P. Baldi et al., Digital photogrammetry and kinematic GPS applied to the monitoring of Vulcano Island, Aeolian Arc, Italy, GEOPHYS J I, 142(3), 2000, pp. 801-811
Digital photogrammetry and kinematic global positioning system (GPS) techni
ques are investigated and compared over a volcanic area as operational appr
oaches to map the topography and monitor surface displacements. The use of
terrestrial and airborne GPS to support the photogrammetric survey allowed
for operational and processing time reduction without loss of accuracy. A d
igital elevation model (DEM) is obtained from the processing of the high-re
solution digital imagery survey, which provides detailed information over a
large area. The internal accuracy of the derived DEM has been verified by
the comparison of two sets of data obtained from imagery acquired in differ
ent epochs; the observed root-mean-square error of residuals ranges from a
few centimetres to 15 cm depending on the morphological features. Kinematic
and pseudo-kinematic GPS surveys are performed to derive accurate 3-D coor
dinates at monumented benchmarks and accurate elevation profiles along foot
paths. The average repeatability of the GPS measurements on benchmarks is 1
cm for measurement durations of 2-3 min. The standard deviation of interpo
lated vertical coordinates obtained at the crossings of kinematic GPS profi
les is 4.3 cm. The high quality of these GPS coordinates justifies their us
e also for the validation of the photogrammetric DEM. A comparison of 6000
common points provides a standard deviation of residuals of 18 cm. The resu
lts show that the deformation pattern of a volcanic area can be rapidly and
accurately monitored even in the absence of geodetic benchmarks. The integ
ration of aerial photogrammetry with GPS kinematic surveys may be considere
d as an optimal approach for deriving high-resolution mapping products to b
e used in support of studies of volcanic dynamics.