[Tagging] [OSM-talk-be] cadastral plan now open data

André Pirard A.Pirard.Papou at gmail.com
Fri Sep 21 23:18:33 UTC 2018

On 2018-09-21 23:22, Martin Koppenhoefer wrote:
> sent from a phone
> On 21. Sep 2018, at 21:32, André Pirard <A.Pirard.Papou at gmail.com 
> <mailto:A.Pirard.Papou at gmail.com>> wrote:
>> The whole cadastral map is offset by that 7m.
>> ...
>> *Picture 3:* So, I dragged his parcel right onto the wall.
>> And now it's correctly located, aligned with the fencing all around.
> how did you know which source was off, the cadastral map or the 
> orthophoto?
The ortophoto is guaranteed with a 20 cm precision all over Wallonia.
On the other hand, all aerial photos cannot be off by the same 7m could 
On the first foot, juxtaposing precisely measured parcels produces huge 
errors that vary all over a village.
I just can't figure.
I did not check if this occurs at gaps when crossing roads or what.
I'm not working for the Cadastre. I pay them ;-)

In Beijing, it was Google Maps that moved.
Satellites (several if I recall) were showing OSM in the right place.

All the best,


>> ...
>> The Belgian cadastre is not the only one with an error shift.
>> With JOSM, I have similarly proved that Google Map has a 120m NE 
>> shift in Beijing.
>> Nobody noticed it.
> it is well known that the chinese government requires all imagery and 
> map providers to use chinese algorithms which distort the map 
> coordinates systematically, in a way that they remain usable as long 
> as your navigation system uses the same algorithms.
> Ciao, Martin
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