Sa (Arithmetical Mean Height)

Sa (Arithmetical Mean Height) | Area Roughness Parameters

surface texture parameters in ISO 25178

Height

Spatial

Hybrid

Functional

Functional volume

Feature

Sa is the extension of Ra (arithmetical mean height of a line) to a surface. It expresses, as an absolute value, the difference in height of each point compared to the arithmetical mean of the surface. This parameter is used generally to evaluate surface roughness.

Search from the parameters list

Height	Sa (arithmetical mean height)
Sz (Maximum height)
Sq (Root mean square height)
Ssk (Skewness)
Sku (Kurtosis)
Sp (Maximum peak height)
Sv (Maximum pit height)
Spatial	Sal (Auto-correlation length) / Str (Texture aspect ratio)
Std* (Texture direction)
Hybrid	Sdq (Root mean square gradient)
Sdr (Developed interfacial area ratio)
Functional	Smr(c) Areal material (bearing area) ratio
Smc(mr) Inverse areal material ratio
Sk(Core height)
Spk (Reduced peak height)
Svk (reduced dale height (reduced valley depth))
Smr (Peak material portion)
Smr2 (Valley material portion)
Sxp (Peak extreme height)
Functional volume	Vvv (Dale void volume)
Vvc (Core void volume)
Vmp (Peak material volume)
Vmc (Core material volume)
Feature	Spd (Density of peaks)
Spc (Arithmetic mean peak curvature)
S10z / S5p / S5v / Sda(c) / Sha(c) / Sdv(c) / Shv(c)

Height

Sa (arithmetical mean height)

Sz (Maximum height)

Sq (Root mean square height)

Ssk (Skewness)

Sku (Kurtosis)

Sp (Maximum peak height)

Sv (Maximum pit height)

Spatial

Sal (Auto-correlation length) / Str (Texture aspect ratio)

Std* (Texture direction)

Hybrid

Sdq (Root mean square gradient)

Sdr (Developed interfacial area ratio)

Functional

Smr(c) Areal material (bearing area) ratio

Smc(mr) Inverse areal material ratio

Sk(Core height)

Spk (Reduced peak height)

Svk (reduced dale height (reduced valley depth))

Smr (Peak material portion)

Smr2 (Valley material portion)

Sxp (Peak extreme height)

Functional volume

Vvv (Dale void volume)

Vvc (Core void volume)

Vmp (Peak material volume)

Vmc (Core material volume)

Feature

Spd (Density of peaks)

Spc (Arithmetic mean peak curvature)

S10z / S5p / S5v / Sda(c) / Sha(c) / Sdv(c) / Shv(c)