THE INTERACTIVE GRAPHICS SYSTEM ON THE ANALYTICAL 
STEREOPLOTTERS FOR DIGITAL MAPS EDITING 
Tuan-chih Chen 
Chung Cheng Institute of Technology 
Tahsi, Taiwan, R.O.C. 
ABSTRACT 
The paper introduces the new theory as well as the new 
practical techniques of building a full-functional inter- 
acti ve graphics system on an analytical stereoplotter, in- 
cluding the hardware, the software and the firmuare, and 
hou they can be used to edit the digital maps. Two inter- 
active color graphics systems designed and programmed by 
the author for ZEISS PLANICOMP and WILD AVIOLYT to edit di - 
gital maps are furnished as examples. 
1. INTRODUCTION 
There are many neu techniques being developed recently in 
the field of the interactive computer graphics. It is now 
possible to have a built-in interactive graphics system on 
an analytical stereoplotter instead of connecting it with 
an expensive graphics system to edit digital maps /3/. 
The limited capacity and performance of a mi crocomputer, 
which normally has been used to control an analytical ste- 
reoplotter, can be complemented by computer graphics soft- 
ware, hardware, and firmware. For instance, an intelligent 
graphics terminal with oun graphics memory and mi croproces- 
sor can take care of the interactive grphics operation and 
therefore minimize the use of host CPU. 
2. SOME NEW CONCEPTS AND TECHNIQUES OF COMPUTER GRAPHICS 
2.1 Graphics memory 
Part of the terminal's memory is used for storing and mani - 
pulating graphics data. Once such graphics data have been 
sent from host computer to terminal, they don't need to oc- 
cupy the memory of the host computer or to be refreshed by 
the host computer more. 
2.2 Graphics output primitives 
Graphics output primitives are the fundamental units of a 
graphics display, the basic building blocks from which 
every graphics display is constructed. A graphically crea- 
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