Pinball Tracking System

Abstract

An entertainment device typically described as a pinball machine, usually found in myriad places such as arcades, restaurants, private residences, etc. A conventional pinball machine allows one or more players to play a game in which points are accrued by physically striking one or more balls on an inclined play field within a cabinet having a transparent top surface. Interaction of the machine with the ball is typically limited to events when the ball strikes an object on the play field. To enable more machine-ball interaction and therefore increase entertainment value ball tracking is needed. A way to track the ball in a very fast manner to better enable open space interactivity while not having excessive cost and while not limiting the game designer.

Claims

1. A pinball tracking system as set forth herein utilizing optical sensors such as cameras under the devices glass covering.

2. A pinball tracking system comprising: a first camera enabled to capture a first Infrared reflected view of a pinball, wherein said camera is further coupled with at least one first Infrared LED; a second camera enabled to capture a second Infrared reflected view of the pinball, wherein said second camera is further coupled with at least one second Infrared LED; and a computing system coupled to said first camera and said second camera enabled with a ball tracking algorithm to process the first Infrared reflected view and the second Infrared reflected view, wherein said algorithm is enabled with a pre-defined geometric relationship between the first camera, the second camera, and a playfield such that the pinball location can be computed with respect to the playfield.

3. The pinball tracking system of claim 2 wherein said computing system is further enabled to sequence repeatedly to process the first Infrared reflected view and the second Infrared reflected view such that the computing system can compute a path of said pinball.

4. The pinball tracking system of claim 3 wherein said computing system is pre-configured with information about stationary objects on the playfield used to continuously calibrate the system and reporting of the ball position.

5. A pinball tracking system comprising: at least one camera each enabled to capture an Infrared reflected view of a pinball, wherein said each at least one camera is further coupled with at least two Infrared LEDs separated by a distance of at least one inch; and a computing system coupled to said at least one camera enabled with a ball tracking algorithm to process the Infrared reflected view from each at least one camera, wherein said algorithm is enabled with a pre-defined geometric relationship between the at least one camera and a playfield such that the pinball location can be computed with respect to the playfield.

6. The pinball tracking system of claim 5 wherein said computing system is further enabled to sequence repeatedly to process the Infrared reflected such that the computing system can compute a path of said pinball.

7. The pinball tracking system of claim 6 wherein said computing system is pre-configured with information about stationary objects on the playfield used to continuously calibrate the system and reporting of the ball position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The detailed description set forth below references the following drawings:

[0010] FIG. 1 shows a top-front view of a prior art package for a pinball machine with a ball tracking function.

[0011] FIG. 2 is a top-front view of a pinball machine containing two upward looking cameras used to locate ball position according to an exemplary embodiment of the present disclosure;

[0012] FIG. 3 is a top-front view of a pinball machine containing two downward looking cameras used to locate ball position according to an exemplary embodiment of the present disclosure;

[0013] FIG. 4 is a top-front view of a pinball machine containing one downward looking camera used to locate ball position according to an exemplary embodiment of the present disclosure;

[0014] FIG. 5 is a side view of a camera mounted to a pinball play field according to an exemplary embodiment of the present disclosure;

[0015] FIG. 6a illustrated a means for calibrating the camera's ball location ability according to an exemplary embodiment of the present disclosure;

[0016] FIG. 6b illustrates the image seen by the camera shown in FIG. 6a according to an exemplary embodiment of the present disclosure;

[0017] FIG. 7 illustrates the means for finding the location of the ball with two cameras according to an exemplary embodiment of the present disclosure;

[0018] FIG. 8a illustrates the image seen by a first camera shown in FIG. 7 according to an exemplary embodiment of the present disclosure;

[0019] FIG. 8b illustrates the image seen by a second camera shown in FIG. 7 according to an exemplary embodiment of the present disclosure;

[0020] FIG. 9 illustrates the means for finding the location of the ball with one camera according to an exemplary embodiment of the present disclosure; and

[0021] FIG. 10 illustrates the image seen by the camera in FIG. 9.

DETAILED DESCRIPTION

[0022] The present disclosure, as demonstrated by one of several exemplary embodiments described below, can provide a means to track a pinball in a fast manner in the open space of a pinball machine to better enable interactive play without encumbering the game designer or exceeding cost targets.

