[OSM-talk] Google Maps comparison

[Andy Robinson]

Richard George wrote:
>Sent: 11 October 2007 10:58 AM
>To: talk at openstreetmap.org
>Subject: Re: [OSM-talk] Google Maps comparison
>
>Andy Robinson wrote:
>> That's really, really nice work. I was quite struck by the sheer number
>of
>> differences. I've seen plenty in my area but as yet haven't looked
>closely
>> enough to see just how many. Your results suggesting 9 per square
>kilometre
>> of urban area would make an astounding number for the whole country if it
>> ramps linearly.
>>
>> As Cory has suggested, we need to make more of these findings..... I
>feel a
>> blog coming on.
>
>Not to knock Dair's work, which is stunning, but I'd be wary about
>announcing too many errors without some specific proof, lest it be seen
>as crying wolf.
>
>The "All of the above" error maps
>(http://geo.topf.org/comparison/index.html?mt0=googlehybrid&mt1=tah&lon=-
>0.0968009&lat=50.9913397&z=17)
>appears to show some errors with both data sets:
>
>Google's routing of that part of Colwell Gardens that crosses Hospital
>Villas is clearly off by their satellite data; OSM gets this right.
>Google's vectors also overshoot the end of the shown roads in numerous
>locations.
>
>The routing and naming of that road are somewhat dubious on OSM.
>http://www.google.com/search?hl=en&q=%22colwell+gardens%22+haywards+heath
>suggests that this name/street exists. A similar search for '"Wellswood
>Road", Haywards Heath' comes up effectively blank.
>
>For this street to have the route now shown, a number of houses would
>have to have been demolished since the aerial photo was taken; this is
>possible but seems unlikely. The 'cap' roads shown in OSM are also
>something of a conjecture - one can be seen to exist on the satellite
>data but the other is a bit of a stretch.
>
>This road, to be honest, looks like an OSM easter egg.

I'll wait for Dair to reply but I suspect your first possibility is more
likely. I have a number of examples of older property being knocked down to
make way for modern squeezed in housing/apartment developments and on the
whole these do not turn up on the generally rather old aerial imagery /
commercial map data yet.

Cheers

Andy

Andy Robinson
Andy_J_Robinson at blueyonder.co.uk