CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
The equations (l.a or l.b) have to be firstly linearized; in this 
way it is possible to solve system 2 through a least square 
solution: 
V = PA-x-P-L 
X = (a t -P-a)'-A t P L <2> 
The first problem to face is the ill conditioning of the system 
that is obtained from the previous linearization. The Tikhonov 
regularization algorithm was used to solve the problem. As 
known, it is based on the addition of a small empiric coefficient 
(l 2 ) to the diagonal elements of the A T PA normal matrix . The 
following system can be written: 
X = (a t -PA + X 2 ■/)"'-A 7 PL (3) 
The Royal Palace of Venaria has been declared a Property of 
Humanity by U.N.E.S.C.O. 
It was built by Castellamonte in the late 17 th century and it 
consisted of a village, royal palace and gardens and extended 
for an axis of 2 km. The building works were then assigned to 
the architect Juvarra in the early 18 th century. 
Figure 2. Royal residence in Venaria (Turin) 
2.2 Images, D.E.M. and cartography 
This operation forces the system to converge after a few 
iterations. 
The second problem is the occurrence of some asymptotes 
during the use of polynomials. An over parametrization test 
was carried out to evaluate which coefficients have to be used in 
the transformation. Firstly a x 2 iest was carried out to 
understand whether raw errors are present or whether the model 
is overparametrized. If overparametrization is detected, further 
analyses (t Student tests) are performed to identify the 
coefficients that can be neglected. 
It was found that both the number of coeffiecient to be used and 
the ill conditioning of the system are closely related to the 
geometric distorsion due to the sensor attitude and to the 
elevation range of the scene. 
2. AVAILABLE DATA 
2.1 Test site 
Two test sites were chosen in the outskirts of the city of Turin 
(Piedmont, Italy): Stupinigi (fig. 1) and Venaria Reale (fig. 2). 
These represent two Italian cultural sites as they are old 
residences. Stupinigi was built in the first half of 18th century 
by the architect Juvarra as a hunting lodge and residence for the 
Savoia family; it is the nucleus around which a National Natural 
Park develops. An ancient medieval castle, Castelvecchio, 
which is well preserved, can be found near the hunting lodge. 
A Spot 5 panchromatic oversampled image and a QuickBird 
panchromatic one were considered for two different scale 
analyses. Correspondent multispectral bands were also available 
for both the images. The main features of these images are 
shown in table 1. 
Spot 5 
QuickBird 
Date (dd mmm yyyy) 
01 Oct 2002 
22 Sep 2002 
Pan Resolution (m) 
2.5 (supermode) 
0.61 
XS Resolution (m) 
10.0 
2.44 
Level 
IB 
IB 
Table 1 - Remotely sensed images available of the test site 
The Digital Elevation Model of the Piedmont Region was used 
during data processings. This model is characterized by a 50m x 
50m grid and an accuracy of ± 5m. 
According to the expected scale mapping (which mainly 
depends on the geometric resolution of the images) the 
following cartographic reference data were used: 
• vector 1:10000 scale Technical Regional Map (CTR, 
used for orthocorrection of the SPOT image); 
• raster 1:5000 scale Technical Provincial Map (CTP, 
used for orthoprojection of the Quickbird image). 
These data were adopted to collect the Ground Control Points 
(GCP): Check Points (CHP) have instead been collected on 
larger scale maps (1:5000 and 1:2000) here called Test 
cartography. 
Reference cartography photogrammetric flights were made in 
1991 (CTR) and 1993 (CTP). This fact permits us to face the 
updating problem as the area of interest has been subject to 
intensive changes over these years. Our interest in particular is 
to demonstrate that satellite high resolution images can be 
useful: 
• to investigate any modifications that have occurred in 
the cultural sites, such as heavy restoration and 
requalification activities; 
• to investigate the management of the surroundings 
devoted to the context in which the cultural sites are 
situated. 
3. ACCURACY TESTS 
Figure 1. Royal hunting lodge and national park in Stupinigi 
(Turin) 
In order to proceed with a correct updating test, we paid 
attention to the accuracy of the positioning (planimetrie) 
problem. It is necessary to say a few words about such problem