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CHANGE DETECTION OF LANDSLIDE TERRAINS USING GROUND-BASED
LIDAR DATA
K. H. Hsiao *,J. K. Liu, M. F. Yu *, Y. H. Tseng*
“ Energy & Resources Laboratories, Industrial Technology Research Institude, Hsinchu 311, TAIWAN, hks@itri.org.tw
? Dept. of Civil Engineering, NCTU & ERL, ITRI, Hsinchu 311, TAIWAN, JKLiu@itri.org.tw
- Dept. of Survey Engineering, National Cheng-Kong University, Tainan, TAIWAN, tseng@mail.ncku.edu.tw
Commission VII, WG VII/5
KEY WORDS: Change Detection, LIDAR, Laser scanning, DEM, Landslides
ABSTRACT
The topographic change has been estimated on basis of 3D laser data and aerial photogrammetric survey. The newly-developed,
time-saving approach is by using airborne and ground-based lidar. A points-cloud of high precision and density distribution can be
obtained in a few minutes for the sensitive latent landslide area. With a limited control survey of precise targets using GPS and total
stations, multiple scans of ground-based laser scans can be registered together to form one cohesive 3D model. And, thus, overlaid the
different period topographic data for estimating the changes of the target areas. Two cases are practiced in this study. For the first case,
a river-bank landslide in Hsin-chu Hsien was scanned with 6 stations. Subsequently, they were registered and joined and re-sampled to
a 2m grid for a comparison with information obtained by digitization of a 1/5000 topographic map. The second case is conducted to
observe the deformation of a large-scaled dip-slope landslide of Jiu-fen-er mountain, which was triggered by the big shock of the
Chi-Chi earthquake at Nantou County of central Taiwan on 1999/09/21. Control points are systematically distributed on the 1000m by
2000m landslide surface. Surveys are made by transits of total stations, GPS, and airborne lidar as well as ground-based lidar data. The
terrain changes on ground surface have been detected in thus a scheme. It is found the largest change of height between the earthquake
event is about 60m. The effectiveness of applying 3D laser scan is proved in this study.
1. INTRODUCTION Due to the extent of a hazardous landslide, a range of more than
500 m is generally required to deal with the accessibility and
arrangements of the location for taking the multiple scans.
Airborne laser systems are able to take multiple returns of
ground echoes, thus to facilitate the differentiation of
vegetations and other artificial features. The first returns depict
a digital surface model (DSM) and the last returns depict digital
ground model (DGM). In the building-up areas, the signals may
depict a digital building model (DBM). Topographic study
usually applies the DGM or last returns to get rid of disturbance
of vegetations and other artificial features above ground
The geophysical settings of Taiwan are characterized by highly
fractured steep slopes, vulnerable to landslides. It is further
enhanced by the big shock of the Chi-Chi earthquake of central
Taiwan on 1999/09/21. This has been proved by the hazards
taken places in the event of Typhoon TORAJI a small-scaled
one on 2000/July/30, causing a damage of more than 100 deaths
and a loose of more than US$300 millions. Topographic
changes can be expected subsequently after events of
earthquakes and heavy rainfalls.
Traditionally, to obtain the information of topographic changes surface.
after a landslide event, ground surveying or aerial
photogrammetric surveys are conducted. The new technology 2.2 Joining Point Clouds
of terrain laser scanning can be a way to improve the efficiency : Goh s
of obtaining the information of topographic changes. A Laser scanner takes point clouds in sight. The ground surfaces
ground-based 3D laser scanner can take very dense point clouds blocked by trees or the likewise features would not be detected.
Multiple scans are usually required to obtain a complete dataset
for an object. And, thus, an observation network of multiple
observing stations is required. In other words, to joint point
clouds of various stations is to transform local coordinate
systems of each stations into a common coordinate system
(Figure 2.1). A hyper-surface matching algorithm is applied for
with high accuracy in the occasion of a landslide. The aligned
and merged 3D models can be used to derive detailed
topographic information for taking mitigating measures or for
making further study on topographic evolution by comparing to
historical topographic datasets.
In this study, ground-based 3D laser scanning is applied to two joining the point clouds in this study. In this algorithm, the
cases. One is a river-side landslide with an area of circa 100 m * overlap portions of two adjacent Scans are used for matching.
200 m, a typical and common one in Taiwan. The other is the Before the exact-matching process, a manual adjustment to
toe area of the large-scaled dip-slope landslide with an area of make the adjacent scans approaches a pseudo-match status is
circa 1000 m * 2000 m of Jiu-fen-er mountain, which was required.
triggered by the big shock of the Chi-Chi earthquake at Nantou
County of central Taiwan on 1999/09/21.
2. 3D LASER SCANNING
Five datasets are employed in this study, e.g. DTM with a grid
of 40m, digitized topographic contours, photogrammetric
heights, airborne and ground-based laser scanning datasets. All
the spatial data are transformed into a common TWD97
coordinate system. The procedures of ground-based laser
scanning adopted in this study are to be discussed as follows.
Figure 2.1. A sketch showing coordinate systems for joining
2.1 Acquisition of 3D Laser Scanning Data multi-scanning point clouds
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