"><code>sd</code></td>
<td align="left">RasterLayer</td>
<td align="left">2-10 x resolution to extent</td>
<td align="left">Invariant to height. Sensitive to non-fractal edges and
outliers.</td>
</tr>
<tr class="odd">
<td align="left">Area</td>
<td align="left"><code>area</code></td>
<td align="left">RasterLayer or mesh3d</td>
<td align="left">2-4 x resolution to 1/8 extent</td>
<td align="left">Sensitive to height; approaches 2 for surfaces with low
height variation, relative to the extent. Less sensitive 