The system described here was implemented and tested in a real environment.
A fixed platform was built to which the camera/lens/filter apparatus
was attached. The whole platform was leveled using the digital inclinometer.
Series of measurements were taken at different times of day, in periods
of one hour. In each hour, six or eight measurements were taken.
All experiments were performed at
latitude/longitude (obtained with GPS).
We obtain accuracy of
, comparable to the accuracy of
the inclinometer.
We show some representative results in what follows.
Figure 18 shows the minimization of Equation (2) for two independent
sets of two measurements. The first two measurements were taken
respectively at 22:50:24 and 23:0:41 (GMT), June 3 1994. The temporal
distance between measurements was small, so the circles of equal
altitude are almost equal. Minimizing equation (2)
with both measurements yields
. Performance varies with random
disturbances; the second set of measurements was taken May 23 1994,
respectively at 22:11:23 and 22:37:59 (GMT). Result of both measurements is
.
