SER ee EE
RUMBA
———'ÉÉÁÉÓÓÁÓÓÁE
————————
figure 3: testfield used for calibration
omega phi kappa [| dXO(m) | dYO(m)
photo1 Ü 0 0 0 0
2 0 0 200 0 0
3 0 0 300 0 0
4 0 0 100 0 0
5 +20 0 300 +0.1 0
6 -20 0 100 -0.t 0
7 0 -10 100 0 +0.1
8 0 | +10 300 0 -0,1
d XO, dYO0 = difference of camera position
reference = photo 1
table 1: configuration of photos for ca-
libration
Jens 2050 SNR Jens 53203 SNR
ck (mm) 72.209 72.887
| dx0 (mm) 0.037 6.9| 0.4416E- 0.9
dyO (mm) 0.008 09| -0.1292E4 20
al 0.5326E-1 0.9 -0.4287E-1 0.5
a2 -0.7984E-5 0.2 0.2404E-4 0.2
a3 -0.1036E-5 1.8 -0.2768E-6 0.3
dek 0.7195E-9 0.2E-4 0.2201E-S 0.5E-5
SNR = adjusted value / standard deviaton
table 2: results of calibration for both
cameras
terminati [e] ontr oint
As mentioned above at the fixing of
control points restrictions had to be
obeyed. Therefore, for each part of a
stone 6 control points were fastened (s.
fig. 4): screws with a diameter of 5 mm
and length of 5 cm. They were inserted in
borings and fixed by a specific adhesive.
The coordinates of control points were
determined photogrametically: spatial di-
stances were measured (s. fig. 4) and
three photos were taken. Two of these
photos are in accordance with the stereo
normal case and serve also for the survey
of the stone surfaces (s. fig. 5). A self
constructed tool was used to measure the
distances within the range of acuuracy of
0.1-0.2 mm.
figure 4: configuration of control points
and measured distances
The following bundle block adjustment
was evaluated as a free spatial net and
the measured spatial distances introduced
with a standard deviation a priori of 0.1
mm /Diippe 1984/. In fig. 6-7 and tab. 3
the standard deviations of control points
and the residuals of the distances are
sumed up for the six parts of stones. One
can see that the required accuracy - es-
pecially for Z-coordinates - was achie-
ved.
The survey in the second epoche re-
quires a check of stability of the fixed
control points. There a strategy
respective to /Pelzer 1985/ will be ap-
plied. In order to guard against the loss
of control points by changing of their
position compared with epoche one addi-
tional signals will be attached to the
stones during the measuring campaign. Af-
terwards they will be removed. This work
will be done in the near future. The re-
sults of the comparison wiil be presented
in a poster session in Washington.
STRATEGY OF DATA COLLECTION AND REPRESEN-
TATION
prelimi idecations
Before evaluating stereo models for
the purpose of surface modelling some ba-
sic considerations are useful. They refer
to the accuracy and quality of digital
elevation models (DEM) derived of measu-
ring a regular grid, the kind of data
collection and the realisation of the
comparison.
