1-1-1 
A ROBUST METHOD FOR REGISTERING 2.5D LASER RANGE IMAGES OF 
URBAN OBJECTS 
Huijing ZHAO , Ryosuke SHIBASAKI 
Center for Spatial Information Science, Univ. of Tokyo 
Email: chou@skl.iis.u-tokyo.ac.jp 
Commission II, Working Group I 
KEYWORDS : laser range image, registration, urban 3D object 
ABSTRACT 
In this paper, a method for registering 2.5D laser range image of urban object is proposed. The problem is solved in two 
levels, pair-wise registration to find the local matching between successive views and multiple views’ registration to 
obtain global matching. A kind of Z-lmage is introduced. Pair-wise registration using Z-lmage is developed, where 4 
transformation parameters, a horizontal rotation angle and three translation parameters, are tracked. In multiple views’ 
registration, accumulation of estimation error in pair-wise registration is solved as a least square minimization problem. 
Through an outdoor experiment for reconstructing 3D model of the buildings at IIS, University of Tokyo, it is demonstrated 
that the registration method has robustness and accuracy in the sense of automation. 
1 INTRODUCTION 
As the development of mobile navigation system, ITS 
(intelligent transportation system) and other 3D GIS 
applications, complete and accurate urban spatial 
database is becoming strongly demanded. Reconstructing 
3D urban objects using ground-based acquisition 
techniques are attracting more and more attentions. 
Several researches using CCD camera have 
demonstrated that 3D information can be extracted using 
motion (S.Ozawa et.al. 1998) and stereo (M.Okutomi and 
T.Kanade 1993) vision techniques. However, the 
difficulties in reliable stereo matching, distortion from 
limited resolution and unstable geometry of CCD cameras 
are the major obstacles to the accuracy of the method. On 
the other hand, recent years have witnessed a substantial 
development of range collecting techniques. Researches 
using range sensors can be founded in C.Thorpe 
ef.a/.1998 in a mobile navigation system, B.Kamgar-Parsi 
et.al. 1991 to obtain a map of ocean floor, Y.Chen and 
G.Medioni 1992, G.Champleboux et.al. 1992, H.Shum 
ei.a/.1994, K.Ng et.al. 1998 to construct 3D models for 
indoor objects. Efficiency and accuracy of range sensors 
serving for spatial object’s reconstruction has been 
demonstrated. In recent years, with the development of 
laser technique, range finder using eye safe laser, with 
long range measurement and high speed is being used 
for urban purpose. One of the major topics in 
reconstructing spatial object using range sensor is the 
registration of range images of different configuration. This 
paper contributes to a practical method for the registration 
of 2.5D laser range images of urban objects. 
To obtain laser range images of urban object, a laser 
range finder is installed on a vehicle or directly on the 
ground. Once a view of laser range image is measured, 
the sensor is moved to the next viewpoint. A three 
dimensional registration method using planar faces has 
been investigated in our previous work (Zhao and 
Shibasaki, 1997). Robustness of method is insufficient in 
urban outdoor environment, since enough number of 
planar faces is difficult to be extracted for the following 
reasons. First, laser range measure in urban area has 
high uncertainty, which might be caused by trees, window 
glasses, passing cars and pedestrians. Secondly, objects 
other than interest, such as window frame, electric cable,