The 30m resolution of SRTM data refers to the spatial resolution,
not the resolution of the elevation reading. A number of factors
come into play when determining the vertical accuracy of SRTM data,
but according to this
link,
the RMS error for SRTM vertical measurements is 3.56M. Because of
the configuration of the satellites used to calculate elevation with
a GPS, the vertical resolution is significantly worse than the
horizontal resolution. Further complicating matters, many Garmin
units contain a barometric altimeter which is preferred over the GPS
reading by the software. However, unless you calibrated the sensor
at a known elevation before starting your readings, you have no idea
how accurate it is.
TL:DR - the SRTM value is probably better than your GPS reading.
On 4/20/2021 5:45 PM, jean Lukusa wrote:
Hi all .
I hope you are doing fine.
I have experienced an issue:
The elevation taken in the field with gps
garmin64 is 623 m but the one given by SRTM download from Qgis
is 612m.
How can I interprete this gap knowing that SRTM
resolution is 30 meters.
Jean Lukusa
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