Three-dimensional measurement approach in small FOV and confined space using an electronic endoscope

It is difficult to implement three-dimensional (3D) measurement in small field of view (FOV) or confined space with traditional sensors, for they cannot be put into or operated flexibly in such circumstances. To solve the problem, a sensor constructed by an electronic endoscope and a pair of mirrors is designed, combining the flexible characteristics of the endoscope transmission wire and the advantages of stereo technology. The calibration of the sensor and two corresponding points matching methods are described. For applications as diameter measurement of 3-D circle, an optimization method is used which directly obtains the diameter using the recovered 3-D points. The experiments show calibration and diameter measurement are of high accuracy, which provide the potential of expanding computer vision applications particularly in small FOV and confined environments.