In this investigation we apply digital photogrammetry
based on high spatial resolution aerial imagery (0.25 m)
to calculate digital surface models (DSM) of winter and
summer terrain. Traditional photogrammetry using analogue
aerial imagery and 8 bit digital sensors faced problems over
snow-covered areas mainly due to saturation and the homogeneous
surface (Kraus, 2004). Modern digital sensors can
acquire data with 12 bit radiometric resolution to overcome
these limitations. We calculate spatially continuous snow
depth maps using the summer and winter DSMs for two test
sites near Davos, Switzerland (145 km2 in total). This technology
is much more economical for covering large areas
than ALS or TLS but still has an acceptable spatial resolution
to map small-scale spatial variability. To assess the accuracy
of our results, we compare the calculated snow depths to
hand measurements, dGNSS points, TLS measurements and
ground-penetrating radar (GPR) transects acquired simultaneously
with the aerial imagery.