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Transactions of the Symposium on Photo Interpretation

to the photogeological survey for the planning of highway construction. Photo-
geological analysis will be carried out in cooperation with the Institute of
Civil Engineering and our Institute. The results will be demonstrated on the
photomaps with overlays.
In this paper, the authors would like to mention in somewhat more detail
the technical matters related to land use surveys.
Technical remarks on land use survey by using
aerial photographs
Land use maps on the scale of 1 : 50,000 aim to show the present status of
land use. Not only rural land use types, but also urban types are shown,
together, with installations for land conservation and land improvement.
75 items to be classified are illustrated by coloured symbols and lines.
The land use survey is carried out by combining aerial photo interpretation
and field investigation. The aerial photographs used in the beginning were on
a scale of about 1 : 40,000, and were taken by the U.S. Air Force. As the pur
pose of land use maps is to show the present status of land use, more recent
photographs are always required. Recently, the widespread use of newer
photographs on a larger scale, taken by the governmental organizations such
as the Forest Agency, the National Railway Corporation etc., became possible.
Infrared photographs and colour photographs are not yet used, because such
photographs were taken only of limited areas. We have never taken new aerial
photographs for land use survey alone.
Here we should consider the changes of social demand according to the
economic development. Although in the beginning of the land use survey,
importance was attached to the comprehensive development plan for the
underdeveloped regions, various projects for the economic development have
been planned for such well developed regions as urbanized, industrial and
suburban areas. Changes of land use in such regions are very rapid and con
sequently we are obliged to carry out our task as quickly as possible. In order
to meet such urgent needs, we have to improve our techniques of land use
survey by introducing new techniques developed in photogrammetry.
For one sheet, covering 400 km 2 the land use survey, including photo
interpretation and field investigation, takes about 2 months. About 4 months
are needed for mapping it on the topographical map on the scale of 1 : 50,000.
It seems that one of the disadvantages to be improved is the length of time
the survey takes. In order to save time, we plan to employ photomaps on
which the land use type is shown, particularly for flat regions. Doing so, it will
be possible to illustrate simultaneously on the photomaps and overlays not
only the details of land use, but also the details of landform and other infor
mation necessary for the users. Our experiences of landform classification and
photomap making will also be utilized for such work.
Land use patterns of Japan are very complicated. Sometimes it is too com
plicated to map on topographical maps on the scale of 1 : 50,000. This is the