A light-pen single camera 3D coordinate vision measurement system is introduced.On the basis of analysis of the system’s image characteristics

a digital recognization method

which is for recognizing the elliptical light spot images of the measured control points

is proposed.On the basis of the pixel number of a measured control point’ elliptical light spot image contour

over large and small images contour can be eliminated.Using the method based on the evaluation for elliptical profile error

the measured control points’ elliptical light spot image can be recognized.The algorithm for this method is given

and the experimental result shows that this algorithm is simple

fast

easy to be realized and practical for the vision inspection system of circular measured control points.It has certain theoretical significance and practical project value.