TRADITIONAL AND CURRENT PRACTICES
IN THE ACQUISITION AND DISPLAY OF LAND COVER DATA IN BRITAIN
The traditional practice for land cover mapping in Britain was
established by Professor L. Dudley Stamp in the 1930s with the First
Land Utilisation Survey of Britain (Stamp, 1931). This involved direct
recording of land cover onto large scale maps during visual inspection
in the field. Collations from these field maps were later generalized
onto smaller scale maps (one inch to one mile) for publication. The
areas occupied by different categories of land cover were measured from
the maps using a simple planimeter. This was very labor intensive and
slow—taking more than a decade to produce a national survey.
The Second Land Use Survey of Britain, begun in the 1960s under Alice
Coleman, essentially followed the method established by Stamp (Coleman,
1961). The high cost of both the data acquisition by field survey and
the data presentation in the form of printed color maps has inevitably
resulted in a far from complete national land use survey.
The first extensive use of aerial photography for the acquisition of
land cover data in Britain was in the mapping of urban land cover of the
developed areas of England and Wales by Fairey Surveys Ltd. for the
Department of the Environment in 1975 (Van Genderen and Smith, 1976).
Although 28 categories of urban land cover were deemed to be detectable,
only 5 major categories were retained (residential, industrial/
commercial, educational/community, transport, and urban open space).
One of the aims was to test the suitability of LANDSAT data for updating
urban land cover; these five categories were believed to be compatible
with the resolution of LANDSAT data. The feasibility of using LANDSAT
for this purpose was investigated by the Atomic Energy Research
Establishment at Harwell using their automated image analysis facility.
The general conclusion of this work was that the ground resolution of
LANDSAT (about 80m) was not yet good enough for regular monitoring of
urban changes (Carter, 1979).
Current land cover mapping projects include two which rely principally
on LANDSAT data. The Macaulay Institute for Soil Research (in Aberdeen)
has produced a land cover map at 1:100,000 scale of part of lowland
Buchan for the Grampian Regional Council (Stove et al., 1981). Aberdeen
University Geography Department is working on the production from
LANDSAT data of a land cover map of Scotland at about 1:500,000 scale.
Both of these projects involve the use of fairly powerful computer
facilities for the handling and classification of the satellite data and
require a considerable learning period before the data can be utilized
successfully.
From a consideration of current practices it was perceived that a gap
exists between the traditional compilation of land cover/use maps in the
field or from air photo interpretation and the semi-automated
classification of land cover from LANDSAT data using a high-powered
computer system.
This has led to the development at Aberdeen University Geography
Department of a procedure which combines the use of aerial photography
and a low cost microcomputer system. The aerial photographic image is
the basic data source and the microcomputer is used for storage and
analysis of the image-derived data.
GENERAL DESCRIPTION OF METHOD