span class="op">(</span><span class="va">points_xyt</span>, res <span class="op">=</span> <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span><span class="fl">0.1</span>, <span class="fl">0.1</span>, <span class="fl">0.5</span><span class="op">)</span><span class="op">)</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># assign a second set of points to the same grid</span></span></span>
<spa