[vtkusers] Any tips for producing greyscale visualisations?

[David.Pont at ForestResearch.co.nz]

Hi,
  I am sure many of you have faced the same issue: how to produce
visualisations suitable for black and white printing? The only obvious
technique is to use a greyscale lookup table and to use a white background
(which is easier for printing than black).
My problem is that surfaces 'coloured' in grey can merge with the
background (white on white). I have tried reducing the range in the lut so
that full white is not reached, but this limits the ability to resolve
different values.

Here are some assorted thoughts:
- Glyphs use geometry to convey value rather than colour, but only at point
locations, it is useful to see gradations across a surface.
- I have thought of outlining the surface in black to separate white=scalar
value from white=background. My current data all lies on a planar surface
so this would be easy, but in general for 3D this would require extracting
a silhouette, I dont know how to do that.
- I have realised it may be sensible to change the lighting for print
images to avoid shading effects that confuse changes in scalar values.
- I have though for a while about using 'stipple' / 'hatching' effects to
display changes in scalar values.

Yesterday I tripped over a paper titled 'Real-Time Hatching', by Praun,
Hoppe, Webb and Finkelstein. They describe a method (based on texture
mapping) for shading surfaces that 'simultaneously conveys material, tone,
and form'. Very cool.
My interest would be to use a similar approach to convey scalar values.
Changes in hatching density could convey changes in scalar. Shading effects
would have to be considered carefully.

So, before I leap into this ('vtkHatchIt'), has anyone out there got tips,
ideas, comments,  on the issue of how to convey changes in scalar values
over surfaces in greyscale?

  regards
     Dave P