179 
AN INTERACTIVE SINGLE-USER COMPUTER GRAPHICS 
SUPPORTED STEREOCOMPILATION SYSTEM 
E. Dorrer, M.T. Erez, R. Tille 
Munich Bundeswehr University 
D-8014 Neubiberg, West Germany 
ABSTRACT 
Computer assisted mapping based on a single-user digital photogramme- 
tric system is discussed. The system entails interactive digitization 
of stereophotogrammetric data verified in real-time by a graphical 
direct view storage tube. Hardware and software components of the ex 
perimental set-up based on a Tektronix 4054 graphics desk-top computer 
with 32 kByte memory and a 450 kByte tape cassette drive is described 
in detail. Special emphasis is placed upon the BASIC application soft 
ware which is divided into three phases. Only phase one and parts of 
phase two have been implemented sofar. Phase one deals with real-time 
data acquisition and interactive editing of most recently digitized 
data. Phase two contains on-line editing of all data accumulated within 
the current stereomodel. Phase three deals with the joining of adjacent 
models and generating different data bases off-line. Despite the mini 
mal hardware configuration used, stereocompilation supported by a 
single-user interactive graphics system is very well suited for photo- 
grammetric digitization. Particular emphasis has to be placed on effi 
cient memory and data file management and on user-oriented ergonomic 
interaction facilities with the human. Visual and audio signals, 
prompts, text and special function keys are carefully balanced in the 
real-time environment. First experience with practical applications has 
demonstrated the feasibility of the system. 
INTRODUCTION 
Computer graphics systems have traditionally been geared to computer- 
aided design, manufacturing and mapping. Due to the heavy load burdened 
on the main-frame computer supporting "dumb" graphics terminals, in 
dustry has worked on several solutions to this problem. One solution is 
based on expensive turnkey systems that depend on a dedicated host com 
puter with sophisticated graphics software for processing. Another 
solution to the problem is a general-purpose terminal with sufficient 
local intelligence and software flexibility to unburden a user's host 
computer. A third solution consists of a stand-alone graphics computing 
system, i.e. a desk-top computer with graphics screen and built-in 
special graphics software integrated into a higher-level language BASIC 
interpreter. Typical is the Tektronix 4050 series of graphics com 
puters. 
In computer-aided-mapping or computer cartography, due to its inherent 
complexity of data structures and data base management, practically 
only very expensive turnkey-type graphics systems are being used. In 
teractive digitization and editing of cartographic data, interactive or 
automatic processing of complicated two-dimensional topological struct 
ures, and automatic plotting of digital data on computer-supported 
plotting tables is practised successfully in many mapping and charting 
organizations throughout the world. Computer cartographies systems 
normally consist of one or several interactive work stations with high-