[OSM-talk] mapnik tile rendering - again

[David Earl]

I'm still puzzled by what causes Mapnik tiles to be rerendered. And I think
there is a rendering bug with highway=secondary at zoom level 11...

One of you said looking at an area makes it a candidate for re-rendering. Is
this is the slippy map at www.openstreetmap.org/index.html or elsewhere or
anywhere? And does it then apply to higher zoom levels, or for a tile to be
rerendered does it have to be viewed at every single zoom level?

I ask because the areas I was originally puzzled about in Osmarender (which
I think I now understand) have now been partly done in mapnik. But the
rendering is extremely patchy. Do I have to touch every single tile at every
single zoom level to make the Mapnik slippy map up to date? [of course, my
browsing to look at this lot may have caused some rerendering, we'll see...)

Consider:
http://www.openstreetmap.org/index.html?lat=52.25212815167521&lon=0.03408109
539150302&zoom=13

As far as I can see, this area is completely rendered from the data I
uploaded. But zoom in one level and at least the central tile is out of
date - the more westerly tile is up to date though. At 15 hardly anything
has been rendered.

Similarly zoom out. At level 12 we're still OK, but at 11 the secondary
highway between Bar Hill and Longstanton has vanished, even though the two
villages which were done at the same time are both there. Particularly
puzzling is why the part of the secondary road which forms a western bypass
to Longstanton doesn't show up on the map, when the roads connecting to it
do, so they are in the same tile. Is this a rendering bug rather than a tile
refresh issue? The secondary road which runs from Cambridge northwards
through and beyond Histon is also missing, so maybe highway=secondary is not
rendered at zoom=11 but it is there at zoom=12.

By the way, I think it would be helpful if highway=cycleway were rendered at
zoom=13. As you'll see at zoom=14 from the above examples, several villages
are linked by cycle tracks, but in the overview you get at 13 it is
invisible.