[OSM-talk] Correcting coastlines

[Collinson Mike]

At 04:39 AM 23/08/2006, OJW wrote:
>p.s. how's Sydney harbour correlating with other data?

I went out today to collect some data and I'm seeing the PGS data 
shifted about 62 m to the north +/- 3 metres and possibly 5 metres 
west from exactly corresponding GPS track data.  The "good" news is 
that this consistent with other data collected on other days/devices 
and that position is not affected by tide.  The bad news is that we 
don't have SBAS or WAAS here so the accuracy of the GPS data is less 
than the figures I quote.

Time permitting, I'll see if the state library has a set of 
topographic maps that I can read off some values at more separated 
locations and compare.  I'd also like to check if there is any "to 
water" or "to land" bias in the data - the areas I've got data for 
are predominantly water to the north, so I can't really tell.

Mike
Oz