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CLASSIFICATION OF SAR IMAGERY FROM AN AGRICULTURAL 
REGION USING DIGITAL TEXTURAL ANALYSIS 
Daniel R. Nüesch 
Department of Geography, University of Zurich, Switzerland 
ABSTRACT 
In June 1981, four channel Synthetic Aperture Radar (SAR) data were gathered 
over the St.Aubin test area in Switzerland. Digital imagery from a 2 x 2 km 
area was obtained using optical processing of the signal film and digital re- 
cording of the output image (Hybrid processor). A digital filter algorithm was 
developed to minimize the effect of coherent speckle. Digital measures of image 
texture, as well as the local approximation to the mean value of individual 
agricultural fields, were used to perform crop discrimination. 
INTRODUCTION 
As part of the SWISSAR - (Swiss Interdisciplinary Study with Synthetic Aperture 
Radar) Project, airborne SAR data collected over an agricultural area near 
St.Aubin, Switzerland have been processed digitally. This paper is intended to 
serve as an input to the extensive investigations which are being undertaken by 
the SWISSAR Project Team (Principal Investigator: Prof.Dr.E.Schanda) in the 
domain of the application of Synthetic Aperture Radar Imagery. The data were 
collected during the european SAR 580 campaign by Intera under sponsorship of 
the European Space Agency (ESA) and the Joint Research Center (JRC) of the 
European Economic Community. 
In this paper we review the analysis of digital multifrequency and multi- 
polarization SAR data for automatic classification of agricultural areas. 
Specifically the paper discusses (a) Data Preparation, (b) Data Preprocessing, 
(c) Texture Analysis, and (d) Crop Classification. 
DATA PREPARATION 
The data which were collected June 10, 1981, 
over the test site of St.Aubin, Switzerland, 
were recorded on High Density Digital Tape (HDDT) 
and on signal film onboard the Convair 580 air- 
craft. While the signal histories recorded on 
HDDT will be correlated digitally at DFVLR in 
Oberpfaffenhofen, the signal film was sent to 
ERIM in Ann Arbor, Michigan, USA, for optical 
correlation (see Figure 1). The SAR imagery which 
was used in this investigation was produced us ing 
ERIM's hybrid optical-digital processor {Ref.1). 
Figure 1. Overview of the St.Aubin Test Area: 
Optically Processed SAR Image 
  
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