blocksubs = roi2blocksub(bpc,roi)
converts the specified ROI roi to the block subscripts
blocksubs of the blocks of the blocked point cloud data
bpc contained within the ROI.
Subscripts of the blocks, returned as a K-by-3 integer-valued
matrix. K is the number of blocks in the specified ROI. The elements
of each row correspond to the X-, Y- and
Z-axes respectively.