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In the ongoing enhancement of this central measuring module of PHOCUS, we are 
incorporating user suggestions from their everyday practical work. Moreover, 
a programming interface enables each user to generate his own specific data 
acquisition functions. This means that the standard measuring program sup 
plied with the equipment can be tailored to the customer's specific applica 
tions. PHOCUS thus meets the demand for an open-ended, flexible system. 
For the acquisition of attribute data, the so-called object names and object 
item names are available at present. To meet the increasing demands that will 
be made in the future by photogrammetric users regarding the creation of geo 
graphic information systems, PHOCUS will be extended by the connection of a 
relational data base, permitting the definition and management of randomly 
structured attribute data. While the geometric data will continue to be sto 
red in the PHOCUS data base, special data elements will be provided to form 
the connection with the relational data base. 
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2.2 PHOCUS PA Workstation 
Customers have frequently expressed the wish to connect the analog stereo 
plotters they are still using to the PHOCUS system, in order to be able to 
benefit from the advantages of object-oriented data acquisition also with the 
existing equipment. 
The connection between the plotter and the PHOCUS computer is formed by the 
DIREC-P digitizing and interface unit. The inputs of the x, y, z encoders in 
the analog instrument are recorded and transformed by this unit and then 
transferred to the PHOCUS computer via a RS 232 standard interface. This en 
sures the connection to the different types of computers on which PHOCUS is 
implemented. Apart from the transformation of model into terrain coordinates, 
the software of the interface unit also performs the time-critical incremen 
tal recording procedures.