n procedure is equiva-
ion and bundle adjust-
image data.
el describing the cam-
maging sequence, it is
nstraints into the bun-
he orbital constraints.
n points is maintained
ude
| (3)
the attitude vector ©
d-on-(1), (2) and (3),
e written as
1,2,94,5,9). (4)
1bined approach is de-
al. (1994) and Ohlhof
ON MOMS-02/D2
TATION
etric processing chain
points in the images.
rate technique to au-
Before starting the
p of the nadir looking
3 to obtain the same
> least squares region-
ke et al. 1996) about
. The standard devi-
re assumed to be 0.3
trips 79 DGPS-derived
P) were available with
,Y and Z. 75 points
| images by Baltsavias
he localization of the
he measured image co-
s routinely performed
elay Satellite System
or orbit #75B is based
ents with a sampling
utes. The force mod-
and 5 parameters de-
> attitude thruster sys-
leviations of the epoch
n X,Y, Z, whereas un-
titude thruster system
o to 50m in X,Y and
fact that the image
imately be related to
| attitude information.
et exists in the bundle
sighting matrix for the
been derived relaxing
ina 1996
the orbital constraints in the along-track direction (Gill et
al. 1995).
Attitude information was derived from gyro recordings of
the IMU of the shuttle Guidance Navigation and Control
System. Based on approximation tests the optimum dis-
tance between two orientation points was found to be 4615
rows, corresponding to a flight distance of 62.3km and a
flight time of 9.1s.
4.2 Combined Adjustment
The combined adjustment was performed in the geocen-
tric coordinate system WGS84. The DGPS-derived GCP
were divided into two groups. The first group consists of
12 GCP, where 3 points each are located in the corners of
the threefold overlapping area to ensure a precise defini-
tion of the global datum. The second group comprises 63
geometrically well distributed points which were used as
check points.
The following data were introduced as observations:
e [mage coordinates of 13 959 conjugate points
(c0 0.3 pixel)
e [mage coordinates of 12 GCP (e —0.5 pixel)
e Image coordinates of 63 check points (c —0.5 pixel)
e Object coordinates of 12 GCP (ox = oy = 0z =
0.1m)
e Epoch state vector components with associated 6x6
weighting matrix
e Attitude parameters (Ç,n, 4) at 8 orientation points
(0, 204 99: 507)
In Table 2 the rms values of the theoretical standard devi-
ations of the check point coordinates X, Y and Z and the
corresponding empirical values are presented. The the-
oretical values were computed from the inverted normal
equation matrix and the a posteriori Go value of the com-
bined adjustment. The empirical values were derived by
comparing the estimated object coordinates of the check
points and the known values.
MOMS #75B theor. | empir.
Hg [m] 113 9.3
hy m). | 133. D. 10.2
la in] |. 89€), 112
PEYZ [m] 11.2 10.3
Table 2: Rms values pix, y, Hz and uzyz OË the the-
oretical standard deviations derived from 63 check points
and corresponding empirical values
The good correspondence between the theoretical and the
empirical values indicates the correctness of the stochas-
tic and the functional model. The empirical values show
that accuracies of about 10m (0.7 pixel) in X, Y and Z
were achieved. Note that these accuracies are related to
the global WGS84 coordinate system. The empirical ac-
curacy referring to a local topocentric coordinate system
amounts to 11.8m in planimetry and 7.3 m in height. The
planimetric accuracy is impaired by localization problems
of the GCP and check points in the images. A graphical
analysis of the residuals in the check points showed that
the results are not affected by systematic errors.
5 COMPUTER SIMULATIONS ON MOMS-2P
IMAGE ORIENTATION
A series of computer simulations have been carried out to
analyze the effect of certain parameters on the accuracy of
MOMS-2P image orientation, especially the effect of block
configuration and control information.
5.1 Input Parameters
a) Block Configurations
The computer simulations were performed for 3 different
block configurations:
e Single strip
e Block of 6 strips with q— 2096 side overlap
e Block of 11 strips with q = 60% (Figure 3)
1BL
—
; |
e
N
Un
e
=
3
o 640 km —
Figure 3: Block consisting of 11 strips with 4 baselengths
each and 60% side overlap
The strip length was chosen to 4 baselengths (640 km).
This results in the fact that points at the beginning and
the end of the single strip are projected into 2 images
only, whereas each point in the central part of the strip
is projected into 3 images. The strip width amounts to
50 km. The entire block covers 320x250 km? (without 2-
ray area), corresponding to the area of Catalonia (270x250
km?), which is the most important calibration site of the
MOMS-2P experiment.
b) Interior Orientation Parameters
All parameters of the interior orientation were introduced
as error-free values.
c) Conjugate Points
The object coordinate system is defined as topocentric
Cartesian system XY Z with the positive direction of the
161
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996
