Video Distance Measurement Method Based on Three Focus Positions

Several precision technologies require video measuring systems that perform fast an extensive number of routine measurements and deliver high accuracy outcome. The quality of achievement is intrinsically determined by the measurement technique where with the applications that operate these systems are designed. The paper advances a simplified and at the same time comprehensive approach, proposing a new video distance measuring method using a single camera. It is designed to assess the distance at which the visual task is from the camera, using three adjacent focus positions. Practically, the method involves two stages: calibration and measurement. Calibration is realized only once for each camera type and involves setting the measuring range for all positions of the focus lens where maximum clarity is obtained. Distance measurement involves the use of the maximum sharpness position of the lens and the correlation with the sharpness values of the positions next to the maximum sharpness position.