[0023] In the first exemplary embodiment, at least two small digital cameras are installed on the play field pointed horizontally such that the ball is in the field of view of one or more of the cameras as it passes by. Each camera views a section of the field from a different angle. On each side of each camera is mounted at least one infrared light emitting diode (LED) having a wavelength between 800 nm and 1000 nm preferably between 840 nm and 860 nm. In some configurations the cameras can share one or more LEDs. Each camera contains a lens system having a material that reflects all visible light, only allowing infrared to be transmitted and picked up by the camera. Each camera takes still shots at a rate between 5 frames per second (fps) and 60 fps or, more preferably, at a rate between 10 fps and 30 fps. Not all cameras must operate at the same frame rate. The frame rate can be substantially faster in other embodiments.

[0024] The Infrared light emitting diodes (LEDs) proximate to each camera flash at the right time during the exposure for the camera to capture light from the LEDs reflected off the surface of the ball. The computing system captures an image from at least two cameras and, per an application specific algorithm, searches through them to find the horizontal position of the ball. The algorithm then further specifies that the ball's absolute X-Y coordinate is calculated with respect to the mounting position of each camera by taking into account the horizontal position of the ball in each camera view as well as the physical geometric relationship of the cameras to one another.

[0025] Vertical calibration can be done automatically with information on the play field by observing the location of other reflective objects such as a post supporting an interactive play feature. In some embodiments, an image of the background could be stored and subtracted from the running image to reject background reflections. The image of the ball reflections in the camera have a curved feature. Other reflective surfaces on the field can be sorted out because they are generally lines coming from reflections of cylinders or rectangular objects.

[0026] In yet another exemplary embodiment, the system can contain only one camera of the type described above that is configured to view the pinball in one area inside the pinball machine. In this embodiment, at least two Infrared LEDs are mounted, at least one on each side of the camera and each LED located at least one inch away from another LED. Because the surface of the ball is spherical, multiple reflections can be captured by the computing system in one image from the one camera. Based on the centroid location of the duplicate reflection in the image and the distance between the two reflections, the X-Y position can be computed.

[0027] In a third exemplary embodiment, at least two cameras of the above described type can be used as before but without the LEDs mounted near the cameras. In this embodiment, one or more LEDs are mounted opposite of the cameras such that the camera is flooded with Infrared light from the LEDs. When the ball passes by, a round silhouette is observed in each of the camera images captured by the computing system.

[0028] In a fourth exemplary embodiment a single camera can be enabled to track the pinball location by viewing the entire ball reflection as a solid circle based on a single Infrared light source. The diameter of the ball in the image is then an indication of how far away from the camera the ball is when the image was captured while the position of the pinball in the reflection is an indicator of the position of the ball in a second dimension. Together, these two pieces of information can be used to determine the 2D position of the pinball. The modern pinball game industry has standardized on a 1.0625″ diameter pinball so the same method can work across multiple games.

[0029] It should be understood that the term camera can be understood to be several different Infrared light detection schemes. By way of example, the term camera can mean an array of individual Infrared detectors such as Infrared transistors either separately packaged or packaged in the same silicon die. The term camera can also refer to the common meaning of a digital camera like the camera found in the modern smart phone. More generally, the term camera refers any device that is sensitive to Infrared light in a way that enables the system in the present disclosure to “see” the reflection of the ball.

[0030] One skilled in art of computing systems will realize that a computing system is enabled by an algorithm that specifies a set of actions to take place in order to accomplish the tracking of the ball. One such algorithm that can be associated with at least one of the embodiments in the present disclosure can be defined as follows; 1) the computing system collects an image from the first camera by illuminating an associated LED while at the same time triggering the capture of the image from the first camera, 2) the computing system collects an image from the second camera by illuminating an associated LED while at the same time triggering the capture of the image from the second camera. The first two steps can take place serially or simultaneously, 3) the computing system locates the ball's location within each image, 4) the location of the ball in each image is used to calculate the ball's X-Y position based on known stereo-optics equations and the physical location of the cameras to one another, and 5) the ball's X-Y location is then acted upon based on the prescribed desires of the game's designer. The algorithm can loop indefinitely or can be triggered to run based on an internal or external trigger.

