OpenStreetMap

PierZen's Diary Comments

Diary Comments added by PierZen

Post When Comment
Analysis of Bounding Box Sizes Over the Last Eight Years over 2 years ago

From the Planet Changesets dump, I did publish brief statistics for 2017 in a Twitter Moment Called Weight of Continents.

I observed for 2017 10 million changesets 6 million where BBOX smaller then 100x100m 11,000 changesets that cover more then a continent

Some kind of Heat Map - I could also represent areas mapped over the continents by tracing all BBOXes except the smaller and larger ones.

Tag Transformations in OpenStreetMap about 3 years ago

I repeat the block for the unformatted table example

key value thematic Feature
amenity hospital Health Hospital
building hospital Health Hospital
amenity clinic Health Clinic
Tag Transformations in OpenStreetMap about 3 years ago

To export OpenStreetMap data to the UNOCHA Humanitarian Portal, I group OSM data by thematics such as health, education, etc. For such an Extract-Transform-Load system, we need to assure that we cover well the various thematics (we identifiy all the key-value combinations) and validate key-values to assure quality.

ogr2ogr let’s me load OSM Planet for a country into PostGIS. Sqlite-Spatialite can be used for smaller projects. It recognizes PostGIS functions. Otherwise PostgreSQL-PostGIS.

This way it is easy to test-validate the data. For DR Congo planet file, I filter data using series of condition statements. But this could be done using a translation table :

key value thematic amenity hospital Health building hospital Health amenity clinic Health

In the example above, we could also create a generic feature variable to group various key/values that represent the same feature (for example, hospitals).

Quite important to support projects like for the Ebola outbreak north of DR Congo, we need to identify all features, even if misspelled tags. Tag classification assures that we dont miss features. It also help validate the data with a summary of key/values combination for the country.

For example

Thematic Major Key/value Flag
Education amenity=school  
Education amenity=university  
Health amenity=doctors  
Health amenity=hospital  
Nd. highway=Rond point Gouvernorat !!!
Nd. amenity=Voyage !!!
Public Services and Offices office=Bureau Commussion Ebola Butembo !!!
OpenStreetMap Carto release v4.19.0 about 4 years ago

It would be nice to start looking at major infrastructures like hydro-electric dams and high-voltage power network. Why not start at the same zoom level then major roads?

Maps Update: 17th of April almost 5 years ago

Zverik, this is an interesting way to monitor big changes, if there was a way to inform the various communities to look at the modifications.

Latest Changes almost 5 years ago

Yes it has been added to JOSM recently. https://github.com/JOSM/changeset-viewer

When zoom-out in JOSM, it is hidden behind a roadway ref. Zooming-in to the building, I could see it. I will open a ticket for more visibility of the icons.

Latest Changes almost 5 years ago

If you click for last month edits you should see in the list Matthew Darwin Feb 12th 2018, 1:47:42 pm «zoom» «achavi» Fix validator errors. It was easier to look at yesterday since there was only this changeset listed. With the Changesets viewer in JOSM, with the same BBOX, we can see that there is no object to visualize inside the bbox, but some in towns 10-15 km from this town.

Latest Changes almost 5 years ago

Nice tool to monitor modifications in our area. It could be improved by focusing on only data modified in the area. Since Overpass returns objects edited in the area, there could be an option to only show data edited inside the selected bbox. This would take care of huge changesets that while they cover the BBOX we look at, might have no or minimal objects modified in the area.

For example, the link below reported today only one changeset. It covers a large area in Canada an north of USA and affects a few hundred nodes, ways and relations. https://tyrasd.github.io/latest-changes/#12/45.4548/-73.3092 https://openstreetmap.org/browse/changeset/56302536 And Achavi cannot help in such cases https://overpass-api.de/achavi/?changeset=56302536

To facilitate monitoring of local areas, it would be great that both Latest-Changes and Achavi offer the possibility to see only objects edited in the BBOX.

Hi Friends about 5 years ago

Quite important also, you are adding Points of Interest for public services, shops, etc. OSM contributors can make the difference locally adding such informations. This is what I call, to «color the map». Have fun.

Building Canada 2020 about 5 years ago

@mikel, you should re-read the thread below where Julia C from MapBox writes to Talk-ca, saying that MapBox is collaborating with StatCan to engage Canadian universities to participate in the Building Canada 2020 project. [Talk-ca] Building Canada 2020 OSMGeoWeek Mapathons https://lists.openstreetmap.org/pipermail/talk-ca/2017-October/008123.html

As it has been answered in the Thread, The OSM Canada community was not consulted, has other priorities and not the resources to cleanup the map afterwards.

2017-11-11[Talk-ca] Integrating the statistical and geospatial data with ECLAC, United Nations https://lists.openstreetmap.org/pipermail/talk-ca/2017-November/008194.html

It looks like we are forcing OSM-Canada community again. But no response yet from the community to support this.

