Area Roughness - Sdar, Spar

Does anyone know where Developed Area (Sdar) and Projected Area (Spar) are calculated from? It seems to be something involving total area minus defect area from our image analysis. Any help is appreciated.

Helo Nuburu,

The Developed Area, Sdar, is defined as the total surface area, taking in account the entire topography of the sampling area including the additional area due to the peaks and valleys. The Projected Area, Spar, is defined as the surface area of a flat x,y plane of the sampling area which is independent of the heights of the peaks and valleys (the volume).

The ratio of Sdar to Spar is linked to the volume of the surface peaks and valleys.

The Developed Interfacial Area Ratio, Sdr, is defined as the percentage of additional surface area contributed by topography within the sampling area relative to the surface area of the sampling area as a flat x, y plane.

If the surface includes pixels with no measured height value, the area of these pixels are not included within the developed and projected areas.


Thank you for this definition Robert