This work has been motivated by our prior efforts for perceptualizing the scientific data sets of surface topography and stiffness distribution measured with a scanning probe microscope. Previously, we showed that the surface topography information with varying stiffness rendered with the conventional penalty-based method can be distorted [5], and developed a topography compensation algorithm based on the theory of force constancy in order to resolve the problem [3]. The theory of force constancy states that the user maintains an invariant contact force level when s/he strokes a surface to perceive its topography. As a follow-up study, this paper investigates the benefits of including surface normal rendering in the haptization of a surface height change with varying stiffness, through a simulation and a psychophysical experiment. Adequate surface normal rendering creates lateral force cues when a haptic interface tool crosses a height change interval. The results indicated that surface normal rendering facilitates correct perception of surface height changes, in particular, for very low height changes.