Another application, to earth resource exploration, will be
explained next. In the field of resource exploration,
features extracted from the shape of the earth surface are
very important. One of them is a lineament which looks
like a straight line on the earth surface. Lineaments often
indicate the existence of faults. It is very important to
extract as many lineaments as possible for the effective
analysis. One experiment has been carried out to
examine the relationship between B/H ratio of
stereoscopic images and extractive lineaments. The
experiment has been carried out at two test areas. One 1s
the Izu peninsula in central Japan and the other is at
Hishikari district in Kyusyu, southern Japan.
Photo 8 and photo 9 are orthoimages of the Izu peninsula
and the Hishikari district. Stereoscopic images of several
B/H ratios have been made from these orthoimages using
DEMs, and the experimental lineament extraction has
been carried out using these stereoscopic images. Table
Photo 8 Orthoimage of the Izu peninsula in Japan
Table 10 The number of lineaments extracted from
stereoscopic images of the Izu peninsula
B/H Total number | Length (km)
0.1 135 305. 86
0.3 284 594.13
0.5 330 730 10
1.0 262 610. 36
10 and table 11 show the number of lineaments extracted
from the stereoscopic images of different B/H ratios.
From these tables, some results can be extracted as
follow:
(1) The number of lineaments extracted differ greatly
with the different B/H ratios of the stereoscopic images,
Two times as many lineaments can be extracted in the
best case as in the worst case.
(2) The best B/H ratio for lineament extraction is not
fixed. It seems to change according to the steepness of
the earth surface. The mountains are very steep in the
Izu peninsula but very gentle in the Hishikari district.
It can be said from this experiment that the B/H ratio of
stereoscopic images is very important for image analysis,
and the most suitable B/H ratio changes with the
landform of the area. It is a big advantage of this kind of
system that stereoscopic images of any B/H ratio can be
made easily and used effectiveiy in image analysis.
Photo 9 Orthoimage of the Hishikari district in Kyusyu,
southern Japan
Table 11 The number of lineaments extracted from
stereoscopic images of the Hishikari district
B/H Total number | Length (km)
0.1 18 152. 1?
0.3 16 189.18
0.5 103 249. 43
1.0 164 309.58 |
270
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996
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