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Influence of Aircraft Attitude Fluctuations on Point Cloud Density and Digital Surface Model (DSM) Accuracy from Airborne LiDAR
J-J. Wang, L-J. Xu, Y-Y. Fan, X-S. Guo and X. Liu

For airborne LiDAR technology, attitude fluctuations of airborne platform can significantly influence the accuracy of the obtained point cloud products. In order to quantitatively evaluate the influencing size of the platform attitude fluctuations, so as to find out appropriate method to eliminate this un-favourite impact, we analysed the influencing mechanism of the platform attitude fluctuations on the accuracy of the reconstructed digital surface model (DSM) based on the two-dimensional (2-D) Whittaker-Shannon Sampling Theorem firstly. Next, through numerical simulation, the influencing characteristics of the platform attitude fluctuations on the point density distribution of the laser point cloud were studied. Finally, a semi-physical simulation system was built to simulate the working procedure of airborne LiDAR under the influence of platform attitude fluctuations, and the impact of the platform attitude fluctuations on the area of coverage and point density of the laser point cloud was validated. The obtained laser point cloud was used to reconstruct a DSM based on the triangular irregular network (TIN) model, and the distortion of the reconstructed TIN-based DSM caused by the platform attitude fluctuations was quantitatively evaluated. Experiment results show that, when the airborne platform has an attitude fluctuation of sinusoidal movement with the amplitude of 3.0º and the frequency of 0.5 Hz, the elevation error of the reconstructed DSM has an increase of 0.062% of the flight height above ground level, corresponding to the increase of elevation error of 31.1 cm for the DSM at the actual flight height of 500.00 m, which means that the platform attitude fluctuations is a much significant factor for deteriorating the accuracy of the reconstructed DSM; therefore, appropriate measures should be taken to prevent from the attitude fluctuations. Future research will focus on the compensation of platform attitude fluctuations for airborne LiDAR.

Keywords: Airborne LiDAR, error analysis, attitude fluctuation, digital surface model (DSM), three-dimensional (3-D) imaging, accuracy, measurement errors, distortion, semi-physical simulation

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