Chapter 4
An Innovative Measurement Instrument:
Topography Meter
Abstract The measurement of failure mass is very difficult because gravity erosion
usually occurs randomly and it combines with hydraulic erosion. Here, we present a
novel structured-light 3D surface measuring apparatus, the topography meter, which
could quantitatively measure the time-variable gravity erosion on the steep loess
slopes. With the topography meter, a 3D geometric shape of the target surface could
be digitally reconstructed, and then, the slope parameters, including the volume,
projected area, and gradient distribution, could be obtained. By comparing the slope
geometries in the moments before and after the erosion incident on the snapshot
images at a particular time, we could obtain the volume of gravity erosion and
many other erosion data. A series of calibration tests were conducted and the results
showed that the accuracy of this technique was high and sufficient for exploring the
mechanism of slope erosion.
Keywords Natural hazard · Gravity erosion · Topography meter · Erosion volume
4.1 Quantitative Monitoring of Gravity Erosion
Applicable and precise instruments are vital to obtain credible data in experiments.
With the development of photoelectric, ultrasonic, and image processing technologies
(Meng and Janssen 2015; Thomas et al. 2014), noncontact observation instruments
with high efficiency and accuracy (e.g., digital photogrammetry and laser method)
have been invented and used in the survey of the terrestrial landform in laboratories.
However, strong sunshine and wind will present great difficulties in making precise
topographic measurements in the field, especially for the laser method. Determining
the best method to manage problems appearing in terrain evolution experiments is
an important subject of survey engineering that must be addressed.
Terrestrial laser scanning is a technology that allows the digital acquisition of
real objects, reproducing them in 3D space and digital form employing a cloud
of points (Du et al. 2013; Casula et al. 2010; Vondrak et al. 2006). Compared to
conventional methods such as triangulation, field and office time of operation was
reduced using laser scanning and GPS. Applications where safety may be an issue,
such as providing accurate measurements on a landslide or debris flow area, would
© Science Press and Springer Nature Singapore Pte Ltd. 2020
X. Xu et al., Experimental Erosion,
https://doi.org/10.1007/978-981-15-3801-8_4
45
An Innovative Measurement Instrument:
Topography Meter
Abstract The measurement of failure mass is very difficult because gravity erosion
usually occurs randomly and it combines with hydraulic erosion. Here, we present a
novel structured-light 3D surface measuring apparatus, the topography meter, which
could quantitatively measure the time-variable gravity erosion on the steep loess
slopes. With the topography meter, a 3D geometric shape of the target surface could
be digitally reconstructed, and then, the slope parameters, including the volume,
projected area, and gradient distribution, could be obtained. By comparing the slope
geometries in the moments before and after the erosion incident on the snapshot
images at a particular time, we could obtain the volume of gravity erosion and
many other erosion data. A series of calibration tests were conducted and the results
showed that the accuracy of this technique was high and sufficient for exploring the
mechanism of slope erosion.
Keywords Natural hazard · Gravity erosion · Topography meter · Erosion volume
4.1 Quantitative Monitoring of Gravity Erosion
Applicable and precise instruments are vital to obtain credible data in experiments.
With the development of photoelectric, ultrasonic, and image processing technologies
(Meng and Janssen 2015; Thomas et al. 2014), noncontact observation instruments
with high efficiency and accuracy (e.g., digital photogrammetry and laser method)
have been invented and used in the survey of the terrestrial landform in laboratories.
However, strong sunshine and wind will present great difficulties in making precise
topographic measurements in the field, especially for the laser method. Determining
the best method to manage problems appearing in terrain evolution experiments is
an important subject of survey engineering that must be addressed.
Terrestrial laser scanning is a technology that allows the digital acquisition of
real objects, reproducing them in 3D space and digital form employing a cloud
of points (Du et al. 2013; Casula et al. 2010; Vondrak et al. 2006). Compared to
conventional methods such as triangulation, field and office time of operation was
reduced using laser scanning and GPS. Applications where safety may be an issue,
such as providing accurate measurements on a landslide or debris flow area, would
© Science Press and Springer Nature Singapore Pte Ltd. 2020
X. Xu et al., Experimental Erosion,
https://doi.org/10.1007/978-981-15-3801-8_4
45