A Low Cost Three-dimensional Vision System Using Space-encoded Spot Projections

Abstract

The vision system described in this paper was developed to digitize the contours of smooth, featureless, curved surfaces, such as aircraft wing surfaces. The information will be used by a maintenance robot to carry out automated ultrasonic material testing on the surfaces. The vision system uses a light spot projector and video camera in a structured-light technique. This employs a 32x32 array of illuminated spots which is first projected onto the measurement surface and then followed by a set of five binary space-encoded patterns to identify the column addresses of the spots. The images of the spot patterns are captured by the video camera. Two surface reconstruction algorithms, nearest neighbour and thin plate model, are implemented to fit a surface to the scattered amplitude samples obtained by the spot projection system.