[Talk-ca] broken forests in eastern Canada

[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.

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.

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.

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".

dega