Abstract:
A computing system for direct three-dimensional pointing includes at least one computing device, and a pointing/input device including at least one light source and a motion sensor module for determining absolute and relative displacement of the pointing/input device. At least one imaging device is configured for capturing a plurality of image frames each including a view of the light source as the pointing/input device is held and/or moved in a three-dimensional space. A computer program product calculates at least a position and/or a motion of the light source in three-dimensional space from the plurality of sequential image frames and from the pointing/input device absolute and relative displacement information, and renders on the graphical user interface a visual indicator corresponding to the calculated position and/or the motion of the light source.

Description:
[0001]    This utility patent application claims the benefit of priority in U.S. Provisional Patent Application Ser. No. 61/942,605 filed on Feb. 20, 2014, the entirety of the disclosure of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to human-computer interaction systems. More specifically, the disclosure relates to methods and systems directed to three-dimensional pointing, using a system allowing determination of an absolute location on an image display apparatus using both active and passive devices. 
       SUMMARY 
       [0003]    The present invention reveals how a user can get an absolute location on an image display apparatus using a system integrated with both active and passive devices. The system consists of a pointing device called Absolute Pointer  22 , an image display apparatus  30  (e.g., a projector, a TV, a monitor, etc.), an image capture device  2  (e.g., a webcam), and a computer  4 . A transferring protocol, which can be wired or wireless, is adopted between the image capture device  2  and the computer  4  (Error! Reference source not found.). 
         [0004]    The Absolute Pointer  22  functions as an infrared pointer, except it moves a cursor instead of a red spot. When an operator O uses Absolute Pointer  22  to aim at a point (e.g., point  6 ) on the image display apparatus  30 , a cursor will appear at the location pointed to by the Absolute Pointer  22 . This cursor will move when the Absolute Pointer  22  is moved, but always to a location pointed to by the Absolute Pointer  22  on the image display apparatus  30 . 
         [0005]    The Absolute Pointer  22  can also be used as a mouse-like input device. The position specified by the Absolute Pointer  22  is acquired through a computation process by the computer, and coordinates of the specified position can be used to identify an item or icon on the screen of the computer. Therefore, by manipulating the Absolute Pointer  22 , a user can interact with most operating systems (e.g., Android® or Microsoft® Windows®), such as select files, programs, or actions from lists, groups of icons, etc., and can freely move files, programs, etc., issue commands or perform specific actions, such as we do in a drawing program. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  shows an image display apparatus according to the present disclosure for use in a system integrated with both active and passive devices; 
           [0007]      FIG. 2  shows a pointing device according to the present disclosure; 
           [0008]      FIG. 3  depicts calculation of an absolute position of a pointer according to the present disclosure; 
           [0009]      FIG. 4  depicts a mathematical model for perspective projection to compute x- and y-coordinates in a world coordinate system according to the present disclosure; 
           [0010]      FIG. 5  depicts the calibration step  508  of  FIG. 3 ; 
           [0011]      FIG. 6  depicts attempting a determination of positions P on an image display apparatus using only a motion vector and a projection point; 
           [0012]      FIG. 7  depicts a calculation of a new position P′ using a three-axis relative positioning subsystem; 
           [0013]      FIG. 8  depicts a direct calculation of a new position P′ using a three-axis relative positioning subsystem; and 
           [0014]      FIG. 9  shows a system integrated for use with both active and passive devices for calculating an absolute position of a pointer on an image display apparatus according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    Three components are embedded in the Absolute Pointer  22 : a LED light source  20  (at the front end), a control panel  18 , and a relative positioning subsystem  16  ( FIG. 2 ). The system uses images of the LED  20  taken by the image capture device  2  and information provided by the relative positioning subsystem  16  to identify the location pointed to by the Absolute Pointer  22 . An absolute position on the image display apparatus  30  can then be precisely computed. 
         [0016]    The front LED light source  20  is used as an indicator of the location of a cursor by the system. 
         [0017]    The control panel  18  consists of multiple buttons, which can provide direct functionality, such as the number keys, arrow keys, enter button, power button, etc. 
         [0018]    The relative positioning subsystem  16  consists of a set of relative motion detecting sensors to provide relative motion information of the device (e.g., acceleration, rotations, etc) to the computer in real time through some wireless channel. The set of relative motion detecting sensors contained in the relative positioning subsystem  16  can include a g-sensor, a gyroscope sensor and so on. 
         [0019]    The image capture device  2  functions as a viewing device for the computer. It takes images of the scene in front of the image display apparatus at a fixed frame rate per second and sends the images to the computer for subsequent processing. Most of the conventional single lens imaging devices, such as a standard webcam, can be used as a image capture device for the system. However, to provide a steady performance, the image capture device should have a frame rate that is at least 30 frames per second. 