[0031] The pinball machines manufactured at the present are lit with LEDs that emit light in the visible spectrum and so there is only background infrared light from outside of the pinball machine to interfere with the system. Some, or all, of this background light is reflected by the glass covering the playfield. In the event that the glass covering the playfield does not prevent all background light from entering the field of view of the camera, a small opaque shield can cover the topside of the camera lens to limit the field of view of the camera so as to eliminate any background interfering light. Similarly, a digital filtering approach can be made use of by subtracting the light captured by the camera during a portion of play where there is no Infrared light generated by the lights associated with the camera. This background light measurement can be used to calibrate out any interfering light thereby increasing the accuracy of the system. Any, or all, of these background light eliminating means can be used together or separately.

[0032] The optics that are a part of the lens system in the camera remove all visible light resulting in an image that is simple to process and find the ball. This greatly reduces the processing power and cost compared with a typical computer vision system. Based on calibration, the cameras only need to sample a small horizontal slice of the viewing area which leads to further processing speed improvements.

[0033] It should be understood that a single pinball game can make use of various different described embodiments herein at the same time to create a pinball following feature across multiple areas on the play field. By way of example, two cameras could be used near the flippers to follow the ball in the open play field while a single camera could be mounted in the upper area near the play field features to observe the ball as it passes through. Likewise, multiple embodiments of the present disclosure can be used in conjunction to view the ball in the same portion of the playfield to increase the accuracy of the overall ball tracking system.

[0034] Furthermore, one skilled in the art will recognize that the cameras can be mounted on the playfield such that the viewing angle is substantially parallel with the playfield or equivalently they can be mounted below the playing surface such that the viewing angle is substantially perpendicular to the playfield along with an Infrared reflective device mounted such that the light path is altered from substantially parallel to the playfield to substantially perpendicular to the playfield. This reflective device can be as simple as a mirror or a more complicated spherical reflective surface that permits a larger field of view. This complicated reflective surface can even act to permit a 360 degree view for the camera located under the playfield. Additionally, the camera can be mounted under the playfield constructed of an Infrared transmissive material surface. In such a configuration, the Infrared light can pass through the playing surface and be observed by the camera underneath.

[0035] In further embodiments, these aforementioned camera-based systems can be used to replace one or more roll-overs; mechanical devices (or inductive sensors in some systems) that trigger when the pinball rolls over them. These roll-overs are used, for example, to start new modes, activate lights, and accrue points. The pinball vision system can replace the common roll over entirely by simply computing the X-Y position of the ball and comparing it to a pre-defined roll-over region in the game. When the ball is in the pre-defined region it initiates the same response as if a mechanical switch was actuated. Furthermore, any and all visible lights on the playfield can be enabled to interact with the passing of the ball. These lights are commonly used to indicate score, announce goals, and entertain the player.

[0036] As an example of the interactivity enabled by the system, an under field light matrix can exist across the entire play field or a subset of the playfield. As the ball passes over the top of the light it can be turned off by the computing system. The goal for the player can be to get all the lights off. Alternatively, the field light matrix can be used to enable path tracing of the ball as it passes over the lights either by lighting up all lights not in the path of the ball or lighting up all lights in the path of the ball. This under field light matrix can be a simple matrix of individual lights or a visual display screen such as the common liquid crystal display (LCD) screen.

[0037] The light matrix can function in myriad ways including the path tracing as above or color changing in the context of a multi-color light matrix. As the score advances past a threshold or the game changes play mode, the color of the ball's path can change or more generally the light matrix can interact differently with the ball.

[0038] Now enabled by the present disclosure is an ability to create a self-play mode wherein the pinball machine can actuate its own flippers to keep a ball in play. This can be advantageous for several reasons including the use of an attraction-mode or a type of life-line for a player to use during the game. In the attraction-mode the machine can play the ball itself to show action taking place to draw a player into the game that may be just passing by. In the life-line scenario, a player may buy or earn the use of a machine-assist mode for a preset amount of time or preset number of flipper contacts wherein the machine would do the work of actuating the flippers at the right time. This machine-assist mode could be initiated by the player pressing a button or by the player hitting a specific target on the playfield.

