Analysis of the Distortion of Marker-Based Optical Position Measurement as a Function of Exposure Time

Marker-based optical position measurement is investigated in this paper. If the exposure time is not very short, it might cause the blur of the marker on the image if fast movement needs to be recorded. This paper investigates the effect of blur on the center point estimate and provides a measure for the distortion to help adjust camera parameters (exposure time, aperture, and ISO sensitivity) in the case of poor lighting conditions. The distortion of the center point estimate is derived as a function of movement of the marker. It is shown that the distortion can be well modeled as integral mean of the marker center. Its distortion can be calculated, and either kept on a limited level by appropriate setting of camera parameters (measure of error is derived) or numerically compensated (inverse filtered). Simulation and measurement examples show the usefulness of the correction.