Feature-Based Characterisation of Areal Surface Topography

In parallel to using ISO field parameters, the areal texture of a surface can be described in terms of the shape, size and spatial arrangement of its most relevant regions, here referred to as areal features. This approach is known as feature-based characterisation and is particularly useful in situations where it is convenient to represent a surface as the result of a spatial arrangement of its most relevant regions, or where it is required that specific portions of a surface are isolated to undergo dedicated assessment. A specific approach to spatially partitioning a surface into regions and computing the regions’ properties to describe the entire surface has been formalised by ISO through feature parameters. However, feature-based characterisation is now emerging as an increasingly larger family of methods that includes the ISO feature parameters and allows freedom on how the topography is partitioned, how feature relevance is determined and how the individual features are described. Feature-based characterisation addresses a wide range of needs, from finding new ways to describe an entire surface, to finding dedicated ways to characterise a selected number of features. The motivation, main methods and applications of feature-based characterisation are described in this chapter.