ortion 
ig the 
Is are 
del, is 
image 
ind of 
of the 
data. 
n this 
1d are 
Nuri Al-Nakib 
  
MAPPING OF LARGE AREAS IN TROPICAL COUNTRIES 
BY USING HIGH RESOLUTION AIRBORNE INTERFEROMETRIC RADAR 
Nuri AL-NAKIB 
Aero-Sensing Radarsysteme GmbH 
c/o DLR, 82234 Wessling, Germany 
nuri.al-nakib Q dlr.de 
Working Group IC-02 
KEY WORDS: Mapping, Radar, High-resolution data/images, Tropical countries, Products. 
ABSTRACT 
Recent developments in high resolution airborne synthetic aperture radar (SAR) sensors allow to map large and 
remote tropical areas, independent of cloud coverage, with high accuracies in position and height. This makes it 
possible particularly for tropical developing countries to get high quality geoinformation reference data within a 
short period of time and at a low cost level, compared with conventional mapping methods. Subject of this paper is 
to present the suitability of this technique on the basis of mapping projects in Indonesia, Brazil, and Venezuela. The 
whole procedure from the data acquisition to the generation of value-added products is pointed out. In each of the 
three projects the data acquisition was carried out by the X-Band subsystem of Aero-Sensing's interferometric 
airborne SAR AeS-1, which is operational since October 1996. SAR ortho images and digital elevation models 
(DEM’s) are the two main products, which are generated from SAR data. Value-added products are for example 
cadastral maps, topographic maps, SAR orthophoto maps, or data support for geographic and cartographic 
information systems (GIS, CIS). 
1. INTRODUCTION 
Vast areas in tropical countries with a high percentage of cloud coverage are currently mapped unsufficiently or in a 
too small scale. In a lot of cases, ground surveys could not be carried out due to the inaccessibility of the area and 
the lack of adequate transportation. Because of the permanent cloud coverage of such areas, it is almost impossible 
to plan and lead aerial mapping campaigns using optical sensors. 
Under these circumstances, high resolution airborne radar sensors allow a nearly weather-independent data 
acquisition. This helps to finish mapping projects according to schedule, and thus, to provide actual geoinformation 
reference data to tropical countries at a relatively low cost level. 
This paper presents the suitability of this technique on the basis of mapping projects in Indonesia, Brazil, and 
Venezuela. Chapter 2 gives an overview on Aero-Sensing’s SAR system AeS-1 and the typical data workflow. In 
chapter 3, each of the three mapping campaigns is figured out. The generation of value-added products is described 
in chapter 4. Also, the results of the mapping projects are presented. Finally, chapter 5 gives an outlook on further 
activities. 
2. THE AES-1 SYSTEM AND DATA WORKFLOW 
In the beginning of 1996, Aero-Sensing Radarsysteme GmbH started to design and construct a high resolution X- 
band interferometric SAR called AeS-1. After first test flights in August 1996, the system became operational in 
October of the same year. 
In the following, an outline of the system design is given: The AeS-1 is configured as a two-antenna single-pass 
interferometric SAR with a ground resolution up to 0.5 m x 0.5 m and a height accuracy up to 5 cm. The system 
consists of a ground and a flight segment. Figure 1 shows the AeS-1 flight segment, while figure 2 shows the radar 
antenna construction, installed on a Rockwell Turbine Commander. The block diagram in Figure 3 shows the 
ground and flight segment of the AeS-1 with its components. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B1. Amsterdam 2000. 19