Measurement of Landslide Movement with 3D Laser Scanner

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Measurement of Landslide Movement with 3D Laser
Scanner
ASANO, Hiroki Erosion and Sediment Control
Research Group Public Works Research Institute
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Contents

• Most observation techniques and problem
• Outline of 3D Laser Mirror Scanner
• Attempt of landslide movement measurement
• with 3D Laser Scanner
• Result of movement measurement
• Summary

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When landslide calamity occurs
Based on the site situation and the observation
value (ground expansion and contraction meter
etc.).
The judgment is demanded promptly. Appropriate
measures is demanded.
Hard measuresFirst aid restoration
worker Software measures Precaution and shelter
recommendation
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Observation technique at calamity suddenly

• Watch with CCD cameras
• Watch with ground expansion and contraction meter

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Concept chart of watch at calamity
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Ground expansion and contraction meter
Storage box
crack
Paling
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Principle of ground expansion and contraction
meter
Record pen
Inn bar line
Rotation of drum
Movement of landslide
Recording paper
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Drum of ground expansion and contraction meter
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Example of setting up ground expansion and
contraction meter
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Insufficient point of ground expansion and
contraction meter

• The installation and the measurement are
  difficult in the place with danger.
• It takes time for the installation (The expansion
  and contraction meter is one/day).
• The installation and the observation at nighttime
  are difficult.

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Measurement image of 3D scanner
landslide
laser scanner
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3D Laser Scanner
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Composition of 3D laser scanner
? range finder electronics of the 3D scanner
LMS-Z210 ? laser beam ? rotating polygon ?
slow scan ("frame scan") ? ECP compatible LPT
printer port ? PC ? software
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Outline of 3D laser scanner

• Measurement range2 350, reflectivity gt 80
  Measurement accuracy/- 2.5 cm,
• in the worst case /- 10 cm
• Range which can be measured 80300 total
• Beam divergenceapprox. 3 mrad
• Eye safetyClass 1 for the scanned beam

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Characteristic of 3D laser scanner

• The pulse of the laser beam is launched
  repeatedly at very short intervals of time.
• Each pulse reflects, the time to returning is
  measured, and the distance is measured.
• The direction of the laser beam is changed and
  three-dimensional shape is scanned. The
  measurement principle is the same as the machine
  and the total station etc. of a general light
  wave measurement.
• A new part is technically a method of scanning
• It is possible to measure without setting up the
  reflection mirror .

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laser pulse
t
t
t
laser scanner
L
?t
Lc ?t (??)
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mirror
laser pulse
laser scanner
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laser scanner
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laser scanner
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laser scanner
Extension angle of 3mrad
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The measurement data displayedto
personal-computer
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Computational graphic
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Computational graphic
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Landslide measurement which uses 3D laser scanner

• Geographical features measurement of landslide
  ?Making of DEM(digital elevation model)
  ?Making of topographical map
• Measurement two or more times
• ?Grasp of displacement situation
• Making of vector chart
• Grasp of range of landslide movement

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laser scanner
Overlapping the data is difficult if there is no
points in evaluation.
Z
X
Y
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point(X,Y,Z)
point (X,Y,Z)
laser scanner
Z
X
Y
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point (X,Y,Z)
point (X,Y,Z)
laser scanner
laser scanner
Z
X
Y
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Reflection seal
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Situation of measurement
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laser scanner
Landslide
Range of measurement (top and bottom) 40
(right and left )85
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Procedure of the measurement data analysis
?The data measurement
?The point data making
?Making of TIN model
?Movement amount calculation
?Plan and section chart making
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Vector chart
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Frequency distribution of measurement error
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11?16?
11?24?
??????
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Landslide movement range chart
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Summary

• ?7cm or less roughly against the amount of the
  movement of 15-20cm.
• ?The respect grasp of the range of the movement
  was possible because of overlapping the
  topographical map before and behind the movement
  amount.
• ?The examination is scheduled to be advanced for
  the improvement of the accuracy in the future.

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Finished

• Thank you for your attention.