ibul 2004 
TREE-HEIGHT MEASURING CHARACTERISTICS OF URBAN FORESTS 
BY LIDAR DATA DIFFERENT IN RESOLUTION 
Y. Imai* *, M. Setojima?, Y. Yamagishi ", N. Fujiwara* 
* Kokusai Kogyo Co., Ltd. , 5 Sanbancho, Chiyoda-ku, Tokyo, Japan - (yasuteru_imai, mseto)@kkc.co.jp 
® Organization for Landscape and Urban Greenery Technology Development , 1-21-8 Toranomon, 
Minato-ku, Tokyo, Japan - yamagishi@greentech.or.jp 
* National Institute for Land and Infrastructure Management , 1 Asahi, Tsukuba-shi, Ibaraki, Japan - 
fujiwara-n92db(à) nilim.go.jp 
Commission VII, WG VII/4 
KEY WORDS: LIDAR, Urban, Vegetation, Multiresolution, Measurement, Accuracy, Comparison 
ABSTRACT: 
Urban forests are important as valuable green resources to give moisture and tranquillity of mind in our living, requiring an efficient 
control of forest increase/decrease and growth rate. In this study, we conducted tree-height measurements using LIDAR data 
different in resolution at urban parks in the suburbs of Tokyo, and investigated the measuring characteristics. As a result, for conifers, 
LIDAR data of high resolution (1 m) of high treetop irradiating probability showed higher measuring accuracy. For trimmed 
broadleaf trees, on the other hand, the LIDAR data of low resolution (2 m) of low penetration probability between branches showed 
higher measuring accuracy, indicating that the tree-height measuring accuracy by the LIDAR data does not necessarily depend on 
the resolution. 
1. INTRODUCTION 
Urban forests are important as valuable green resources to give 
moisture and tranquillity of mind in our living. In recent years, 
much attention has been directed to the diversified functions of 
urban forests such as the contribution to the prevention of 
global warming through the absorption of CO, of plants, 
mitigation of heat island phenomena by the evapotranspiration 
of vegetation and disaster prevention effect such as the creation 
of sheltering space and prevention of fire spread. Especially, 
high expectation is accorded to the prevention of global 
warming by CO, absorption function of plants in relation to the 
Conference of the Parties to the United Nations Framework 
Convention on Climate Change (COP) (Handa & Teshirogi, 
2002). 
The continuous monitoring of increase/decrease and volume of 
growth of plants is necessary to promote the conservation and 
creation of urban forest. To this end, LIDAR is effective means 
in monitoring wide ranged area, and many studies have been 
conducted in recent years as the measurement of tree height 
using LIDAR provide basic parameter of CO, absorption 
volume (Yamagata et al., 2002). However, the measurement of 
tree height by LIDAR has been mostly conducted at mountain 
forest, and the case studies at urban forest are rather scarce. In 
addition, the platform of LIDAR is roughly classified into 
rotary wing (helicopter) and fixed wing (Cessna) but the study 
on the comparison of both platforms is very few. 
In this study, we measured the tree height of urban forests using 
the LIDAR data of different acquisition density obtained by 
rotary wing and fixed wing, and studied their measuring 
characteristics. 
  
* Corresponding author. 
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2. MATERIAL 
2.1 Study Site and Field Survey 
Target area is set to Koganei Park in Tokyo, Japan (Figure 1). 
The park comprised of area of 77 hectares containing variety of 
trees with blend of the different combination and density. Study 
sites area selected from this park because the park contains 
different types of tree and the ground truths for the verification 
of those areas are easily obtained by the field survey. Five sites, 
named St.1, St.2, St.3, St.4 and St.5, are selected regarding to 
the tree types, the height, and the density. Detail information 
are shown in the Table |. 
Field surveys are conducted in the all sites on November 5 and 
6 of 2002. For each tree, the position, the height, the diameter at 
breast height, and the species are obtained as the ground truth. 
The positions and heights of every tree are acquired using the 
differential GPS (GPS Pathfinder Pro/XR) and the laser 
measurement instrument (LaserAce300). Information about the 
diameter at breast height and the species are based on the actual 
measurement. 
2.2 Multispectral Satellite Image 
In this study, we used IKONOS data to extract the vegetation 
area. IKONOS data we used is that obtained on September 21, 
2000 and the ortho-corrected multi-spectral (red, green, blue 
and near infrared) image, and its spatial resolution is 4 m 
(horizontal accuracy +/- 3.5 m) (Table 2).