<p><code>hvar</code> and <code>sd</code> estimates are identical (i.e.,
invariant to z-scaling) and <code>area</code> and <code>cubes</code>
estimates are higher. This dichotomy raises an underlying philosophical
question about fractal surfaces: does the fractal dimension of an
surface change if it is transformed along a dimension?</p>
<p>The answer will likely depend on what you are analyzing. For example,
if you are examining landscapes, then <code>area</code> and
<code>cubes</code> methods will not be mu