[Talk-GB] [OSM-talk] London party maps

Dave osm.list at randomjunk.co.uk
Thu Jan 25 10:22:49 GMT 2007


On 1/25/07, Robert (Jamie) Munro <rjmunro at arjam.net> wrote:
>
> OJW wrote:
> > "Each sector will have a map of the existing OSM coverage, and an
> > out-of-copyright street map to help with street naming, and a printout
> of the
> > Yahoo imagery overlain with the existing data (see illustrations)."
> >
> > Sector 1b seems to already have this on the wiki. But are old maps and
> outline
> > osmarenders available for the other zones?  I'm meeting some people who
> don't
> > want to faff visiting Fleet Street to pick up maps, just get out
> exploring a
> > different part of London without the delay, so can we have some more
> outline
> > maps available they can print before arriving.
> >
> > Has any aerial-photo tracing been done in advance to put correct street
> > positions on the blank maps, or are people expected to do that
> afterwards and
> > correlate it with their notes?
> I've been doing lots of photo tracing with the applet in the area
> bounded by Park lane, Oxford Street, Regent's street and Picadilly.
>
> Because of shadows and trees, I'm not sure everything I've marked is
> really a road, or if I've got every road, so we'd need to walk the
> streets to double check everything and get the road names. We could
> possibly compare to an old map and then only walk to places that don't
> seem to match up.


I have a pile of printed sheets containing the aerial photos and the
osmarendered outlines (without street names) that I'm bringing along to
fleet street. They're big enough to draw and write on which means you don't
have to do correlation after, or guess about whether a shadow is a street or
not before hand.
I can tell you from this overlay that there is no part of central London
where the map is "complete" even street wise, except a small part of the
City which I've done myself recently using the aerial photos.

I have the png's at home which I can make available tonight if anybody
really wants to print their own, but coordination is really important so as
not to ruin someone's day! The sheets don't quite match up with the sectors
because the sectors are weird shapes and bits of paper all the same size are
rectangular... but I don't really see a problem here.

Presegmenting on the applet can actually do more harm than good, given the
large numbers of roads that get marked but aren't there, the roads that are
one way but you don't know which way the segments go, having to pick out
segments that form a way and were defined in opposite directions etc. At
least the applet now has an insert node function, cos before that
presegmenting made things almost impossible as you couldn't properly add
roads that weren't marked but attached to something that was.

Should be fun.

Dave
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