On Aug 14, 2009, at 1:58 PM, Andrew Leach wrote:
>
> On Aug 14, 11:17 am, Rossko <ros...@culzean.clara.co.uk> wrote:
>>
>> For the car application, the interest would be in the accuracy of  
>> road
>> placement, it doesn't matter at all if the coast is wrong.
>
> It may be worth noting that coastlines *can* be extremely accurate
> *if* that data exists. Have a look at 
> http://www.achurchnearyou.com/parishmap.php?pcode=10/386
> for example: the red line comes direct from Ordnance Survey data
> (correctly licensed!) which means the map coastline must have done
> too.
>
> I do agree though, that the coastline probably isn't of much interest
> to car drivers, so it's more likely to be an approximation than
> actually accurate.

In all fairness, though, the TeleAtlas data is sometimes just OFF to  
the point of being useless. For a great example of this, check out  
Sitka, AK on maps.google.com. Compare the optical data to the road  
data. From my own personal GPS readings, the optical data  
(DigitalGlobe, GeoEye, TerraMetrics) is spot on, whereas the road data  
(TeleAtlas) is off by about 400m (a quarter-mile!) At least in that  
area, when it comes to any sort of lat/lon analysis, even on the most  
minimal of levels, the TeleAtlas data is complete garbage. I imagine  
Sitka isn't unique in this "feature."

-G

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