20 
The absolute orientation of the stereomodel is supported within PHOCUS by an 
orientation program which computes the setting data for the orientation ele 
ments, while making allowance for the different types of terrain involved. If 
a model has already been oriented in PIanicomp and stored in the stereomodel 
file, e.g. during a aerotriangulation measurement and adjustment process, 
this orientation data is used for the computation of the setting data. As a 
result, the speed of relative and absolute orientation of the stereomodel is 
considerably increased. After completion of the orientation process, the 
transformation parameters are transferred by a driver program to the digiti 
zing and interface unit. The driver program also ensures that input data is 
correctly supplied to the internal PHOCUS interface. The data acquisition 
programs can therefore be used without modifications both in the PIanicomp 
and the analog instrument. These 
The PHOCUS multi-workstation system permits the connection of several analog 
instruments to one computer, with the possibility of combining them with 
PI ani comp, digitizing and editing stations. 
2.3 PHOCUS DEM Measurement Program 
2.3.1 MDTM 
The standard measuring program for digital elevation models (MDTM) comprises 
the functions: 
Measurement of single points 
Manual positioning of the floaing mark or 
prepositioning using the input file, e.g. 
for the determination of volumes 
Measurement of a regular grid 
Prepositioning of the floating mark to a 
selectable, regular grid 
2.3.2 
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