4.4 Results and Discussion
57
where the laser could not reach. Though we are fortunate that we didn’t meet such
a perplexity in our studies, it’s still a limitation of the technique. With the improvement of the construction of the laser source and the enlargement of the monitoring
range, the apparatus could be updated and this disadvantage could be eliminated.
Another serious shortcoming of the topography meter comes from the laboratory
image processing. The equipment of a camera similar to the traffic light, which
could autonomously take a snapshot as the failure occurs, could probably solve this
problem. At that time, the volume of individual collapse could be directly shown
on the screen, as the laser stripes are auto-vectored with ArcGIS, R2V, or other
professional software (e.g., Fechteler and Eisert 2009).
The topography meter could be applied in the field test as an appropriate observation environment, e.g., a portable tent, is provided. Presently the authors are conducting a site experiment using the topography meter on the Loess Plateau of China.
In the near future, our findings could be generalized to different regions which might
have different hydrological responses (e.g., Zhang et al. 2014).
4.5 Conclusions
A novel structured-light 3D surface measuring technique was developed to
quantitatively measure time-variable gravity erosion on the steep loess slopes. The
topography meter, mainly consisted of a camera, laser source, and positioning device,
has a function of recording slope deforming process under laser marking. Hence, 3D
vector images at the moment of erosion incident could be obtained. Erosion data,
including the amount of each failure mass, the total amount of soil loss eroded by
overland flow, etc., could accordingly be calculated. A series of calibration tests
indicated that the apparatus was at a sufficiently high accuracy, enough for the mechanism exploration of slope erosion, especially for that caused by gravity. More than
120 rainfall simulation events were also measured, further testifying its feasibility
and reliability. The apparatus is very promising in field observations after improving
the laser source and the imaging process.
References
Abellán A, Vilaplana J M, Martínez J. 2006. Application of a long-range Terrestrial Laser Scanner
to a detailed rockfall study at Vall de Núria (Eastern Pyrenees, Spain). Engineering Geology,
88(3): 136–148.
Casula G, Mora P, Bianchi M G. 2010. Detection of terrain morphologic features using GPS, TLS,
and land surveys: “Tana della Volpe” blind valley case study. Journal of Surveying Engineering,
136(3): 132–138.
Du J C, Teng H C. 2007. 3D laser scanning and GPS technology for landslide earthwork volume
estimation. Automation in Construction, 16(5): 657–663.
57
where the laser could not reach. Though we are fortunate that we didn’t meet such
a perplexity in our studies, it’s still a limitation of the technique. With the improvement of the construction of the laser source and the enlargement of the monitoring
range, the apparatus could be updated and this disadvantage could be eliminated.
Another serious shortcoming of the topography meter comes from the laboratory
image processing. The equipment of a camera similar to the traffic light, which
could autonomously take a snapshot as the failure occurs, could probably solve this
problem. At that time, the volume of individual collapse could be directly shown
on the screen, as the laser stripes are auto-vectored with ArcGIS, R2V, or other
professional software (e.g., Fechteler and Eisert 2009).
The topography meter could be applied in the field test as an appropriate observation environment, e.g., a portable tent, is provided. Presently the authors are conducting a site experiment using the topography meter on the Loess Plateau of China.
In the near future, our findings could be generalized to different regions which might
have different hydrological responses (e.g., Zhang et al. 2014).
4.5 Conclusions
A novel structured-light 3D surface measuring technique was developed to
quantitatively measure time-variable gravity erosion on the steep loess slopes. The
topography meter, mainly consisted of a camera, laser source, and positioning device,
has a function of recording slope deforming process under laser marking. Hence, 3D
vector images at the moment of erosion incident could be obtained. Erosion data,
including the amount of each failure mass, the total amount of soil loss eroded by
overland flow, etc., could accordingly be calculated. A series of calibration tests
indicated that the apparatus was at a sufficiently high accuracy, enough for the mechanism exploration of slope erosion, especially for that caused by gravity. More than
120 rainfall simulation events were also measured, further testifying its feasibility
and reliability. The apparatus is very promising in field observations after improving
the laser source and the imaging process.
References
Abellán A, Vilaplana J M, Martínez J. 2006. Application of a long-range Terrestrial Laser Scanner
to a detailed rockfall study at Vall de Núria (Eastern Pyrenees, Spain). Engineering Geology,
88(3): 136–148.
Casula G, Mora P, Bianchi M G. 2010. Detection of terrain morphologic features using GPS, TLS,
and land surveys: “Tana della Volpe” blind valley case study. Journal of Surveying Engineering,
136(3): 132–138.
Du J C, Teng H C. 2007. 3D laser scanning and GPS technology for landslide earthwork volume
estimation. Automation in Construction, 16(5): 657–663.