The chapter on filtering covers this in detail. For purposes of this chapter, in order to measure any modified profile, you will need to measure more of the surface than your final evaluation length, and the portion of the surface that you measure is always shorter than the portion of the surface that you physically traverse. The height resolution of an instrument is the minimum height deviation in a profile that can be distinguished from background noise. The height range is the maximum peak to valley height that an instrument can measure accurately. The range is determined by the gain of the electronics and the electrical and mechanical limitations of the transducer and probe.
Some transducers become nonlinear outside a specified range, some have mechanical constraints.
The range to resolution ratio is the ratio of the height range of an instrument to the resolution of an instrument. This is a key measure of the capability of an instrument. Some instruments allow the user to trade range for resolution, maintaining a roughly constant range to resolution ratio. Sampling Interval Instruments which digitize the profile and store an array of height values have a particular sampling interval. This is the interval between points in the x direction, along the trace length.