-B4, 2012
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, we compared
AR data, which
International Archives of the Photogrammetry, Remote Sensin
g and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
was obtained prior to the disaster, then quantified changed
volume for the damaged area (Sohn et al., 2011).
Leica
Scanstation 2
Trimble GX
Figure 4. Terrestrial LiDAR scanner
Trimbie CX
4. EXPERIMENTAL RESULT
41 Study Area
Mt. Umyeon is located on a central region of Seoul and
surrounded by urban facilities. Analysis results from a forest
map produced by Korea Forest Service showed that most forest
types around Mt. Umyeon were the deciduous and the mixed
stand forest and over 30 years old tree reached 97% nearly. A
natural ecological park with a small-size reservoir was
developed at the southern area of Mt. Umyeon. Around Mt.
Umyeon, there was no district zone designated as a disaster risk.
Legend
© CNES 2011 Landslide area
T T
?
x: m "AVE
Figure 5. Location of Study Area (Mt. Umyeon)
42 Multi-sensor Data Processing for Damage Analysis
In order to extract the damaged extent, pre- and post- aerial
photos, a variety of digital map from NDMS (National Disaster
Management System) Database, and the Optic and SAR images
from International Charter were utilized in this study.
Simultaneously, point clouds of the landslide area were
collected and processed through the terrestrial and the aerial
LIDAR, For damage extent extraction caused by landslide and
flood for the study area, collected pre- and post-disaster
Imagery were used as an experimental data to apply for image
algebra change detection algorithm (John, 1996).
20 = Vy Jd y Slain S (1)
Where,
Di; = change pixel value
Z1 brightness pixel value at time 1
S20 = brightness pixel value at time 2
c — constant
The total landslide extent of three damaged regions (red collar
polygons on Figure 6) in the study area estimated by change
detection algorithm was about 8.6 ha.
3T 29H
Y anon
TWH
WE £
Figure 6. Extraction of damage are
a by landslide
Aerial photos from the small manned helicopter and Unmanned
Aerial Vehicle were conducted by post-processing procedure.
For geometric correction and rectification of aerial images
through an aerial triangulation (AT), Ground Control Points
(GCPs) were extracted from 1/1,000 scale digital map produced
at National Geographic Information Institute (NGII). After
Aerial triangulation processing, the digital terrain model with
Im spatial resolution and 5cm-level ortho-rectified photos were
generated. Final mosaicked ortho-imagery was made using
DTM data and ten ortho-rectified photos with an accuracy of
1.45m (RMSE).
Figure 7. Ortho-rectified photos (left) and aerial LiDAR by
RAMS (right)
Before terrestrial LiDAR scanning, Ground Control Points
(GCPs) survey was carried out using static GPS method as
setting up eight control points around the landslide and the
reservoir's bank collapse area for almost eight hours. The data
process of collected LiDAR point clouds was performed as
following; point cloud geo-referencing and registration, outlier
eliminating, 3D mesh/surface generating and editing, DTM
generating, and 3D modelling of the study area.
311