FEATURE EXTRACTION FOR METRIC CHARACTERIZATION OF RESIDENTIAL URBAN FORM OF HANOI CITY.GUIDELINES FOR AUTHORS ASIAN CONFERENCE ON REMOTE SENSING ACRS 2010

摘要

The development of Hanoi city has undergone different historical and socio-economic periods of Vietnam and it is explicitly reflected in the variety of urban forms of the residential space of different quarters of Hanoi. It is important to quantitatively characterize the difference of the urban form of residential areas for a better interpretation of the context in which the quarters have been formed and as well as the current urban landscape of the living space of Hanoi. This paper presents the results of urban form extraction from high resolution image and the results of metric analysis of these forms in relation to vegetation cover in four pilot quarters of Hanoi: the residence quarter constructed during 1960's, Kim Lien Quarter, Giang Vo Quarter, Thanh Cong Quater and a new residential area, Trung Hoa - Nhan Chinh Quarter which has been constructed by the end of 1990's. A high resolution Quickbird image of Hanoi in 2004 is used for this study. Building, tree canopy are two main objects extracted from this image by object-oriented algorithm with eCongition software. The first step of extraction is to delineate the boundaries of the objects by segmentation in using different parameters such as compactness, color, shape and scale (maximum number of pixel used for an object) of the objects. These parameters are balanced so that the objects you are interested in fit well your visual perception. To classify the extracted objects we use a set of rules consisted mainly of their metric parameters: Perimeter, Area, Rectangular Fit, Elliptic Fit, Roundness, Number of Edges, Length/Width Ratio. The analysis of metric parameters allow us to quantitatively characterize the difference of three quarter constructed in three different periods. This difference is reflected through the housing density, green space form and density versus building and house form in each quarter. The quantitative description of urban forms of residential space in three quarters allows us to evaluate the relation between urban form configuration and the planning concept of each period, guidelines are provided to make it easy to read with the consistent format.