[0039] Furthermore, the self-playing machine can be enabled with a learning database such that a type of artificial intelligence system can be built. This system can learn the proper timing to strike the ball with flipper to hit a specific target. Since each machine is located on a specific slope and has specific and changing response timing to its actuators, the learning database can be used to account for these unknowns and changing variables.

[0040] Additionally, the above described system can track more than one ball in play at the same time. With two balls in play at the same time there could be possibility of a ball collision on the play field which could be observed by the tracking system and rewarded in game play. Alternatively, one of the balls could be captive in position on the playfield and if a collision took place between the ball in play and the stationary ball, the tracking system could reward the player.

[0041] Play field objects that might otherwise include mechanical switches to detect ball hits would no longer require those switches, wires, and associated maintenance. Each object hit can be detected by the ball position, ball motion vector, and the change in the ball vector caused by the collision.

[0042] Turning now to the drawings, FIG. 1 illustrates the prior art pinball machine designated generally by the reference numeral 150. The pinball machine 150 in FIG. 1 is enabled to track the position of the ball during play. The pinball machine 150 includes a cabinet 101 which houses a playfield 103 which may be inclined. Generally, the cabinet 101 has mounted atop a score display 100. The playfield 103 supports a game piece such as a rolling ball 110 and has a plurality of playfield features and devices as well as a generally open area 104 where nothing interferes with the rolling of the ball because nothing is in the way to impede its travel. These features and devices may take a number of forms and some relatively simplified play features are targets 102A, 102B, 102C, 102D, and 102E and bumpers 106A and 106B. The ball 110 may be initially introduced into the playfield 103 by shooting the ball 110 with a plunger element 114. If the playfield 103 is inclined the ball tends to roll back generally in the direction of a pair of flippers 108A and 108B located at a bottom end part of the playfield 103. The flippers 108A and 108B, which are activated by buttons 112A and 112B on the sides of the cabinet 101, are used by the skilled player to propel the ball back into the playfield 103. The playfield 103 contains a touch screen 116 enabled to track the ball's position during play based on the physical contact between the ball 110 and the screen 116. The physical contact can be pressure caused by gravity or by the capacitive or inductive nature of the ball 110. Inherently, screen 116 is expensive and takes significant computing power to enable ball tracking. Even then the ball tracking performed is slow and does not allow the level of interactivity desired. The playfield devices and features may include a number of elements not shown in FIG. 1.

[0043] FIG. 2 illustrates an exemplary embodiment of the present disclosure. The pinball machine 250 in FIG. 2 is enabled to track the position of the ball during play using the methods of the present disclosure. The pinball machine 250 includes a cabinet 201 which houses a playfield 203 which may be inclined. Generally, the cabinet 201 has mounted atop a score display 200. The playfield 203 supports a game piece such as a rolling ball 210 and has a plurality of playfield features and devices as well as a generally open area 204 where nothing interferes with the rolling of the ball because nothing is in the way to impede its travel. These features and devices may take a number of forms and some relatively simplified play features are targets 202A, 202B, 202C, 202D, and 202E and bumpers 206A and 206B. The ball 210 may be initially introduced into the playfield 203 by shooting the ball 210 with a plunger element 214. If the playfield 203 is inclined the ball tends to roll back generally in the direction of a pair of flippers 208A and 208B located at a bottom end part of the playfield 203. The flippers 208A and 208B, which are activated by buttons 212A and 212B on the sides of the cabinet 201, are used by the skilled player to propel the ball back into the playfield 203. The playfield 203 further contains camera modules 216A and 216B wherein camera module 216A contains a field of view bounded by edges 218A and 218B and camera module 216B contains a field of view bounded by edges 218C and 218D. It should be understood here that camera modules 216A and 216B contain all critical elements necessary to enable the functionality of the system including but not limited to a lens system, a digital camera, a visible light filter, integrated electronics enabled to transmit data either by wired or wireless interface, and an illumination device such as one or more Infrared LEDs. If the edges 218A, 218B, 218C, and 218D are extended, a region is formed where both camera modules 216A and 216B can view the ball. It is in this shared region that the two-camera tracking system is enabled to track the ball 210. Through the camera module's 216A and 216B connection to pinball computing system 220, this system is enabled by an algorithm to track the ball's position during play based on the presence of the ball 210 in the field of view of camera modules 216A and 216B. The playfield devices and features may include a number of elements not shown in FIG. 2. Numerous features, not shown, can be connected to computing system 220 such that the numerous features can be controlled by computing system 220 based on the current location or path of ball 210. For example, these features could include lights, light matrices, display screens, actuators, and speakers.

