Line thickening

[Conn Copas]

Some geometric advice for a beginner would be appreciated. The situation is
this: I have a rasterised stream network which displays fine in plan view.
However, when draped over an elevation map in perspective view, the network
all but vanishes. Thus, I have concluded that I need to create buffer zones
around the streams to improve 3d visualisation, and I am trying to decide
upon a theoretically well-founded approach. My initial guess is to make stream
thickness a linear function of observer azimuth; is this the standard sort of
approach? 

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Conn V Copas
Loughborough University of Technology          tel : +44 509 263171  ext 4164
Computer-Human Interaction Research Centre     fax : +44 509 610815      
Leicestershire  LE11 3TU              e-mail - (Janet):C.V.Copas at uk.ac.lut   
G Britain                                      (Internet):C.V.Copas at lut.ac.uk