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18th International Congress for Photogrammetry and Remote Sensing, Vienna, Austria, July 1996
Commission IV, Working Group IV/2-ISPRS
INTERNATIONAL MAPPING FROM SPACE
Gottfried Konecny
Institute of Photogrammetry and Engineering Surveys, University of Hannover
Nienburger Str. 1, D-30167 Hannover, Germany
KEY WORDS: Satellite Mapping, Satellite Systems
ABSTRACT
The paper outlines first the reasons, why mapping from satellites is a necessity (lack of adequate map
coverage in developing continents, lack of timely updates). Secondly it describes the changing philosophy
of the ISPRS Working Group "International Mapping from Space". Thirdly it lists all current and planned
satellite missions capable of providing data for mapping from space. The development of new satellite
systems with increased performance by many space nations is an indication that operational use of space
mapping is to be expected widely soon.
1. INTRODUCTION
ISPRS isthe international and scientific organization
principally concerned with data acquisition for
mapping. Aerial Photogrammetry, in fact, became
the only efficient tool to solve the World's mapping
program in priority areas. Presently 1/3 of the land
area of the World is topographically mapped at the
scale 1:25 000, 2/3 at the scale 1:50 000 and 95 96
at the scale 1:250 000. Thematic maps are based
on topographic mapping. The advantage of the
mapping system based on aerial photography is that
it easily reaches planimetric and altimetric require-
ments of + 5 m, if adequate geodetic control exists,
and it permits to detect objects larger than 1 m on
the ground.
The disadvantage of the current system lies in the
fact that updating is on a world average not carried
out more often than every 20 years for the scale
1:25 000, every 45 years for the scale 1:50 000 and
every 30 years for the scale 1:250 000. Only few
areas of the world (e.g. Europe) have a more
satisfactory situation, while the developing conti-
nents (Latin America, Africa) have a lesser progress,
because the current mapping system is too costly in
comparison to other national priorities.
Satellite remote sensing, as a new tool, is capable
of offering relief, if accuracy specifications can be
met for planimetry and height, and if object detect-
ability is sufficient for the particular mapping scale
(e.g. 1-2 m Pixel for 1:10 000, 3-5 m Pixel for 1:25
000, 5-10 m Pixel for 1:50 000; for photo-graphic
Systems a relation of 1 Ip = 2 to 3 Pixel should be
assumed).
Restitution by satellite imagery is by a factor of 2 to
4 less costly, and it can lead to much faster results,
especially for map updates, which are the real
bottleneck.
465
2. THE ISPRS WORKING GROUP
The ISPRS WG IV/2 is the heir to initial activities
within ISPRS during the Hamburg (1980), Rio
(1984) and Kyoto (1988) Congresses under A.
Colvocoresses. At that time the objective was to
show to the space community, that from the point of
view of the mapping community the resolution of
available earth resources satellites, like Landsat,
was too coarse in resolution, as to provide a tool for
mapping and map updating. An exception were the
experimental efforts by Germany (Metric Camera in
1983) and by the USA (Large Format Camera in
1984).
However, due to the experimental nature of these
systems, the satellite uses for mapping never took
off. This changed in 1986 with the launch of Spot 1,
however, the programming of the satellite became a
handicap for obtaining stereo imagery from two
different orbits.
Theaim of the WG effort before the Kyoto Congress
was, therefore, to design a satellite system with
parameters, suitable for mapping at medium and
small scales. Such a proposal was prepared as
"Mapsat' by the US Geological Survey with the
endorsement of the Working Group.
At the Kyoto Congress in 1988 the Intercommission
Working Group l/IV "International Mapping from
Space" was created. At the Commission | Symp-
osium of 1990 in Manaus, Brazil, a series of papers
was produced and published, which made recom-
mendations regarding the following topics:
e legal aspects regarding an open skies policy, not
limiting spatial resolution
e the suggestion to the United Nations and the
international multidonor community for technical
and economic cooperation to developing countries
to internationalize efforts
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996