Algorithm 2 Combine single frames into a group.

Input:   (1) F: A single frame point clouds.   (2) L: The classification result, the value is $wire$, $dropper$ or $pole$.   (3) S: The set of single frames. This output is used as the next input.   (4) C: The category of S. The value is $wire$, $dropper$ or $pole$, and the default is $wire$. This output is used as the next input.   (5) M: The map consisting of C and the minimum number of frames forming a group representing C.  Output:    $result$: The combined single frames. It may be $null$. 1:initial $result\leftarrow null;$ 2:push the single frame into the set $S.append\left(F\right);$ 3:if$L\ne wire$then 4:     $C\leftarrow L;$ 5:end if 6:if$Length\left(S\right)\ge M\left[C\right]$and$L=wire$then 7:     $result\leftarrow S;$ 8:     $S.clear\left(\right);$ 9:     $C\leftarrow wire;$ 10:end if 11:return$result$, S, C