[Tilesathome] Tackling the Z12 tile enclosed by landuse issue

[Frederik Ramm]

Hi,

> 1. Use a relation type=enclosed to connect any node or way within   
> the tile (role=within) to the enclosing landuse (role=enclosing).  
> Change the data download to download the enclosing landuse whenever  
> the enclosed relation is downloaded.
>
> Pros: Simple, easy to implement. Good for smaller enclosing areas.  
> Can be maintained using JOSM
> Cons: Will be clumsy for large enclosing forests.

Too clumsy IMHO.

> 2. Expand the current oceantiles process from just water/land to  
> include other landuse types using other colors as needed.
>
> Pros: Easier to maintain (for people who can cope with png2tileinfo)
> Cons: Hard to maintain (for people who cannot cope with  
> png2tileinfo). More work to implement.

Almost there ;-)

I suggested something similar when I came up with the close-areas  
script, but not using an extra png file; instead, I suggested  
creating a "hint node" somewhere within the level-12 tile area,  
tagged something like

close-areas:hint_key=natural
close-areas:hint_value=wood

It would be relatively easy for the close-areas script to detect  
whether any such hint node was on the tile, and if so, assume the  
whole area to be natural=wood.

Pros: Can be maintained using JOSM, can be easily set up for any type  
of area
Cons: slightly hackish as it introduces render-specific stuff in the  
database

I am still very fond of this idea and think it is superior to the two  
choices you have offered. Someone else has suggested an improvement  
over this by using a relation:

http://wiki.openstreetmap.org/index.php/Relations/Proposed/Hint

That way, you would not have to tag the hint node with the kind of  
area, as the connection is made through the relation. This is more  
elegant, but it would require close-areas.pl to evaluate the  
type=hint relations and download the area with an extra request.

As for 80n's suggestion to use the OsmXAPI for this by downloading a  
larger area: I don't like the idea because you would have to hard- 
code which types of areas you area interested in (mostly natural= and  
landuse=, but who knows), and you would have to guess the size of the  
download bounding box (double the size of largest lake in Canada...?)  
and even though the OsmXAPI might be zappy I don't think we should  
needlessly waste resources (it's also the t at h renderer's bandwitdh we  
are talking about).

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00.09' E008°23.33'