filled it in to connect it from source to sea, smoothed some of the PGS river islands, added riverbank along the upper reaches, added tributary streams, etc.

Starting with OSM Mapping: Mapping my hometown, Jorhat over 2 years ago

I saw the Mapbox blog post and was inspired to spend some time armchair mapping Jorhat this evening, added hundreds of more details, mostly in the area around the town. I can only add geometry tho, so someone local needs to fill in the names!

Missing Roads - The Missing Manual over 2 years ago

It's working great for me; i added roads it found in a few places. At least one place was quite dramatic, the entire large town of Cortazar, Mexico, entirely missing from OSM; i added just a bit of it.

My only feedback on the plugin is the red circles, they jump around quite oddly, sometimes they just vanish for no clear reason. When i do get one to stay steady, i can zoom in and find the tiles. Perhaps this is just a result of the clustering algorithm being used. In that case, perhaps the clustering could be a little finer-grained (more points, less clustering) so it isn't so jumpy.

Did somebody delete Hyderabad, India? almost 3 years ago

Thanks for the great work everyone, I see Hyderabad is back on the map. I also refreshed the main site's cache so it appears on zoom levels 7-12. It's even showing up in Nominatim - that was fast!

I am wondering about setting up some kind of process to get notified when someone deletes or commits a change anywhere to a place=town or place=city. We could catch this sort of thing more quickly and not have to wait for someone to stumble across it.

Top OSM Rank: Who are these crazy, amazing people? almost 3 years ago

Thanks @EdLoach, I've noted that you are not a bot :) That's great details on your wiki user page!

Top OSM Rank: Who are these crazy, amazing people? about 3 years ago

@PurpleMustang I would say that CanvecImports has made more than "a dent" with noderank #3 :) and your main account is also impressive.

@joost schouppe Thanks for the props to lodde1949, I've added that note.

@DaCor I've added you now :) I would have found you sooner if you showed up as recently active on (not sure why not).

Top OSM Rank: Who are these crazy, amazing people? about 3 years ago

@Stalfur, there should be an award for "most disparate places", I cannot imagine two countries less alike than Iceland and Botswana! There is user "ulil" who has done a lot of work in exactly two countries: Paraguay and Georgia, and "mindedie" Lithuania and Hokkaido.