During the process of watermelon seeds characteristic extraction as well as separation, watermelon seeds' major and
minor axes, the length and width ratio have played a very important role in appearance regulating degree evaluation. It is
quite difficult to find the answer of orthogonal bi-axes because the watermelon seeds are flat and irregular in shape and
what's more there is no rule to follow. After a lot of experiments and research, the author proposed the algorithm of
orthogonal bi-axes algorithm for granulated object. It has been put into practice and proved in the application of auto-separation
system for watermelon seeds. This algorithm has the advantage of lower time complexity and higher precision
compared with other algorithms. The algorithm can be used in the solution of other similar granulated objects, and has
the widespread application value.