The medium-high side of the mountain, where the ground
is more sloped and rough, was surveyed by means of an
electronic distance-meter - called MDL - which is able to
operate also without using the reflecting prism, allowing
direct answer of the ground; the instrument allows
motorized survey too.
In conditions of medium visibility, the range without the
prism has been of 350 m with shaving visuals (on muddy
around), while in best conditions of light motion (at
sunset) and with incident visuals, range greatly increases;
the maximum distance which was measured is longer
than 650 m.
In figure 2 is shown the ground survey of the landslide
called SA60; dark grey pattern refers to the points
surveyed by MDL, light grey to those ones surveyed by
means of GPS on the special vehicle and finally black
one to the points surveyed by means of GPS in handy
held.
Density of the points surveyed on the ground depends
both by ground rough and its practicability on foot. The
survey carried out on the ground are compatible with a
representation scale variable from 1:1000 to 1:2000.
Some external points were surveyed even if ground
doesn't slid down in order to make a comparison with
ante-event situation.
Figure 1 - Operator with the prism on a landslide
4520100-)
4519900
4519700
4519500H
4519300
4519100
# MDL points
GPS on special vehicle
• Hand held GPS
2487400 2487800 2488200 2488600 2489000
Figure 2 - SA60 survey
3. GPS FRAME- NETWORK
In the first phase, each survey has been calculated in a
local co-ordinate system. Some points belonging to the
local surveys were joined to a frame network by means of
GPS in order to have co-ordinates in the National system.
The frame network includes some vertices known both in
geodetic and cartographic Italian systems, belonging to
IGM95 network.
A benchmark belonging to the leveling net was also
connected; it was the only one present in that area.
On the whole a GPS network made by 54 vertices and 89
baselines was surveyed.
The main frame-network is shown in figure 3.
