| Method of detecting position of rectangular object and object detector -> Monitor Keywords |
|
|
  Method of detecting position of rectangular object and object detectorUSPTO Application #: 20060141433Title: Method of detecting position of rectangular object and object detector Abstract: A method of detecting a position of a rectangular object includes the steps of: capturing an image of the object by an image sensor having a rectangular image plane having four edges; detecting, for each edge of the four edges, a distance to a point of the image of the object closest to said each edge; and determining a position of a predefined point of the image of the object based on the detected distances. (end of abstract)
Agent: Harness, Dickey & Pierce, P.L.C - Reston, VA, US Inventors: Cheung Chuen Hing, Hiromu Ueshima USPTO Applicaton #: 20060141433 - Class: 434247000 (USPTO) Related Patent Categories: Education And Demonstration, Physical Education The Patent Description & Claims data below is from USPTO Patent Application 20060141433. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention generally relates to a method and an apparatus for detecting a position of an object and its angle to a specific reference and, more particularly, it relates to a method and an apparatus that precisely detects a position and its angle of a tool used in computer games. [0003] 2. Description of the Background Art [0004] Sports computer games directed to baseball, football, golf, tennis, table tennis, bowling, and so on forms one of the categories of computer games. Most of these sports games require associated tools for playing. A bat for baseball, a racket for tennis or table tennis, a bowling ball for bowling, to name a few. The game program running on a CPU (Central Processing Unit) of a game apparatus creates virtual game situation where a user is supposed to be a player, generates a video image of the surroundings, and shows the image on a television set (TV). When a specific situation arises, the player is requested to take an action using the tool. In response to the player's action, the game program changes the virtual situation, and the player is requested to take a next action. [0005] Take a golf game as an example. At the start of a game, the golf game program creates a scene of a teeing ground. The green can be seen on the backside of the teeing ground and the virtual golf ball is placed at the center (or any other place) of the teeing ground. When the scene changes and the golf ball is displayed at the center of the screen, the player "addresses" an image sensor unit placed on the floor and try to hit the virtual with a club, i.e., swings the club above the image sensor unit. [0006] When the player swings the club, the image sensor detects the positions of the moving club head and associated computation program within the image sensor unit computes the speed and the direction of the club head. The detected speed and the movement are applied to the golf game program. In response, the golf game program computes the direction and speed of the club head, computes the resultant trajectory of the imaginary golf ball hit by the imaginary golf club in accordance with the direction and the speed of the club head, and creates a new game situation in accordance with the new position of the golf ball. [0007] Naturally, specific hardware is necessary for detecting the position of the club head. Japanese Patent Application Laying-Open (Tokkai) No. 2004-85524 discloses an apparatus for detecting such positions of a game tool. The apparatus is used in a computer golf game and includes a stroboscope having four LED's (light emitting diodes), a CMOS (Complementary Metal-Oxide-Silicon) image sensor (hereinafter "CIS"), and a processor. A retro-reflector is attached to the bottom (sole) of a club head or a putter head. The retro-reflector has a long rectangular shape with circular ends. The apparatus is connected to a TV monitor and a golf game program running on the processor generates the video image of a virtual golf course in response to the player's action with the club or the putter. [0008] In operation, the CIS captures two kinds of images: images during the stroboscope LED's are on (emitting light); and images during the stroboscope LED's are off. The image signals are applied to the processor, where necessary computation is carried out. [0009] When LED's are emitting light, the retro-reflector reflects that light to the CIS; therefore, the CMOS sensor forms the image of the retro-reflector. Other light sources also form images on the CIS. When the LED's are off, the retro-reflector does not reflect the light; their images are not formed. Only other light sources form their images. By computing the difference between these two kinds of images in the processor, therefore, the processor can detect the images of the retro-reflectors separate from other images. [0010] The processor detects two points farthest from each other in an image of the retro-reflector. These two points indicate the two ends of the mid line of the retro-reflector; by knowing the X and Y coordinates of these points, the processor can know the position of the club head or the putter head as an average of these two points. By computing this point for each of the captured images, the processor computes the direction and the speed of the movement of the club head. Also, the processor can compute the angle .theta. between