that
5 ds
o is
with
both
the
U as
was
from
GCPs
/ for
the
indle
ond -
ment
and
d the
ints
ngs,
‘ners
| are
the
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But
es in
Fig.
round
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ation
ontal
. The
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IT IN
| plan
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oints
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Though roots of electric poles or manhole lids
could be easily found everywhere, they were
intentionally excluded, because the center of a
root of an electric pole is difficult to find and
manhole lids are not clearly imaged. In some
places with no signs on roads or parks, however,
those points were unavoidably included.
Since, unlike with GOKUU, simultaneous observation
is impossible with BC-1, the judgment on whether
signs on roads had been redrawn or not was in some
cases difficult. The operator excluded such points
as have very different displacements from the
trend of surrounding points. But we are stil]
afraid of some points being mis- identified. Eig.7
and 8 show a part of obtained horizontal and
vertical displacement maps respectively.
6.CONCLUSION
This paper describes the constitution and func-
tions of a digital-image-based plotter GOKUU with
a special interest on the modified least squares
correlation for matching orientation points.
GOKUU's measurement performance was presented in
the experimental application to the project of
measurement of ground displacement in the Kobe
earthquake. The measurement precision was compared
with an analytical plotter, BC-1. According to an
experiment, both the positional and densitometric
resolutions were shown to be insufficient for
precision measurement. But in turn GOKUU was
proved far advantageous in simultaneous and
comparative observation of images by operators to
identify corresponding points in the photographs
taken before and after the earthquake.
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Fig.1 Screen Design of COMPARATOR MODE
fur. Detiee Scope y
Ru
Testi ccs
twn); qu
CAMEBME UAE 3 700 He Mate TMD $004] -—
Fig.2 Screen Design of RECTIFICATION
Fig.3 Screen Design of PLOTTER MODE
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996