3-2-1
Positioning Principles and Accuracy of Airborne Laser-
Ranging & Multispectral-lmaging Mapping System*
Liu Shaochuang You Hongjian Xiang Maosheng Liu Tong Li Shukai
Dept, of Iconic Informatics
Institute of Remote Sensing Applications
Chinese Academy of Sciences
100101, Beijing, P.R.China
E-mail: iconinfo@irsa.irsa.ac.cn
Commission II, Working Group 1
KEY WORDS: Geographic Georeferencing, GPS/INS, Laser Range Finder, Multispectral Imaging,
Airborne Laser-Ranging & Multispectral-lmaging Mapping System (ALIMS)
ABSTRCT This paper provides a systematic description to the positioning accuracy of Airborne Laser-Ranging &
Multispectral-lmaging Mapping System (ALIMS). This airborne integrated mapping system is developed for
capturing topographic and multispectral information of the earth surface in the form of georeferenced multispectral
imagery with Digital Elevation Model (DEM). It is driven by the availability of Global Positioning System (GPS),
compact ruggedized solid state lasers, high precision airborne inertial navigation systems and rugged precise high
speed multispectral scanner, The DEM and georeferenced multispectral imagery matched accurately when they are
captured. This is essential for many remote sensing purposes, such as geometric and radiometric rectification of
the multispectral image, the utilization of auxiliary information for multispectral image classification etc. This is
reached by using Laser-Ranging & Multispectral-lmaging Coupled Scanner (LRMICS) that developed by our
team in IRSA.
1. Introduction
Today primary data acquisition for Geographic Information System (GIS) is one of the most
important and challenging tasks of photogrammetry and remote sensing. Until recently, in the
context of airborne GIS data acquisition the role of photogrammetry and remote sensing has been
changed slightly different. Although it is traditional approach to produce geometric description of
the earth surface, photogrammetry is characterized by highly complicated, expensive stereo
measurement instrument and skilled operators(Holger et al 1994). For many remote sensing
applications, DEMs are based on existing data and numerous ground control points (GCPs). The
coordinates of ground control points have to be determined. It can be measured from existing
topographic maps or terrestrial measurements. The former is often low quality and the latter
results in high production cost. Both approaches are characterized by time-consuming. An optimal
tool for GIS data acquisition would have the following properties: fast, cost-effective, area-covering,
kinematic, automatic, easy to handle, real-time (or at least close to real time), accurate, reliable and
large scale ( Holger et al 1994).
Airborne laser scanning technology is emerging as an attractive alternative to the traditional
techniques for large scale geospatial data capture (Flood and Gutelius 1997) and used in the field of
topographic terrain mapping, coastal, surveying and surveillance of infrastructures such as roads,
power lines etc.(Lillycrop, 1994, Estep et al 1994, Lohr 1997, Hug 1996, Haala et al 1996, Schade et
al 1994, Ward 1997, Vaughn et al 1996, Kappari et al 1996, Kraus et al 1998). It is proven that
these systems have the capabilities of high accuracy, rapid area coverage, high sample density, day
and night operation. The use of these systems is growing quickly. Airborne Laser-Ranging &
Multispectral-lmaging Mapping System (ALIMS) is integrated mapping system for capturing the
topography of the earth surface in the form of Digital Elevation Model (DEM) and spectral
information in the form of georeferenced imagery (Li S. 1996). The development of ALIMS is driven
by the availability of compact ruggedized solid state lasers, high precision airborne inertial
navigation systems (INS), high precision differential Global Positioning System (GPS), high
precision and high speed scanner as practical laser-based topographic terrain mapping and remote
sensing system.
♦This paper was partly supported by Chinese Post-Doctoral Sciences Funds
