Urban Vegetation Cover Mapping with Vegetation Cover
Naoki Shirai*, Masahiro Setojima*, Akira Hoyano**, Donkyu Yun**
(*Kokusai Kogyo co., Ltd., **Tokyo Institute of Technology)
2 Rokuban-cho, Chiyoda-Ku, Tokyo, 102-0085, Japan
Tel: (81)-3-3288-5812 Fax:(81) -3-3262-6250
E-mail: nshirai@kkc.co.jp
Abstract
Since most vegetation in urban area is small scale one, VCRP ( vegetation cove ratio is in a pixel) is known as a suitable method for vegetation cover mapping in urban area. Putting to practical use of the vegetation cover mapping, tow practical method have been proposed , which are quantification of VCRP and sub- classification vegetation to tree, grass and lawn. The method was applied to Kanazawa area. Comparing the results of field survey, it was confirmed the adaptability of the method.
Introduction
In recent years , a realization of an environmental friendly urban is raised as an important subject in Asian countries . especially, an urban revegetation is attracted attention on the point of vegetation environmental alleviating effect. It is essential work for revegetation in urban are required, considering the thermal environment in urban and the living environment in ecosystem. Since the effect of the subcategories is different on the aspect of environment adjustment, it is also required to classify the vegetation into subdivided subcategories of tree, grass and lawn.
Proposal for putting to practical use of the vegetation cover mapping with VCRP using he multispectral data is aim of this study. Concrete themes are to propose a practical method for VCRP quantification and sub classification vegetation to tree, grass and lawn.
Quantification of VCRP
Most of urban vegetation is small scale one such as roadside tree, garden trees, and so on. It should not be ignored on the point of the environment adjustment effect. In this respect, the spatial resolution of satellite remote sensing data ( including commercial satellite in near future ) should be not profitable for pixel wise analysis on the urban vegetation. Authors have been developing the vegetation mapping with VCRP.MRVI (Modified Ratio Vegetation Index ) is an index for extracting VCRP
[1].
Since MRVI is approximately linear to VCRP, which can be estimated mean MRVI values of pure vegetation and non-vegetation , respectively . therefore, obtaining method for mean MRVI values of pure vegetation and pure none-vegetation has been proposed using arbitrary multispectral data. Figure 1 explains the method for extracting the mean MRVI values of vegetation and non-vegetation. Part A and B indicate the MRVI frequency of pure vegetation and pure non-vegetation, respectively. Mean MRVI values can be derived from the calibration of part A and B.
Fig.1 Schemestic histograms of vegetation, non-vegetation and all pixel.
Figure 2 shows an example adapted the calibration method to Kawasaki area. The reference data for comparison had been used vegetation cover map constructed by the field survey. The border line between vegetation and non-vegetation regard as mixed of vegetation and non-vegetation . the difference between mean MRVI obtained by above method and that obtained by field survey was 0.01 (vegetation ) and 0.02 (non-vegetation ) respectively, which correspond within VCRP5 percent. From the results, it has been found that the method is adequatabel for VCRP estimation method.
Fig.2 MRVI histogram in kawasaki area (Airborne/MSS ,1.9m) and separating the histograms of vegetation and non-vegetation from all MRVI histogram
