The Rq surface texture parameter is the root mean square of surface roughness. Rq is like calculating a standard deviation. If the surface has a relatively bell shaped distribution of heights with few outlying peaks and valleys, Rq can describe how a surface may scatter light, hold lubrication, etc. Rq is calculated from the roughness profile. The calculation can also be performed on the waviness profile (Wq) and primary profile (Pq).
Learn more about surface texture parameters in our Texture Parameter Video library.