difficulties in absolute orientation.
In photogrammetric analog instruments the ranges
for tilt, inclination and base components as well
as the model ranges, above all the ranges of 9, uw,
bx, by, bz and of course the Z-range are often too
small for the adjustment of terrestrial parameters.
Also in this respect it is obvious that the numer-
ous limitations can only be overcome by using an
analytical stereoplotting system.
2.5 Output of data and data processing
Relating to the output of data there are also
existing some differences between the topographi-
cal and non-topographical application. While in
the topographical evaluation of aerial photographs
the result is represented either by planimetry
mapping with contour lines or by digital output of
coordinates (triangulation data or digital terrain
models), there are a lot of special cases and addi-
tional clients! requests in the non-topographical
field. So, normally a both graphical and numerical
output is necessary. In many cases also horizontal
or spatial distances, angles, areas, volumes or
centres of gravity like values derived from coor-
dinates are of interest. Surveying objects
variable in time (movements, deformations) mostly
an immediate comparison of coordinates (before and
after movement, respectively between nominal and
actual values) is desired. This direct comparison
is only possible in analytical systems. A great
support for locating the model points in the com-
parison process is the automatic positioning of
single points or grid points.
A further problem (mainly occuring in the non-
topographical photogrammetry) is the graphical re-
presentation in oblique planes and perspectives as
well as in unusual projections. Of great impor-
tance are unwindings of surfaces not only for
architectural application but also for industrial
survey. This type of representation can be
generated with an analytical system in the on-line-
mode, i. e. in quasi-real-time.
2.4 Conclusions for the choice of a restitution
system
The list of peculiarities demonstrates that aero-
photogrammetric analog instruments don't comply
with most of the specifications of non-topographi-
cal photogrammetry. Some of the problems being
mentioned can be solved by analytical off-line
restitution, i. e, by digitizing of the objects'
data. The off-line method, however, is mainly
efficient for the evaluation of single points. For
graphical representations in planes and sections
the off-line method is not possible because with-
out orientation during the measurements there is
no reference to the planes and projections to be
mapped,
Analytical on-line restitution seems to be more
appropriate, because the results are immediately
available and can be checked and estimated at once
in regard of completeness, accuracy and statisti-
cal evidence. Completion, modification and repe-
tition of measurements are easily possible.
Due to the comprehensive software and easy oper-
ation the ZEISS Planicomp analytical system seems
to be exceptionally predestinated to non-topo-
graphical work. In the following a general des-
cription of the instrument as well as references
to special service programs are given.
98
3e Description of the ZEISS PLANICOMP C 100
The analytical stereoplotting system PLANICOMP
C 100 (fig. 1) consists of the hardware-components:
- basic opto-mechanical unit
- photogrammetric control panel
- electronic control unit
= minicomputer HP 21 MX
- terminal, printer
- digital tracing table DZ 6
Some of these components are described in the fol-
lowing passages.
Fig. 1: Planicomp C 100 with HP 21 MX mini-
computer, video display and line printer
5.1 The basic opto-mechanical unit
The opto-mechanical unit is more or less in confor-
mity with a stereocomparator, but with the
difference that the images are driven by the com-
puter. The instrument contains two separate servo-
driven systems of photo carriages moving in x and
y and a fixed optical unit for viewing. As
floating mark either a selective reversible black
point can be used or a luminous mark with variable
intensity and of 40 um or 20 um diameter. By a
prism-control unit the choice between orthoscopic/
pseudoscopic and binocular monoscopic viewing of
the left-hand and right-hand photo is possible.
Slip-on eyepieces for 8 x or 16 x viewing magnifi-
cation are on disposal.
5.2 The photogrammetric control panel
The control panel allows perfect control and
checking of practically all operations required
for orientation as well as for numerical and
graphical evaluation. The fictitious model is
controlled by the two handwheels with high and
low gears and foot disk. A free-handed motion is
possible by using a joystick acting in a non-
linear way. Regarding the movement of the floating
mark there can be selected between normal model
Scanning, terrestrial evaluation and profile
scanning.
The control panel disposes of an eight-digit
coordinate display for either photo-coordinates
xy y'y x", y", model coordinates x, y, z or
ground coordinates X,Y,Z. Of importance for the
program control are the decision keys "Continue/
Yes/Start", "Repeat/No/Stop" and "Execute" as well
as the indicators for program status "Busy",