Re: [OSM-talk] Multiple errors in the same location

[Paul Norman]

On 2018-11-21 2:29 PM, Jem wrote:

> It is a CanVec import from 4 years ago

Is there subtext to this? I saw the weird natural=wood CanVec features 
yesterday (polys cut up into quadtrees) and wondered about its 
validity. Is the CanVec import notable for being problematic?


Yes. CanVec is built from multiple sources, so there can be different 
issues in different regions. The issues here with overlapping forest and 
water geometries and overlapping data with existing data are common to 
many CanVec imports. Four years ago is recent enough that the user 
should have known that they needed to fix these problems. Where I live 
there are problems like some data being 40-50 years old.


From a practical side, when fixing an area, my first step is generally 
to delete any data bears no resemblance to reality. In this case, if I 
wanted to fix just around this lake I would do it by


1. deleting whichever of the water traces is worse;
2. getting any obvious water improvements;
3. deleting the forest inner way; and
4. adding the water as an inner to the forest multipolygon relation.

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Re: [OSM-talk] Multiple errors in the same location

[Mateusz Konieczny]

AFAIK yes. See for example http://blog.imagico.de/openstreetmap-at-its-worst 


21. Nov 2018 23:29 by jem.maw...@gmail.com :


> Is the CanVec import notable for being problematic?___
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Re: [OSM-talk] Multiple errors in the same location

[Mateusz Konieczny]

22. Nov 2018 03:06 by pierz...@yahoo.fr :


> There were some imports made, duplicates created trying to follow OSM rules, 
> a lot of ctirics and tensions, and less and less contributors ready to edit 
> in these areas.




Can you can give examples of duplicates created "trying to follow OSM rules" 
rather than created

by runaway imports discouraging editors?




I tried to edit once or twice in Canada, but before doing anything at all it 
was necessary to delete

massive amounts of low-quality data imported without consultation.




See http://blog.imagico.de/openstreetmap-at-its-worst 
 for more detailed 
exploration

what went wrong.

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Re: [OSM-talk] Multiple errors in the same location

[Pierre Béland]

Hi Sandor
Let me present the more general context. To represent forestry and lake areas 
of northern countries such as Canada,  Russia, Scandinavia, etc. is more 
complex then it seems. These northern territories are covered by millions of 
lakes surrounded by forests, have islands, with sometimes again small lakes 
inner these islands. There were some imports made, duplicates created trying to 
follow OSM rules, a lot of ctirics and tensions, and less and less contributors 
ready to edit in these areas.

To see the complexity of some relations, look at the relation for Pipmuacan 
Resevoir https://www.openstreetmap.org/relation/381076 where there are 601 ways 
with inner role and 64 ways with outer role. My portable computer memory is 
often stressed trying to update such relaions with JOSM. Notice also that the 
surrouding forest around the reservoir is not yet defined. 

This make me think, Can we find such complex relations in West Europe urban or 
rural areas? And could we reduce the complexity, the burden for mappers that 
contribute to OSM?

It seems that the major problem we are faced with is that rendering sofwares 
need to determine where they apply wood texture and that the developpers try to 
reduce the time to compute the information to represent adequately such areas. 
There were strict rules implemented recently to enforce Mutlipolygon relations.

To follow these rules represents a lot of  burden for small communities (67 
contributors per day in Canada, 504 in Germany).  

I understand that developpers are also limited. But still, we should ask if the 
expectations about the OSM contributors are always realistic enough. 

You want answers how to map. I suggest that the community should look at 
solutions to reduce the burden of mappers. If we could progress in the 
discussion between contributors and developpers and try to look at other 
solutions to map northern territories, I think that this would be fantastic.
It would be interesting to look if some of the burden could be transferred to 
softwares developpers with the objective to reduce the database size, and 
increase coherence and quality.    For northern forest territories, if a 
polygon did trace forests outer limits, could for example softwares establish 
the lakes, natural features, landuse areas, airports, etc which are inner the 
forest and should not be rendered with the forest style ? 

Establish the polygons inside a polgyon and render them after this polygon ? 
Any other solutiojn?
Pierre 
 

Le mercredi 21 novembre 2018 04 h 24 min 20 s HNE, sandor 
 a écrit :  
 
 
Mateusz, this was really a quick and simple answer, probably made on reading 
the title only.

The issue is much more complicated than you can imagine. You could really help 
me (and the original mapper) if you describe your suggestion how to resolve the 
lake and the hole mismatch in the case from the link. More precisely, assume 
the other mentioned problems are resolved but the (newer) lake – hole in forest 
fitting problem. So, how to move/transform these two objects to fit together? 
Further, how to do the same for really large number of cases where a manual 
procedure by me or “wait until it is done by someone else” is, for many 
reasons, unrealistic. Thanks.

  

Sent from Mail for Windows 10

  

From: Mateusz Konieczny
Sent: søndag 18. november 2018 21:12
Cc: talk@openstreetmap.org
Subject: Re: [OSM-talk] Multiple errors in the same location

  

16. Nov 2018 17:06 by sandor...@gmail.com:


When multiple errors appear in the same location the question is what to do?


  

The same as with a single error - fix the problem (how it should be done 
depends on situation) or

  

wait until it is done by someone else.

  
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Re: [OSM-talk] Multiple errors in the same location

[Jem]

> It is a CanVec import from 4 years ago

Is there subtext to this? I saw the weird natural=wood CanVec features
yesterday (polys cut up into quadtrees) and wondered about its validity. Is
the CanVec import notable for being problematic?

