基于CZMIL Nova的中国海岸带机载激光雷达测深潜力分析

Potential evaluation of China’s coastal airborne LiDAR bathymetry based on CZMIL Nova

浑浊水体导致激光脉冲能量急剧衰减,并在回波信号中产生大量噪声,导致点云密度降低,甚至无法探测到水底。因此机载激光雷达测深作业需要水体光学特性信息提供支撑,以减少无效测量。首先,基于CZMIL Nova理论测深,根据MODIS反演的中国海域水体漫衰减系数K_d(490 nm)数据,计算CZMIL Nova在海岸带水域的最大理论测深值,最大理论测深超过GEBCO(general bathymetric chart of the oceans)水深数据的区域,即为潜在可测区;然后,根据最大理论测深与GEBCO水深比值倍数进行可测潜力分类;最后,选取从清澈到浑浊3种水域实测数据对分类的合理性进行验证。结果表明,中国近海有21. 19万km^2区域具备开展机载激光雷达测深工作的潜力;适合开展海陆一体连续测量的区域为海南岛文昌—东方段、北海及雷州半岛东西岸、山东半岛日照—青岛段、辽东湾银州—绥中段,根据K_d(490 nm)值估算分别为水深20~40 m,10~20 m,20~25 m,10~15 m以浅范围。

Water transparency is the key factor of airborne LiDAR bathymetry.Turbid waters produce noise in LiDAR echo signal and weaken the laser pulse or cause a gap.Therefore,it is necessary to study water optical properties.Using MODIS K d(490 nm)and general bathymetric chart of the oceans(GEBCO)bathymetric data,the authors calculated the maximum detectable depth in China’s coastal area based on CZMIL Nova,and classified the result into 3 types.CZMIL test data from different areas were used to verify the accuracy of the classification.The results show that a total of 211,900 km 2 sea area is suitable for the performance of bathymetric survey with airborne LiDAR.The coastal area of Wenchang to Dongfang of Hainan,Beihai and the east and west of Leizhou peninsula,Rizhao to Qindao of Shangdong and Yinzhou to Suizhong of Liaodong Bay are suitable for the performance of land and sea integrating topographic survey,with the maximum measurable depths estimated by K d being 20~40 m,10~20 m,20~25 m,10~15 m,respectively.