<code>cubes</code> methods
result in estimates close to 2: a flat surface. If we transform the
z-scale to match the extent (L=128), we get the following.</p>
<div class="sourceCode" id="cb5"><pre class="downlit sourceCode r">
<code class="sourceCode R"><span><span class="va">surf_z</span> <span class="op">&lt;-</span> <span class="va">surf</span></span>
<span><span class="fu"><a href="https://rspatial.github.io/terra/reference/values.html" class="external-link">values</a></span><span class="op">(</span><spa