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:st...@nexusuk.org sip:st...@nexusuk.org http://www.nexusuk.org/ Servatis a periculum, servatis a maleficum - Whisper, Evanescence _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk