Thomas Lake wrote:
> 
> I remember a couple of people's posts to my images mentioning that a
> better way to make a flat wood surface is to use a height_field with
> matching wood texture. How exactly do you go about doing this? Would you
> place the height_field just above the surface of the wooden object?
> Would you use a wood texture created by pov as the bit map for the
> height_field?

I haven't actually tried it myself but I would thing the proceedure
would be to design a wood pattern that you like. While keeping
all of the settings in the color map(s) for the wood the same change
only the pigment colors to shades of gray. Apply it to a flat object
that fills the screen and render the image. Use this to create a HF
object. Apply the original woo pattern over the HF with attentoin to
alignment and scale so that the patterns in the texture match those
of the texture.

 That is the basic description for the process. I would imagine you
could could use your original colored wood texture in the first stage
and convert it to gray scale in a paint program later. This has the
disadvantage of being unpredictable in how the height will vary but
shold come fairly close. Remember that differnt colors give different
height values. Even if you convert them to grey scale it does not
mean they sill be the correct shades of gray to give the heights you
are looking for.
 I would think that you would want to avoid large changes in color
between the adjacent pattern areas. You are only looking for a small
amount of height change to see a visible diffeene in the grain structure.
I would reccommend something like rgb 15-16 for the smooth areas
between the grain and 16-20 for the grain patterns themselves.
Amount much over this variance will make very noticable differences
in the heights between bordering areas.
  Seriously this approach sounds like overkill to me unless you are
trying to model the end of a snaped off piece of lumber. A simple
bump map in a normal statement would be much easier to control in
my opinion. You could use the same approach to the manufacture of
the image for the bump map but instead of creating a height field
apply it to standard pov generated objects.







-- 
Ken Tyler

mailto://tylereng@pacbell.net

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