On Tue, Mar 10, 2009 at 8:44 AM, Ed Avis <[email protected]> wrote: > Karl Newman <siliconfiend <at> gmail.com> writes: > > >>Are any of you aware of a conflation algorithm that "snaps" GPS tracks > >>to the street grid? This could be a useful way to verify existing > >>road networks and fill in any gaps. > > >To do that you'd ideally want to know the margin of error for the GPS > readings. > >My GPS unit (Garmin eTrex Vista HCx) shows an error circle on its screen > > >I have a Vista HCx, too. Bafflingly, Garmin does not store the DOP with > the > >tracklog and there is no way to extract it after the fact (or even > realtime, I > >don't think). > > Oh, that is disappointing. > > >If you can get an NMEA stream, you can get the HDOP (which is what you > care > >about for this application). The USB-only Garmin units (like the Vista > HCx) > >cannot emit a NMEA stream like the serial-enabled units could. > > Apparently the Windows program GpsGate can convert the output from the USB > Garmin devies to NMEA format. I wonder if there is a free equivalent to > get it > working with gpsd or similar on Linux? >
Well, GPSBabel is your cross-platform friend for translating between GPS data formats, but my impression is that the Garmin USB protocol does not contain DOP information. I would be happy if I were completely wrong on that point, though. Karl
_______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
