Spatial quantization errors in active vision inspection

Abstract

The spatial quantization error is inherent in the two-dimensional automated visual inspection system. This kind of uncertainty introduces significant distortion on the inspected dimension of a specified part. For example, centroid, area, perimeter, length, orientation of parts are inspected by the vision inspection system. This paper discusses the effect of the spatial quantization error on the precision measurement of the length of an edge line. Statistical analysis in terms of the resolution of the image is developed for one dimensional and two dimensional quantization error. The mean and variance of these errors are computed. Given that the orientation and position of the sensor are known, the effect of this error on the dimension measurement is also analyzed. Based on the developed analysis, we investigate whether a given set of sensor setting parameters in an active system is suitable to obtain a desired accuracy for specific line segment dimensional measurements. In addition, based on this approach, one can determine sensor position and view direction which meet the necessary range for tolerance and accuracy of inspection. Developing these mechanisms is helpful for achieving effective, economic and accurate inspection system. >