Symposium on Remote Sensing for Resources Development and Environmental Management/Enschede /August 1986 
© 1987Balkema, Rotterdam. ISBN 90 6191 674 7 
993 
Small Format Aerial Photography for analysing urban housing 
problem (Case study: Bangkok Metropolitan Region) 
C.Chanond & C.Leekbhai 
National Housing Authority, Bangkok, Thailand 
ABSTRACT 
Small Format Aerial Photography (SFAP) made with a light aircraft has been used to provide a low cost 
data base for analyzing housing and landuse problems of the Bangkok Metropolitan Region (BMR). 
Photography and navigation over the 5000 sq.km area was done by a professional aircrew of the Royal 
Thai Air Force Reconnaissance Squadron. The cost of airphoto was 5 times less than that of large 
format. This paper gives some details about the SFAP flight and discusses in detail the methodology 
applied for the housing stock inventory. Airphoto interpretation was done from enlarged prints 
of the 55mm B & W 1:52,000 negatives. Major landuses including vacant land for potential housing were 
counted from the airphotos, although in some cases area based estimates were used. Some of the results 
from the study are also given. 
1 INTRODUCTION 
Bangkok, the capital of Thailand is an outstanding 
example of a primate city. Bangkok’s population in 
1985 was estimated at 5.6 million people which is 
fifty times larger than the next largest city: 
Chaingmai. Its increase, resulting from in-migration 
alone is equal in scale to that of one Chaingmai 
each year. The high rate of population growth and 
massive migration from rural areas, both seasonal 
and permanent, have adversely effected the human 
settlement within the city. 
The government is examining ways to improve urban 
efficiency through integrated urban development by 
integrating sectoral investment programs into one 
regional investment program. 
In April 1984, the government requested the National 
Economic and Social Development Board (NESDB) and 
the International Bank for Reconstruction 
Development (IBRD) to carry out a joint pre 
investment study for the 6th Five Year Plan (1987 - 
1991) relating the future of Bangkok Metropolitan 
Region (BMR). 
The study was confined to population and employ 
ment, urban transport housing and the urban poor, 
water resource and public finances, and should give 
an overview and a synthesis of the trends of change 
over the past 10 years as a basis for a prognosis of 
the changes over the next 10 years and beyond. 
The sectoral study of housing and the urban poor 
was assigned to the Center for Housing and Human 
Settlement Study (CHHSS), National Housing Authority 
(NHA). The Housing is particularly important because 
much of the physical development of the region is, 
and will be, residential. 
2 DATA NEEDS FOR THE HOUSING SECTOR 
The terms of reference for this sectoral study 
indicated: 
1) Assessment of the change in the housing stock 
over the last 10 years in terms of composition 
quality, quantity and locational aspect. Areas 
where current problems are particularly severe 
should be indicated. 
2) A review of available information on housing 
demand. 
3) Other aspects of the housing market such as the 
availability of land and housing finance, and 
potential housing locations for the Sixth Five 
Year Plan. 
The terms of reference suggested the use of census 
data to determine how the condition of housing stock 
has changed in the last decade by substracting the 
number of units in 1970 from those in 1980. When the 
study was commenced, it was found that the housing 
census tape of 1970 is no longer available. In the 
1980 housing census, dwelling units are not quan 
tified, only the number of households in various 
types of dwelling is provided. In addition, the 
tabulations in the census report of 1970 and 1980 
provide very few indicators of the quality of 
housing. The conclusion was that available data 
could not be used to compute the changes in housing 
condition with much confidence. 
Other approaches such as the use of updated large 
scale maps, the building record register or ground 
survey, have been examined but it was found that no 
single method could be used alone for the following 
reasons: 
- Available urban maps cover only part of the 
built-up area . 
- In the building records, housing units are not 
counted separately. 
- Ground survey would be too labourious and time 
consuming. 
The alternative for providing a reasonably ac 
curate quantitative and locational assessment of the 
change was to compare the 1974 1:10,000 airphotos, 
with new airphotos to be taken in 1985. 
The use of airphotos would enable the collection 
of much information quickly, reliable and 
economical. As airphotos portray the physical mor 
phological structure as it is in all its aspects, a 
combination of issues can be studied at the same 
time. Moreover, the accuracy of data obtained can be 
confirmed afterwards.