Optical rangefinding from image focus

Paul R. Weckler; Glenn A. Kranzler

doi:10.1117/12.19999

1 January 1990 Optical range finding from image focus

Paul R. Weckler, Glenn A. Kranzler

Proceedings Volume 1260, Sensing and Reconstruction of Three-Dimensional Objects and Scenes; (1990) https://doi.org/10.1117/12.19999
Event: Electronic Imaging: Advanced Devices and Systems, 1990, Santa Clara, CA, United States

Abstract

A method for gauging the distance from a video camera to an object of interest is described. By using a calibrated camera-lens system, range was related to focus of a selected object. Optimum focus of the image was determined by maximizing the high-frequency content of the Fourier transform of the object image. The Walsh- Hadamard transform was investigated as an alternative focusing function. Software was developed to determine optimum image focus and control a motorized camera lens. Range values from the video camera to target objects were calculated by the system. Calculated values were compared with measured distances. For any given distance, the difference between calculated and actual distance averaged less than 1.2%. Distance values calculated using the Walsh-Hadamard transform differed from values calculated with the Fourier transform by less than 1%.

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Paul R. Weckler and Glenn A. Kranzler "Optical range finding from image focus", Proc. SPIE 1260, Sensing and Reconstruction of Three-Dimensional Objects and Scenes, (1 January 1990); https://doi.org/10.1117/12.19999

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KEYWORDS

Cameras

Distance measurement

Image quality

Video

Fourier transforms

Software development

3D image processing

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