[talk-au] GPS drive tracks are not accurate.

David Findlay david at davsoft.com.au
Fri Jun 6 00:19:58 BST 2008


> I got very keen and loaded lots of roads by tracing them off Yahoo maps,
> making sure the trace was an accurate reflection of reality. Then someone
> overwrote my plots with a GPS track that was the result of driving these
> roads once, with no understanding of the unavoidable inaccuracies in GPS
> tracks.
>
> The straight plot of what I knew was straight road was replaced by a wavy
> line. I gave up.

What about the copyright ramifications of tracing maps? I've done a lot of GPS 
tracks and through making multiple passes at various times I've found them 
very accurate. Frequently I've found real maps having curves that aren't 
there and the GPS is more accurate. It depends on the quality of the GPS fix 
and how many times you go over it, if it's just been done once, well chances 
are it's could be 10-25m out. 

David




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