Telecentric Vision Measurement Method of Space Size Based on Datum Correlation

This study investigated a spatial dimension telecentric vision measurement method based on benchmark correlation that aims at the long-axis workpiece with the characteristic of the protruding tip of the cross-section. First, telecentric imaging was used to realize the image feature extraction and position measurement of the local elements to be measured by the longer-scale workpiece. Then, a measurement transfer chain between the local elements and the axis reference elements outside the camera imaging field of view was established. The local element dimensions were converted into the global radial dimensions through calculations to achieve fast and accurate measurement beyond the scale of the imaging field of view. A measurement experiment environment was constructed to verify the effectiveness of this method, trace and analyze the error source, and give suggestions to further improve the accuracy. This method can realize the measurement of the spatial geometric quantity of the three-dimensional workpiece under the condition of telecentric parallel projection and is particularly suitable for on-site measurement applications that require high speed and accuracy.