In San Francisco the building layer is really nice and complete. But in most of the other cities i’ve looked at around the world it seems very patchy.
Is there a way to get a ranking of cities by building layer completion?
Thank you! OSM Love!
How are you going to know how many buildings are there?
good question :). well, maybe I should refine my question to: have there been any recent studies to assess building layer completion globally? (i.e. maybe confirming visually with satellite imagery)
Well, considering the Netherlands is one of a few countries that has both had an import of official government cadastral building data, and a reasonably well established process for updating also based again on official cadastral records, I think the building data in the Netherlands is among the most complete.
There are of course other countries that have had full cadastral imports, like e.g. France, but I don’t know if they have a similar “updating” process as well.
So, as to the specific small case of countries having had (full) cadastral building imports, asking the question when this happened, and if there are established processes for updating, should give you an assessment of completion and currency.
Of course, this is only a fraction of the total number of countries…
Estonia had some semi-automated import of buildings and its addresses from official sources a year ago.
It depends on what you mean by “complete”, I think. The statement “here is a building” doesn’t tell you much, but the questions “what is in this building” and “if there is an earthquake, will it fall down” are far more relevant.
For example, large areas of the world have had “buildings and nothing else” added remotely. From that you could probably get statistics about number of buildings per square km for a given size, and you might be able to infer something about population, but it’d be a bit of a stretch to do anything else useful with that data.
If you wanted to know how much useful data there is you’d probably ignore building tags and look at the other data in OSM.
Thank you all very much for your help! Netherlands, France, Estonia - building layers are really nice and complete.
A small fraction is fine, but i’d like to get as many as possible. I’m searching for more. This page has a list of all large imports to OSM: http://wiki.openstreetmap.org/wiki/Import/Catalogue. I’m going through it
If anyone knows of any other countries who have done mass imports like the 3 above, do let me know!