On Wed, 21 Nov 2018 at 19:16, sandor  wrote:

> Mateusz, this was really a quick and simple answer, probably made on
> reading the title only.
>
> The issue is much more complicated than you can imagine. You could really
> help me (and the original mapper) if you describe your suggestion how to
> resolve the lake and the hole mismatch in the case from the link. More
> precisely, assume the other mentioned problems are resolved but the (newer)
> lake – hole in forest fitting problem. So, how to move/transform these two
> objects to fit together? Further, how to do the same for really large
> number of cases where a manual procedure by me or “wait until it is done by
> someone else” is, for many reasons, unrealistic. Thanks.
>
>
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
>
>
> *From: *Mateusz Konieczny 
> *Sent: *søndag 18. november 2018 21:12
> *Cc: *talk@openstreetmap.org
> *Subject: *Re: [OSM-talk] Multiple errors in the same location
>
>
>
> 16. Nov 2018 17:06 by sandor...@gmail.com:
>
> When multiple errors appear in the same location the question is what to
> do?
>
>
>
> The same as with a single error - fix the problem (how it should be done
> depends on situation) or
>
>
>
> wait until it is done by someone else.
>
>
> ___
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> talk@openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk
>
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Re: [OSM-talk] Multiple errors in the same location

[sandor]

Mateusz, this was really a quick and simple answer, probably made on reading 
the title only.
The issue is much more complicated than you can imagine. You could really help 
me (and the original mapper) if you describe your suggestion how to resolve the 
lake and the hole mismatch in the case from the link. More precisely, assume 
the other mentioned problems are resolved but the (newer) lake – hole in forest 
fitting problem. So, how to move/transform these two objects to fit together? 
Further, how to do the same for really large number of cases where a manual 
procedure by me or “wait until it is done by someone else” is, for many 
reasons, unrealistic. Thanks.

Sent from Mail for Windows 10

From: Mateusz Konieczny
Sent: søndag 18. november 2018 21:12
Cc: talk@openstreetmap.org
Subject: Re: [OSM-talk] Multiple errors in the same location

16. Nov 2018 17:06 by sandor...@gmail.com:
When multiple errors appear in the same location the question is what to do?

The same as with a single error - fix the problem (how it should be done 
depends on situation) or

wait until it is done by someone else.

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Re: [OSM-talk] Multiple errors in the same location

[Mateusz Konieczny]

16. Nov 2018 17:06 by sandor...@gmail.com :


>
> When multiple errors appear in the same location the question is what to do?
>




The same as with a single error - fix the problem (how it should be done 
depends on situation) or




wait until it is done by someone else.

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Re: [OSM-talk] Multiple errors in the same location

[Nelson A. de Oliveira]

On Fri, Nov 16, 2018 at 3:13 PM James  wrote:
> could be many things:
> 1. CanVec import without corrections to todays standards
> 2. Old CanVec version1 imports(was pretty bad)
> 3. Someone added data that was already there

It is a CanVec import from 4 years ago:
https://www.openstreetmap.org/changeset/23092008

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Re: [OSM-talk] Multiple errors in the same location

[James]

could be many things:
1. CanVec import without corrections to todays standards
2. Old CanVec version1 imports(was pretty bad)
3. Someone added data that was already there

On Fri., Nov. 16, 2018, 11:57 a.m. Nelson A. de Oliveira  On Fri, Nov 16, 2018 at 2:08 PM SandorS  wrote:
> > A careful analyses shows that there are several serious errors in this
> location. Let us mention some.
>
> What you are seeing is a side effect of badly/blindly importing data
> and possibly without a proper discussion.
>
> OSM already had https://www.openstreetmap.org/way/28420555
> The user who did import the overlapping data should have seen this.
>
> The user needs to be contacted, as it seems that he is still importing
> data.
>
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Re: [OSM-talk] Multiple errors in the same location

[Nelson A. de Oliveira]

On Fri, Nov 16, 2018 at 2:08 PM SandorS  wrote:
> A careful analyses shows that there are several serious errors in this 
> location. Let us mention some.

What you are seeing is a side effect of badly/blindly importing data
and possibly without a proper discussion.

OSM already had https://www.openstreetmap.org/way/28420555
The user who did import the overlapping data should have seen this.

The user needs to be contacted, as it seems that he is still importing data.

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[OSM-talk] Multiple errors in the same location

[SandorS]

When multiple errors appear in the same location the question is what to do? 
The simplest option is, nothing. Wait until a mapper is correcting all the 
related errors. 
Most of the detectors, inspectors, renderers, data preparation tools… select 
this option today. Consequently, all publicly available maps repeat the same 
errors what is, of course, wrong. 
Let us take an illustrative example here https://osm.org/go/cCcWZjGW . 
A careful analyses shows that there are several serious errors in this 
location. Let us mention some.
1.There are two radically different partly overlapping lakes in the location.
2.None of the lakes are close to fit into the hole in the forest area.
3.The forest and any of the lakes overlap considerably.
4.The island in one of the lakes is just partly invisible (overwritten by the 
other lake).
5.The obsolete natural=land tag is used for several node objects in the lakes.
6.The place=islet tag is used for several nodes without the name tag and value 
(so, meaningless).
If there were just a few cases like described one could contact the 
corresponding mappers or just make a note description on the location. 
Unfortunately the number of cases like the illustrated is so large that neither 
of the mentioned source data correction models is feasible. Yet, it is worth to 
mention that some data preparation chains perfectly resolves this complex error 
issue in their GIS or map-making systems.
Sandor


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