Rpi is the height of the highest profile peak of the roughness profile within one sampling length.

Rvi is the depth of the deepest profile valley of the roughness profile within one sampling length.

The sum of Rpi + Rvi is the single roughness depth Rzi. Rp or Rv is the arithmetic mean of the Rpi or Rvi.

According to ASME B46.1, Rp describes the highest profile peak and Rv the lowest profile valley within the measurement path ln. According to ASME B46.1, Rp + Rv = Rt applies.