         [0020]    The computer  4  provides the functionality of light source location recognition that will recognize the location of the LED light source  20  in the image sent by the image capture device  2 , and then converts the LED light source  20  location in the image to a point (e.g., point  6 ) on the image display apparatus  30 . When the computer  4  receives an image from the image capture device  2 , it first identifies the location of the LED light source  20  in the image using image recognition techniques, it then finds x- and y-coordinates of the LED light source location in the image with respect to the origin of the coordinate system of the image. In the meanwhile, using a tilt vector provided by the relative positioning subsystem  16 , the computer  4  can compute the distance between the Absolute Pointer  22  and the image display apparatus  30 . The x- and y-coordinates of the LED light source location in the image are then used with the distance between the Absolute Pointer  22  and the image display apparatus  30  to determine the location of a cursor in the x-y coordinate system of the image display apparatus  30 . Therefore, by moving the Absolute Pointer around in front of the image display apparatus  30 , one can determine the location of a cursor on the image display apparatus  30  through the LED light at the front end of the Absolute Pointer  22 . 
         [0021]    The calculation process of the system is shown in  FIG. 3 . In Step  502 , the operator O powers on the Absolute Pointer  22 , and allows the computer  4  to start with the LED light recognition process through images taken by the image capture device  2 . In Step  504 , the image capture device  2  starts capturing images while the computer  4  starts recognizing the location of the LED light source  20  in the images and records the coordinates of the LED light source in the images. In Step  506 , coordinates of the recognized LED light source in the images recorded from the previous step (Step  504 ) are put into a mathematical model for perspective projection to compute x- and y-coordinates in the world coordinate system ( FIG. 4 ). In Step  508 , the operator O aims the Absolute Pointer  22  at some specific point (e.g., the upper left corner  30 A) on the image display apparatus  30 , while the computer records the tilt data of the Absolute Pointer  22  sent by the relative positioning subsystem  16 . The input provided by the relative positioning subsystem  16  is used subsequently as auxiliary information to increase processing accuracy after calibrating the initial coordinates. In Step  510 , the tilt data (acquired in Step  508 ) is used to establish a second mathematic equation. In Step  512 , using the two mathematical equations obtained in Step  504  and Step  510 , real coordinates of the LED light source  20  can then be solved. The subsequent positioning process can be done in two different approaches. The first approach (Step  516 ) is to use only the acceleration, tilt, and rotation angle information of the Absolute Pointer  22  provided by the relative positioning subsystem  16  to solve for the position on the image display apparatus  30 . The second approach (Step  514 ) is to use both the relative positioning subsystem  16  and the image capture device  2  to solve for the position on the image display apparatus  30 . In the second approach (Step  514 ), the image capture device  2  is responsible for the detection of the LED light source  20  location, and the relative positioning subsystem  16  is responsible for detecting the depth (z-axis) offset only. 
         [0022]      FIG. 4  is a diagram of the perspective projection of Step  506 . In this step, point Q is captured by B (image capture device  2 ) and then the acquired image is mapped to point P on CCD  60 . The parameter f is the focal length of the image capture device B, A x  is the horizontal distance between P and center of the CCD, W is the scaling factor between the CCD and the resolution, L z  is the distance between point Q and the image capture device B, and L x  is the horizontal distance between point Q and device B. 
         [0023]      FIG. 5  is a sketch of the calibration step described in Step  508 . When the light source  20  (Point L) is at a distance from the image display apparatus  30  (e.g., the distance plane  50 ), and the Absolute Pointer  22  is aimed at a specific spot (e.g., Point P ( 30 A), the upper-left corner) on the image display apparatus  30 , the image capture device  2  captures an image with the LED light source  20  in it and maps the light source to a point A on CCD  60 . At this moment, the vector from Point L to Point P is parallel to Vector          , the axis of the tilt Absolute Pointer  22 . 
         [0024]    Combining Steps  504  and  508 , we can construct the following equations: 
         [0000]    Notation definitions (the underlined parts are known parameters): 
         [0000]        P =( X, Y,  0): Calibration point 
         [0000]                =( v   x   , v   y   , v   z ): Slope vector 
         [0000]        L =( L   x   , L   y   , L   z ) : Actual position of light spot 
         [0000]        A =( A   x   , A   y ): Projected point on CCD 
         [0000]        f : Webcam focal length 
         [0000]        W : Scaling ratio between CCD and image resolution 
         [0000]    By projection relationship: 
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         [0000]    The next questions are:
   1. (Step  516 ) Given a motion vector          =(v x , v y , v z ) and a projection point A=(A x , A y ) only, how to find the screen coordinates P′=(X, Y, 0)?   2. (Step  514 ) Given a motion vector          =(v x , v y , v z ), calibration location L=(L x , L y , L z ) and moving direction          =(t x , t y , t z ) (e.g., acquired by g-sensor), how to find the screen coordinates P′=(X, Y, 0)?   
 
