pnorman has commented on the following diary entries

Post When Comment
Mapping Errors in Guatemala and Honduras 3 months ago

As a first step, I always recommend starting a changeset discussion. If the users do not reply, two options to consider are reverting their changesets or contacting the Data Working Group. In the case of a user ignoring discussions or messages about their mapping the DWG can require a user to respond to the discussion before continuing mapping.

Experimenting with ClearTables, self-hosted vector tiles, and Tangram client-side rendering 8 months ago

Which tool did you used to generate vector tiles?

The vector tiles were pre-rendered Kosmtik, using Mapnik. I just scraped my local development setup with curl. There are better ways to do this, but this had the advantage of being easy.

It takes some time to render the demo

I looked at the network timeline, and the slowness is coming from a few causes

  • Some vector tiles are large and unoptimized
  • The server isn't the fastest and has no CDN
  • All access is done on one domain, so there are limits on how many parallel connections browsers will do
It sounds official: OSM Standard style tiles are for mappers 8 months ago

The purpose of and the other OSMF-run rendering infrastructure is to serve mappers. Other OSMF infrastructure may be different, e.g. is primarily used by data consumers. The purpose of OpenStreetMap Carto which is the default style on is different but related:

There are multiple primary purposes of the map style, which pull in different directions

  • It's the primary feedback mechanism for mappers to validate their edits - so detail is useful
  • It's a major part of the impression visitors to receive - so clear design is useful
  • It's an examplar stylesheet for rendering OSM data - so easy customisation is useful

It must always be borne in mind that a map style cannot show every detail of the OSM data, and in many cases it is more appropriate to show the detail in other, more specialist styles.

"Welcome-to-new-mappers" program in the Netherlands comes to an end. 9 months ago

Hence, sending a message to those mappers is rather useless because they are not aware of the fact that there is such a thing as a private mail-box in their account

It's not useless since it'll go to their email. Response rates aren't great, but that's not unique to

Finding no difference in retention rate between those messaged and those not backs up the analysis out of Poland which found no difference. 50% of new users were messaged based on their user id, and there was no statistically significant difference between the two groups. In fact, the percentages had those who had received messages slightly less likely to be retained as mappers.

Deriving centerlines from riverbanks without. 9 months ago

For a long time now I've been thinking on a problem: OSM data sometimes contains riverbanks that have no centerline. This means that someone mapped (part of) the coasts of a river (or stream!), but didn't care about adding a line that would mark its centerline.

When I looked at this problem I concluded it would be far simpler to add the missing data then add a complex step to data transformations. The tools have gotten better since then, but I'd still rather fix the data once for everyone.

Highway shields, state by state 9 months ago

For now, no mainstream renderer or router knows how to process road route relations

They are certainly processable in Mapnik with SQL. The problem with OpenStreetMap Carto is the need to support more than just the US and the need to by default colour the way's highway tag. If you are only worried about supporting route relations it's fairly trivial, and route relations + way ref tags isn't too hard if you don't care about the way's highway tag.

Instead, when an OSM way is baked into a vector tile, a spatial query determines the relevant ISO 3166-2 code (the country code plus the postal abbreviation), which goes into an iso_3166_2 field

Where can we see this logic?

Is Vancouver's SkyTrain a subway? 10 months ago

The SkyTrain is a railway=subway as defined in OSM. As the text usually underground indicates, most railway=subway systems are underground, but this one isn't for much of the length.

The Evergreen line was originally planned to be light rail, but was changed to use the same technology as Skytrain. There are also tentative plans for light rail sometime in Surrey

Making a multilingual map of India using OpenStreetMap data about 1 year ago

Can't really recommend one over the other since I have not tried generating vector tiles myself. My guess is that the standard osm2pgsql/postgres setup should work.

That's a database setup, not a vector tile setup. The issue isn't the software, but the source definitions.

Making a multilingual map of India using OpenStreetMap data about 1 year ago

pnorman, the first step is to create vector tiles of the data you want to render. One can do this from a regular mapnik source using .

What Mapnik source do you recommend to generate vector tiles with so that the tiles will work with the work you describe in this post?

Making a multilingual map of India using OpenStreetMap data about 1 year ago

It's good to see native language rendering.

One question is if someone wanted to reproduce this themselves without relying on third-party services, is there any way, or is it tied into components which can't be reproduced like the Mapbox Streets vector tile set?

