[OSM-talk] Google Maps comparison

David Earl david at frankieandshadow.com
Thu Oct 11 11:20:28 BST 2007


On 11/10/2007 10:58, Richard George wrote:
> 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.

Indeed. I have found numerous OSM errors while connecting to existing 
mapping in my area, and made many myself - obviously I've corrected the 
ones I have discovered. Often these are things like where a street name 
changes along its length, the second name is missing or the change is in 
the wrong place; but also place names - I corrected someone's Gamblingay 
to the correct Gamlingay (in two different contexts) earlier this week 
(don't mean to point fingers, I've made errors like this too).

Of course the biggest OSM error is that lots of streets are missing 
altogether. Often this is obvious because there's just a skeleton, but 
sometimes people have mapped 2/3 of streets spread evenly in a village 
(i.e. not the west half of the village, say, but an apparently random 
distribution which makes it look plausible).

So long as we can't say in some way that we believe this is a complete 
area, I don't think it makes sense to talk about errors.

David




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