tests/spheres.obj: res 100x100 
, nodes 4, spatial median @ axis(1) -198.500
left 0, leaf
right 0, nodes 3, spatial median @ axis(0) 0.000
 left 1, leaf
 right 1, nodes 2, spatial median @ axis(0) 1.500
  left 2, leaf
  right 2, leaf
done