130
The special geometric conditions of SPOT images have been determined with the
program BLASPO of the program system BLUH (Jacobsen 1988 c) which is
respecting the orbit of the satellite.
Several data sets have been handled, typical results are shown in table 4. The
results achieved with Landsat TM have been published by (Ehlers 1988).
sensor
area
image scale
base/height
Sx Sy
[ml
Sz
(ml
MC
N. Germany
1
820 000
1
3.3
7.7
20.2
LFC
Alps
1
770 000
1
1.6
5.8
8.6
KATE
Munich
1
1400000
1
2.8
27.2
47.7
TM
Georgia
1
1200000
1
5.5
22.0
42.0
KFA
Hannover
1
275 000
1
8.3
6.9
36.2
SPOT
Marseille
1
400 000
1
1.0
12.4
6.5
SPOT
Hannover
1
400 000
1
2.9
5.0
19.1
table 4: accuracies of independent check points determined by bundle adjustment
The results listed in table 4 are typical for the sensors. In other areas similar
results have been achieved. The horizontal accuracy is mainly depending upon the
quality of the used control points and the point identification. The standard deviation
Sx, Sy in the case of the SPOT-model in Marseille is limited by the poor control
points digitized from maps 1 : 25 000. The unaccurate results of the KATE 200
and Landsat TM are caused by the problems of point identification. The resolution is
limited, so only intersections of highways and edges of forests could be used. With
the exception of the KATE and TM the horizontal accuracy is sufficiant for mapping
1 : 50 000.
The vertical accuracy is mainly determined by the base to height ratio. So the
optimal results have been achieved with the SPOT in the case of a base to height
ratio of 1:1 (inclination +/- 27°) and LFC. But the listed values are only valid for
control points which are selected in areas with higher contrast.
In an area close to Hannover grid measurements have been made with images from
the KFA 1000, panchromatic SPOT, multispectral SPOT and as reference with high
altitude photos.
sensor
number of points
Sz
morefold
Sz against RMK
base/height
RMK
961
+/-
0.9 m
_
1 : 0.6
KFA 1000
961
+/-
16.3 m
15.1 m
1 : 8.3
SPOT pan
368
+/-
8.6 m
21.9 m
1 : 2.9
SPOT multisp.
961
+/-
8.4 m
35.5 m
1 : 3.4
table 5: accuracy of height measurements
(RMK = aerial camera f=8.5 cm, flying height = 10 500 m)
