The point samples are arranged in a hierarchic data structure in a manner such that each point sample is an end point, or leaf node, in a hierarchical tree, wherein the branch points in the hierarchy tree are average values of the nodes lower in {HEAD ~ the hierarchy} of {TAIL ~ the tree} 
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The point samples are arranged in a hierarchic data structure in a manner such that each point sample is an end point , or leaf node , in a hierarchical tree , wherein the branch points in the hierarchy tree are average values of the nodes lower in { HEAD ~ the hierarchy } of { TAIL ~ the tree }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL