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4 An Innovative Measurement Instrument …
measuring apparatus. The horizontal stripe pattern with a 3.0 cm contour interval is
generated by a laser source and is recorded by the camera with the sighting direction
perpendicular to the laser planes. Positioning marks are placed on fixed positions
with the same height. As the slope terrain deforms over time, the erosion process is
recorded by video, and then imported into the computer to acquire a snapshot image
at a particular time sequence. Given depth in ArcGIS, the 3D geometric shape of
the target surface can be computed accurately. By comparing the slope geometries
in the moments before and after the erosion incident, we could obtain the volume
of gravity erosion and many other erosion data. In this study, the topography meter
covers a monitoring range of 3.0 m × 2.0 m, and the SONY HDR-XR550E video
camera has a resolution of 6.63 Megapixel.
In order to testify the validity and accuracy of the topography meter on detailed
gravity erosions, calibration tests were conducted on conceptual slopes. The topographical characteristics were initially measured by the conventional instruments,
e.g., steel rule and level instrument, and then surveyed with the topography meter.
The tests consisted of two stages, as shown in Figs. 4.2 and 4.3. In the first stage, a
wooden brae was measured with the topography meter, and then the lengths of brae
edges covered with the laser footprints were gauged with a steel rule to calculate the
volume of the brae. Subsequently, the brae was placed in the other gradients, and also
observed by the topography meter and the steel rule respectively. In the second stage,
Fig. 4.2 A laboratory calibration test for measurement of the slope volume. The wooden brae was
placed in various slope gradients, and was investigated by the topography meter. Then the bulk of
the brae covered by the laser beam was elaborately gauged by a steel rule
4 An Innovative Measurement Instrument …
measuring apparatus. The horizontal stripe pattern with a 3.0 cm contour interval is
generated by a laser source and is recorded by the camera with the sighting direction
perpendicular to the laser planes. Positioning marks are placed on fixed positions
with the same height. As the slope terrain deforms over time, the erosion process is
recorded by video, and then imported into the computer to acquire a snapshot image
at a particular time sequence. Given depth in ArcGIS, the 3D geometric shape of
the target surface can be computed accurately. By comparing the slope geometries
in the moments before and after the erosion incident, we could obtain the volume
of gravity erosion and many other erosion data. In this study, the topography meter
covers a monitoring range of 3.0 m × 2.0 m, and the SONY HDR-XR550E video
camera has a resolution of 6.63 Megapixel.
In order to testify the validity and accuracy of the topography meter on detailed
gravity erosions, calibration tests were conducted on conceptual slopes. The topographical characteristics were initially measured by the conventional instruments,
e.g., steel rule and level instrument, and then surveyed with the topography meter.
The tests consisted of two stages, as shown in Figs. 4.2 and 4.3. In the first stage, a
wooden brae was measured with the topography meter, and then the lengths of brae
edges covered with the laser footprints were gauged with a steel rule to calculate the
volume of the brae. Subsequently, the brae was placed in the other gradients, and also
observed by the topography meter and the steel rule respectively. In the second stage,
Fig. 4.2 A laboratory calibration test for measurement of the slope volume. The wooden brae was
placed in various slope gradients, and was investigated by the topography meter. Then the bulk of
the brae covered by the laser beam was elaborately gauged by a steel rule