<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">André, i don't really see your point with the argument you made about cadastre data. i don't know of anybody looking to use this data to add building into OSM. It is outdated data regarding buildings and roads in a lot of different place in Belgium. And as, the people at cadastre are not the source for these data, they don't need to update it anymore ! Most people are only using the default imagery (they often don't know about anything else).</div><div dir="ltr"><div><br></div><div>When tracing buildings, we should always base our self on the PICC for Wallonia or Urbis for Brussels or GRB for Flanders and the relevant best imagery in each case (comparing them keeping in mind that vectorial data are not up to date everywhere at the same time). </div><div><br></div><div>To quote a report from the last PICC meeting in June, wallonia have the following idea on official source : </div><div><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class="gmail_quote">Wallonia is planning a “<b style="line-height:22.28px;margin:0px">georeferentiel</b>” (base of layers that are high accuracy and authentic source) within the application of INSPIRE.There are 4 major datasets that will be made as accurate as possible and with one authentic source for each:
<ul style="background-color:transparent;font-family:sans-serif;font-size:13.93px;font-variant-numeric:normal;font-variant-east-asian:normal;margin:4.18px 0px 0px 22.29px;padding:0px"><li style="margin-bottom:1.39px"><i style="list-style-type:disc;margin:0px;padding:0px">buildings</i> (in PICC),</li></ul><ul style="background-color:transparent;font-family:sans-serif;font-size:13.93px;font-variant-numeric:normal;font-variant-east-asian:normal;margin:4.18px 0px 0px 22.29px;padding:0px"><li style="margin-bottom:1.39px"><i style="list-style-type:disc;margin:0px;padding:0px">admin limits</i> (in cadastre),</li></ul><ul style="background-color:transparent;font-family:sans-serif;font-size:13.93px;font-variant-numeric:normal;font-variant-east-asian:normal;margin:4.18px 0px 0px 22.29px;padding:0px"><li style="margin-bottom:1.39px"><i style="list-style-type:disc;margin:0px;padding:0px">addresses</i> (in ICAR) and</li></ul><ul style="background-color:transparent;font-family:sans-serif;font-size:13.93px;font-variant-numeric:normal;font-variant-east-asian:normal;margin:4.18px 0px 0px 22.29px;padding:0px"><li style="margin-bottom:1.39px"><i style="list-style-type:disc;margin:0px;padding:0px">Roads</i> (in PICC/”direction des routes” collaboration with attributes (like primary, secondary, highway, bridge,…) on road, not only geometry).</li></ul></blockquote><span style="background-color:transparent;direction:ltr;font-family:sans-serif;font-size:13.93px;font-variant-numeric:normal;font-variant-east-asian:normal">
</span></div><div>from: <a href="https://wiki.openstreetmap.org/wiki/WikiProject_Belgium/Contacts_with_local_autorities/Wallonia/Compte_rendu_Rencontre_des_utilisateurs_du_PICC_Juin_2018">https://wiki.openstreetmap.org/wiki/WikiProject_Belgium/Contacts_with_local_autorities/Wallonia/Compte_rendu_Rencontre_des_utilisateurs_du_PICC_Juin_2018</a></div><div><br></div><div>So cadastre is really about admin. limits and parcels :</div><div>- For admin. limits i already talked about it before (as quoted, it is even the authentic source for all Belgium apparently), </div><div>- and for parcels, there is an open debate about adding this information to OSM (mainly because it is huge amount of work to maintain it) -> as discussed on the wiki page <a href="https://wiki.openstreetmap.org/wiki/Parcel">https://wiki.openstreetmap.org/wiki/Parcel</a> <br></div><div><br></div><div>So there is no ambiguity in what official data exist, the only problem is that ICAR for the addresses is not yet finished for all municipalities (and not complete in the PICC as far as i know ?! but i may be wrong about that) and more importantly, it is not open nor viewable except for special customers. So we still need to rely on tracing from the imagery and the PICC WMS at the moment (for buildings, roads and addresses) and now, the Cadastre data (or wms) to maybe update admin limits.</div><div>Note that these official data are considerably improving over time ! They are still outdated or imprecise in some place, but even then it is still the official source at the moment (so we should NOT copy blindly as you said, but compare with recent imagery and survey !!!). The plan is to make an update cycle closer to 1-2 years (for every municipalities) for the PICC, but they are still far from it (6.5 years of average update time).</div><div><br></div><div>Is there something i'm missing out in your explication ? If so tell me, i may not understand all your point ! </div><div><br></div></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">Le ven. 21 sept. 2018 à 23:23, Martin Koppenhoefer <<a href="mailto:dieterdreist@gmail.com" target="_blank">dieterdreist@gmail.com</a>> a écrit :<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><br><br><div id="m_2832488146347584755m_-2663258395573793586AppleMailSignature">sent from a phone</div><div><br>On 21. Sep 2018, at 21:32, André Pirard <<a href="mailto:A.Pirard.Papou@gmail.com" target="_blank">A.Pirard.Papou@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div align="left">The whole cadastral map is offset by that 7m.<br>...</div>
<br>
<div align="left"><b>Picture 3:</b> So, I dragged his parcel right
onto the wall.<br>
And now it's correctly located, aligned with the fencing all
around.</div></div></blockquote><div><br></div><div><br></div>how did you know which source was off, the cadastral map or the orthophoto?<div><br></div><div><br><blockquote type="cite"><div align="left">
</div>
<div align="left">...</div><div align="left">
<br>
The Belgian cadastre is not the only one with an error shift.<br>
With JOSM, I have similarly proved that Google Map has a 120m NE
shift in Beijing.<br>
Nobody noticed it. </div></blockquote><br></div><div><br></div><div>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.</div><div><br></div><div>Ciao, Martin </div></div>_______________________________________________<br>
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