On Tue, 13 Apr 2010, Andrew Errington wrote:
> My GPS accuracy (reported
> by the device itself) is at best 4m, but in mountainous regions or in cities
> it is 5m or 6m at best, often worse. How accurate is my mouse when I click
> on a pixel? Visually I am interpolating the (inaccurate) GPS trace to get a
> smooth, pleasing curve or shape. Although we strive for accuracy you have to
> remember we are not surveying, we are making a map; there is a difference.
Well yes, but the SRTM DEM has 90 metre pixels. If you're using the data
that has been processed into contour lines then that is going to be a
whole lot worse even before you start taking into account stuff like void
filling and contour smoothing. Like it or not, tracing SRTM contours is
probably going to leave you a couple of orders of magnitude away from GPS
accuracy.
--
- Steve
xmpp:[email protected] sip:[email protected] http://www.nexusuk.org/
Servatis a periculum, servatis a maleficum - Whisper, Evanescence
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