, Y2)</code> define two opposing corners of the desired rectangular sensor region in units of grid points, where <code>(1, 1)</code> defines the upper left corner of the grid. Multiple rectangles can be specified by adding additional column vectors to <code>sensor.mask</code> as shown below.</p>

<pre class="codeinput">
<span class="comment">% define the first rectangular sensor region by specifying the location of
% opposing corners</span>
rect1_x_start = 25;
rect1_y_start = 31;
rect1_x_end = 30;
rect1_y_e