)es on radar imagery 
iration on LANDSAT 
luous woodland and 
| on radar is the 
eral genera of 
mangrove in Darien 
'eturn, apparently 
king network of 
“igure 5) is repro- 
of mangroves in 
ired in other areas 
signatures for 
/egetation is from 
'all configuration 
'rom multiple reflec- 
same manner that 
jh in the field the 
'edding within the 
juter limits of the 
/ large flat areas 
;. A small area of 
n but has yet to 
je season dependent 
is of young oil palms 
nooth return (Figure 
from the coconut 
ars to be little 
species (Figure 9a, b), 
ture of the return. 
| of the oil palms 
11d also be considered. 
such signatures 
other environments. 
tation. In a large 
ists can be observed 
ists may be related 
/ shadowing along 
ifferences in species, 
irn when looking at 
ivala and Ulaby, 1976; 
^ vegetation types 
it 3 cm (x-Band) 
1 only one band of 
splays the terrain 
    
Such examples point not only to the need for extensive investigation and 
documentation of unique vegetation signatures but also to the potential ulti- 
mately sought for automated mapping. 
Geologic Elements 
An anticline in the Cretaceous sequence north of the Benue River in Nigeria 
(Figure 10a-d) provides an excellent example of the importance of "dual opposing 
looks" and shadowing in geologic mapping from SLAR imagery (Gelnett, Dellwig, 
Bare, 1978). Within the core of the structure, thin resistant sandstone units 
which can be identified on the SLAR images are defined primarily on the basis 
of radar shadowing. Such units cannot be detected on the LANDSAT image. In a 
similar manner, faults and joint patterns at the southwest and northeast ends 
of the structure are prominent and in some instances detectable only on the 
SLAR image. Whereas the shadowing enhances these structures, it may also 
obscure the true position of a fracture occupying a topograhic low (Figure 3), 
but which may be revealed with illumination from the opposite direction. In a 
like manner thin sandstones within the core on the north side are shadowed in 
by the south "look" image but revealed in the north "look" image. One can also 
compare the radar image with the LANDSAT image (Figure lla-c) of several of the 
many ring dike complexes southwest of Lere, Nigeria, and further document the 
importance of shadowing in SLAR imagery. Comparison with distribution of 
granite and granite porphyry lithologies in the Precambrian complex shown on 
the geologic map of Nigeria, indicates the value of utilization of SLAR imagery 
at reconnaissance scale for refining otherwise-obtained map data. 
Recent generation (May, 1976) of radar imagery over the northwest shore 
of Manila Bay (Bataan Peninsula) as part of a site selection study for a nuclear 
power plant offered the opportunity of evaluating SLAR and LANDSAT imagery 
(Figure 12a-c) for providing necessary geologic data in this earthquake-prone 
area. On the basis of tone-texture signatures, good correlation between mapped 
units and imagery units could be achieved with little difficulty. Lineaments 
(in such an environment reasonably interpreted as faults) not previously mapped 
were located. In contrast, correlation of units found on LANDSAT MSS imagery 
with those on the geologic map was poor and the lineaments totally lacked 
expression on the LANDSAT images. Texture on LANDSAT imagery in this terrain 
which is dominated by relatively-unweathered young volcanics is subdued on 
LANDSAT imagery because of the lack of rock contrast between the influves and 
valleys, the lack of shadowing across valleys, and finally the nearly perpetual 
cloud-shrouding of the peaks. 
Radarmaps© 
Radar imagery may also be reproduced in such a way as to provide a plana- 
metric map format in which terrain elements can be easily and rapidly identi- 
fied by the unskilled map reader (Figure 3). Maps of a similar nature have 
been generated for years by European cartographers and more recently by the 
U. S. Geological Survey, combining the topographic data of the traditional 
map with a shaded relief presentation so that the configuration of the surface 
is immediately obvious (Figure 4). 
: With a built-in shadowing capability, a mosaic generated from SLAR 
imagery enhances terrain elevation varaition in the same manner as does the 
shaded relief map. Printed in brown or green with superimposed data derived