Field Mapping Setup about 1 year ago

Are you using the Garmin Virb X or XE? I've found GPS problems when taking photos with the XE at a 2 second interval, how often do you take them?

African Roads and a Western Bias in Mapping about 1 year ago

highway=track isn't about road surface and never has been. Unfortunately, some people use it for unpaved roads, which is wrong, and leads to these problems.

Is there possibility to retag addr:housenumbers without european scheme? (updated) about 1 year ago

I regularly tag 5-digit addresses with the Karlsruhe schema for addresses and it works fine. There are no problems with addresses that jump by large numbers when there is a crossing street.

Updated contributor stats over 1 year ago

The last few years have had drops around end of year/start of year, but this one is about twice the absolute size of previous drops.

OpenStreetMap active users over 1 year ago

Ideally such stats should also include users who contributed only in changeset discussions and with notes - it would be especially interesting to know if these are primarily a domain of otherwise active mappers or if there is a distinct group of users who primarily engage in discussion only and do not perform edits themselves.

I've got the discussion data in the same DB, so it would be easy to run. My impression is that discussions won't make a big difference, but there are more note-only contributors. Unfortunately, I don't have notes in a PostgreSQL DB so can't check this.

Paul did you remove zero-edit changesets?

No. I'd have actually preferred to generate a graph based on user logins or other activity, but for obvious reasons this isn't possible.

In principle although the choice of a 30 days window is perfectly reasonable as a you have to pick one solution it would be nice to have a more detailed spectrum of the contributor activity w.r.t. frequency

Using custom Mapbox layers for mapping missing features in JOSM over 1 year ago

I'd suggest using tms[19] instead of tms[99]. You don't want JOSM to request the imagery for silly-high zoom levels.

How large are our national contributor communities and how are they developing? over 1 year ago

I'd be interested in how the growth of active contributors is per country. This is influenced by both the rate that people join, and the rate they leave. There's a few ways to define an active contributor, but the contributor terms includes a reasonable one

a natural person (whether using a single or multiple accounts) who has edited the Project in any three calendar months from the last 12 months [and is contactable for a request to vote]

We can't easily look at a natural person, but having changesets in at least three months over the last 12 months is the type of criteria that's easily evaluated.

Overall, the growth is linear in the last few years

More specifically, it's 232 additional active contributors per month, R^2=0.996.

The problem I had when I tried to break it down was

  • People who are active contributors overall, but not in any one country
  • People who are active contributors in multiple countries
  • Migration of mappers

Maybe these don't matter and you could just use current location estimates for each active mapper, and then break down the list each month.

OpenStreetMap Carto Complexity over 1 year ago

In addition to Mapbox Streets there are also other styles that use preprocessing. Like OpenTopoMap

I hadn't counted those lines, but there's only about 50 there. And of those, only about 10 lines seem to be ones you should run, the rest are a SQL statement that doesn't seem to do anything.

CartoDB basemaps also use some preprocessing, but not trigger-based like Mapbox streets.

3k lines of preprocessing triggers and other SQL is, in my experience, unique.

In fact you could say through the coastlines all styles make some use of external data preprocessing that is based on additional code

None of them are maintaining their own coastline code, except perhaps to import coastlines into PostgreSQL. I think I counted it where they're doing that but shouldn't have, because I didn't count osm-carto which is also probably longer than other styles.

Quite a lot of the code complexity in osm-carto is there to work around limitations of the capabilities of the software used

All the styles use PostgreSQL, PostGIS, and Mapnik. I don't think any of them are making any assumptions about versions, unless they happen to create databases and use the CREATE EXTENSION syntax. I guess some of the CartoCSS styles would also work with Mapserver and magnacarto instead of Mapnik and carto, but no one is targeting that.

many styles use external non-osm data which often essentially means externalizing processing complexity

With the possible exception of CartoDB, they're not editing the external sources. If they don't have to edit them, it doesn't add to the maintenance burden.

Quantifying HOT participation inequality: it's complicated. over 1 year ago

I think referring to the workload spread as "unfair" is misleading. "Inequality", although probably correct from a statistics point of view, is also a word that is associated with discrimination.

I'm not surprised to see power-law distributions. When I looked at overall contributor stats, changeset size, API reply size and several other measures, I saw power laws coming up.

Use Grass&Green and enhance the data classification over 1 year ago

So, it's basically an editor that just shows you only features with some natural and similar tags?

It's interesting to call forest grass-covered, since neither natural=wood or landuse=forest implies the presence of grass.