--- On Thu, 11/6/09, Ben Kelley <ben.kel...@gmail.com> wrote:
> To use the river/streams example from above, I'd
> say that if you have the chance to _accurately_ trace a
> waterway, it might be worth doing before most of the things.
> Other people who come along later will be able to get the
> roads, but they may not have a boat to go down the river
> on.
>
>
>
> Tracing most waterways accurately when all you have is
> Landsat is pretty difficult IMHO. Fortunately a lot of
> waterways form boundaries for town/suburbs, so some of the
> ABS data traces waterways.
I've traced a number of water ways, mostly from yahoo sat imagery and ABS
boundaries, that flow into the Darling river system, someone else had already
done the Darline from Bourke to the Murray, but not much apart from a few
rivers skirting towns had been done otherwise.
The ABS data and yahoo sat images don't always line up, not sure if it's a
datum issue, an alignment issue or what but they deff seem to be out some what
most of the time, but not by more than 20-50m.
It's not hard to see most water ways on sat imagery, even at the low res yahoo
graciously provides, but the ABS boundaries usually add a lot more points and
make water ways look more like rivers etc.
I personally don't think it would be very practical to try and do river ways
unless you kayak, or you know people kayaking, up and down rivers you are
unlikely to get very much data that would be any more useful, since the
distances rivers go, especially west of the great dividing range literally go
for 1000s of km. If that's not bad enough, a lot of it goes between or through
properties so you'd have issues with accessing it by anything but
boat/kayak/canoe etc.
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