809 
Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Visual aerial photograph texture discrimination for delineating 
homogeneous residential sectors: An instrument for urban planners 
Maria de Lourdes Neves de Oliveira 
Instituto de Pesquisas Espaciais/MCT, Sâo José dos Campos-SP, Brazil 
ABSTRACT: This paper presents a method for the definition of a geographical reference system to be used by 
planners in urban residential area analysis. The purpose of the method is to exploit, in the diagnosis, the 
spatial component of the town which is the concrete result of the interactions between its physical and social 
elements. The assumptions made are: a) the urban residential areas in Brazilian towns are extremely 
differentiated as a result of the social stratification existent in the country; b) there is a strong 
association between physical aspects of these areas and the socioeconomic characteristics of their resident 
population. The method preconizes the use of panchromatic aerial photographs at a scale of 1:10000 for the 
delimitation of homogeneous residential sectors. The procedures described are based on the human visual 
capability to descriminate different textures. In order to test its validity, survey data obtained through its 
application tq Sao José dos Campos, SP, Brazil, were analysed using cluster analysis technique. The results 
of the work showed that photointerpretation, besides being a quick and economical instrument for urban 
analysis, may be usefully applied for delineating homogeneous residential urban sectors, to be used by urban 
planners. 
1 INTRODUCTION 
Urban planning, as any decision-making process, 
depends on an efficient information system for 
support. Urban system related decisions, 
specifically, require the availability of a wide 
range of information, particularly those associated 
with an appropriate geographic reference, that allows 
the orientation of specially located actions. 
Among these types of information we would mention 
that related to the residential differentiation on 
urban soil, the corresponding distribution of the 
different populational segments on this soil, as well 
as its socioeconomic features. Such information is 
essential for the planning of residential areas that 
involve, among others, decisions related to the 
placement of locally used urban equipment, as well 
as to the distribution of determined urban services. 
The present paper suggests a method for defining 
the urban residential sectors aiming at assisting 
the planner in the analysis of the town residential 
areas that directs him towards the study of problems 
which require all of the above mentioned information 
at the same time. 
This method was developed having in mind the 
Brazilian towns with their extremely diversified 
compositions of residential areas resulting from the 
pronounced stratification of their society 
2 DESCRIPTION OF THE METHOD 
This method is based upon visual photograph texture 
discrimination over panchromatic aerial photographs 
on the scale of 1:10.000. When town areas of 
residential use are investigated, the sectors with 
similar textures are delineated, thus forming urban 
units for data collection, analysis and storage. 
Its result is a mosaic map, built up from small 
differentiated parts, in which neighboring sectors 
will show different textures. 
This proposal is based upon the hypothesis that to 
these neighboring homogeneously textured sectors 
correpond different physical residential 
environments, to which correspond populational 
segments also differentiated according to their 
socioeconomic features. 
The basic element of the aerial photographs for 
delineating homogeneous residential sectors is the 
texture, produced by the aggregation of small 
details, no longer analysed individually, but as a 
whole. 
The capacity of the human visual system to 
perceive differences between determined textures is 
fundamental to the suggested sectorization process. 
According to Haralick (1979) the texture is a 
phenomenon of area organization and has two basic 
dimensions: 
a) one that refers to the primary elements that 
composes it; and 
b) one that refers to the dependency among primary 
components, i.e., their spatial organization. 
This being so, texture variation is defined by 
different primary components or by components of 
different sizes, and also by the density of these 
elements, their relative position and their spatial 
distribution. In residential areas this means that 
the textures of the sectors are type-depending: 
mansions are different from small houses; one-store> 
houses are different from apartment houses; high 
density areas are different from low density areas; 
arboreous areas are different from areas without 
vegetation; areas for exclusively residential use 
are different from mixed use areas. And so are their 
textures. 
Basically, the process of delineating homogeneous 
sectors consists of the following: 
a) Visual discrimination of the different texture 
areas through an overall perception of adjacent 
point sets. 
b) Identification, within these areas,of the 
primary components of the textures as well as the 
spatial organization, investigating urbanistic and 
architetonic details of their elements, such as 
sizes of buildings and open areas, maps of the road 
system, existence of natural greenery, building 
density, nonresidential constructions. 
c) Determination of whether there is 
differentiation between textures of visually 
discriminated areas based upon information collected 
from item (b). 
d) Outlining of the limits that define the 
residential sectors of the same texture.