3.1 Data used 3.4 Cross correlation between image
; ; chips of stereo pair
An experiment with the following P
SPOT/HRV stereo pair of images Was It
is X
conduct ed. expected that
planimetrically corrected Stereo pair
shows a good cross correlation. Widely
distributed 8 image chips consists of 32
3.2 GCP location X 32 pixels were extracted from the
: Y stereo pair of SPOT/HRV. Cross
The following three GCPs with correlations between the image chips of
almost same height (around 600 m above the stereo pair are shown in figure 2
sea level) were extracted from About 0 to 98% of cross correlation was
topological map. A portion of SPOT/HRV increased after the planimetrie
image and topoglaphic locations of the correction.
GCPs are shown in figure 1. Study area
is stuated in a montaintanuous region of 3. 5. DEM estimation accuracy
Kiso-Komagatake in the middle of Honshu
in Japan. Height in this area ranges 9 GCPs were used for evaluati
ion of
from about 600 to 2500 m above sea : : :
level. an effect of the planimetric correction.
Table 3 shows DEM derived from
topological map and estimated DEM with
3.3 Planimetric correction ; 3 : :
and without planimetric correction.
Based on the aforementioned Affine
transformation with the coefficients
derived from the GCPs, planimetric
distortion was removed. Assuming the
following relationship between line
pixel coordinates for before and after
the planimetric correction, (L,P) and
(La Pa), planimetric distortion was
evaluated with the selected 9 GCPs for
evaluation.
RMS error of estimated DEM for the
proposed method was reduced by one 14th
compared to without planimetric
correction.
4. Concluding remarks
The proposed method is simple and
effective for improvement of DEM
estimation accuracy. Just before DEM
estimation, Affine transformation with 6
La=al+a2L+a3P+a7L”2 +a8LP +a9P 2
= S ^ 4) coefficients derived from 3 GCPs with
p ALS GRFE LOL SHE LIERAGLZPCH ( almost same hieght is applied to the
a ala stereo pair of images. In this case
^ 5 292
+a16L 3+al7L ZP+al8LP with SPOT/HRV, the experimental results
show that planimetric fidelity is
remarkably improved, cross correlation
between image chips of stereo pair is
Table 2 shows the coefficients of
the above equation for before and after
the planimetric correction.
Table 1 Data used
Acquisition Pointing GRS Process Remarks
date angle level
Dec. 8’ 86 13. 6deg. 327-278 1b Kiso-Komagatake in
Dec. 12' 86 20.2deg. 327-218 1b Japan
Table 2 A comparison of the coefficients of the Affine
transformation for system corrected and planimetrically
corrected SPOT/HRV data
System corrected data Planimetrically corrected data
al —2.16 E 6 6.45 E 5
a2 2.04 E 3 =b. 31 BE 2
a3 5.44 E 2 —-2:.26 E 2
a4 4.96 E 6 -—4.29 E 5
ab —4.64 E 3 3.01 E 2
a6 z1.26 E 3 1.96 E 2
a7 -6.51 E 1 1.48 E-1
a8 —-3.11 E-1 1.16 E-1
a9 =6. 11 E-2 3.10 E-2
a10 1.48 E 0 =5. T7 E-2
all 7.21 E-1 —-1.09 E-1
a12 1.42 E-1 —2.32 E-2
a13 7.63. E-5 —1. 70 E-5
al4 3.17 E-5 —7,59 E-6
a15 2.08 E-5 1.36 E-5
a16 —1.78 E-4 3. 89 E-6
al’ =7.33 E-5 9. 85 E—-6
a18 -6.22 E-5 1.03 E-5
858
