d) nearly vertical view ( A I)
e) terrain height differences below ca. 1000 m.
ui
If we may accept these restrictions, the approximate model (3) gives
the same result as the rigorous model of type (2) (see BAHR 1978).
However, the earth rotation effect should be eliminated in advance.
4. Orientation Operations at the Analytical Plotter
After having proven, that we are in principle allowed to process
LANDSAT MSS imagery by an analytical plotter, we face more problems,
at least for the PLANICOMP, when trying to form a classical "Stereo-
model", which of course is not possible with LANDSAT imagery. But
the analytical stereoplotter logically requires such a model.
+ + m
Landsat Landsat
Channel n Channel m
Left Image Right Image
Fig. 1: Measuring "fiducial" marks at left an right image in order
to simulate a "base".
In order to overcome this problem, one may artificially introduce
a "base" between a left and a right picture and thus simulate a stereo-
model. Fig 1 shows how it is done if the base is taken from marginal
cross-marks ("first option"). Both images, left and right, are geo-
metrically identical. When measuring the " fiducials " for the
interior orientation at the left ends of the horizontal cross bars
for the left picture and at the right ends for the right picture
respectively, a horizontal parallax is introduced. Afterwards one
may go on with the relative orientation as if both pictures would
form a stereomodel, using the von Gruber point configuration.
The availability of two images (left and right) which show diffe-
rent spectral channels is very useful during the interpretation pro-
cess. On the other hand, however, it is also possible to do the
orientation with a single image ("second option"). A horizontal
parallax can be introduced, without having a reference image, purely
by observing the image coordinate display and adding the selected
base length for the non-existing picture.
Once the relative orientation performed, the absolute orientation
corresponds to the procedure done for conventional stereomodels. As
for ground control, one has to observe the requirements for LANDSAT-
MSS imagery: more than ten, well distributed points in order
