[Tilesathome] Lowzoom Place Labels displaced

[Sebastian Spaeth]

Frederik Ramm wrote:
> Hi,
> 
>     I have somehow lost overview over the lowzoom process. A user has 
> reported displaced placenames on t at h z11 to me:

Shame on you :-)

> http://informationfreeway.org/?lat=50.47202017317468&lon=7.795465134494669&zoom=11&layers=B000F000F 
> The label offset is about 10km north(-east-ish) in the whole area.
> 
> Is this still normal behaviour (I know we used to have projection 
> issues), or should this have been fixed in the mean time?

This is still the case. The lower zoom, the worse. That is why I turned 
of lowzoom captions on z0-6 again. Continent captions, country captions 
were far (extremely far) out of place. I think the place where Oslo is 
located was labeled "Italy" :-).

Fixing this to use proper projection and have labels be displayed 
correctly would be awsome. Basically, it would use the correct "Project" 
functions in 2-3 places in orp (as the patch you forwarded me once did), 
   right? bobkare was interested to do the same in XSLT (apparently they 
have cos/sin emulation now), which would make us use proper projection 
which would be good anyway. Frederik, do you think you (or somebody 
else) could have a go at that?

I'd love to being able to reintroduce labels in lowzoom.

> Also, the same user reported some white squares on zoom levels 11 and 
> smaller, which seem to be lowzoom artifacts. Can I tell him to just go 
> to z8 on informationfreeway and hit "r", or what is the current 
> established procedure to either update a lowzoom tile yourself or 
> request that someone else do it?

No, they are autogenerated, and there is no way to request a lowzoom 
rendering. I have seen the while squares (empty land) too in current 
stable t at h clients.

2 1/2 reasons:

- There is a bug (that I won't be able to look into) that makes 
"captionless" create one empty land tile, even if the OSM file contains 
loads of stuff. This is even with stable t at h clients. I have not looked 
deeply into this.
Someone should examine this. I tried e.g.
./tilesGen.pl --Debug=1 --Layers=captionless xy 2208 1376

- I am deleting old legacy tiles and for areas where no new captionless 
has been produced yet, it will be replaced by whatever oceantiles.dat 
tells us (empty land usually)

- There is also one bug on the server side (in addition) that somehow 
seems to create an "unknown" lowzoom tile if underlying captionless 
tiles are not existing. It should fall back to oceantiles.dat 
information in these cases and I will look into that next week.

HTH