Inherits Operation.
The position is specified in world co-ordinates, relative to the Grid offset. The interpolation type can be nearest neighbour, bilinear or bicubic for a two-dimensional Grid. For a one or three dimensional Grid the interpolation type is bilinear. The line can be made up of two points 'Line start' and 'Line end' or a poly line, if this is given. The poly line is composed of an array of Vector3dGroup point locations. Either the line or the entire poly line is sampled at a regularly spaced number of points. Outputs are the values at the point locations, the x, y and z values of the point location and the cumulative distance along the line or poly line.