[0044] FIG. 3 illustrates a second exemplary embodiment of the present disclosure. The pinball machine 350 in FIG. 3 is enabled to track the position of the ball during play using the methods of the present disclosure. The pinball machine 350 includes a cabinet 301 which houses a playfield 303 which may be inclined. Generally, the cabinet 301 has mounted atop a score display 300. The playfield 303 supports a game piece such as a rolling ball 310 and has a plurality of playfield features and devices as well as a generally open area 304 where nothing interferes with the rolling of the ball because nothing is in the way to impede its travel. These features and devices may take a number of forms and some relatively simplified play features are targets 302A, 302B, 302C, 302D, and 302E and bumpers 306A and 306B. The ball 310 may be initially introduced into the playfield 303 by shooting the ball 310 with a plunger element 314. If the playfield 303 is inclined the ball tends to roll back generally in the direction of a pair of flippers 308A and 308B located at a bottom end part of the playfield 303. The flippers 308A and 308B, which are activated by buttons 312A and 312B on the sides of the cabinet 301, are used by the skilled player to propel the ball back into the playfield 303. The playfield 303 further contains camera modules 316A and 316B wherein camera module 316A contains a field of view bounded by edges 318A and 318B and camera module 316B contains a field of view bounded by edges 318C and 318D. It should be understood here that camera modules 316A and 316B contain all critical elements necessary to enable the functionality of the system including but not limited to a lens system, a digital camera, a visible light filter, integrated electronics enabled to transmit data either by wired or wireless interface, and an illumination device such as one more Infrared LEDs. If the edges 318A, 318B, 318C, and 318D are extended, a region is formed where both camera modules 316A and 316B can view the ball. It is in this shared region that the two-camera tracking system is enabled to track the ball 310. Through the camera module's 316A and 316B connection to pinball computing system 320, this system is enabled by an algorithm to track the ball's position during play based on the presence of the ball 310 in the field of view of camera modules 316A and 316B. Furthermore, computing system 320 is connected to buttons 312A and 312B such that the computing system 320 can actuate flippers 308A and 308B thereby enabling pinball machine 350 with a self-play mode. The computing system 320 connection to buttons 312A and 312B is completed in such a way that allows both the player and the computing system 320 to actuate flippers 308A and 308B as desired. The playfield devices and features may include a number of elements not shown in FIG. 3. Numerous features, not shown, can be connected to computing system 320 such that the numerous features can be controlled by computing system 320 based on the current location or path of ball 310. For example, these features could include lights, light matrices, display screens, actuators, and speakers.

[0045] FIG. 4 illustrates a third exemplary embodiment of the present disclosure. The pinball machine 450 in FIG. 4 is enabled to track the position of the ball during play using the methods of the present disclosure. The pinball machine 450 includes a cabinet 401 which houses a playfield 403 which may be inclined. Generally, the cabinet 401 has mounted atop a score display 400. The playfield 403 supports a game piece such as a rolling ball 410 and has a plurality of playfield features and devices as well as a generally open area 404 where nothing interferes with the rolling of the ball because nothing is in the way to impede its travel. These features and devices may take a number of forms and some relatively simplified play features are targets 402A, 402B, 402C, 402D, and 402E and bumpers 406A and 406B. The ball 410 may be initially introduced into the playfield 403 by shooting the ball 410 with a plunger element 414. If the playfield 403 is inclined the ball tends to roll back generally in the direction of a pair of flippers 408A and 408B located at a bottom end part of the playfield 403. The flippers 408A and 408B, which are activated by buttons 412A and 412B on the sides of the cabinet 401, are used by the skilled player to propel the ball back into the playfield 403. The playfield 403 further contains camera module 416 having a field of view bounded by edges 418A and 418B. Located near camera module 416 are two Infrared LEDs 422A and 422B enabled to illuminate the field of view of camera module 416. It should be understood here that the camera module 416 contains all critical elements necessary to enable the functionality of the system including but not limited to a lens system, a digital camera, a visible light filter, and integrated electronics enabled to transmit data either by wired or wireless interface. Through the camera module's 416 connection to pinball computing system 420 and the connection of LEDs 422A and 422B to the same computing system 420, this system is enabled by an algorithm to track the ball's position during play based on the presence of the ball 410 in the field of view of the camera module 416. The playfield devices and features may include a number of elements not shown in FIG. 4. Numerous features, not shown, can be connected to computing system 420 such that the numerous features can be controlled by computing system 420 based on the current location or path of ball 410. For example, these features could include lights, light matrices, display screens, actuators, and speakers.

