OpenStreetMap
AltitudeWRTSeaLevel vs. reality
ddoubrava erabiltzaileak 5 Uztaila 2009 datan argitaratua English hizkuntzanI realized that Altitude reported by (A)GPS device reports roughly 40 meters Alt near to sea level.
Tracks from the trim will be available later.
NOTE: I know that Geoid is just approximation.
Eztabaida
kaerast erabiltzailearen iruzkina 5 Uztaila 2009 11:47-eann
GPS is generally pretty terrible at altitudes, it just gives a very rough idea. Also, it'll be altitude above mean sea level not actual sea level where you are.
Skippern erabiltzailearen iruzkina 5 Uztaila 2009 16:33-eann
You can callibrate altitude in most advanced handheld units, but mark that Geoid altitude and reality differs around the planet, +/- 60 meter AFAIK.
Biogenesis_ erabiltzailearen iruzkina 6 Uztaila 2009 04:55-eann
Altitude calibration is for any hand held unit which has a barometric altimeter in it. Ie, one which estimates altitude based on changes in air pressure.
Garmin units which have the required hardware include the eTrex Vista HCx (top of the line eTrex) and several of the Summit units.