Area Roughness Parameters

surface texture parameters in ISO 25178

Sv is the absolute value of the height of the largest pit within the defined area.

Height	Sa (arithmetical mean height)
	Sz (Maximum height)
	Sq (Root mean square height)
	Ssk (Skewness)
	Sku (Kurtosis)
	Sp (Maximum peak height)
	Sv(马克西mum pit height)
Spatial	Sal (Auto-correlation length) / Str (Texture aspect ratio)
Spatial	Std* (Texture direction)
Hybrid	Sdq (Root mean square gradient)
Hybrid	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)

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