title: PCL library, how to access to organized point clouds?
body: <p>I have a very simple question:</p>
  
  <p>I have an <a href="http://pointclouds.org/documentation/tutorials/basic_structures.php" rel="noreferrer">organized</a> point cloud stored in a <code>pcl::PointCloud&lt;pcl::PointXYZ&gt;</code> data structure.</p>
  
  <p>If I didn't get it wrong, organized point clouds should be stored in a matrix-like structure.</p>
  
  <p>So, my question is: is there a way to access this structure with row and column index? Instead of accessing it in the usual way, i.e., as a linear array.</p>
  
  <p>To make an example:</p>
  
  <pre><code>//data structure
  pcl::PointCloud&lt;pcl::PointXYZ&gt; cloud;
  
  //linearized access
  cloud[j + cols*i] = ....
  
  //matrix-like access
  cloud.at(i,j) = ...
  </code></pre>
  
  <p>Thanks.</p>