[0046] FIG. 5 illustrates a side-view of a camera module mounted in the playing surface. Playfield 502 has mounted to it a bracket 508 which further mounts to backplate 506. These three elements provide the physical structure to hold camera 500 steady during play. Further, an LED 504 can be mounted to the same backplate 506 or can mount to a secondary structure. Finally, signal generating and routing module 510 also connects to the same backplate 506 and acts to route the electrical signals to and from the camera 500 and LED 504 including any pre-processing and to communicate the required image data back to a central computing system (not shown). Backplate 506 can be a metal bracket, a printed circuit board, or any combination thereof. FIG. 5 illustrates only one preferred embodiment for inserting a camera module into the playfield 502. Several other means are possible including mounting to the top surface of playfield 502, mounting below the top surface of playfield 502 combined with a mirror, or mounting below playfield 502 wherein playfield 502 is constructed of Infrared transmissive material.

[0047] FIG. 6a illustrates a top view of the camera to understand a means for calibrating the camera according to the present disclosure. Camera 600 is shown with a precisely known location with respect to an X axis 608 and a Y axis 610 having a cartesian coordinate system with an origin 606. Camera 600 has an X axis 608 location 620 and a Y axis 610 location 622. Also illustrated are two playfield features 602 and 604. These features 602 and 604 are stationary objects that can be used by camera 600 to calibrate the image taken by using a series of pre-programmed geometric equations that would be entirely dependent on the game at hand and the position of the camera with respect to the features. Feature 604 has an X axis 608 location 618 and a Y axis 610 location 624. Feature 602 has an X axis 608 location 616 and a Y axis 610 location 626. Furthermore, camera 600 has an angle of orientation with respect to features 602 and 604. The angle of orientation is defined with respect to the Y axis 610 such that the left edge of the field of view of camera 600 is defined by a parallel line 628 to Y axis 610. The location of the features 602 and 604 are further defined by angles 612 and 614 respectively wherein angle 612 is the angle between the field of view edge 628 and the image vector 630 of feature 602 and angle 614 is the angle between the field of view edge 628 and the image vector 632 of feature 604.

[0048] FIG. 6b illustrates the camera's view as outlined in FIG. 6a. Here, camera view 650 contains a field of view edge 656 and two reflections 652 and 654 wherein reflection 652 is associated with the feature 604 from FIG. 6a and reflection 654 is associated with the feature 602 from FIG. 6a. Reflection 652 has a position in the image that is a number of pixels 658 away from the field of view edge 656 while reflection 654 has a position in the image that is a number of pixels 660 away from the field of view edge 656. The number of pixels 658 and 660 can be used in conjunction with the geometry of FIG. 6a to compute the specific calibration of the camera with respect to its location inside the pinball game playfield. It will be recognized by one skilled in the art that each camera will have its own playfield features that will be captured in a calibration image and the required computations will be specific to each camera and its location. By way of example, one camera may have three playfield features located at varying distances from the camera while a second camera may have four playfield features at equal distance from the camera. In some cases, more than one camera can use the same set or partially the same set of playfield features to calibrate from. In this case the two cameras can calibrate their positions with respect to one another.

