Transform {
  translation -1.5 -1.5 0
  children [
  Shape { 
          geometry DEF nurb NurbsSurface {
                  uOrder 4 
                  vOrder 4 
                  uDimension 4 
                  vDimension 4 
                  uKnot [ 0, 0, 0, 0, 3, 3, 3, 3]
                  vKnot [ 0, 0, 0, 0, 3, 3, 3, 3]