[Talk-nz] Continuing the import of LINZ data into OSM

Alan Jamieson alwynwellington at gmail.com
Mon Sep 13 00:02:41 UTC 2021


Kyle, thank you for your considered response.

For rivers, based on my limited experience, I suggest:

for those that are not physically wide (say less than 2 metres) a single 
line be mapped

for wide waterways imports be a two step process:

     1) Map the river banks, particularly including the variable shingle 
banks.

     2) Where appropriate, introduce one or more lines to indicate the 
streams (braiding) between those banks. In real life the streams are 
likely to change their exact position over time and any any mapping 
should not be expected to show the exact number and position, rather the 
"complexity" of the subject river.


I appreciate this is slightly at variance with the various suggestions 
in "https://wiki.openstreetmap.org/wiki/Rivers".

It is offered as, for many of our rivers, water often shifts it position 
from one season to another. It my view our mapping should tend towards 
worst case and out of an abundance of caution to avoid possibly 
understating the dangers that our rivers can pose.

And, so the intrepid traveller, contemplating a foot crossing of the 
back country Tauherenikau or the near urban Te Awa Kairangi, has some 
warning of what lies ahead.


I note the "OSM tag called ref: ..." proposal.  I am not certain what is 
a contributor should do post import ex LINZ when a difference is noted.  
Should they remove the "OSM tag called ref: ... " as they edit away or ... ?



On Sat 11 Sep 21 13.50, Kyle Hensel wrote:
>
> Hi Alwyn,
>
> I agree that vegetation succession is a problem in OSM - I've seen 
> bush mapped as natural=scrub 10 years ago which has grown so much that 
> it should now be tagged as natural=wood.
>
> In terms of landuse and vegetation, only the tree-row layer remains to 
> be imported. All other landuse/vegetation layers are over 95% complete.
>
> The other remaining layers are mostly human-made features (like masts, 
> fences, quarries), and the big one: rivers.
>
> There is still an issue that some of this data will be out of date in 
> a few years time.
>
> To mitigate this, one thing we are doing differently this time is 
> adding an OSM tag called ref:linz:topo50_id to every imported feature.
>
> This tag contains the ID used by LINZ to identify that node or area.
>
> This will allow mappers in 5 or 10 years time to compare the data in 
> OSM with LINZ's data, to identify which features have been removed, 
> edited, or recently added.
>
> We know it’s possible to efficiently compare LINZ and OSM’s data using 
> the ref:linz:topo50_id tag beacuse we already do this monthly for 
> street addresses.
>
> I hope this will prevent the issue you described from occurring with 
> these new layers.
>
> Let me know if you’ve got questions
>
> Kyle
>
> *From: *Alan Jamieson <mailto:alwynwellington at gmail.com>
> *Sent: *Friday, 10 September 2021 16:16
> *To: *talk-nz <mailto:talk-nz at openstreetmap.org>
> *Subject: *[Talk-nz] Continuing the import of LINZ data into OSM
>
> My limited experience is to note elements typically dated to 2012 or 
> earlier
>
> For items that refer to the natural environment, such a rivers and
> vegetation, I regulalry note recent aerial imagery has ''moved on'' from
> what was imported .
>
> With rivers the import might have included gravel banks. Typically these
> change their position each wet season.
>
> In my experience, vegetation, especially in places with little or no
> human activity, openings and scrub had become, or was tending to natural
> wood, or similar.  And many areas marked as ''managed forest'' tended to
> be pine plantations that had now passed their use by date (were not in
> fact managed).
>
> My suggestion is imports be only for the built environment.
>
> -- 
> nga mihi
>
> Alwyn
>
>
> _______________________________________________
> Talk-nz mailing list
> Talk-nz at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-nz 
> <https://lists.openstreetmap.org/listinfo/talk-nz>
>
-- 
nga mihi

Alwyn

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-nz/attachments/20210913/19f80cf7/attachment.htm>


More information about the Talk-nz mailing list