Automatic speed measurements of spherical objects using an off-the-shelf digital camera

A method for automatic speed measurements of spherical objects using a digital camera is presented. Conventional speed measurement techniques use radar or laser based devices, which are usually more expensive compared to a passive camera system. In this work, a single image captured with object motion is used to estimate the speed of a spherical object (such as baseball). Due to the relative motion between the camera and a moving object during the camera exposure time, motion blur occurs in the dynamic region of the image. By identifying the motion blur parameters, the speed of a moving object can be obtained. Automatic target identification and motion estimation are first done by motion blur analysis, followed by more accurate blur identification using circle fitting of the spherical object. Finally, the object speed is calculated according to the imaging geometry, camera pose, and blur extent in the image.