question: public BallNode buildTree ( ) throws Exception { ArrayList < TempNode > list = new ArrayList < TempNode > ( ) ; for ( int i = 0 ; i < m_InstList . length ; i ++ ) { TempNode n = new TempNode ( ) ; n . points = new int [ 1 ] ; n . points [ 0 ] = m_InstList [ i ] ; n . anchor = m_Instances . instance ( m_InstList [ i ] ) ; n . radius = 0.0 ; list . add ( n ) ; } return mergeNodes ( list , 0 , m_InstList . length - 1 , m_InstList ) ; }
target:  Builds the ball tree bottom up. 