Area roughness parameters

Description of surface texture parameters in ISO 25178

This parameter represents the number of peaks per unit area.
A larger number indicates the more points of contact with other objects.

Spd (Density of peaks)

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)
Spatial	Std* (Texture direction)
Hybrid	Sdq (Root mean square gradient)
Hybrid	Sdr (Developed interfacial area ratio)
Functional	Smr(c) (Areal material ratio)
	Smc(mr) (Inverse areal material ratio)
	Sk (Core roughness depth)
	Spk (Reduced peak height)
	Svk (reduced dale height)
	Smr (Peak material portion)
	Smr2 (Valley material portion (percentage of the measurement area that comprises the deeper valley structures associated with Svk))
	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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