Xianhai Bu

Shandong University of Science and Technology

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Fanlin Yang

Ministry of Natural Resources

Fangzheng Xu

Shandong University of Science and Technology

Zhendong Luan

Institute of Oceanology

Miao Fan

Beijing Children’s Hospital

Sai Mei

Qingdao Institute of Marine Geology

Yue Ma

Wuhan University

Wenyi Duan

Zhengzhou Fruit Research Institute

Zejie Tu

Shandong University of Science and Technology

Dongyue Tang

Zhejiang Institute of Hydraulics & Estuary

Zhe Xing

Fifth Affiliated Hospital of Zhengzhou University

Cooperative Institutions

Shandong University of Science and Technology

Ministry of Natural Resources

Chinese Academy of Sciences

Ocean University of China

National Administration of Surveying, Mapping and Geoinformation of China

China University of Petroleum, Beijing

Second Institute of Oceanography

Zhejiang Institute of Hydraulics & Estuary

Ministry of Industry and Information Technology

Lanzhou University

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Continuous-Scale 3D Terrain Visualization Based on a Detail-Increment Model

ISPRS International Journal of Geo-Information (2019)

Bo Ai Linyun Wang Fanlin Yang Xianhai Bu Yaoyao Lin

Triangulated irregular networks (TINs) are widely used in terrain visualization due to their accuracy and efficiency. However, the conventional algorithm for multi-scale terrain rendering, based on TIN, has many problems, such as data redundancy and discontinuities in scale transition. To solve these issues, a method based on a detail-increment model for the construction of a continuous-scale hierarchical terrain model is proposed. First, using the algorithm of edge collapse, based on a quadric error metric (QEM), a complex terrain base model is processed to a most simplified model version. Edge collapse records at different scales are stored as compressed incremental information in order to make the rendering as simple as possible. Then, the detail-increment hierarchical terrain model is built using the incremental information and the most simplified model version. Finally, the square root of the mean minimum quadric error (MMQE), calculated by the points at each scale, is considered the smallest visible object (SVO) threshold that allows for the scale transition with the required scale or the visual range. A point cloud from Yanzhi island is converted into a hierarchical TIN model to verify the effectiveness of the proposed method. The results show that the method has low data redundancy, and no error existed in the topology. It can therefore meet the basic requirements of hierarchical visualization.

Raised-relief map

Triangulated irregular network

10.3390/ijgi8100465

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A Backscattering Angular Response Removal Method Combining Kirchhoff Approximation with Mathematical AR Curves

Qiyao Xu Sai Mei Zejie Tu Xianhai Bu Feng Wang

Acoustic backscatter from seafloor is dependent on incident angle, and generally the angular dependence is removed by angular response (AR) models. For the research of high-frequency multi-beam sonar, not many angular response models have been proposed, most of which are obtained by simple mathematical averaging methods, which leads to the problem of low reliability of backscatter strength in the nadir spectral reflection area. To solve this problem, in this study, the traditional acoustic scattering method (Kirchhoff approximation) constrained by the genetic algorithm is combined with the mathematical method to build a new AR model. The range of incident angle is divided into two domains, and the AR models in different domains are established separately according to different methods to improve the correction effect of the sonar image. R2Sonic 2024 multi-beam echosounder dataset (400 kHz) collected in the Jiaozhou Bay is used to test the validity of proposed method, and the experimental results show that the standard deviation of the backscatter strength deviations of the conjugate points in the overlapping area is reduced from 7.41dB to 4.87dB, which meets the error requirement. The proposed method is verified to effectively eliminate the backscattering angular dependence and improve the quality of the multi-beam sonar image.

Backscatter (email)

10.1109/icccbda51879.2021.9442595

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Erratum to: Automatic calibration for wobble errors in shallow water multibeam bathymetries

Journal of Oceanology and Limnology (2022)

Tianyu Yun Xianhai Bu Zhe Xing Zhendong Luan Miao Fan

Speed wobble

10.1007/s00343-022-2473-7

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Citations (1)

A Precise Method to Calibrate Dynamic Integration Errors in Shallow- and Deep-Water Multibeam Bathymetric Data

IEEE Transactions on Geoscience and Remote Sensing (2021)

Xianhai Bu Sai Mei Fanlin Yang Zhendong Luan Fangzheng Xu

Acoustic remote sensing with multibeam echo-sounder systems (MBESs) has been extensively used for coastal and ocean survey works. The imperfect integration of multibeam echo sounder and motion sensor can introduce integration errors, which manifest as high-frequency wobbles in swaths and hinder the accurate expression of high-resolution seabed topographic maps. To address this issue, a precise method is developed to calibrate these integration errors based on a simplified georeferenced model. First, an equivalent attitude coordinate (EAC) system is defined to represent mutual transformation between equivalent attitudes and the beam launch vector; then, with the help of equivalent attitudes, a simplified footprint georeferenced model is deduced that considers the effect of the parameterized integration errors (including time delay, motion scale, yaw misalignment, and lever arm errors); finally, in a selected flat region, integration errors are inverted by regressing the bathymetric data to the corresponding fitted plane via the differential evolution (DE) algorithm. The results indicate that the proposed method can effectively eliminate wobbles in multibeam bathymetries caused by single or multiple integration errors in both shallow- and deep-water areas. By comparing the data before and after calibration with the in situ measurements, the accuracy of the calibrated shallow- and deep-water data is controlled within approximately 0.15% and 0.06% of the water depth, respectively.