       Solution of Question 1 
       [0027]    First, we notice that the solution is NOT unique (FIG.  6 )! 
         [0028]      FIG. 6  shows that given a motion vector          =(v x , v y , v z ) and a projection point A=(A x , A y ) only, there could be an infinite number of solutions P. As shown, when the light source  20  of the Absolute Pointer  22  is at different distances from the image display apparatus  30  (e.g., Point L 1    20 D, Point L 2    20 E, and Point L 3    20 F) but projected to the same point (e.g., Point A) in perspective projection on CCD  60 , the same tilt vector           will result at different positions on the image display apparatus  30  (e.g., Points P 1 , P 2 , and P 3 ). 
         [0029]    However, if we start at calibration location L=(L x , L y , L z ) ( 20 J) and record the moving direction          =(t x , t y , t z ) ( FIG. 7 ), then from equation (2) we have 
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         [0030]    Therefore, if the light source is moved from position  20 J to another position (e.g. such as  20 I), then it only needs to start with the calibrated 3D coordinates L=(L x , L y , L z ) and keeps recording the moving direction (using the relative positioning subsystem  16 ) to get the displacement vector t z . Thereafter, using t z  in conjunction with the given ≈=(v x , v y , v z ) and A=(A x , A y ), the computer  4  can solve the new position P′ on the image display apparatus  30  pointed by the Absolute Pointer  22 . 
       Solution of Question 2 
       [0031]    When there is no image capture device  2  as an auxiliary tool, we then use the nine-axis relative positioning subsystem  16  for direct calculation. If the front light source is moved from position  20 H to another position (e.g. such as  20 G in  FIG. 8 ), then we start with the calibrated 3D coordinates L=(L x , L y , L z ) and keeps recording the moving direction (using the relative positioning subsystem  16 ) to get the moving vector          =(t x , t y , t z ). Then, with the given          =(v x , v y , v z ), the computer  4  can solve the new position P′ on the image display apparatus  30  pointed by the Absolute Pointer  22 . 
         [0032]    We can use  FIG. 8  to depict the phenomenon. Since 
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                               v 
                               x 
                             
                           
                           
                             v 
                             z 
                           
                         
                       
                     
                   
                 
                 
                   
                     
                       Y 
                       = 
                       
                         
                           ( 
                           
                             
                               L 
                               y 
                             
                             + 
                             
                               t 
                               y 
                             
                           
                           ) 
                         
                         - 
                         
                           
                             
                               ( 
                               
                                 
                                   L 
                                   z 
                                 
                                 + 
                                 
                                   t 
                                   z 
                                 
                               
                               ) 
                             
                              
                             
                               v 
                               z 
                             
                           
                           
                             v 
                             z 
                           
                         
                       
                     
                   
                 
               
             
             _