Acquisition of underwater topography in a mountain channel using Terrestrial Laser Scanning
Acquisition of underwater topography in a mountain channel using Terrestrial Laser Scanning
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使用地面激光扫描获取山地通道中的水下地形
DOI：
10.1117/12.2067143
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Y. Asano
中科院分区：
文献类型：
--
作者：
N. Miura;Y. Asano
为了更好地进行风险管理，需要对河道和河床结构进行详细和定量的测量，以吸收和预测山区河道中的水和泥沙流动情况。我们之前的研究表明，绿色波长TLS在测量陡峭山槽中的淹没河床方面表现出了良好的性能。结果还表明，水深和流速单独不会影响TLS测量的精度。相反，有人指出，数据采集的规范可能会对派生的数字地形模型(DTM)的精度产生影响。因此，本文研究了TLS的采集协议对山区航道数据采集精度的影响。首先，检验了不同扫描器高度，即入射角对数据采集的点密度和精度的影响。然后，检验最小点间距的差异，以找出它对所得到的数字地面模型的影响程度。还分析了不同方向采集的多个TLS数据的组合是否比单次测量的数据提高了数据精度。TLS获取的所有水下数据都经过了水折射改正，并利用野外测量数据进行了验证。试验结果表明，提高扫描仪高度或从多个方向采集数据可以提高DTM的精度，但获取密度较大、最小点距为1 mm的点云并不能提高数据的精度。
For better risk management, detailed and quantitative measurement of channel and stream-bed structure is required to assimilate and forecast how the water and sediment flow in mountain channels. Our previous research demonstrated good performance of green-wavelength TLS for measurement of submerged stream-bed in a steep mountain channel. The results also showed that each of water depth and flow velocity alone does not affect the accuracy of TLS measurement. Instead, it was indicated that the specification of data acquisition may have an impact on the accuracy of derived Digital Terrain Models (DTMs). Therefore, this paper examines how the acquisition protocol of TLS affects the accuracy of data collected in the mountain channel. First, it is tested whether different scanner height, that is, incident angle affects the data acquisition in terms of point density and accuracy. Then, the difference in minimum point spacing is examined to find how much impact it has on derived DTM. It is also analyzed whether a combination of multiple TLS data acquired from different direction improves data accuracy, compared to the data acquired by single measurement. All the acquired underwater data by TLS are water refraction corrected and validated using field surveyed data. The results of these tests showed that the accuracy of derived DTM was improved when the scanner height was raised or data was acquired from multiple directions, however, acquiring denser point cloud with minimum point spacing of 1 mm did not improve the accuracy of the data.