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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-