This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. Content-Type: text/plain Hi, On a Gridded2DSet I am plotting a scalar value (density) as well as streamlines for a 2D vector field (velocity). Right now I have the density mapped to the ZAxis and my streamlines lie in the z=0 plane. My goal is to have the streamlines lie on top of the density surface. I came up with (( x , y ) -> ( density )) -> ( u , v ) which clearly violates the FunctionType constructor. Are there any easy ways to accomplish this? Thanks in advance.