[0049] Furthermore, it would be recognized by one skilled in the art that it is possible to manufacture the game with the disclosed system wherein the calibration means is simply pre-programmed into the system based on the predetermined location of all the objects. Alternatively, the calibration can be accomplished by taking the ball and positioning it in a series of known locations around the playfield and in view of the camera being calibrated. In each position the system is able to adjust the image position to correspond to the ball's predetermined location. Furthermore, instead of adjusting the image to correspond to the ball's predetermined location, the camera position or angle can be adjusted such that the ball's predetermined location corresponds to the image without adjusting the image. Likewise, any element on or near the playfield can be physically adjusted to interact with the passing ball at the proper time and location. By way of example, a light grid located on the playfield surface can be adjusted on the 2D surface to correspond with where the ball is understood to be by the system. In this way, a ray-tracing light grid can be easily calibrated to be visually accurate to the player.

[0050] FIG. 7 illustrates a ball location method with two cameras. Cameras 700 and 702 are shown with precisely known locations with respect to an X axis 708 and a Y axis 710 having a cartesian coordinate system with an origin 706. Camera 700 has an X axis 708 location 726 and a Y axis 710 location 716 while camera 702 has an X axis 708 location 722 and a Y axis 710 location 718. FIG. 7 additionally includes two Y axis 710 parallels 728 and 730 for reference purposes. Also illustrated is the ball 704. Ball 704 has an X axis 708 location 724 and a Y axis 710 location 720. Ball 704 is in the field of view of both cameras 700 and 702 such that the image vector 732 of camera 700 is at an angle 712 with respect to the Y axis parallel 728 while the image vector 734 of camera 702 is at an angle 714 with respect to the Y axis parallel 730. One skilled in the art will realize that the geometric computations will depend on the specific orientation of the cameras and their proximity to one another.

[0051] FIG. 8a illustrates the view of the camera 700 from FIG. 7. A ghost image of ball 804A is shown only for illustrative purposes as it does not show up in the actual image 802A of the camera. Reflection 806A is found in the image from the camera located a distance 810A from the left edge 808A of the image.

[0052] FIG. 8b illustrates the view of the camera 702 from FIG. 7. A ghost image of ball 804B is shown only for illustrative purposes as it does not show up in the actual image 802B of the camera. Reflection 806B is found in the image from the camera located a distance 810B from the left edge 808B of the image.

[0053] Together the images in FIGS. 8a and 8b are processed to determine the specific distances 810A and 810B and based on the pre-calibrated positions of the cameras and their associated orientations, the location of ball 804A,B can be understood very quickly. It should be understood that FIGS. 8a and 8b constitute one frame from each camera and that this process of computing the ball location can take place as fast as 60 times per second such that the ball location is known every 16.7 ms.

[0054] Furthermore, with such accuracy and speed, the same computing system can generate a path that the ball is traveling and thereby cause interactions to take place. Additionally, since the frame rate of the cameras are controlled, the computing system can also understand not only where the ball has been but where it is projected to be both based on learning the slope of the machine in its installed location and by understanding a predefined vector of the ball, its mass, and expected rolling resistance on the playfield.

[0055] FIG. 9 illustrates a single camera method for determining a ball position on the playfield. Camera 900 is flanked by LEDs 902 and 904. LED 902 emits light in a cone that contains light vector 908 which reflects off the ball 906 and travels into the camera 900 lens via vector 910. LED 904 emits light in a cone that contains light vector 912 which reflects off the ball 906 and travels into the camera 900 lens via vector 914.

[0056] FIG. 10 illustrates the image seen by the camera in FIG. 9. Field of view 1000 is quite large but even though the camera is capable of capture such a large image the computing system can ignore all portions of the image outside of window 1002 because the ball 1004 (ghost imaged here as it doesn' t actually show up in the image) is known to be traveling on the surface of the playfield and therefore cannot exist outside of window 1002. In this window 1002 the centroid 1014 of reflections 1006 and 1008 is observed to be a number of pixels 1010 away from left window edge 1012. Furthermore, reflections 1006 and 1008 are found to be a number of pixels 1016 away from one another. Based on the number of pixels 1010 and 1016 the position of the ball 1004 with respect to the camera capture the image 1000 can be known by taking into account the pre-calibration geometry and associated values.

[0057] While the present disclosure has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the appended claims. The right to claim elements and/or sub-combinations that are disclosed herein as other present disclosures in other patent documents is hereby unconditionally reserved.