FIGURE 18.

A complete tessellation of a region containing objects of varying size and shape. If the counting rules are applied, each object is counted at least once and never more than once independent of its size, shape, or orientation. The objects are marked with a plus sign in the image of the frame in which they are counted. Sometimes one also needs to know how many counting frames have been applied to a region of interest (see Section 6.5). Any selection of the corners of a counting frame, in this case the top‐left and bottom‐right corner, can be used to estimate the number of entire counting frames that fell on the structure. Eight of the selected corners (arrowheads) fall inside the gray region of interest. Objects were therefore counted in an area estimated to that of 8/2 = 4 counting frames [Color figure can be viewed at wileyonlinelibrary.com]