The data contains addresses and buildings (outline, building started date, and an identifier to make updates easier). This means we removed all existing buildings and addresses in the country, which felt really risky, but because the import was done manually and only tool-assisted, it seems we managed to get it right. Took a few months, but once enough volunteers hopped on, it went quite fast. If I remember correctly, once you got the hang of it (your third import or so), an average municipality took about 2 hours (we have 350 municipalities).
For the Dutch speakers among us, more info about the project can be found here: https://wiki.openstreetmap.org/wiki/NL:BAG
I am not sure where Mapbox' height data comes from. In OSM, you can give a "levels" tag to indicate how many levels a building has (from which the height can be estimated), or a height tag in meters if it is known, but the buildings don't have that. Perhaps it is just assumed that large buildings are a bit taller and building=house is an average house height unless otherwise noted? Or maybe they use the Dutch AHN, which is a very accurate height scan of the Netherlands. Some people made it into a 3d picture, e.g. https://snipboard.io/Sq6C38.jpg (this only uses AHN data, not OSM, so it only has the tops of objects as points, but that's still quite an accurate outline).
(Disclaimer: some of the images, and especially the code formatting, don’t seem to have survived very well)
I wrote there a bit more about the data processing side of this, and I tried to make a compelling mobile visualization that was fast. I’d use it a lot for demo and pitch-type meetings, and especially with an HDMI connector direct from iPhone to a 50, 60 or 70” display, the frame rate and fluidity was super impressive.
To this day, I just plain love the tech that we built.
Much more precise data is also also available: there are height maps of NL with a resolution of 5 points per square meter, IIRC (not my field). Eg , but perhaps more parties do similar work.
And as mentioned elsewhere, they indeed misrepresent renovations & construction work as building dates.
If you spot errors, contact your local municipality, since they provide this data to the central registry.
I'm not going to correct it, because it doesn't matter.
It does matter (although it is possible you simply don't care). This data is used for a lot of purposes, which may include the calculation of your house's estimated worth for taxation.
Most municipalities do appreciate the feedback via https://bagviewer.kadaster.nl. A more accurate public dataset benefits society as a whole.
Strange thing is, they're inconsistent about it. De 1914 building De Vereeniging is listed as 1914 even though they've at the very least added a large conservatory to it since as well as a humongous - and very ugly and cheap looking - backstage area (though that was only this year, so maybe that hasn't ended up in the data set yet).
Oh well ...
(I am not related to the project above, just in case.)
It feels similar to me to OSMand+ (an open alternative to the very laggy Google Maps).
There seems to be a free software alternative for OsmAnd+ called OsmAnd~ by the way:
The non-premium version called OsmAnd seems to be FOSS too.
Here's the St. Lawrence church from the first picture of the article: https://parallel.co.uk/netherlands/#15/51.92139/4.485/0/40
It is possible to provide feedback there; your local municipality will look into any feedback provided.