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INVESTIGATIONS OF INTERPRETABILITY OF IMAGES BY DIFFERENT SENSORS
AND PLATFORMS FOR SMALL SCALE MAPPING
G.Konecny, W.Schuhr, J.Wu
Institute for Photogrammetry and Engineering Surveys
University of Hannover
Nienburger Strasse 1
3000 Hannover 1
Federal Republic of Germany
ABSTRACT
Overlapping High Altitude Photography at scales varying from 1:125000,
satellite imagery (Skylab, Landsat) and radar imagery has been used to
derive the mapping capability of topographic objects by monocular and, if
applicable, stereoscopic observation.
The interpretation of digital imagery has been simulated by digitizing
the high altitude photographs on the Optronics Scanner using varying
pixel sizes between 1 m and 100 m referred to the ground.
Pixel sizes of about 3 m are required for monocular observation and 6 m
for stereoscopic observation to detect objects to be shown on a 1:50 000
map.
WORLD MAPPING NEEDS
In Dresent times every country in the world has an increasing demand for
maps in quantity and quality to satisfy the different requirements of so
ciety such as:
- survey and management of natural resources
- observation and planning of the environment
- geo-referenced data concerning the human activities.
The current status of world mapping leaves much to be desired. Especially
developing countries still do not have medium scale maps. There is gene
rally a deficit in map scales between 1:50 000 and 1:200 000. According
to a United Nations Study in 1976 /10/ the world wide demand for maps at
scale-ranges of 1:50 000 is about 63.4%, and of 1:100 000 about 48.2 l.
In a study for the requirements for mapping from space prepared for
the German government /6/ it was concluded that about 50 % of the produced
maps are limited in usage because of inadequate map revision. Consequent
ly initial map coverage does not represent the total mapping demand, since
the task of cartography consists of continuous map revision, especially
with regard to planimetry.
MAPPING METHODS
Up to now map production and map revision is carried out by two alterna
tive data acquisition methods:
1) terrestrial survey
In view of the relatively slow speed and high costs, the classical
surveying method is limited to small areas, which eliminate this method
for a worldwide production and revision of medium scale maps.
2) conventional photogrammetry
For the task of the worldwide map production and revision of 1arge
scales conventional photogrammetry using aircraft is the only accep-
