Algorithm 1 Cluster Registration.

Require:$\{\mathcal{C}\}$:Set of registered clusters Require:$C_x$:Cluster waiting for registration Require:$C_0,C_1,C_2\in \{\mathcal{C}\}$:Three clusters closest to $C_x$ in $\{\mathcal{C}\}$  1: for each $i\in \{0,1,2\}$ do  2: if sqrDist($O_i,O_x$)>maxDist then  3:  $\{\mathcal{C}\}\leftarrow (C_x\&a{p}_x=1)$; break;  4: end if  5: if sqrDist($O_i,O_x$)<minDist then  6:  $\{P_i\}\leftarrow (\{P_x\}\&a{p}_i++)$;  7: else  8:  $count\leftarrow 0$;  9:  for all $p_j\in \{P_x\}$ do 10:   if radiusSearch($p_j$,$\{P_i\}$,rad)>minNum then 11:    $count++$; 12:   end if 13:  end for 14:  if $count$>sizeof($\{P_x\}$) / thresholdNum then 15:   $\{P_i\}\leftarrow (\{P_x\}\&a{p}_i++)$; 16:  end if 17: end if 18: end for