This technique works very well, but unfortunately is only suited to 
imagemaps.

I took my heightfield and blurred a copy, thus rounding the sharp edges. I 
then subrtacted the original sharp image from the blurred image using Gimp, 
leaving only the blurred regions which were higher than the unblurred. This 
resulting image was then inverted, tweaked, and applied to the heightfield 
as an imagemap. 

The results look great, in my opinion.

The only problem I have is that the resulting texture is an opaque 
imagemap, which makes blending it with an onderlying texture a little 
tricky. I tried setting it to filter 1.0, but this does not allow the 
degree of grime to be adjusted, short of modifying the imagemap itself.

Couple of attached images showing the procedure and results.

-- Simon

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Attachments:
Download 'Grime4.jpg' (8 KB) Download 'Grime1.jpg' (16 KB) Download 'ReliefCloseup3.jpg' (21 KB)

Preview of image 'Grime4.jpg'

Preview of image 'Grime1.jpg'

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