Rebar inspection integrating augmented reality and laser scanning

Abstract

Assuring conformity regarding the number, spacing, and location of rebars is an important quality control task in a rebar operation. Nonconformity attributed to missing or mislocated rebars adversely affects structural performance and construct-ability. Rebar craftsmen normally read two-dimensional (2D) shop drawings and install rebars after converting 2D objects to three-dimensional objects in a cognitive image. To ensure conformity, the installation is inspected manually, hence, being tedious and costly. Existing sensing technologies do not lend themselves to effective visualization of the data obtained by the sensing process either in practice or academia. This paper presents an end-to-end method that addresses the existing limitation by hybridizing augmented reality (AR) and laser scanning technologies to provide intuitive and accurate rebar inspection. The AR prototype visualizes rebar inspection outputs and provides rework instructions in an effective manner. An experiment validating the method was performed using a laboratory-scale rebar layout. The results confirmed that the method successfully highlights detailed dimensional information of mislocated rebars and provides inspectors with intuitive rework instructions. Indeed, the method provides a way to detect and repair the nonconformity involved in rebar positions regardless of type, shape, and/or complexity. The method encourages accurate rebar dimensional inspection and intuitive visualization, hence, contributing to effective rebar quality control.