EuroSDR Projects - Host Ireland

Abstract
The EuroSDR “Sensor and Data Fusion Contest” is concerned with the question of whether mapping
information usually obtained from optical imagery can also be derived from radar data with a comparable
quality. In the first phase of the contest both optical and SAR data were processed visually in
four test regions. To prepare a standardized evaluation procedure, reference data sets were generated
for each test region providing the basis for qualitative as well as quantitative data comparison. In the
first part of this report the four test site areas are introduced. Subsequently the description of the
generation of the reference data is given. The evaluation methods are then explained in detail. Results
of the comparison of contest participants' map data with reference data are in the form of percentage
values of false positive and false negative extractions with respect to existing objects and a visual
interpretation of the map data. Furthermore, taking the individual nature of each participant's results
into consideration, we conclude that a pixel accurate evaluation is not possible for all information
types. Finally, short conclusions are given summarizing the results of the visual interpretation phase
of the contest.
1 Introduction
In the last few years, high quality images of the earth acquired by synthetic aperture radar (SAR)
systems carried on a variety of airborne and spaceborne platforms have become increasingly available.
During the past couple of decades much research has been performed regarding Synthetic Aperture
Radar (SAR) satellite systems such as ERS-1/2, JERS, and RADARSAT-1, demonstrating the
potential of SAR for a wide variety of applications, such as deriving DEMs, geomorphological
mapping or extracting object of different types.
1.1 Aim of the Project
The aim of the contest was to answer the questions (1) Can state-of-the-art airborne SAR competes
with optical sensors in the mapping domain? (2) What can be gained when SAR and optical images
are used in conjunction, i.e. when methods for information fusion are applied?
On the one hand there are indications that airborne SAR images will play a major role in topographic
mapping in the future, due to its major advantages, namely independence of day light and cloud cover.
On the other hand the interpretation of SAR images is difficult for a number of reasons: The geometry
and spectral range is different compared to optical imagery and more importantly differs from the
imagery perceived through human eyes. In addition, the reflectance properties of objects in the
microwave range depend on the frequency band used and may significantly differ from the usual
assumption of more or less diffuse reflection at the earths surface. This effect can be particularly
strong for buildings or metal surfaces. Speckle, a consequence of coherent radiation needed to exploit
the SAR principle and other disturbing factors complicate the interpretation. Therefore, mapping staff,
for example photogrammetric operators, often have difficulties interpreting SAR imagery for topographic
mapping.
The EuroSDR sensor and data fusion contest was initiated in order to find out to what extent SAR
imagery can compete with high resolution optical imagery for topographic mapping applications and
to investigate the potential of fusing data of both sensor types.
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