Original post is quoted below my reply here.

Heightfields can be made to have no pixelization appear unless the camera
is right near the surface. I gather this is what you are doing though and
of course you would always see the individual "squares" if the camera
either zooms in or is real close no matter what the original resolution
was. Seems a problem of proximity if anything. Basically what you describe
you want to use is further refinement of the resolution or a enhanced
tesselation, ie. more division of the pixels, or more correctly the
vertexes. Since these would originally be flat squares I'm guessing the
production of a HF creates triangles having these as vertex points
instead; meaning a image used to make the HF, if black and white pixels in
a checkerboard pattern, would become a HF of as many peaks and valleys as
there are pixels. So it is feasible I would suppose to subdivide what
exists in some sort of interpolation manner.


Lummox JR wrote:
> 
> I'm using a height field in one of my scenes to simulate sand dunes--a
> nice enough effect, except for a problem I'm having with the diffuse
> reflection off the surface. Some of the triangles face the light source
> a little too directly, no matter where I put it, so that I get marching
> diagonal rows of light spots, shaped like checkerboard squares.
> The "smooth" keyword is present. The image does indeed look worse
> without it.
> Using multiple light sources and area lights does not improve the shiny
> checkerboard effect; if anything, it sometimes makes it worse by
> creating even more rows of light spots, though usually not as noticeable
> as the first row.
> I should mention that because the height field is simulating sand dunes
> from close up, it's scaled to <100,8,100> (as I recall).
> 
> I've played around a lot with the bit depth and size of the height field
> file I'm using. Increasing the resolution just makes the checkerboard
> areas smaller, but they do not go away. Currently I'm using the maximum
> bit depth of 16, with a 1200x1200 height field. The height field is a
> 1.9 MB PNG file, and anything 2400x2400 or larget is not only unwieldly,
> but still produces the same patterns (just a bit smaller).
> 
> With the smooth keyword on, there should be no noticeable light spots
> such as I'm getting, but they're there. I had an idea for preventing
> that.
> Since the smooth keyword seems only semi-effective, why not make it
> possible to use a numeric operator? Equate "true" to 1.0, the default
> value if "smooth" is used, and "false" to 0. Thus, something "smooth
> 5.0" would do even more smoothing, causing much more of a rounded
> appearance, while "smooth "0.5" would produce something more like the
> typical unsmoothed flat look, but with a bit of smoothing near the
> edges.
> 
> Lummox JR

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