International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
determined by using reference points. The calibration
procedure, as shown in chapter 3.2 delivers a relation between
image coordinates (i,j) and object points (X,Y,Z). Now, all
3D-LS distance data can be transformed in the panoramic
coordinate system and by that its pixel position in the
panoramic image can be computed. For this position the actual
grey value of the panoramic camera is correlated to the
instantanuous laser image point. Figure 6 depicts the
combination of both images. The ground sampling at the wall is
about 1.5 mm. The fact that colour shifts are not visible in the
image verifies the calculated alignment between both systems.
The strong red shift is caused by the black cable carrying board
(s. Figure 3). This board causes poor 3D laser scanner data due
to bad reflecting properties.
Figure 6. Merged images of 3D-LS and Panoramic Camera
4. POSLAS-PANCAM
Before the POSLAS-PANCAM was used in field experiment
the recording principle was studied in a laboratory environment.
4.1 POSLAS-PANCAM in Laboratory
The functioning of POSLAS-PANCAM (PLP-CAM ) was first
verified by surveying the test field described in chapter 3.
During this experiment a robot was used as a moving platform.
As GPS reception was impossible in the laboratory the position
data and orientation data were obtained from the camera
tracking system ARTtrack2 which comprises two CCD
cameras. The IMU measurement data were also recorded
parallely. This means, redundant orientation information is
available and the accuracy of the orientation system can be
| Targetss s
IMU NN
Figure 7. PLP-CAM carried by robot
510
verified. Figure 7 shows the robot with PLP-CAM. Figure 8
depicts one of the two tracking cameras. The robot is remotely
controlled by a joystick.
Figure 8. PLP-CAM robot and tracking camera
The results of this experiments were used to develop algorithms
to integrate the data of the three independently working
systems. It could be shown, that the data sets can be well
synchronized. Furthermore, the whole system could be
calibrated by using the targets (s. Figure 3).
4.1 POSLAS-PANCAM in the Field
For a field experiment the PLP-CAM was mounted in a
surveying van. The GPS-antenna of POS was installed on top of
the vehicle. The car drove along the fassade of the Neue Schloss
in Stuttgart (s. Figure 9).
M in front of Neues Schloss Stuttgart
As the range performace of the 3D-LS was too low, only image
data of the CCD-line camera and the POS-Data were recorded.
The left image in Figure 10 shows the recitification result on the
basis of POS data alone. By applying image processing
algorithms the oscillation can be reduced and a comprehensiv
correction is achieved by using external laser scanner data
recorded independently during another survey (s. right image in
Figure 10).
The high performance of the line scan camera is documented in
Figure 11 and Figure 12. An heraldic animal at SchloB Solitude
in Stuttgart was surveyed by PLP-Cam. The object is hardly
recocknizable (s. Figure 12) from the original PANCAM data.
However, after correcting the data a high quality image is
obtained. The zoomed in part illustrates the high camera
performance.
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