CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
208 
to underline that a correct geometric positioning of the objects 
is as important as the recognition of their modifications. 
The self-developed RFM algorithm was applied to orthoproject 
both images. It should be noted that the Rational Function 
Model is very unstable and depends on many parameters, such 
as the distribution of the GCPs, the range of the elevation 
values, the sensor attitude and the Tikonov coefficient: all these 
parameters have to be evaluated for each different image. Poor 
estimations of these parameters can lead both to a decrease in 
the positioning accuracy and to the occurrence of asynthops in 
the final image (raw distortions). 
A detailed statistical analysis was carried out to evaluate which 
map scale the obtained orthoimages are suitable for, taking into 
consideration the map tolerances (in Italy the usually accepted 
value is of 0.2 mm at the map scale and the tolerance is 
interpreted as two times the RMSE of the coordinates). This 
means that a 1:10000 map has a 2 m tolerance and a 1:5000 
map has a 1 m tolerance. Residuals can been considered as 
statistical variables (one for each test) and their mean and 
standard deviation can been calculated. 
CHK 
AE 
(pixel) 
AN 
(pixel) 
RMS 
(pixel) 
1 
0,16 
-0,82 
0,83 
2 
-0,26 
0,63 
0,68 
3 
-0,67 
0,82 
1,06 
4 
0,87 
-2,15 
2,32 
5 
0,02 
0,07 
0,07 
6 
-1,95 
0,01 
1,95 
7 
0,51 
-0,03 
0,52 
8 
0,73 
-0,03 
0,73 
9 
-1,24 
0,97 
1,57 
10 
-1,06 
1,08 
1,52 
11 
2,24 
0,46 
2,29 
12 
0,55 
1,42 
1,52 
13 
-0,06 
-1,01 
1,01 
14 
0,04 
1,64 
1,64 
15 
0,56 
-1,47 
1,57 
V 
o v 
0,03 
1,0069 
0,11 
1,0817 
RMSE 
1,43 
Table 2. Residuals on CHK over the SPOT5 image 
Fitting statistical tests can be made on each residual distribution 
in order to understand whether they would fit a normal 
statistical distribution or whether they are affected by systematic 
or raw errors. In particular, the % 2 test was performed. The 
residuals (v) successfully passed this test in both cases. 
In such situations, according to the Tchebycheff theorem 
(/i — 2(7 < V < /A + 2(7 ), at least 95% of the residuals fall 
into following ranges for the Spot5 orthoprojected images: 
-4.95<AX< 5.11 m 
-5.14 <AY< 5.67 m 
These results suggest that Spot5 orthoimages are not suitable 
for a 1:10000 scale map updating; however tolerance values can 
be accepted for a 1:25000 scale map. 
CHK 
AE 
(pixel) 
AN 
(pixel) 
RMS 
(pixel) 
1 
1,20 
-1,82 
2,18 
2 
1,23 
-1,73 
2,12 
3 
-0,19 
-0,06 
0,20 
4 
1,57 
-0,26 
1,59 
5 
0,16 
0,10 
0,19 
6 
-1,53 
0,35 
1,57 
7 
-0,92 
1,31 
1,60 
8 
0,87 
0,12 
0,88 
9 
0,50 
0,18 
0,53 
10 
-0,71 
0,27 
0,76 
11 
-0,13 
1,06 
1,07 
12 
0,23 
0,47 
0,53 
13 
1,05 
1,79 
2,07 
14 
0,54 
-0,05 
0,54 
15 
-0,05 
0,16 
0,17 
16 
0,86 
-1,16 
1,44 
1L_ 
0.2531 
0.1271 
<T V 
0.8724 
0.9521 
RMSE 
1,32 
Table 3. Residuals on CHKs over the QuickBird image 
As far as QuickBird orthoimages are concerned, their 
Tchebycheff relation appears, as shown below: 
-0.91<AX< 1.22 m 
-1.08 <AY< 1.24 m 
Such results show that 95% of the residuals are lower than 
1.25m and suggest a potential use of Quickbird orthimages for 
upgrading 1:10000 scale maps (whose tolerance is about 2.0 m). 
Another tolerance evaluation method can be considered 
according to the technical rules that are adopted for the 
production of the used 1:10000 regional reference cartography. 
They indicate that the following relationship has to be satisfied: 
RMS, = [{e™ k - E° rtho j + (n™ k - N° rtho J J< 4.0m (4) 
However also this approach shows that Spot 5 orthoimages 
seem to be not suitable for a 1:10000 scale map updating. 
It is important to note that a more rigorous test should take into 
consideration the check points precision q t (that is the same of 
the test cartography), according to te following relation: 
<7 v (5) 
where (J u = precision of the up-to-date cartography. 
Such an approach is less limiting and so it has been cautionally 
decided to consider <7 T equal to zero. 
4. CARTOGRAPHIC UPDATING 
One of the main aims of this paper is to establish whether the 
geometric information of the orthoprojected remotely sensed 
images are suitable for cartographic updating (at a scale that 
depends both on the geometric resolution of the image and on