Echo sounding

Footprint

10.1109/tgrs.2021.3097723

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Improved calibration method for refraction errors in multibeam bathymetries with a wider range of water depths

Applied Ocean Research (2021)

Xianhai Bu Fanlin Yang Mingzhen Xin Kai Zhang Yue Ma

Nadir

10.1016/j.apor.2021.102778

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Characterisation of Terrain Variations of an Underwater Ancient Town in Qiandao Lake

Remote Sensing (2020)

Fanlin Yang Fangzheng Xu Kai Zhang Xianhai Bu Hao Hu

The underwater ancient town of Chunan is of great importance in archaeology and tourism. Hence, the efficient mapping and monitoring of the topographical changes in this town are essential. An attractive choice for the efficient mapping of underwater archaeology is the multibeam echo sounder system (MBES). The MBES has several advantages including noncontact survey, high precision, and low cost. In this study, the topographical changes of the ancient town under Qiandao Lake were quantitatively assessed on the basis of time-series MBES data collected in 2002 and 2015. First, the iterative closest point (ICP) algorithm was applied to eliminate the coordinate deviations between two point sets. Second, the robust estimation method was used to analyse the characterisations of the terrain variations of the town on the basis of the differences between the two matched point sets. Obvious topographical changes ranging from −0.89 m to 0.88 m were observed in a number of local areas in the town. On the global scale, the mean absolute value of the depth change in the town was merely 0.12 m, which indicated a weak global deformation pattern. The experiment proved the effectiveness of applying MBES data to analyse the deformation of the ancient town. The results are beneficial to the study of underwater ancient towns and the development of protection strategies.

10.3390/rs12020268

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Multibeam seafloor reverberation simulation considering ocean and seafloor environmental parameters

Yu Luo H. Wang Xianhai Bu

As a controllable, lowcost and repeatable test method, reverberation simulation plays an important role in developing sonar device. With the development of sonar systems such as multi-beam bathymetry systems, the requirements for reverberation simulation are getting higher and higher. In this paper, the unit scattering model is used for modeling, and parameters such as the propagation loss, sound absorption coefficient, bottom reflection loss and seabed roughness are considered.The seafloor reverberation simulation model is established by using the three-parameter model and the semiempirical formula of sound absorption coefficient. The output of the simulation is in concodence with the statistical properties of a large number of seabed reverberation secondary beam data. And in comparasion with real reverberation signal, the effectivemess of this model is verified.

Seabed

Seafloor Spreading

Reflection

Reflection coefficient

10.1117/12.3019400

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Simplified calibration method for multibeam footprint displacements due to non-concentric arrays

Ocean Engineering (2019)

Xianhai Bu Fanlin Yang Yue Ma D. Wu Kai Zhang

Footprint

10.1016/j.oceaneng.2019.106862

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Citations (8)

Automatic calibration for wobble errors in shallow water multibeam bathymetries

Journal of Oceanology and Limnology (2022)

Tianyu Yun Xianhai Bu Zhe Xing Zhendong Luan Miao Fan

Speed wobble

10.1007/s00343-021-1283-7

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An Intelligent Detection Method for Different Types of Outliers in Multibeam Bathymetric Point Cloud

IEEE Transactions on Geoscience and Remote Sensing (2022)

Fanlin Yang Fangzheng Xu Miao Fan Xianhai Bu Zejie Tu

Bathymetric Multibeam echo sounder systems (MBESs) are the most effective and reliable way to survey the earth’s seafloor. However, multibeam bathymetric data inevitably contain different types of outliers due to measurement characteristics and complex underwater environments. The traditional automatic approach to eliminate outliers may lead to more than one of the questions of reliability, limitation, and efficiency, respectively. This paper offers an algorithm aiming to detect different types of outliers by considering their characteristic of distribution and distance of them, rapidly. First, a coding octree based on Morton code is built to guarantee perfect efficiency and space division. Second, coarse outlier removal is performed by octree-based voxelized representation of the bathymetric data, and outliers far away from the seafloor will be detected and eliminated by connected component labeling. Third, fine outlier removal is employed to delete outliers connected closely to the seafloor by the improved morphological method based on the combination of the k-d tree and octree. Experimental results show that the proposed algorithm can achieve promising results. The percent of outliers that are detected by the hand-edit method that is regarded as a reference result is 5.06%. 4.70% of points in a total number of 3645541 points are detected in our method. Compared with other classical filtering methods, the intelligent method for detecting different types of the outlier from coarse to fine attains favorable performance in a reasonable time, avoiding over-filtering, and demonstrates high reliability for multibeam bathymetric point cloud.

Octree

10.1109/tgrs.2022.3209344

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Citations (7)