The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
375
W ‘ -Uif + ( v -V/) 2
Where Z,:height of the point clouds
u u v,: image coordinates of the point clouds
: hight of the interesting point
u, v: image coordinates of the interesting point
tfl, 1
0
H
1
A
0
N
1
¿*31 1
0 o
1 1
A ^
•+Æ32 1
l+ a 2 2 (
M„)
[r-r.)
>+ aj
,+ a 2 3 l
N N
1 1
N N
O O
031*
1
o
l+ tf 3 2 (
lr-r»)
l+ tf33 (
N
1
N
O
where u, v: image coordinates
/: focal length
: rotation matrix
X, Y, Z: ground coordinates of interesting point
X 0t Y (h Z 0 : exposure station of platform
Figure 2. Flowchart of pseudo GCPs generation
the triplet images were generated 3 stereo pairs, interesting
point P(X,Y,Z) has different 3 ground coordinates for each
stereo pairs which are shown in Figure 3.
Therefore, triplet restriction was applied so that the each
residual AP for the X,Y,Z become minimum in calibration
procedures. Here, each residual AP are computed from
equation (4).
AP AB P ave. P AB
AP BC~ Pave - P BC
(4)
AP AC ~ Pave. - P AC
p Zw,p,
Zw,
where, ground coordinates of the interesting point
APÿ : differences of each stereo pair
lF,:weight of each point
ABC
4. EXPERIMENT
3.3 Data acquisition
In order to confirm the validity of the proposed simultaneous
adjustment, data acquisition was performed in our test field.
Test field has 117 GCPs, and 26 GCPs can be utilized in triplet
area. GCPs were obtained by static observations using GPS that
were set on the edge of road paints. Table 1 shows data
component which used in this investigation, and Figure 4 shows
the centre image using in this investigation. It was taken with
about 1270 m, and photo scale is about 1/21,000. Therefore,
GSD (Ground sampling distance) shows about 20cm.
Figure 5, 6 shows GCP image, and it can be realized that image
quality is not clearly. Pointing were performed in each
calibration with 1/1000 pixel accuracy, but it is speculated that
pointing accuracy haven’t 1/1000 pixel accuracy.
3.2 Simultaneous adjustment
In order to improve the calibration accuracy, triplet restriction
was adopted into the calibration using Pseudo GCPs. Due to