[OSM-talk] Wood & Park mapnik carto anomaly?

[Dave F.]

On 17/09/2014 13:04, Martin Koppenhoefer wrote:
>
>
> 2014-09-17 10:43 GMT+02:00 Dave F. <davefox at madasafish.com 
> <mailto:davefox at madasafish.com>>:
>
>     On 16/09/2014 14:59, Martin Koppenhoefer wrote:
>>
>>     2014-09-16 15:32 GMT+02:00 Dave F. <davefox at madasafish.com
>>     <mailto:davefox at madasafish.com>>:
>>
>>         I find it surprising something as arbitrary as size is used
>>         as the defining factor. Comparing actual tags would surely
>>         make more sense.
>>
>>
>>
>>     well, size surely has some correlation with importance. For
>>     practical reasons it is generally working quite well to have
>>     first render the bigger stuff and then render the smaller stuff
>>     on top, because it leads typically to less covering.
>
>     This, IMO, is lazy rendering & should be discouraged. To allow the
>     smaller stuff to display is one of the reason mutli-polygons were
>     developed.
>
>
>
>
> no, multipolygons have nothing to do with this issue. Multipolygons 
> are there to cut holes into polygons or to build polygons from outer 
> ways which are also otherwise used. Here they would not serve at all, 
> as the park and the wood both occupy the same area (locally).

True, for this case, but I was talking in more general terms.

>     Refer also to the layer tag which is disappointingly under used by
>     renderers.
>
>
>
> yes, it is indeed underused, but it also has nothing to do with the 
> issue here, as both objects are on the same layer.

That's my point. If the layer tagged was implemented by more renderers 
it would encourage mappers to use it, solving my current problem.

>
>
>>     In this particular case more detailed mapping of the tree areas
>>     could solve it, e.g. split the wood object at the cutting roads
>>     and waterways, but admittedly in this case by looking at the bing
>>     aerial imagery it seems indeed to be a continuity of trees on
>>     both sides of these.
>
>     That's mapping incorrectly to suit the renderer &, for obvious
>     reasons, should be criticized.
>
>
>
> how would splitting an area be incorrect? It is just another 
> representation of the same. There are infinite correct ways to 
> representate the same object.

As an example: If it has a name you'd have two objects of that name, 
when in fact there's only one. If someone wanted to find out how many 
named wood there are in a city it would return inaccurate data.

>
> cheers,
> Martin



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