Plate 1 Overview of I?S Digital Stereoplotting system 
Results 
System Utility 
Jaksic (1978) has described the criteria for analytical plotter 
evaluation, and the digital plotter can be assessed using these: 
1) 
2) 
3) 
Position and measuring devices. The fundamental criteria 
for this sub-system are accuracy, speed and stability. The 
digital plotter hardware is inherently perfect in these 
respects, allowing for the pixel limitation in accuracy and 
the refresh cycle of movement. 
Image transfer. This refers mainly to the optical design, 
but as viewer development has not been a priority, the 
optical system is presently poor. The image quality also 
depends on the CRT monitor, which should have a high scan 
rate (to minimise flicker) and a brightness control. It has 
been found desirable to view the image at pixel resolution, 
but at this magnification the screen phosphour dot structure 
becomes visible. Images displayed at 2x magnification on a 
1024 pixel monitor would improve this situation. 
Operator/instrument/computer interface. The major problem in 
this sub-system is the lack of a Z control. The instrument/ 
computer interface can be slowed to unacceptable levels by 
heavy system usage,but would be overcome by giving the 
system a high priority. 
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