IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT, VOL. 62, NO. 9, SEPTEMBER 2013 2549
A Proposal to Compensate Platform Attitude
Deviation’s Impact on Laser Point Cloud
From Airborne LiDAR
Jianjun Wang, Lijun Xu, Senior Member, IEEE, Xiaolu Li, Member, IEEE, and Zhongyi Quan
Abstract—The attitude deviations of an airborne stabilized
platform have significant impact on the distribution and point
density of the laser point cloud obtained from airborne LiDAR.
On one hand, the attitude deviations can cause the laser point
cloud to horizontally shift along the scanning direction, leading to
the coverage area deviating from the target terrain and resulting
in missing scan of some important topography. On the other
hand, the attitude deviations can cause the point density to
be nonuniform, further deteriorating the elevation accuracy of
the digital surface model (DSM) reconstructed from the laser
point cloud. Among the three attitude deviations of the airborne
stabilized platform, the roll and pitch deviations have more
significant impact than the heading deviation. Thus, it is of
practical importance to take appropriate steps to compensate the
attitude deviations of the airborne stabilized platform, especially
for the roll and pitch deviations. In this paper, firstly, an attitude
compensation device was designed to compensate the impact of
both the roll and pitch deviations in real time. Then, through
numerical simulation and semi-physical simulation experiments,
the compensation effectiveness of the device was evaluated.
The experimental results show that the device can effectively
compensate the roll and pitch deviations. After the compensation
of the roll and pitch deviations, offsets of the distribution of the
laser point cloud were well corrected, and the elevation accuracy
of the reconstructed DSM was improved.
Index Terms—Remote sensing, airborne LiDAR, attitude de-
viation, compensation, laser point cloud, DSM, accuracy.
I. Introduction
A
IRBORNE LiDAR is a novel and efficient topographic
surveying and mapping technology that can obtain the
laser point cloud of the surveyed terrain in real time or
semi real-time [1], [2]. After post-processing methods such
Manuscript received July 26, 2012; revised November 17, 2012; accepted
November 18, 2012. Date of publication July 9, 2013; date of current version
August 7, 2013. This work was supported in part by grants from the Major
State Basic Research Development Program of China (973 Program) under
Grant 2009CB724001, and the National Natural Science Foundation of China
under Grant 61201316. The Associate Editor coordinating the review process
was Dr. Mark Yeary. (Corresponding author: L. Xu)
J. Wang, X. Li, and Z. Quan are with the State Key Laboratory of Inertial
Science and Technology, School of Instrument Science and Opto-Electronic
Engineering, Beihang University, Beijing 100191, China (e-mail: wangjian-
jun@aspe.buaa.edu.cn; xiaoluli@buaa.edu.cn; quanzhongyi@gmail.com).
L. Xu is with the Key Laboratory of Precision Opto-Mechatronics Tech-
nology of Ministry of Education, School of Instrument Science and Opto-
Electronic Engineering, Beihang University, Beijing 100191, China (e-mail:
lijunxu@buaa.edu.cn).
Color versions of one or more of the figures in this paper are available
online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TIM.2013.2256763
as filtering and surface fitting, high-quality Digital Elevation
Model (DEM) and Digital Surface Model (DSM) or other
mapping products can be obtained [3], [4]. Because airborne
LiDAR has obvious advantages as compared with other tra-
ditional surveying technologies such as Photogrammetry and
Interferometric Synthetic Aperture Radar (InSAR), airborne
LiDAR technology has, in the past two decades, been rapidly
developed and widely applied in many fields such as topo-
graphic mapping, city modeling, hazard assessment, virtual
reality, reverse engineering, and heritage conservation [5], [6].
The elevation accuracy of the DSM reconstructed from the
laser point cloud is mainly dependent on the distribution,
point density and positioning accuracy of the laser point cloud
[7], [8]. Among them, the positioning accuracy of the laser
points mainly depends on the measurement accuracies of the
subsystems in the airborne LiDAR system, including the GPS,
the inertial navigation system (INS), laser rangefinder, and
optoelectronic rotary encoder, etc. [9]–[12]. The error in the
trajectory and the attitude deviations of the mounted platform
of a LiDAR have significant impacts on the distribution and
point density of the laser point cloud in the case of airborne
[13], but also in terrestrial measurement systems [14]. The de-
crease of the laser point density lowers the sampling resolution
of the laser footprints for the scanned terrain, further resulting
in decrease of the elevation accuracy of the reconstructed DSM
[15], [16].
The mechanism of the attitude deviations affecting the laser
point cloud and the elevation accuracy of the reconstructed
DSM is described as follows. Ideally, during the normal
measuring process of the airborne LiDAR, the airplane should
fly along a predesigned linear straight route with uniform
speed, so the attitude deviations are all zero. If the parameters
of the airborne LiDAR such as the scanning frequency, pulse
repetition frequency (PRF), flight altitude, speed, and attitude,
are all reasonably configured, the measured laser point cloud
can have ideal regular distribution area and uniform point
density. So, when such an ideal laser point cloud is used to re-
construct the DSM, which may have minimum distortion [17].
However, during the actual flight, due to various disturbances
such as gusts, turbulence, engine vibration and performance
defects of the control system, the airborne platform can not
maintain ideal flight state, but generate deviations in both flight
trajectory and attitude angles [15], [16], and [18]. The platform
attitude deviations have significant impact on the coverage area
0018-9456
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2013 IEEE