[Talk-ca] broken forests in eastern Canada

john whelan jwhelan0112 at gmail.com
Thu Sep 1 12:47:48 UTC 2016


It would appear that Michael has no appreciation of how we the local
community work or of how large Canada is nor does he appear to be able to
communicate with us and understand our concerns.

I suggest we formally request that he is prevented from making any changes
within Canada and his reversals be reverted.

The Canvec data was imported with the knowledge and support of the local
mappers and I think that's all that matters.

Cheerio John

On 1 September 2016 at 08:39, Michael Reichert <nakaner at gmx.net> wrote:

> Hi,
>
> Am 01.09.2016 um 01:21 schrieb dega:
> > On Aug 31, Daniel Bégin wrote:
> >> On the same topic, it has been suggested to split wooded areas in
> smaller
> >> chunks by using features on the ground as outer limits (mostly roads,
> >> streams, rivers) and get rid of arbitrary rectangles from Canvec.
> >> Is it something we are aiming at?
> >
> > The grid is an important source of problems. Here are some examples:
> > 1) If a lake is on the grid, it will be split in 2 parts. Each part will
> have
> > a name tag and and 2 identical names will be displayed on the map, one
> on each
> > part. This problem exist in thousands of lakes. I even saw a lake with a
> > triplicated name.
> > Merging the parts would require modifying 2 or more relations and many
> > importers don't do it (even if they use JOSM) because of the complexity.
> Some
> > have used a quick fix where they remove names from the parts and put it
> in a
> > POI. It looks fine but that's bad for database integrity.
>
> If someone does not merge two lakes because it is too "complex", he
> should evaluate if he is the right person to import such data. If an
> import contains much multipolygon relations, the people how import the
> data should know how they work, what can be done wrong, how to edit and
> how to fix them. :-/
>
> > 2) A addr:interp way may be split in 2 parts. 2 consequences:
> > - the interpolation way become useless because it's now 2 different
> objects.
> > - the mid-point becomes 2 superposed nodes. Useless duplication.
> >
> > 3) A grid tile has a fixed size. It may be appropriate for unpopulated
> areas
> > but it is too large for urban areas where editors work at a high zoom
> level
> > (17 and up). It's easy to damage a relation without knowing it.
> >
> > But there are other problems (not related to the grid):
> > 4) the relations seem to be designed to be stand-alone. Thus the relation
> > borders don't share a way. They use 2 superposed ways. Useless
> duplication.
> > It's very confusing and we frequently alter the wrong way.
> >
> > 5) lakes are represented by 2 superposed identical objects, one for the
> hole
> > and one for the lake. If the hole happen to be on top, the name will not
> be
> > displayed. It's an unjustifiable complexity for the casual user.
> > I've also seen triplicated contour (one for the lake, on for the inner
> role
> > and one for the outer role)
> >
> > Yes, all these quirks can be fixed manually but it's time-consuming and
> error-
> > prone.
>
> What about reverting the tiles which have all these issues and seem to
> be uploaded with too few checks beforehand, run a better version of the
> preprocessor on the CanVec raw data and reimport them again? (That
> causes a loss of OSM history but an import changeset is not as much
> valueable than a manual changeset)
>
> > Ideally, the contour of a forest must not split any object and it's not
> > possible with a grid.
> > The sole advantage of a grid IMHO is to simplify the CanVec exports.
>
> What about replacing the grid by less artificial borders, e.g. roads,
> rivers, powerlines etc. If an area has too few of theses objects,
> artifical borders could be automatically drawn which are optimized to
> cut as few objects as possible into two parts.
>
> > Some years ago I would have proposed that someone write a guide "How to
> fix a
> > CanVec import". But now I would rather propose that someone write a "How
> to
> > pre-process a CanVec export before importing it into OSM".
>
> +1
>
> All ongoing changesets which import CanVec data should either use an
> improved version of the preprocessor or should undergo the manual
> quality checks I described in my other emails and the changeset comments.
>
> Best regards
>
> Michael
>
>
> --
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>
>
>
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