Abstract
Accuracy verification of airborne large-footprint lidar data is important for proper data application but is difficult when ground-based laser detectors are not available. Therefore, we developed a novel method for lidar accuracy verification based on the broadened echo pulse caused by signal saturation over water. When an aircraft trajectory crosses both water and land, this phenomenon and the change in elevation between land and water surfaces can be used to verify the plane and elevation accuracy of the airborne large-footprint lidar data in conjunction with a digital surface model (DSM). Due to the problem of echo pulse broadening, the center-of-gravity (COG) method was proposed to optimize the processing flow. We conducted a series of experiments on terrain features (i.e., the intersection between water and land) in Xiangxi, Hunan Province, China. Verification results show that the elevation accuracy obtained in our experiments was better than 1 m and the plane accuracy was better than 5 m, which is well within the design requirements. Although this method requires specific terrain conditions for optimum applicability, the results can lead to valuable improvements in the flexibility and quality of lidar data collection.
Highlights
Light detection and ranging integrates laser technology, the global positioning system (GPS), and the inertial navigation system (INS) into a highly accurate measurement system
Japan launched the lunar satellite with the Lunar Orbiter Laser Altimeter (LOLA) in 2007 [13], and China launched the ZiYuan3-02 (ZY3-02) satellite in May 2016 [14] and the GaoFen-7 (GF-7) satellite in November 2019 [15]
Using the proposed accuracy verification method for airborne large-footprint lidar based on terrain features (Section 2.3), the elevation and plane accuracy of the data processed by the processing flow shown in Figure 2 are verified
Summary
Light detection and ranging (lidar) integrates laser technology, the global positioning system (GPS), and the inertial navigation system (INS) into a highly accurate measurement system. Lidar can be divided into small-footprint systems that discretely record a small amount of echo data in higher detail, and large-footprint (8–70 m) systems that record complete waveforms over a broader range, which exhibit greater ability to penetrate vegetative canopies but have relatively lower resolution [1]. The latter allows accurate measurements of surface information at larger scales and plays an important role in polar ice sheet measurement, vegetation height inversion, biomass estimation, and other fields [2,3,4,5,6]. Japan launched the lunar satellite with the Lunar Orbiter Laser Altimeter (LOLA) in 2007 [13], and China launched the ZiYuan (ZY3-02) satellite in May 2016 (the first experimental satellite payload equipped with a laser altimeter for Earth observation) [14] and the GaoFen-7 (GF-7) satellite in November 2019 (the first formal spaceborne laser altimeter equipped for global stereo mapping) [15]
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