the present invention provides apparatus and methods involving hardware and software aspects to instantaneously diagnose ball and / or player movements associated with a sports - related activity , followed by the development of a database of performance statistics , which may also include historical data . as mentioned , the system is applicable to a wide variety of situations , particularly ball - oriented sports though it may also be used for non - ball activities , and even in contact - type sports . thus , though the following description will concentrate on the use of methods and apparatus according to the invention in relation to a baseball situation , the other potential uses of the teachings herein should be kept in mind as applicable extensions . in a baseball environment , then , the system may be used to provide all relevant information on how the hitter and / or pit ( her move , including all relevant steps associated with the pitch and hit of the ball , including all relevant movements of the ball itself . in terms of hardware , the system may include at least two video cameras 102 and 104 to measure the pitch and batted ball 106 , at least two cameras 105 and 107 to measure pitcher movements ( if an automatic pitching machine is not used ), a sensor 108 to measure the batter &# 39 ; s swing , a bat - mounted sensor ( not visible in the figure ) to measure the location of contact along the bat , and a computer system 110 incorporating software to analyze measurements and generate a database containing measurements and completed analyses . each device is continuously monitored by the computer system 110 , and once the devices are set out in the evaluation area , all devices make completely automatic measurements of each pitch and hit without any action of the operator . the video cameras are preferably high - speed digital type cameras facilitating recording at a rate of 1 , 000 frames per second or greater . such cameras , which may be purchased from the kodak company as model ektapro may be used to measure all pitched and batted ball characteristics , including speeds , pitcher movements , pitch type , location at the batter , and direction of hit . the cameras may be set up to view the field in front of the batter from overhead and from the side , as shown in fig1 . the overhead camera 102 allows a planned view of the field and measurement of pitch , movement relative to the plate and batted ball direction in fair territory . the side view camera 104 provides the measurement of downward pitch movement , of pitch speed and of batted ball speed and angle . camera 107 is preferably positioned to view the human pitcher from the side , whereas camera 105 is preferably placed behind the pitcher so as to include the player in the field in the view , and may be used with both a human pitcher and pitching machine . together , the two cameras allow both the pitch and hit to be &# 34 ; tracked &# 34 ;. the following discussion will concentrate on the way in which a plurality of cameras are coordinated to track batter movements with the understanding that similar principle are used to track and coordinate pitcher movements , as appropriate . fig2 and 3 illustrate the techniques used with the video system to measure the pitch and batted ball parameters . in fig2 the top sketch shows a sequence of positions of the pitch , viewed from above ( position 0 , 1 , 2 and 3 ) and of the hit ( positions 4 and 5 ), in this case a hit to right field . while position 0 is not seen by the camera , the camera does see all other ball positions . the sequence of video pictures or frames seen by the side - view camera for ball position 0 through 5 is shown in the sketches in the bottom of fig2 . in frame 0 the camera sees the background but no ball . in all other frames , the camera sees both the background and the ball , with the ball appearing in different locations as it passes by the camera . in frames 1 , 2 and 3 , the pitch passes in front of the camera from right to left . the batted ball , seen in frames 4 and 5 , pass from left to right . in a preferred embodiment , the ball is isolated from the background using an image processing technique similar to those utilized in radar systems . this technique eliminates all parts of the image which do not change from frame to frame , i . e ., the background , and leaves the part of the image which does change position from frame to frame , i . e ., the ball . the process , as is commonly known by those skilled in the art of image processing , works by subtracting the image of one frame from the image in the frame directly following it . that is , the image in frame 0 is subtracted from 1 . this leaves the differenced image shown as &# 34 ; frame 1 minus frame 0 &# 34 ;, as illustrated in the lower section of fig2 . repeating the process for all frames and adding the results together provides the &# 34 ; composite image &# 34 ; shown in fig2 showing all ball positions as seen by the side view camera for a single pitch and hit . using geometry , the composite image , and the timing of the frames , the ball speed and upward angle of the hit may be determined . as an alternative , or for use in conjunction with the ball - isolation technique just described , the system may also support point identification and tracking . more specifically , a pointing device such as a cursor may be used to click on any points of a player to be recorded , or the ball itself , from which point those identified areas will be monitored to provide a measure of their movement , in isolation . such techniques , which are known in the art of crash testing , for example , are quite reliable , particularly if the &# 34 ; marked &# 34 ; points are sufficiently discernable on a frame - by - frame basis . also similar to crash testing applications , according to the invention , multiple points of multiple players may be marked for isolation purposes , including a pitcher &# 39 ; s elbow , a batter &# 39 ; s knee , and so forth . fig3 shows the same sequence of ball positions as seen within the field of view of the overhead camera 102 . the frames taken by the overhead camera are synchronized with those taken by the side - view camera . the same differencing processing is preferably carried out with the frames from the overhead camera to provide another composite image . the composites are combined by the computer to provide locations of the ball at the time of each frame in 3 dimensions . these locations are then used to determine the type of pitch , pitch speed and position of the ball relative to the strike zone , and batted ball speed , angle and direction . a hitter , filmed at high speed , proceeds through a normal hitting sequence which is broken down into steps shown in the table of fig8 . the film is digitized and analyzed by software , and the resulting data is then available in the database and may be viewed by interested parties in a variety of formats although not necessary to the invention , a laser system ( fig4 ) may be used to measure swing characteristics , including bat speed before and after contact , swing angle and height of the bat above the plate . this laser swing monitor may be located on the plate , such that when the batter swings at the ball , his bat passes over the swing monitor , passing through the light beams of several lasers . the timing of the bat cutting through the lasers allows the bat speed to be measured before and after the hit . it also allows measurement of the height of the swing and the angle of the swing . the swing monitor may be similar to that disclosed in u . s . pat . no . 