the automatic procedures of flat target recognition can be 
used at distances greater than 50 m (up to 75-80 m); 
the possibility to perform automatic recognition of 6" 
dedicated spherical targets; 
the possibility to perform a manual search on the point 
cloud of the desired area (e.g. relative to the position of a flat or 
spherical target or of any natural point) and to launch a more 
detailed survey on it (the dimensions of the area and the points 
density is set by the operator); this possibility was greatly 
exploited in the present study because it allowed us to position 
the target/GPS system at distances greater than 75-80 m (even 
up to 150-200 m). 
We now describe the main characteristics of the 
instrumentation: 
LASER SCANNER CYRAX 2500™ 
Company 
Country 
principle 
eye safety 
class 
CYRA 
technology 
U.S.A. 
t.o.f 
Class 2 
PERFORMANCES 
max. range 
on natural 
targets 
horizontal 
scan 
range 
vertical 
scan 
range 
scan 
mechanism 
250 m 
44 gon 
44 gon 
rotating 
mirror 
horizontal 
angle readout 
accuracy 
vertical 
angle readout 
accuracy 
range 
accuracy 
point 
accuracy 
@ 50m 
±3.8mgon 
±3.8mgon 
±4mm 
±6mm 
OTHER FEATURES 
beam 
divergence 
scan rate 
dimensions 
weight 
<6mm @50m 
7,6mgon 
1 column/sec 
@1000 
pts/column 
400 X 330 X 
430mm 
d X w X h 
20.5kg 
Table 1. CYRA specifications about Cyrax 2500™ 
Figure 2. Cyclone 3.2 
As is known, the GPS is a positioning system based on 
reception of radio signals emitted by a constellation of artificial 
satellites in orbit around Earth. For precise positioning, the GPS 
is used in relative mode, with at least one pair of receivers: a 
master receiver placed on a vertex of known coordinates in the 
WGS84 geocentric system and other rover receivers on the 
points to be measured (Hoffmann - Wellenhof; 1997). 
In the present study, we used four Ashtech ZXII double 
frequency geodetic receivers in rapid-static mode, with the 
session duration and sample rate set to allow a centimetric 
precision of single baselines in normal situations. The baselines 
were analysed with GeoGenius™ 2000 commercial software. 
Figure 1. Laser scanner Cyrax 2500™ 
Figure 3. G.P.S. Antenna and receiver