On Mon, 07 Jun 1999 07:37:53 -0500, Bob wrote:
>Well, anyway, reason for all this is to see what a HF is made up of, at
>least an attempt to. I looked from all sorts of vantage points and camera
>angles and darned if I know yet what it is. Triangles perhaps?

Yes, triangles.  Each 'cell' in a heightfield is a pair of triangles
whose vertices are the values of the four pixels surrounding the cell.
The simplest case is when you have an image of 2x2 pixels.  In that
case, you get a heightfield of a single cell, composed of two triangles.

If you look at the heightfield from the +y direction with a sky of +z,
it will be constructed like this:

   z=1,x=0  x=z=1
    +------+
    |\     |
    | \    |
    |  \   |
    |   \  |
    |    \ |
    |     \|
    +------+
   0        x=1,z=0

Here's what you get with a 3x3 source image:
  
   +---+---+
   |\  |\  |   
   | \ | \ |   
   |  \|  \|   
   +---+---+
   |\  |\  |   
   | \ | \ |   
   |  \|  \|   
   +---+---+

In the absence of interference effects, a checkerboard like the one 
you're using will always be rendered as a series of diagonal ridges 
and valleys.

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