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ENVIRONMENTAL MAPPING WITH SAR: 
A SIX-YEAR RETROSPECTIVE ON GLOBAL APPLICATIONS 
J.B. Mercer 
Manager, Special Applications 
M.D. Thompson 
Manager, Resource Information Services 
D.R. Inkster 
Manager, Business Development 
ENTERA Technologies Ltd. 
Calgary, Alberta, Canada 
ISPRS COMMISSION VII 
Synthetic aperture radar (SAR) has been used extensively for environmental mapping worldwide over the past six years, and shows 
promise of even greater application for a range of earth environment mapping and monitoring in the near future. The present paper 
examines the environment-related uses of INTERA’s STAR Systems: digital airborne SAR systems in operation since 1983 which 
have completed data acquisition of over 50 million square kilometres worldwide. 
The STAR systems (STAR-1 and STAR-2) have been used for a range of environmental mapping applications: sea ice mapping and 
monitoring, forest cover and forest depletion monitoring, agricultural crop inventory and monitoring, environmental emergencies such 
as oil spills and flooding, land use mapping, soil capability mapping, environmental impact assessment (related to geological explo 
ration, forestry and agriculture) and topographic mapping. Programs have been carried out in North, Central and South America, in 
southeast and central Asia, in Europe, in Africa and in Australia. System developments since 1983 have improved such capabilities 
as data turnaround, user-specified products, georeferencing capability, digital analysis methodology and expert systems applications 
for environmental applications. Further such developments and expanded environmental applications are planned for the future. 
Key Words: Radar, SAR, Environment, Topographic Mapping, Forestry, Sea Ice, Environmental Impact, Environmental Emergencies 
INTRODUCTION 
Synthetic aperture radar (SAR) has been used worldwide for 
environmental mapping over the past six years. Since 1983, 
digital high resolution airborne SAR data have been acquired 
over 50 million square kilometres with the STAR systems of 
INTERA Technologies Ltd., of Calgary, Alberta, Canada. Based 
on the work completed to date in the fields of sea ice mapping and 
monitoring, forest cover and forest depletion monitoring, agri 
cultural crop inventory and monitoring, environmental emergen 
cies such as oil spills and flooding, land use mapping, soil capa 
bility mapping, environmental impact assessment, and topo 
graphic mapping, SAR has been demonstrated to have even 
greater application for a range of earth environment mapping and 
monitoring in the near future. Concurrent with the development 
of such new applications for radar data, have been continued 
system developments and improvements to further the environ 
mental uses and applicability of these data. The following 
sections describe the environment-related uses of the STAR 
systems, STAR system developments, and an outlook to the 
future of airborne radar. 
CURRENT STAR SYSTEM STATUS 
INTERA owns and operates two SAR systems at the present 
time: STAR-1 and STAR-2. 
STAR-1 System 
The STAR-1 system is a fully digital, lightweight X-band syn 
thetic aperture radar system (Nichols et al. 1986) which has been 
operational since 1983 in a Cessna Conquest aircraft. It has two 
modes of data acquisition: standard resolution (6x12m) and high 
resolution (6x6m). The system in single polarized, transmitting 
and receiving in HH mode, and includes a seven-look real-time 
processor and display. The system was initially used for ice 
reconnaissance in the Canadian Arctic, but since about 1985 has 
been used extensively for terrain and resource surveys. Over 50 
million square km have been imaged with this system, in the 
Arctic (for ice monitoring, about 35 million square km) and 
worldwide (about 15 million square km) for geological explora 
tion, forest management programs, land use and environmental 
programs, etc.). The SAR data have also been used in the 
STARMAP topographic mapping process, which creates topo 
graphic maps and Digital Elevation Models (DEMs) from stereo 
high resolution STAR data (Mercer etal. 1989; Mercer and Kirby 
1987). 
Typical output products from this system include computer 
compatible tapes; stereo flightline prints (typically 1:250.000 
scale for standard resolution and 1:100.000 scale for high reso 
lution data); and digital mosaics (at similar scales). The STAR 
data represent a significant improvement over earlier generations 
of side-looking airborne radars and synthetic aperture radars 
because of the fully digital capability, high quality/high resolu 
tion image information, low cost (compared to previous systems 
flown in much larger airborne platforms), and digital mosaicking 
capabilities, in addition to the optional production of digital 
topographic information from the stereo high resolution data. As 
a result, such data are now being applied to much more rigorous 
mapping programs than before.