  Aims: The statistics of the photospheric granulation pattern are investigated
using continuum images observed by Solar Dynamic Observatory (SDO)/Helioseismic
and Magnetic Imager (HMI) taken at 6713~\AA.
  Methods: The supergranular boundaries can be extracted by tracking
photospheric velocity plasma flows. The local ball-tracking method is employed
to apply on the HMI data gathered over the years 2011-2015 to estimate the
boundaries of the cells. The edge sharpening techniques are exerted on the
output of ball-tracking to precisely identify the cells borders. To study the
fractal dimensionality (FD) of supergranulation, the box counting method is
used.
  Results: We found that both the size and eccentricity follow the log-normal
distributions with peak values about 330 Mm$^2$ and 0.85, respectively. The
five-year mean value of the cells number appeared in half-hour sequences is
obtained to be about 60 $\pm$ 6 within an area of
$350^{\prime\prime}\times350^{\prime\prime}$. The cells orientation
distribution presents the power-law behavior.
  Conclusions: The orientation of supergranular cells ($O$) and their size
($S$) follows a power-law function as $|O| \propto S^{9.5}$. We found that the
non-roundish cells with smaller and larger sizes than 600 Mm$^2$ are aligned
and perpendicular with the solar rotational velocity on the photosphere,
respectively. The FD analysis shows that the supergranular cells form the
self-similar patterns.
