the 
the 
the 
onal 
‚and 
uted 
0m 
nent 
2 to 
ting 
OT 
ned, 
din 
the 
stin 
lese 
; of 
rate 
n of 
tive 
Own 
ctor 
ters 
ons 
also for the cases where only one or two control 
points are available. 
In the processing of strips of scenes, the attitude time 
series are concatenated, and the individual scene 
parameters are connected by orbital constraints 
(Westin, 1991). In this way, the number of parameters 
used for the whole strip can be limited to the same 7 
parameters used for one single scene. This is of great 
importance for the stability of strip triangulation. 
3.2 Analysis of attitude rates 
Before the tests, the attitude data were analyzed by 
integrating the gyro rates present in the telemetry 
data. Figure 3 shows the development of attitudes 
over the six scenes in the strip. Especially the roll 
rates are very high. Part of the time, it is higher than 
the roll rate 3 o specification of 0.0007 deg/sec 
(NASDA, 1990). This gives rise to about 500 m 
distortion in the cross track directions and it is obvious 
that a rigorous attitude correction is essential. 
  
  
  
  
0.02 MÀ 
0.00 j«——— — 7 -— Yaw | 
© x — 
$ 1 Pitch 
o -0.02 4 N. + 
© 
S M Roll 
o * 
3 -0.04 by, 0 a P 
E m 
-0.06 4 y 
-0.08 W 1 v Ï T T T 
0 20 40 60 80 
Time [sec] 
Figure 3. Attitude variation in the strip. 
A close-up of the pitch variation (Figure 4) also 
reveals a high frequency variation with an amplitude 
of about 0.5 10? degrees. This causes short time 
distortions of about 5 m, and is further evidence of the 
necessity of correct treatment of the attitude 
information. 
939 
Pitch angle [mdeg] 
o =o „oO 
© N A 
1 À J 
5 5 
A N 
i L i 
  
© 
Oo 
  
T T T T T i * | 
0 2 4 6 8 10 
Time [sec] 
Figure 4. Pitch short time variation. 
4. PLANIMETRIC ACCURACY 
4.1 Test strategy 
A number of tests were designed to investigate 
different aspects of the planimetric accuracy and 
stability of JERS-1 rectification: 
1. Single scenes with many control points. 
2. Strip of 6 scenes with many control points. 
3. Strip of 6 scenes with one control point in each end 
of the strip (interpolation). 
4. Strip of 6 scenes with two control points in the first 
scene of the strip (extrapolation). 
5. Strip of 6 scenes with only one control point in the 
first scene of the strip (extrapolation). 
The first two tests are intended for verifying the 
correctness of the model and for investigating the 
potential accuracy achievable. The last three test are 
rather extreme cases for investigating stability of 
rectification. In these tests, only VNIR band 1 was 
used. 
A total of 123 control points were collected from the 
topographic maps, distributed with approximately 20 
points in each scene. In the first two test cases, all 
control points were used in the adjustment. In the last 
three test cases only two or one control point were 
used in the adjustment, while all 123 points were later 
used as check points in the evaluation. Figure 5 
shows the distribution of the control in the different 
cases. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B4. Vienna 1996