[Talk-GB] tracing lakes with Potlatch

[Andy Robinson (blackadder-lists)]

Henry Gomersall wrote:
>Sent: 06 April 2010 5:39 PM
>To: Jason Cunningham
>Cc: talk-gb at openstreetmap.org
>Subject: Re: [Talk-GB] tracing lakes with Potlatch
>
>On Tue, 2010-04-06 at 17:26 +0100, Jason Cunningham wrote:
>> The detail for water is excellent and may be the most 'detailed'
>> vector data OS is going to provide. It's far better than the OSM
>> community could achieve with GPSr's and aerial image tracing.
>
>Do you know how OS do the water detail? I've often wondered how they
>manage to get such good detail of really tiny streams in the middle of
>nowhere, often obscured by trees.

They do have about 200 years head start ;-)

A lot of stuff nowadays is done from aerial imagery, but they can still drop
back to traditional surveying methods if required.

Cheers

Andy 


>
>Looking at the second link, there are islands in the stream that are
>marked on the map, but simply not visible on the aerial imagery. I
>suspect ground imaging radar would highlight water, but surely this has
>similar tree obscuring issues.
>
>cheers,
>
>Henry
>
>
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