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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
datasets. Figure 3.9 shows a result of the study (Shih et al.,
2002). Furthermore, two times ground-based lidar scanning
were performed. Figure 3.10 shows the images of ground-based
lidar scanning of Jiu-fen-er mountain area.
In summary, though accuracies of various datasets have not yet
been estimated, a preliminary result shows a significant change
of the topography of the area for different times. Figure 3.11
shows the change of DTMs before and after the earthquake. The
post-earthquake DTM was generated by aerial photographs
taken on February of 2003. Similar results can be drawn from
Figure 3.12 of which the posterior DTM is generated by
airborne lidar.
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Figure 3.6.Modeling DEM of Jiu-fen-er mountain area
(b SPOT me 3D
perspective image
(a) 40m DTM Simulated
sunshine image
Figure 3.7. Jiu-fen-er mountain before earthquake
(b) Aerial survey (c) Aerial survey
data simulated
(a) DTM data
before earthquake data simulated
perspective image perspective image
Figure 3.8. Simulated 3D perspective images of two periods of
aerial survey of Jiu-fen-er mountain.
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i 5 a Eua; 7 Zub de
(b) DSM [a (c) DTM data
(a) Scanning scope
Figure 3.9. The airborne lidar data simulated Jiu-fen-er
mountain 3D perspective image (Shih et al., 2002)
(a) a ield photo of (b) Ground- based iS round: based
Jiu-fen-er mountain|Lidar scanning map|Lidar scanning map)
Figure 3.10. The images of ground-based lidar scanning of
Jiu-fen-er mountain area
survey data
(a) DTM data (b) Aerial survey data (c) E image Sof
before earthquake after earthquake different terrain data
Figure 3.11. A comparison of DTM and aerial survey terrain
data of Jiu-fen-er mountain area
Airborne Lidar data
(b) Aitor ne Lidar (c) Compared image or
before earthquake data after earthquake different terrain data
(a) DTM data
Figure 3.12. A comparison of DTM and airborne lidar data of
Jiu-fen-er mountain area
To monitor the change of micro topography of a landslide area,
ground observation stations are usually employed for taking
leveling and horizontal measurements by tradition means such
as EDM or even GPS. However, the disadvantages of limited
density of observations are obvious. The accuracy of 3D laser
scanners is mostly in the range of a few centimeters for a
ground-based system and in the range of sub-meters for an
airborne system. This feature makes it meaningful to apply for
landslide monitoring.
Figure 3.13 shows the results of 5 profiles of a traverse survey
by Total Stations of a monitoring network on the landslide
surface. A sequence of 5 times of observations is taken to
observe the changes of the coordinates of the stakes installed on
the slide surface. With the analysis of the variation of the
coordinates of each stakes, the deformation and micro
topographic change can be observed (origin of the datasets:
Bureau of Soil and Water Conservation, 2003). It is found the
largest change of height between the earthquake event is about
