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3D terrestrial laser scanner (TLS) provides both 3D point coordinates and intensity data of scanned object surface. The intensity data can be used to discriminate different materials, since it partly represents the object reflection characteristic at the laser wavelength. In addition to laser reflectance properties of object, the intensity data is influenced by many other factors, such as instrument mechanism, environmental condition, distance and incidence angle. In this paper, the effects of distance and incidence angle are studied. Except for standard reflector, some building facades of various kind of material were used as experimental samples. Experimental survey find that the intensity is inversely proportional to distance and incidence angle, but their relations do not agree with the theoretical model. Several models were selected to describe the relations between intensity and distance, intensity and incidence angle. The suitability of each model was analyzed by its correlation coefficient.

Terrestrial laser scanner (TLS) can provide the measurement of a large number of physical points distributed on the observed surface. A fast earthwork calculating method is proposed based on the redundant number of acquired points, which leads to a very accurate and high resolution reconstruction of the observed surfaces. This paper describes the three main steps of the method, namely the acquisition of the earthwork data based on TLS, the pre-processing of point cloud data, the earthwork calculation and accuracy evaluation based on point cloud data. Furthermore, it illustrates the performance of the proposed method with a validation experiment.

Deformation monitoring is typically undertaken using spare, point-wise geodetic surveying techniques, such as total station or GPS. Deformation monitoring using terrestrial laser scanning is gaining considerable attention mainly due to the high spatial resolution of the acquired data. It can provide dense 3D information of the surface of an object. A disadvantage of the technique may be the difficulty to assess some fixed benchmarks on the surface of the deforming area, unless they are special targets that can be recognised by the accompanying software. To solve this problem, a new automatic deformation acquisition method based on nurbs surface was presented. The paper discusses methods of nurbs surface modelling implemented for deformation monitoring and approaches used to measure the deformation from surfaces. Finally, applications involving the use of laser scanning in bridge are presented.

This paper proposes a underwater acoustic coherent chaotic communication scheme which is suitable for shallow water channel mainly at 80bps rate. The encoding uses a decoupling mode, and the modulated signal doesn't contain common binary information. Orthogonal basis signals are engendered directly by Gaussian white noise carriers. The tolerance of time synchronization and the ability of resistance to inter-symbol interference (ISI) are achieved. The binary mapping decoding is engendered in correlation demodulating mode, and the copy correlator is used to match processing. Some problems have been considered, such as the system detection threshold, Doppler matching, the frequency compensation of copy sample, etc. The theoretical calculation and test method are provided. We use 1 kHz narrowband signal to enhance the ability of anti-dispersive fading in shallow static and dynamic experiments. Robust communication is achieved while the receiving threshold is above 0dB, and meanwhile the transmission loss rule is verified in shallow water channel.

The Xixiayuan project is a regulating reservoir in china. The concrete dam section is constructed on soft rock foundation. In this paper, we present the case study on the treatment for the soft rock foundation. The treatment includes the construction of concrete cut-off wall, reinforcement by dynamic compaction method, and installation of the stone columns. The treatment was justified by the field instruments installed in the foundation. The measured data show that the treatment can reduce significantly the settlement at the foundation. Moreover, layered settlement was employed in the analysis. The results demonstrate that very small total and differential settlement occurred in the foundation. The analysis illustrate the success of the treatment for the soft rock dam foundation, and useful for gaining experience for future designs and analysis.

LIDAR (Light Detection And Ranging) has become a reliable technique for the data collection of the earth surface. Building extraction based on LIDAR data is one of the important applications. The image edge is one important feature of a building, which can reflect the most valuable information of the image. And it can roughly describe the characteristics of the building. So building edge extraction from LIDAR data is of great significance. This paper presents an automatic extraction method of building edges from LIDAR data, using image segmentation technology. In the first stage, the LIDAR point cloud data are converted into DSM images. In the second stage, a threshold selection method based on the transition region determination is used to segment the DSM images. Finally, the building edges are extracted on the segmented image. The results obtained on the data sets with different ground point density, gathered over the town of Xuzhou (China) with TopScan airborne laser scanning system, are shown to illustrate the effectiveness of the proposed approach.