the line connecting the two end points of the retro-reflector and a prescribed reference line. From this angle .theta., the angle of the head face can be computed. [0011] A golf game program running on the processor processes these data, determines the trajectory of the virtual golf ball, and creates next virtual situation. [0012] However, in order to determine the two farthest points in the image of the retro-reflector, the processor have to compute the distance of each combination of two points in the image of the retro-reflector. This is relatively complicated operation and requires a considerable amount of computing time. Further, the CIS has a 32.times.32 pixel, 8 bits per pixel image plane. The data size of one image therefore amounts to 8192 bits=1024 bytes. The processor needs to receive the data from the CIS, store the data, and carry out the above-described computations on the stored data. [0013] Therefore, a processor with relatively high performance is necessary in order to carry out the computation necessary for the game in real time. Also, the processor needs to have storage with a capacity large enough to store the data output from the CIS. This results in a computer game machine with a relatively high cost. Because children are the main users of the computer game machines, the game machines should be inexpensive although they should have enough performance to fully operate in real time. SUMMARY OF THE INVENTION [0014] Therefore, one of the objects of the present invention is to provide an object detector that detects a position of an object with a simple operation and a method thereof. [0015] Another object of the present invention is to provide an object detector that detects a position of an object with smaller amount of computation compared with the prior art and a method thereof. [0016] Yet another object of the present invention is to provide an object detector having simple structure that detects a position of an object with smaller amount of computation compared with the prior art and a method thereof. [0017] In accordance with a first aspect of the present invention, a method of detecting a position of a rectangular object includes the steps of: capturing an image of the object by an image sensor having a rectangular image plane having four edges; detecting, for each edge of the four edges, a distance to a point of the image of the object closest to said each edge; and determining a position of a predefined point of the image of the object based on the detected distances. [0018] The distances of the four points closest to the respective edges of the image plane from the respective edges can be detected with simple operation and does not require a large amount of computation time. Therefore, a method that can detect a position of an object with a simple operation can be provided. [0019] The step of determining may include the step of determining a position of the center point of the image of the object based on the distances. [0020] Preferably, a coordinate system having a first axis and a second axis is defined on the image plane. The first axis of the coordinate system is perpendicular to a first pair of opposite edges of the image plane, and the second axis of the coordinate system is perpendicular to a second pair of the edges of the image plane. The step of determining a position of the center point may include the step of: determining first-axis coordinates of points closest to respective edges of the first pair of edges; calculating a first-axis coordinate of the center point by averaging the first-axis coordinates determined in the step of determining first-axis coordinates; determining second-axis coordinates of points closest to respective edges of the second pair of edges; and calculating a second-axis coordinate of the center point by averaging the second-axis coordinates determined in the step of determining second-axis coordinates. [0021] Scanning the image plane searching for four points closest to the four edges from the edges can be implemented with simple algorithm. By detecting these four points, the center point of the image of the object is easily calculated. Therefore, a simple method for detecting a position of an object is provided. [0022] More preferably, the method further includes the steps of calculating an angle .theta. that one of the edges of the image of the object forms with one of the four edges of the rectangular image plane using the first-axis coordinates determined in the step of determining first-axis coordinates, and the second-axis coordinates determined in the step of determining second-axis coordinates. Continue reading... Full patent description for Method of detecting position of rectangular object and object detector Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method of detecting position of rectangular object and object detector patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method of detecting position of rectangular object and object detector or other areas of interest. ### Previous Patent Application: Fencing training sword Next Patent Application: Training device for golf swing and similar motions Industry Class: Education and demonstration ### FreshPatents.com Support Thank you for viewing the Method of detecting position of rectangular object and object detector patent info. IP-related news and info Results in 0.27605 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , |
||