If we are looking at the Missing Map Projects, a lot of marketing is done by the Partner organizations, projects started everywhere with not enough support from the organizations that initiate these projects. And the problems are left to the OSM community. If you are not convinced, go back to what has been done for Haiti in 2016, prior to the October Cyclone and the two weeks after the cyclone. Quite disturbing! Re-read the threads on the HOT list. We dont want that in Canada.

OSM is a community driven organization. Partner organizations should respect this, not force the hand to the communities for projects they planned without discussion with the community.

OSM Contributors Outlook - The Pulse of OpenStreetMap Contributors over 5 years ago

I uploaded the tables on Github since it has minimal Markdown table formatting that OSM Diary do not recognize.

See https://github.com/pierzen/OsmContributorStats-Changesets/blob/master/Pulse_of_OpenStreetMap_Contributors_2017-10-11

OSM Contributors Outlook - The Pulse of OpenStreetMap Contributors over 5 years ago

Table formatted

Contributors, Monthly average of participation by year

           All Veterans Veterans 
Year Contributors        in % of year 
2010	13,059 	6,598 	50.5% 
2011	16,003 	8,531 	53.3% 
2012	20,078 	10,182	 50.7% 
2013	21,594 	11,857 	54.9% 
2014	25,322 	13,506 	53.3% 
2015	27,048 	15,176 	56.1% 
2016	38,357 	16,393 	42.7% 
2017	47,486 	22,839 	48.1%
OSM Contributors Outlook - The Pulse of OpenStreetMap Contributors over 5 years ago

VS Graph 4a contributions, we observe a constant fluctuation of new contributors with an increae at the end of every year. At the same time, there is a significative retention of veterans after the first years of contribution. The table below shows the average contributors by year for each yearly cohort. I also added for each year of contribution the share in % of veterans. Has we see, their share decreased in 2016-2017 with the increase of new contributors. The impact on Total contribution, this is an other story.

Contributors, Monthly average of participation by year All Veterans Veterans Year Contributors in % of year 2010 13,059 6,598 50.5% 2011 16,003 8,531 53.3% 2012 20,078 10,182 50.7% 2013 21,594 11,857 54.9% 2014 25,322 13,506 53.3% 2015 27,048 15,176 56.1% 2016 38,357 16,393 42.7% 2017 47,486 22,839 48.1%

OSM Contributors Outlook - The Pulse of OpenStreetMap Contributors over 5 years ago

Second point, the days of participation is one of the measure of Intensity of contribution. While I consider it better then the number of changesets, it is exact that it cannot take account of all the contribution profiles. Analysing these statistics of contribution, we see that averages do not worth much with outliers being more the norm.

What type of synthetic indicator of intensity other then the cumulative number of Contributions could explain intensity of contribution? There is a great variety of behaviors, with more or less days of participation and more or less volume of edits per day.

OSM Contributors Outlook - The Pulse of OpenStreetMap Contributors over 5 years ago

Thanks for your comment,

You are right, Graph 1 is in fact a serie of graphs sticked together. And yes, it could be confusing if interpreted as a long timeserie. I show only 12 months, but I could have a longer period for each graph. By placing these graphs side by side, it let you compare behavior from year to year. We could also group data for longer periods. I amended the text with a note on this serie of graphs.

We often see statistics of big numbers like the new entries every year. Here we can see for month 1 of earch yearly cohort these entries, and follow the contributor’s behavior in the months that follow. We see that there is a constant behavior from year to year.

It let’s observe a Pareto distribution that some also call the Long tail distribution. It let’s us observe survival functions from month 1 of the contribution.

Géocodage d'établissements scolaires over 5 years ago

Voici une requête Overpass qui permet d’interroger OSM simplement. Umap permet également des requêtes dynamiques vers Overpass. http://overpass-turbo.eu/s/sg7

Travail de sabotage over 5 years ago

Bonjour, j’ai utilisé la section commentaire du changeset pour inviter le contributeur à modifier ou venir en discuter sur talk-ca.

À noter qu’il est important de nous respecter entre contributeurs et penser que les uns et les autres sont de bonne foi. À éviter, les superlatifs ! Le diary n’est pas consulté par tous. Il est plus efficace de communiquer avec le contributeur via la section commentaire du changeset et présenter le problème à la communauté OSM soit sur le groupe de discussion talk-ca ou le groupe de discussion de Montréal.

Cordialement

Analysis Walk-thru: How many contributors are editing in each Country? over 5 years ago

A recent blog did show that 50% of the Canada population only occupy 2% of the territory. To take account of large territories like Canada, where there is almost no poputation in the nordic parts, a good comparizon would be the contributors per city area in the main cities.

Preparing accurate history and caching changesets almost 6 years ago

I talk about developping scripts to analyze the data. If we could obtain this data as geojson outputs, it would be great.

Preparing accurate history and caching changesets almost 6 years ago

Great geohacker.

To monitor an area, we need to query for the changesets for a given BBOX and datetime period. We cannot rely on the OSM API to provide the list of changesetid since the Api service limits the no. of changesets to query. And Overpass do not provide this facility.

Do you plan to provide such service? This would let develop tools without first installing a server and loading all OSM data.