3D Surface Roughness and Wear Measurement, Analysis and Inspection

Surface Texture Parameters Glossary

The Surface Texture Parameters Glossary provides information on many of the surface roughness parameters that are commonly used in industry and research. It includes definitions of each parameter, along with information about when they are used, and details on how to apply the parameters in real-work applications.

Click on the Parameter Name or Symbol column heading to sort the parameters. Click on the column heading a second time to toggle from ascending to descending order. View parameters grouped by family.

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Parameter Name Symbol Family
2D Average Roughness Ra Legacy Parameters
Angular Power Spectral Density Function APSDF 3D Spatial Parameters
Areal Material Ratio Smr(c)  Material Ratio - Bearing Area
Autocorrelation Function ACF 3D Spatial Parameters
Autocorrelation Length Sal 3D Spatial Parameters
Average Maximum Height of the Surface Rz Legacy Parameters
Average Maximum Peak Height Rpm Legacy Parameters
Average Maximum Profile Height Along X, Y Stylus (X,Y) Rz 2D Stylus
Average Maximum Valley Depth Rvm Legacy Parameters
Average Roughness Sa 3D Height (Amplitude) Parameters
Average Roughness Along X, Y Stylus (X,Y) Ra 2D Stylus
Band Pass Filter Band Pass Filter 3D Filtering
Core Material Volume Vmc(p,q) 3D Functional Parameters
Core Roughness Along X, Y Stylus (X,Y) Rk Material Ratio - Bearing Area
Core Roughness Depth Sk 3D Functional Parameters
Core Void Volume Vvc(p,q)  3D Functional Parameters
Dale Void Volume Vvv(p) 3D Functional Parameters
Developed Interfacial Area Ratio Sdr 3D Hybrid Parameters
F-Operator λf 3D Filtering
Inverse Areal Material Ratio Sdc(mr) Material Ratio - Bearing Area
Kurtosis Sku 3D Height (Amplitude) Parameters
Long Wavelength Pass Filter S-Filter 3D Filtering
Material Ratio mr Material Ratio - Bearing Area
Material Volume Vm(mr) 3D Functional Parameters
Maximum Height of Surface Sz 3D Height (Amplitude) Parameters
Maximum Peak Height Sp 3D Height (Amplitude) Parameters
Maximum Profile Height Along X, Y Stylus (X,Y) Rt 2D Stylus
Maximum Valley Depth Sv 3D Height (Amplitude) Parameters
Mean Profile Spacing Along X,Y Stylus (X,Y) Rsm 2D Stylus
Mean Summit Curvature Ssc 3D Hybrid Parameters
Normalized Surface Volume NormVolume Legacy Parameters
Notch Filter Notch Filter 3D Filtering
Peak Density Along X,Y Stylus (X,Y) Pc or Rpc 2D Stylus
Peak Extreme Height Sxp (p,q) 3D Functional Parameters
Peak Material Portion SMr1 Material Ratio - Bearing Area
Peak Material Volume Vmp(p) 3D Functional Parameters
Reduced Peak Height Spk Material Ratio - Bearing Area
Reduced Peak Height Along X, Y Stylus (X,Y) Rpk Material Ratio - Bearing Area
Reduced Peak Height to Core Roughness Ratio Spk/Sk Material Ratio - Bearing Area
Reduced Peak Height to Reduced Valley Depth Ratio Spk/Svk Material Ratio - Bearing Area
Reduced Valley Depth Svk Material Ratio - Bearing Area
Reduced Valley Depth Along X, Y Stylus (X,Y) Rvk Material Ratio - Bearing Area
Reduced Valley Depth to Core Roughness Ratio Svk/Sk Material Ratio - Bearing Area
Root Mean Square Profile Wavelength Along (X, Y) Stylus (X,Y) λq 2D Stylus
Root Mean Square Roughness  Sq 3D Height (Amplitude) Parameters
Root Mean Square Slope Along X,Y Stylus (X,Y) Δq 2D Stylus
Root Mean Square Slope in X,Y Slope Rq (X,Y) Legacy Parameters
Root Mean Square Surface Slope Sdq 3D Hybrid Parameters
Short Wavelength Pass Filter L-Filter 3D Filtering
Skewness Ssk 3D Height (Amplitude) Parameters
Stylus Pc Ratio Stylus X Pc/ Stylus Y Pc 2D Stylus
Stylus Ra Ratio Stylus X Ra/Stylus Y Ra  2D Stylus
Stylus Rz Ratio Stylus X Rz/Stylus Y Rz 2D Stylus
Stylus Δq Ratio Stylus X Δq/Stylus Y Δq 2D Stylus
Stylus λq Ratio Stylus X λq/Stylus Yλq 2D Stylus
Summit Density Sds 3D Hybrid Parameters
Surface Area Index SAI Legacy Parameters
Texture Aspect Ratio Str 3D Spatial Parameters
Texture Direction Std 3D Spatial Parameters
Valley Material Portion SMr2 Material Ratio - Bearing Area
Void Volume Vv(mr) 3D Functional Parameters

The definitions and more detailed discussions of the various surface texture parameters may be found in the following references:

ISO 25178-2:2009 “Geometrical product specifications (GPS) – Surface texture: Areal Part 2 Terms, definitions and surface texture parameters.

ISO 25178-3:2009  “Geometrical product specifications (GPS) – Surface texture: Areal Part 3 Specification operators.

ISO 1302:2002  “Geometrical product specifications (GPS)- Indication of surface texture in technical product documentation.

ANSI/ASME B46.1-2002  “Surface Texture (Surface Roughness, Waviness and Lay),” American Society of Mechanical Engineers, 2002.

ISO 4287:1997 “Geometrical Product Specifications (GPS) – Surface texture: Profile method – Terms, definitions and surface texture parameters”

ISO 13565-2:1996 “Geometrical Product Specifications (GPS) – Surface texture: Profile method; Surfaces having stratified functional properties – Part 2: Height characterization using the linear material ratio curve”

D. J. Whitehouse, Handbook of Surface Metrology, Institute of Physics Bristol, 1994.

Leigh Mummery, Surface Texture Analysis, The Handbook  Hommelwerke GmbH, 1992   ( (203) 827-8500)

H. Dagnall M.A., Exploring Surface Texture, Rank Taylor Hobson Limited, Leicester, England, 1986   ( (800) 872-7265)

K. J. Stout, Development of Methods for the Characterisation of Roughness in Three Dimensions, 2000, Penton Press,
London, UK ISBN 1 8571 8023 2.