Data Compression of Airborne Laser Scanner Data

Data Compression of Airborne Laser Scanner Data

T. Asanuma
1Pasco Corporation, 1-1-2 Higashiyama, Meguro-Ku, Tokyo 153-0043, Japan
Email: toshikazu_asanuma@pasco.co.jp

N. Monma, T. Sasagawa, and H. L. Guan
Pasco China Consulting Co., Ltd, 610 Level 6, Tower E2,
Oriental Plaza, No.1 East ChangAn Ave.,
DongCheng District, Beijing, 100738, China
Email: naokazu_monma@pasco.co.jp, tadashi_sasagawa@pasco.co.jp, hongliang_guan@pasco.co.jp

1. Introduction
One of the methods that can automatically find the area of destroyed buildings caused by the disaster is to compare the digital surface models between before and after the disaster. It is difficult to transmit the huge laser scanner data acquired from the airborne to the ground station at the moment. However, in this study, the laser point density needed to judge the disaster was determined as the buildings were target, and the compression ratio was evaluated to transmit acquired data to the ground by the current transmission ratio. Although, the compression ratio was not satisfied using the standard compression methods, a compression method on real time from mission was realized and suggested.

2. Definition of the target compression ratio

2-1. The transmission ratio from airborne to the ground
It is reported that the airborne transmission of captured data on real time was successful using N-STAR satellite by the National Institute of Information and Communication Technology. Experiments were also made to consider using the ultra high-speed Internet satellite, WINDS. The maximum transmission ratio was 6.0 Mbps from these reports, and the actual transmission rate was defined as 3.0 Mbps in this study as the transmission efficiency

2-2. Laser point density and acquisition conditions
The area of the ground structure was determined from the 3D model in a city, and the minimum area for the building structure was defined. Fig. 1 shows the distribution of the surface area of the structures. The distribution of the surface area for each structure was calculated, and the minimum area defined as thebuilding was set to 20 m2. Then the minimum number of pulse needed to judge the shape of the building was set 4 pulses, and the flight plan was decided by this precondition. Table 1 and 2 show the specifications of the data acquisition and the amount of the acquired data, respectively.

Fig. 1. The distribution of the surface area of the structures.
Table 1. The specifications of data acquisition.

Time
FOV
Altitude
Flight speed
Pulse rate
Scan rate
Laser side lap
Cross track [max]
Along track [max]
Point density [min]

1.05 H
40 degree
6500 ft AGL
110 knots
45000 Hz
24.44 Hz
30
%2.10 m
2.32 m
0.205 points/m2

Page 1 of 3
| Next |