1. A method comprising: receiving a reference map comprising a set of reference map pixels having corresponding reference pixel values, wherein the reference map pixels have a height determined by the corresponding reference pixel values; receiving a perturbance map comprising a set of perturbance map pixels having corresponding perturbance pixel values, wherein the perturbance map pixels have a height offset determined by the corresponding perturbance pixel values; creating an output map comprising data values having a height corresponding to the height determined by the corresponding reference pixel values and an offset corresponding to the height offset determined by the corresponding perturbance pixel values, wherein the offset increases or decreases the height of the data values, relative to the height determined by the corresponding reference pixel values, in the output map; and displaying the output map on a display.