Method and apparatus for tracking position of a ball in real time

A method for tracking an object using at least one pair of video cameras, each outputting a video image including a current frame and a previous frame, the method comprising the steps of:

• for each camera of the at least one pair of cameras:
• obtaining a current frame and a previous frame of the video image including an image of the object;
• differencing the current and previous frames to obtain a binary image including motion regions;
• converting the binary image to hue saturation intensity space;
• and
• extracting a motion region corresponding to the object from the converted binary image based on a hue saturation model of the color of the object;
• matching the motion regions corresponding to the object from each camera to obtain the motion region of the object in three-dimensional space;
• obtaining a current frame and a previous frame and matching the three-dimensional motion region of the object in each, respectively, thereby obtaining a motion vector corresponding to the three-dimensional movement of the object from the previous frame to the current frame;
• and
• updating a three-dimensional trajectory of the object based on the three-dimensional motion vector of the object obtained in said obtaining step.

A method for tracking an object using a plurality of pairs of video cameras, each outputting a video image including a current frame and a previous frame, the method comprising the steps of:

• for each camera of the plurality of pairs of cameras:
• obtaining a current frame and a previous frame of the video image including an image of the object;
• differencing the current and previous frames to obtain a binary image including motion regions;
• converting the binary image to hue saturation intensity space;
• and
• extracting a motion region corresponding to the object from the converted binary image based on a hue saturation model of the color of the object;
• matching the motion regions corresponding to the object from each camera in each pair of cameras to obtain a motion region of the object in three-dimensional space from each pair of cameras, respectively;
• combining the motions of region corresponding to the object from each pair of cameras to obtain a single motion of region corresponding to the object, based on the motions of regions corresponding to the object from the plurality of pairs of cameras;
• obtaining a current frame and a previous frame and matching the single three-dimensional motion region of the object in each, respectively, thereby obtaining a motion vector corresponding to the three-dimensional movement of the object from the previous frame to the current frame;
• and
• updating a three-dimensional trajectory of the object based on the three-dimensional motion vector of the object obtained in said obtaining step.

An apparatus for tracking an object in real time comprising:

• at least one video camera;
• a computer connected to said at least one video camera, said computer including:
• a frame grabber constructed and arranged to separating a current frame of a video image and a previous frame of the video image;
• a host memory for storing the current and previous frames of the video image;
• a CPU constructed and arranged to operate on the current and previous frames of the video image so as to derive tracking information corresponding to the object and to convert a binary image obtained in said derivation of tracking information into hue saturation intensity space, and to return said derived tracking information and said converted binary image to said host memory;
• an I/O interface constructed and arranged to output said tracking information received from said host memory;
• a video output card constructed and arranged to output the current and previous frames of the video image received from said host memory.