Crack Fundamental Element (CFE) for Multi-scale Crack Classification

Abstract

With the advance of sensor and information technology, high-resolution 2D image and 3D range data are available to support crack classification. However, crack classification still remains a challenge because state Departments of Transportation (DOTs) engineers often use multi-scale crack characteristics (e.g. crack width/length, intersection, pattern, etc) to classify the crack types, and these characteristics are not fully modelled for a reliable crack classification. Based on the new 3D range data, this paper proposes a Crack Fundamental Element (CFE) to characterize cracks at different scales. After an analysis of the fundamental and multi-scale crack characteristics, CFE is proposed for the fundamental line segment approximation of the crack characteristics on multi-scale grid cell analysis, and it is characterized by its density, relative area, bounding box, length, width, center, and orientation. Based on the low-level CFEs, a topological crack graphical representation is, for the first time, built by extending the CFEs into significant crack curves, intersecting crack curves, and approximating polygons of closed crack pieces/spalls at multiple scales. The crack can then be classified using the characteristics of CFEs and their density measures on multi-scale levels. An experimental test using actual 3D data taken in Savannah, Georgia, demonstrates the feasibility of the proposed CFE for multi-scale crack classification. Future research is also discussed.