International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004 
  
stanbul 2004 
r of control 3.3 SPOT4 The comparison between the developed program for point- 
racy limits. based projective equations and those of Erdas Imaging and 
2 where it is Two SPOT4 images were used in this case. The first is a [/RASC was performed and results confirmed their 
achieve the panchromatic image with 10-m resolution (Figure 3) and the — equivalence as shown in table 7. Then, line-based and 
second is multispectral with 20-m resolution (Figure 4). combined point/line-based projective equations developed 
programs were used with only 5 control lines and 3 control 
The panchromatic image covers the East Cairo region. The lines & 2 control points, respectively. RMS results of the same 
developed program for point-based projective equations was used 25 check points are listed in Table 7. It is clear the overall 
first to achieve the best accuracy limits. A number of 30 control quality of the results of the lines and combined point/line 
points was needed to reach the 1.3 pixel accuracy. RMS values of ~~ techniques with those of the point technique; however, using 
  
  
  
25 checkpoints are presented in Table 4. much fewer control features than the needed 30 control points. 
RMS 5 10 15 20 30 
control | control control control control 
points | points points points points 
X(m) | 110.22 | 94.65 77.45 38.54 13.36 
Y.(m) |.112.05.]. 96.80 76.99 37.00 13.13 
  
  
  
  
  
  
  
  
Table 4. RMS Values of 25 Check Points for SPOT4 
Panchromatic Image Using Point-based Technique with Various 
Number of Control Points 
The comparison between the developed program of point-based 
projective equations with that of Erdas imagine and I/RASC is 
performed next and results are shown in Table 5. Then, the line- 
based and the combined point/line-based techniques were applied 
with various number of control features to reach the same 
accuracy as with 30 control points. Table 5 demonstrate the RMS 
values of the same 25 check points with only 5 control lines for 
the line-based technique and 3 control lines & 2-control points 
for the combined point/line technique. 
  
its Control 
tion 
  
  
25 
control 
points 
16.68 
16.72 
  
  
  
  
  
\NDSAT7 
ique with 
rogram Was 
ing /RASC. 
im was used 
nt/line-based 
trol lines and 
check points 
  
  
  
Figure 3. SPOT4 Panchromatic Image over East Cairo with its Figure 4. SPOT4 Multispectral Image over Rashid with its 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
juivalence of Control (ed) and Check (plac) Points Distribution Control (red) Features and Check (black) Distribution 
control lines 
learly shows RMS | Erdas , | Point- Line- | Combined 
es as control magine URAS C | based | hased-| Pointiline 
X (m) | 13.36 13.32 13.36 13.35 13.35 RMS 5 10 15 20 30 
Y (m) | 13.14 1317 13.13 13.17 13.14 control control control control control 
Combined points points points points points 
Point/Line X(m)y |- 130.22 90.65 64.52 | 40.54 | 20.06 
Table 5. RMS Values of 25 Check Points for SPOT4 Y(m) | 129.95 90.80 6535 | 4023 ] 2071 
16.36 Panchromatic Image Using Point, Line, and Combined 
16.62 PoinuLinc Techniques Table 6. RMS Values of 25 Check Points for SPOT4 
Multispectral Image Using Point-based Technique with 
ANDSAT7 The second set of experiments was carried out using a Various Number of Control Points 
multispectral image of SPOT4 covering the Rashid region in the 
northern part of Egypt. As shown in Table 6, which lists the 
RMS values of 25 check points, a number of 30 control points 
was needed to reach the best possible accuracy figure of 1 pixel. 
'ombined 
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