An anaglyph approach is possible using red and green images; however this precludes the use of 
colour images or overlays. Tektronix markets a polarising system in which the two images of the 
stereopair are alternatively displayed on the monitor. This requires a TAAC board for fitting onto a 
SUN. 
Figure 1. Proposed architecture for fast digital image processing. 
Algorithm development and implementation 
The software requirements of a DPW are shown in table 6. The main operations are broken down 
into specific tasks. 
Table 5. Software requirements for a DPW 
INSTRUMENT OPERATIONS Stereo display, overlay vector images 
Zoom 
Scroll 
Measure image co-ordinates 
Operator interface 
Edit and update database 
ORIENTATIONS Transformation, bundle adjustement etc. 
REAL TIME SUPPORT Measuring co-ordinates, identification of ground 
control points, Validate products produced 
automatically;; 
Image enhancement; 
Extracting features in ground co-ordinates; 
Automatic identification and extraction of features 
Control line following by automatic removal of x 
parallax; 
OFFLINE OPERATIONS Computation of orientation parameters; 
Stereo matching for DEM determination; 
DEM manipulation; 
GIS; 
Animation and simulation; 
The operation shown in italics are those where development is required. 
There are few problems remaining in implementing instrument operations. The systems which are 
in existence demonstrate this. The larger systems such as the Kern DSP1, the Traster T10N and 
the Context Mapper have a fully universal system. Use can also be made of the human interface 
provided by computer manufacturers particularly the use of windows, icons, menus and pulldowns 
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