How can I compare Surface Normal with related value of a surface measurement?

Hi fellow MATLAB users,

I have atomic force microscope data (x,y,z positional data) as well as a value for a measurement (in this case it's an electrical measurement) with the same matrix sizes. What I'd like to do is get surface normal (or honestly the dihedral angle to the view plane which can be done with subspace against z (001)) and compare it to a corresponding value for the surface with the electrical measurement.

I envision some complications here... the electrical data (let's call it E for ease here) is at the same positions as the XYZ positional data. But, I assume a surface normal would make a facet face for the normal calculation. I would then have to apply the same facet faces (and possibly average) to the related E matrix- is this correct?

I've seen similar/related questions- i.e., color a surface facet face by a related data value X,Y,Z,C. Would this approach work with the surface normal built in commands?

Any and all suggestions are greatly appreciated. The ultimate goal for this project is some correlation between the angle of the face(t) and the electrical measurement (E). I assume a scatter plot of the angles from subspace(norm,viewplane) -v- E(position or averaged facet) would work for my purposes.

Thank you for any and all suggestions! I greatly appreciate them all! -Allen