Trilinear interpolation of data from measurements

Hi all,

I have three arrays (x_position, y_position, z_position) which form the position in 3D and a corresponding array for the value at each position. All of them have a size of 68*1 values.

Now I want to do a trilinear interpolation between the value points at each position.

For this purpose I've found the promising matlab function interp3. But therefor I would need a matrix (68 * 68 * 68) for each position and the corresponding values. How can I generate them? For the position I've used the meshgrid function:

    [xq,yq,zq] = meshgrid(x, y, z))
   and 
    [X,Y,Z] = meshgrid(-34:1:33, -34:1:33, 1:1:68)

Now I have Matrices for the positions.

But how to generate a matrix for the value?

For this purpose I've used the scatteredInterpolant function. Is this the right way?

 scatteredInter = scatteredInterpolant(x', z', y', stdX_C1', 'linear');
 vq = scatteredInter(xq, zq, yq);

This creates a 68*68*68 matrix for vq. Afterwards I used slice to visualize the interpolation. But it looks not as expected! The interpolation isn't smooth at all. I want to have a smooth interpolation. It can be seen in the attached file "slice.fig". I've also attached my m-file for interpolating and the x, y, z and value(stdX_C1) array in "position_value.mat".

I'm really looking forward for any idea or solution. Thanks a lot! Juliane