necessary, theoretical and methodological preparation, as
well as scientific analysis of results. The photogrammetric
research can extend, as necessary, into related fields in
which an interaction takes place, such as sensor
technology, data processing, information systems,
automation, cartography and geodetic methods. It is to
include in particular the integration of data from different
origins and the combination to higher level systems of wide‘
Scope."
5.2 Changed working procedures
An organisational structure and the related working
procedures, should aim at increasing the efficiency (doing
the things right) and effectiveness (doing the right things) of
an organisation. The OEEPE organisational structure and
working procedures as defined in the eighties, had become
too cumbersome to permit the OEEPE to function
adequately in the research context of the nineties.
It has not been the intention to fundamentally change the
OEEPE Structure, but rather to regard it as a frame in which
the organisation can manage efficiently and effectively a
portfolio of research programmes and projects addressing
as well cost saving technology as GIS strategic issues.
Emphasis has been put on (quality) monitoring of the
research efforts, by means of improved project planning and
control, and improved cooperation with other international
organisations.
5.3 Improved external relations
During the reporting period, the OEEPE has strengthen its
cooperation with the ISPRS, as a Regional Member; this
has been achieved through cooperation between ISPRS
and OEEPE Working Groups on related subjects, but also
by means of active participation of OEEPE members in
different ISPRS Symposia in 1994; it is further concretised
by the OEEPE organising a Special Session in the
framework of the present ISPRS Congress.
Similarly, the OEEPE Working Group on Automatic
Generalisation has been very active in the framework of the
ICA (International Cartographic Association); this has been
concretised by the organisation of a workshop on
Generalisation during the last ICA Conference (1995).
Since 1992, the OEEPE is closely cooperating with CERCO
(Comité Européen des Responsables de la Cartographie
Officielle) under an official agreement; the aim of the
cooperation is for the OEEPE to better appreciate the
research requirements of the European Geoinformatics
community.
During the reporting period, OEEPE representatives have
been heavily involved in the standardisation activities of the
CEN/TC 287 (Comité Européen de Normalisation), with
particular relevance to the standard for data quality.
Cooperation with AM/FM Europe has also been started in
the perspective of a join research project on the feasibility
of the use of the ISO-9000 series guide lines in a GIS
environment.
Finally, the OEEPE is active (with the Observer status) in
the framework of EUROGI (European Umbrella
Organization for Geographical Information), with particular
relevance to harmonisation and standardisation issues.
6. OEEPE SPECIAL SESSION IN THE FRAMEWORK
OF THE XVIII ISPRS CONGRESS
The OEEPE has been allocated a Special Session [SS02]
in the framework of the XVIII ISPRS Congress; the Session
will start by a short introduction on OEEPE current activities
and perspectives; this will be followed by the presentation
of three papers, and their subsequent discussion. The three
papers are summarized hereafter.
6.1 Experimental tests on fast ambiguity solutions for
airborne kinematic GPS positioning (by F. Ackermann)
High precision kinematic GPS positioning, based on
differential methods, has always had the problem of correct
ambiguity solutions for the phase observations, especially
under the conditions of airborne applications for
photogrammetry and remote sensing. Methods have
successfully been worked out and applied which do not rely
on exact ambiguity solutions after loss of lock of signals.
Instead, the resulting systematic GPS position errors were
subsequently corrected with the help of external constraints
by combined block adjustment, for instance. Aerial
triangulation and block adjustment on that basis has been
shown to work very well, even if only L1 signals are used.
It is a particular feature of the method that the GPS ground
receiver stations can be positioned very far from the flight
area, up to 500 km or more.
Recently, the appearance of dual frequency receivers and
the development of methods for fast ambiguity solutions,
known as "on the fly" (OTF) solutions, have created a new
situation. It is possible now to re-establish ambiguity
solutions after disruptions of signals, as they happen during
flight turns in particular. There are several software
programs in use which can handle the problem. The result
is that continuous GPS flight trajectories are obtained for
complete flight missions. If they are linked to a base line
initialisation before take-off then the GPS flight trajectories
are practically absolute, with regard to the WGS 84
reference system or to any other reference system related
to it.
Those methods simplify the airborne kinematic GPS
application considerably, especially also the application to
photogrammetric block adjustment. The use of cross strips
could be abandoned, as (almost) no systematic errors
would be effective any more. Also flight trajectories could be
used directly which are not supported by image blocks, like
laser scanning trajectories, for instance. Thus, obtaining
completely continuous GPS flight trajectories is an
important development which is highly welcome from many
points of view.
There is the problem, however, that the present methods for
fast ambiguity solutions are not very reliable. Safe
application seems to be limited to short distances between
receivers, i.e. the stationary GPS receiver(s) must be close
104
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996
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