THE ROLE OF REMOTE SENSING AND GIS FOR AN OPERATIONAL STATE-WIDE
ENVIRONMENTAL MONITORING
Manfred Ehlers and Ulrich Rhein
[ehlers, urhein]@ispa.uni-osnabrueck.de
ISPA - University of Vechta, P.O. Box 1553
D-49364 Vechta, Germany
Intercommission IV/1
KEY WORDS: Remote_Sensing, GIS, Fusion, Change_Detection, Classification
ABSTRACT
Remote sensing image analysis systems and geographic information systems (GIS) show great promise for the integration of a wide
variety of spatial information supporting tasks such as urban and regional planning, natural resource management, agricultural
studies and topographic or thematic mapping. Current and future remote sensing programs are based on a variety of sensors that
will provide timely and repetitive multisensor earth observation on a global scale. GIS offer efficient tools for handling,
manipulating, analysing and presenting spatial data that are required for sensible decision making in various areas. To combine the
power of both spatial technologies, however, efficient synergistic processing techniques have to be developed to cope with large
multisensor image datasets and to automatically extract information for GIS. This paper describes the role of remote sensing and
GIS for an operational monitoring. The inspiration for this paper came from the project "Environmental Monitoring — State-wide
Comparative Landuse Classification in Lower Saxony Focusing on Moor and Pasture Areas". Goals of this project are a continuos
landuse/landcover analysis based on the classification of remotely-sensed imagery and a consequent change analysis of the state of
Lower Saxony. Additional methods are being developed to make use of satellite imagery for assessing ecologic conditions of peat,
boglands and pasture areas. Working in an integrated GIS/remote sensing environment allows taking advantage of the
functionalities of both GIS and remote sensing image analysis techniques.
1. INTRODUCTION
We are modifying our environment at unprecedented rates and
scales. We can, however, debate the specific spatial
dimensions, rates and significance of these changes.
Throughout history, technology has always been a key factor
facilitating change. Today's technology can create
environmental change at previously unknown spatial and
temporal scales. Yet, it also offers us the ability to facilitate
our investigations leading to a more complete understanding of
human impact on our environment. Through appropriate use of
technologies we can move a significant step towards an
environmentally sound management of the Earth's natural
resources. Planning and development can no longer take these
natural resources for granted. We have to consider not only the
needs of current generations but also those of future
generations.
Significant among these technologies are remote sensing and
geographic information systems (GIS). Remote sensing devices
on aeroplanes and satellites are capable of recording
environmental information at staggering rates with significant
economies of scale for many purposes. GIS can integrate these
data with other spatial data (e.g. maps) and non-spatial data
(e.g. tables or text) to facilitate new forms of analyses. It has to
be noted, however, that these technologies are crossing the
boundaries of many traditional disciplines, and the
development of academic programs in "Remote Sensing and
GIS for Environmental Monitoring and Management" poses a
challenge to established programs [Ehlers, 1995].
Remote sensing technology and GIS are both tools for
managing spatially distributed information in large quantities
and at a variety of scales. Both provide a systemic or synthetic
view of spatial information. Both increase the capabilities of
human decision-makers and planners to grasp relationships at
larger scales and in more complex settings than has hitherto
been possible. GIS and image processing systems tend to two
different forms of representing spatial information, i.e., vector
and raster representation. These representations are
characterised by different algorithms for spatial analyses,
although the end results are, in theory, comparable [Ehlers,
1992].
Section 2 gives an overview about the case study. It shows the
main tasks of the environmental monitoring project. A review
of imagery used is given in section 3 followed by a description
of the ground truthing campaign and the integration of these
data (section 4). After describing the geometric pre-processing
in section 5, the results of the classification are presented in
section 6. This section shows also the advantage of an
integrated GIS/remote sensing environment. Section 7 gives a
conclusion.
2. THE CASE STUDY
The "Environmental Monitoring - State-wide Comparative
Landuse Classification in Lower Saxony Focusing on Moor and
Pasture Areas" may serve as a convincing example of the
operational use of integrated GIS/remote sensing technologies.
This project is supported by Lower Saxony's Department of
Environment and the German Space Agency (DARA) and
started in July 1994. The overall goal of the project is to assess
the capabilities of satellite remote sensing for the analysis of
landuse changes, especially in moor and pasture areas. These
areas are recognised as areas crucial to the mission of the
Department of Environment and therefore to be placed under
an extended level of protection. It is of critical importance,
however, to have accurate and current information about the
ecological and economic state of these sensitive areas.
The Environmental Monitoring Project which is conducted
jointly by the GIS and Remote Sensing Section of the Institute
for Spatial Analysis and Planning in Areas of Intensive
Agriculture (ISPA) and the Lower Saxony's Department of
Environment, consist of the following tasks:
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