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higher requirement than the one specified here. It is of course to be 
expected that a system designed for map compilation would be more suited 
to that task than an existing system designed for image analysis. If the 
full potential of digital image processing is exploited, including 
enhancement and use of multispectral data, then again the specification 
would be more demanding. 
The main hardware requirements are mass storage devices, storage with. 
real time access and display. Mass storage for scenes containing 107 
pixels or more will probably be provided by optical discs. Tests are 
already going on into the use of this medium for storing images. 
1024 x 1024 frame stores would be ideal for real time access but 
mosaicing of 512 x 512 stores can be used very efficiently. A 
requirement not fully investigated is that for high quality stereoscopic 
display. Single displays of sufficient resolution exist and stereo 
displays have been used, for example by Real (1982) and Boyde and Ross 
(1975). More recently Bedwell (1980) has investigated the use of two 
screens for stereo viewing of photographs, and Petrie (personal communication) 
is investigating a dual screen flicker system. Split screen polarised 
systems and anaglyph systems are also possible. 
A number of proposals have been made for the use of digital systems for map 
compilation and work is going on to develop such systems. Case (1982) 
has proposed a digital stereo comparator/compiler (DSCC) which is designed 
to use automatic correlation of all points using digital imagery. Whilst 
being designed for central perspective images, the concept is applicable 
to any geometry. Colvocoresses (1982) has proposed an automatic compilation 
system for use with Mapsat data, utilising epipolar lines of data which are 
recorded by the satellite under constant guidance. At the ITC an interactive 
digital restitution system is being developed and at University College London 
proposals along the lines of those discussed above are being investigated. 
Conclusions 
It has been shown that existing equipment can be used to produce maps from 
data acquired in space, however in all cases the methods available must 
be carefully analysed and assessed as regards their suitability for the 
specific data. Analytiæ\ stereo plotting instruments appear to have the 
greatest potential when using hard copy images and examples are given of 
their application. Work is going on in several centres to develop the 
use of digital imagery and the technology exists to develop such instruments 
but it is to be expected that different instrumentation and method will be 
used for different types of image and the next four years will provide 
interesting developments in this field. 
References 
ALLAN, T.D., 1983. Satellite Microwave Remote Sensing. Ellis Harwood. 
Chichester. 526 pages. 
BAUDOIN, A. and LESTRINGAND, G. 1981. Cartography, Photogrammetric 
Restitution. SPOT imagery simulation, Sheet CAZ CNES, Toulouse 
6 pages. 
BEDWELL, C.H. 1980. Investigation of visual performance in stereo plotting 
using video technology. International Archives of Photogrammetry 
23(B2): 28-37. 
BODECHTEL, J. 1983. The modular optoelectronic scanner, MOMS, on STS-7 
June 1983. Proceedings of a EARSel ESA Symposium on Remote Sensing 
Applications for Environmenta] Studies. Brussels 1983. Pages 65-68.