3D sculptured surface analysis using a structured-light approach

The contribution aims at describing a computer-based structured light imaging system to be applied to automated recovery of quantitative 3D information on sculptured surfaces, in order to take in charge (industrial) inspection/3D reconstruction tasks. Recovery is based on evaluation of images of the light pattern induced by projection into the scene of a specifically deviced parallel grid. The system has been designed for direct use in industrial environments, e.g. for integration into on-line quality control systems. Consequently, particular emphasis has been put on efforts for fulfilling requirements usually implied by this type of application, such as simplicity of set-up, application real-time, high accuracy, and low cost. This paper gives a discription of the system realized, including the algorithms specifically designed and implemented for calibration, nonambiguous labeling of the imaged fringes, and subpixel evaluation of their locations. The integration of the system into an on-line inspection system for 100% control of manufactured parts illustrates its application. Inspection is based on comparison of extracted features gained from a CAD model of the part and including tolerance information. Currently, a measurement accuracy of the order of 25 micrometers can be routinely achieved.