[OSM-talk] Map search accuracy

Tom Hughes tom at compton.nu
Thu Dec 20 14:55:55 GMT 2007


In message <1198161611.5262.96.camel at tomchancepc.BIOREG.LOCAL>
        Tom Chance <tom at acrewoods.net> wrote:

> I've noticed that searching for small features exposes a slight
> inaccuracy with the placement of the red arrow. For example, searching
> for "Edgecombe House" and then zooming in twice shows this:
>
> http://www.openstreetmap.org/?lat=51.470354&lon=-0.085346&zoom=18&layers=B0T
>
> Which is not exactly far off, but then it is pointing at the wrong
> building so if you followed the arrow at the default zoom level from the
> search link (which doesn't show building names to help you spot the
> mistake) you'd end up in the wrong place!

Well the first thing you need to do is to work out what part of
the tool chain is at fault - are those the correct coordinates
or not is the first question?

If they are then the problem is either with OpenLayers or with our
lat/lon to mercator projection code or the tiles are not projected
right.

If the coordinates are wrong then it is probably an issue with
the Namefinder - I'm not sure how it decides what coords to return
for a polygon like that.

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/




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