4 , 577 , 863 to s . ito . the apparatus is housed in a plate approximately 2 &# 34 ; thick and contains a plurality of lasers and light detectors . optimally , six lasers and light detectors may be used . the monitor is placed over home plate during the batter testing . as the batter swings , the bat crosses through the lasers . at each laser , light reflects off the bat back to a light detector which determines the time of the crossing very precisely . the sequence of times from the several lasers provides sufficient information to calculate the speed of the bat both before and after the ball is hit , as well as the height of the bat above the plate and the swing angle . now making reference to fig5 a sensor , mounted on the bat , is preferably utilized to measure the location of ball contact on the bat . preferably , a miniature sensor is mounted on the knob of the bat . on ball contact , the bat sensor measures the vibration of the bat and radios the vibration to an analyzer . the analyzer determines if the batter hit the ball on the &# 34 ; sweet spot &# 34 ; or more toward the end of the barrel or toward the handle . this measurement makes use of the fact that handle vibration or sting for a &# 34 ; sweet spot &# 34 ; hit is much less than for a hit off the handle or the end of the barrel . when contact is made , the vibration is radioed to an analyzer interfaced to the computer system , which compares the details of the vibration to previous measurements of vibration taken when the bat was hit with a hammer or other object in the three locations shown . vibrational . characteristics are sufficiently different that hit location is unambiguous . while the sensor and radio transmitter may be affixed to the knob , location of the sensor and transmitter may vary along the length of the bat . given pitch , swing and contact data , the actual database development and performance analysis is accomplished with a computer and software . the table of fig1 shows the timing of a typical measurement sequence for a single pitch . fig6 shows the computer components and functions which accomplish the entering of data as measured by the measurement devices and computation of a performance analysis . the computer programs preferably utilize video image processing computers to provide the pitch and batted ball parameters , which are then passed to the computer database . bat swing monitor and sensor data are transmitted directly to the computer database where they are processed , and swing parameters and hit locations determined . an analysis program utilizes the data to compute and update performance statistics . fig7 illustrates the various hardware and software components within the system . all historical data , such as batter identification , can be selected from the database before a test session starts . details of the test may be monitored by an operator to be sure that the quality of the data is maintained . results for each pitch and for test analyses are automatically stored but are available for immediate playback and review . a typical database for batter evaluation includes an extensive list of parameters , as detailed in the table of fig8 . data typically fall into three categories , two of which are inputs to the system and one of which is externally derived . the inputs include historical data such as defining batter , bat , and pitcher used for a test . these data are readily available and are transferred to the computer for each batter . the second input to the system is measured data , provided by the measurement devices on the field , such as pitch speed and batted ball speed . the externally derived data may include the previous results of batter performance . such results determine the size and scope of the database required , the analysis procedures to be followed , and the equipment , computer and software needed to provide them . in operation , a test sequence according to the invention may proceed as follows : the pitch is thrown and viewed by the video cameras ; pitch type and speed are determined and recorded ; the batter swings , and if contact is made , contact location on the bat and ball speed before and after contact are computed and recorded ; if contact is not made , both a miss and ball location are recorded ; if the ball is hit within view of the cameras ( typically encompassing fair territory ), the batted ball speed and direction are determined and recorded . at this point , the system is ready to accept another pitch . once the test sequence is completed , the performance statistics are compiled and reported . the apparatus aspect of the invention may be portable and easily set up . batter , bat and pitcher data may be entered ahead of time , if known , or on the scene if not known . an operator identifies personnel , enters data if necessary and monitors test progress . when a test is complete , the operator may review the data with an evaluator . when all testing on all batters is completed , the operator may print summary statistics for each batter as a field test report . all test data may be retained in the computer database for comparison with other tests and with other batters . once baseline data is established under controlled conditions for a given batter , lightweight digital cameras may be subsequently taken into the field to make additional recordings of selected characteristics . fig1 a to 11d depict a variety of batter images captured according to the invention along with statistical data superimposed thereon . indeed , the invention may be used to surreptitiously analyze the performance of players without them knowing it , for example , on an opposing team . although it may be a challenge to incorporate a laser - based bat - swing monitor and / or vibration tester into the playing field , numerous high - speed digital cameras may be used outside of the playing field , for example , with telephoto lenses , along with player or ball isolation software , if required , and analysis software to develop performance statistics on a real - time or historical basis .
a sports analysis and testing system includes a plurality of high - speed digital video cameras , each aimed at a player from a different perspective to record their movements and those of a ball in play . in a baseball application , a programmed computer interfaced to the video cameras and various optional sensors includes application software to generate performance statistics as a function of the pitch , hit , and bat swing . if previously obtained batter performances data are available , the system may also be used to generate a database containing historical performance statistics , including real - time measurements of many characteristics , including pitched and batted ball speeds and trajectories , bat swing timing , speeds , and swing angles , location over the plate , and ball - bat contact location .