amera Bussola XB
X
Figure 8. Relationship between the components of the
POLIFEMO system.
The program carries out the following operations:
l. controls the internal coherence of the files, verifying that
the number of certified lines coincides with the number of
lines present inside each file; if the two do not match then
the procedure is interrupted;
calculates with a linear interpolation the value of the
Azimuth, Elevation and Bank angles at the moment of
shooting;
3. calculates the rotation matrix RE between the POLIFEMO
DD
System Xy , Y, e Zy and the Local Geodetic System X, ,
Yi eZ
cos cos K cosósin K sin$
=
wr
Il
cosQOsin K--sinósinQcosK cosQcosK-sinósingQsinK —sin cos
Sin @sin K — Sin cosmCcosK sinaocosK-sinócososinK — cosecosó
4. passes from the WGS84 system to a system with parallel
axis and with the origin that is the origin of the local
geodetic system;
5. calculates the rotation matrix between the Local System
and the WGS84 System:
—sin(Aw) -cos(Aq)sin(Qw) | cos(A.y )cos(Quw )
RS -| cos(Aw) -sin(Aw)sin(Qw) | sin(J.y )cos(«w)
0 cos(Pwy ) sin(Qw )
1. calculates the coordinates of the centre of POLIFEMO
within the Local Reference System;
M L9 AB. op e DE S LUN Ly B
Tenn = Fors + Ra (aps + puc) 7 tom = Rivstors T Ras touc)
where:
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
pt y = position of the Projection Centre in relation to the Local
System;
L e > 5 ; : :
Fops = position of the GPS aerial in relation to the Local
Geodetic System;
„WGS
Taps
Centre in relation to the WGS84 System:
= coordinates of the vector GPS Aerial — Local System
B a . 3 ai ;
I'cps = position of the Phase Centre of the Aerial in relation to
the System Body;
B o nS = - lr
Foye ^ position of the Centre of Shot in relation to the System
Body.
6. generates an output file containing the six exterior
orientation parameters for every camera shot moment. An
example of this output file is shown in Table 9.
Coordinates of the lens centre Attitude
Xp Yo Zo k Q QP
70.3906 9.5925 1.5868 53°.6200 -5°.6840 38°.9360
70.3906 9.5926 1.5868 $39 6510 -5? 6747. 389.0143
70.3703 9.3651 1.6108 52?.1478 -4?.4100 38?.9266
70.3792 9.5653 1.6107 52°.1784 -4°.4100 38°.9051
Table 9. Example of the output of the software for calculating
the exterior orientation parameters
5. FIRST EXPERIMENTAL RESULTS
The main aim of Polifemo is to directly define the six exterior
orientation parameters of an image. The accuracy of the 3D
coordinates of the points belonging to the object photographed is
a consequence of the whole process which involves GPS
positioning, DMC attitude determination, system calibration and
any other useful auxiliary data that can be used to improve the
accuracy of the system (GCPs coordinates, distance between the
object and the camera etc.).
A test on the Tower of Cetara, in the port of the village on the
Amalfitan Coast in Italy (see figure 10) was carried out in order
to compare the orientation parameters obtained from Polifemo
with those estimated indirectly through standard
photogrammetry.
A three points polygonal (S1, S2 and S3) was materialized on
the terrain, as seen in the figure, to survey the position of the
GCPs using standard techniques. The position of the three points
was also surveyed using the GPS in static mode. The coordinates
of approximately 20 points were taken from both SI and S2
using a Total Station Leica TCRA1103, some were signalled in
advance, others were natural. How the GCPs were distributed
can be seen in figure 10, put over a facade (from C. Carluccio).
Galileo 2000 software was used to elaborate the standard
measurements.
The Polifemo system was then placed on C1 and a kinematic
survey was simulated, placing the GPS master station on S3.
Data acquisition including images, coordinates and angles, began
after having synchronized the times (GPS measurements and the
compass) with the software described in section 3.1.
th
