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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part Bl. Istanbul 2004 
  
geometrical interpretation connected with the parameters of 
camera of the image distortion factors, therefore it is called the 
"non-parametrical" model. These models take into account 
DEM height values for imaging terrain, and to a great extent 
they are free from the common disadvantages of polynomial 
coefficient transformations. 
The Parametrical model (PM) describes actual relations 
between the land and its image, therefore the terms of this 
model have a precise geometrical interpretation. The basis for 
construction of the precise model for satellite imaging is the 
condition of co-linearity. In this point, however, it may be 
applied not to the entire image, but only to a single line. 
Parametrical models are less susceptible to photo-points 
distribution and possible errors in data. In the framework of 
research we used PCI software, taking into consideration the 
approach of doctor T. Touitn on parametrical relations for VHR 
type images. In the framework of survey conducted we 
presumed that the orthophotomap generated would be created in 
the *1992" Projection Gauss-Kruger; Spheroid: GRS80; Datum 
ETRS89 system, hence all auxiliary data for this process, 
namely GCP and DEM, had been previously transformed for 
this system. We also presumed that for accurate analysis of 
orthophotomaps created, only the VHR images in panchromatic 
range were used. 
3. RESALTS AND ANALYSIS 
We acquired orthophotomaps for images (QuickBird and 
IKONOS) with a use of the parametrical method (PM) (with use 
of a camera model) and the Rational Polynomial Coefficient 
(RPC) method, based upon PCI software. Uniform distribution 
of adjustment points for both methods was presumed. Figures 3- 
10 present a specification of acquired accuracy of generated 
orthophotoprocess. Each figure presents the achieved accuracy 
of ortho-adjustment for a given sensor and type of terrain 
depending on a number of GCP points. Achieved accuracy was 
checked on controlling points, which did not take part in the 
process of ortho-adjustment. In the framework of each scene we 
checked upon the accuracy achieved on controlling points (ICP) 
in number of some 20-30. These points were not used for 
adjustment process by possible support of DEM accuracy. In 
other words, for these points the value of Z for the process of 
correlation was not used. The figures presented show the 
following scenarios of orthorectification processes used: 
- used values of Z in the process of ortho-adjustment on the 
basis of used points GCP from GPS survey, 
- used values of Z in the process of ortho-adjustment on the 
basis of used points GCP “read only ” from DTM. 
  
10.00 
9.00 | 
— Parc rie © ac 
8.00 \ Parametric approach 
7.00 i \ 
6,00 | \ ee RPC approach 
5.00 i 
\ \ 
4.00 i \ 
3.00 \ i 
2.00 i = 
RMSE on check points - (ICPs) [m] 
1.00 
  
  
  
0.00 
Number of GCPs points 
Figure 3. Accuracy of IKONOS for Warsaw area with "Z^ 
values from GPS 
  
  
  
  
  
  
  
Correction RMS (m) Maximum (m) 
Method X Y X Y 
Parametric | 0,96 0,84 1,77 2.02 
RPC 0,89 0,86 2,00 2,40 
  
Table 2. Comparison of RMS and maximum errors over 35 
ICPs of parametric model and RPC computation with 
  
  
  
  
10 GCPs 
10.00 
I 
— 9.00 
E | 
= | — — — Parametric 
£ 8.00 approach 
© 70 | 
T | " - RPC approach 
= 6.00 
e 500 
= | 
$ 400 \ 
? \ 
= 3.00 \ 
e 200 \ 
= ; — 
ax 1.00 Vz 
0.00 
01 2 3:04 5293161135 8.39 10H. RB HS WITT REQI 
Number of GCPs points 
”„ 
Figure 4. Accuracy of QuickBird for Warsaw area with "Z 
values from GPS 
  
  
  
  
  
  
Correction RMS (m) Maximum (m) 
Method X Y X Y 
Parametric | 0,94 0,64 2.25 1,44 
RPC 1.31 1,05 3,93 1,94 
  
  
Table 3. Comparison of RMS and maximum errors over 17 
ICPs of parametric model and RPC computation with 
10 GCPs 
  
  
  
  
10.00 i 
= 559.00 | 
= | 
= — — — ~ Parametric approach 
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& \ 
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5:26:00 \ RPC approach 
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0:1 3-3 245758: 567 7: —8 9:10 1-712-743-1413 106717 18-49 20. 21 
Number of G CPs points 
Figure 5. Accuracy of IKONOS for Nowy Targ area with "Z^ 
values from GPS