[OSM-talk] Overlapping & Crossing ways

[Richard Fairhurst]

Mark Williams wrote:

> I can't imagine this was done knowingly; I suspect that the redraw  
> was sufficiently slow that it looked unmapped to a less experienced  
> user, and allowed time to re-draw the ways before it showed up.
>
> Would it be possible to make it draw ways & nodes BEFORE the aerial  
> photography, so this can't happen is less likely?

Not sensibly, I'm afraid.

It's a server speed thing - basically it takes longer for our server  
to respond to "send me a way" than it does for a tile service to  
respond to "send me a tile" (fairly understandably - the effort  
required to look something up from the database is greater than that  
required to just send something from the filesystem). TBH I'm not  
sure the presence of aerial photography or otherwise is an issue; it  
can still be slow to load if you're in an area without any.

There's a few things that I think could help. One which I'm already  
planning is to have one of those little whirry "please wait, loading"  
carousels that OS X popularised a couple of years back and are now  
everywhere on the web, to make loading more visible. Potlatch could  
also theoretically say "loading n ways", though they all come down in  
one chunk, so this wouldn't update one-by-one as they arrive.

The second is for various parts of the site that invoke Potlatch to  
do so at a higher zoom level than they do at present - in particular,  
if you search for a placename, then click "Edit", it invokes Potlatch  
at z11. Loading such a large area is always going to take a lot of  
time, especially in an area like London where there's oodles of nodes  
and ways. It would be better, IMO, to do this at z13. There are  
people much more qualified to do the Rails changes for this than me,  
so patches very welcome. :)

(Should I also just disable z11 on Potlatch altogether? Thoughts  
welcome: personally I don't use it, but then I don't use the Yahoo  
imagery either.)

And the third thing is to put some magic juice in to speed up the  
server!


On a slightly related issue, I'll be interested to see how  
changesets, and the easier ability to monitor an area, affect this.  
0.6b went live on 15th January, 0.8a on 30th March, so these  
duplicated ways have been around there for a while: I'm slightly  
surprised that they hadn't been noticed before.

cheers
Richard