THE DISCOVERY OF CHUANLI RING (BRUSH) STRUCTURE AND STUDYING 
FOR THE INTERPRETATIVE FEATURES OF IMAGING RADAR IMAGE 
Shi Jizhong 
(Shijiazhuang University of Economics, P.R. China) 
KEY WORDS: SIR-image 
Geological interpretation 
Airborne imaging radar image 
Ring Structure Brush structure 
ABSTRACT 
This paper discusses and analyses the factors of the influence upon the geometric shape (slope, aspect) of targets 
on the imaging radar (SIR-A) image, surface roughness, physical and electric characteristics of targets and the 
interpretative features on SIR-A image in bedrock area. The Chuanli ring structure is found. It is difficult to show 
the ring structure on the other remotely Sensed image. Combining geological conditions of regional 
minerogenesis. The conceal matrix and mineral deposit are prospected in study area. 
1, The interpretative characteristics of SIR-A 
image 
SIR-A image, Same as other remote sensing images, is 
used to recognize the culture based on its interpretation 
keys — such as hue, texture, shape, size, location, 
shadow etc.. However, synthetic-aperture side-looking 
radar images show significant difference from photo or 
Scanning images in characteristics and imaging 
principle of SIR-A image. First, its working wave band 
Is microwave which has a long wavelength, its culture 
spectrum characteristics is different from that of 
visible light and infrared wave band; second, it is 
active remote sensing, its imaging principle and 
recording and processing are different from that of 
passive sensing; Third, instead of vertical looking, its 
looking direction is side-looking. So, the image 
information such as hue, shape and size on imaging 
radar image is different from that of visible light and 
infrared image, it has special connotation and more 
attention should be paid to it when interpretation be 
made. In some limited parameter of radar system 
characteristics, the hue of culture on imaging radar 
image mainly depend on the intensity of radar wave 
back scattering for culture, more intensive is the 
back wave, lighter is the hue. The intensity of back 
wave for back scattering mainly is related with the 
geometry (slope and its declining direction), surface 
roughness and physical characteristics (dielectric 
constant) of the culture, as well as the relative spatial 
location between radar beam and culture. The 
intensive back wave was generated when the incident 
radar beam is vertically with the linear culture, for 
instance, railroad, highway and embankment are light 
lines on image. The incident radar ray is from south to 
Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 
north, so east-west extended linear structure, valleys 
and rivers show light hue. When the normal line of 
planar culture has a small incident angle with incident 
radar ray, intensive back wave was generated and 
show light hue. Sometimes, too intensive back wave 
energy make the receiver pare-saturated, which 
resulted in“ blooming ” ; As the angle increases, the 
back wave intensity decreases and hue becomes dark, 
this is so-called direction effect (Fig. 1). The steep 
south slope was constituted by Jixian series dolomitic 
limestone, Cambrian limestone, Ordovician limestone 
and Jurassic volcanic rocks, when the slope angle is at 
about 40°, its normal line only has a 10° angle with the 
radar ray which is 50° incident angle from south to 
north, that is to say, the incident radar ray is nearly 
vertical with the south slope plane, nearly all incident 
wave are reflected back to radar system, the image 
show light hue, even up to white. 
The hue of north slope (back to radar) varies with the 
relationship between slope angle (a) and radar 
depression angle (B ) . When a<B, the hue is 
influenced by the roughness of the slope. If the slope is 
very rough, it would scatter the radar wave, some back 
wave would make the image show light gray or gray 
hue. If the slope is smooth, the back wave would very 
weak, the images show dark hue; When a=, radar ray 
parallel brushes the slope, there is nearly no back wave, 
so the images show dark hue; When a», blind area 
which is unable to be brushed by the radar ray would 
form radar shadow because of steep peak (Fig. 2). 
Shadow areas are usually very dark, so the culture 
characteristics in these areas is difficult to be 
distinguished. The shadow enhances the stereo of the 
image, the linear or ring structures are more promoted, 
this is favorable for structure interpretation. 
591