[Tilesathome] Falling back to tile stitching

[Christopher Schmidt]

So, I've seen a lot of failed tiles at z8 showing up because of memory
limits. (An example is 120,84,8. I can dig up more if people are
interested.) Watching these on my 32bit machine, they both die at 2.8GB
of RAM used by Inkscape.

I've been taking these tiles and rendering them manually via the old
lowzoom stitching mechanism so that we don't end up with big gaps: the
results don't line up exactly, but I think it's way better than having
broken tiles all over the map. 

What do people think about having inkscape failures lead to a
lowzoom-stitching attempt? Should it be client-side (slower) or server
side (not really sure where it would kick in)? Perhaps I should write a
server side piece to go through and generate all the z8 tiles using
stitching if they are bigger than some certain cutoff of OSM data?  

Thoughts welcome, but I think we need to do something other than what we
are now (even if we ignore the fact that our render rate has dropped
drastically) ... 

Regards,
-- 
Christopher Schmidt
MetaCarta