The present invention relates to a method for detecting the motion of a hand used for input of coordinates in an input device, and the input device using the same.
An input device which uses a human hand, a human finger and the like as an input body for manipulation has been developed as a user interface for a device capable of interaction with a two-dimensional video picture or a three-dimensional video picture which is displayed. This input device includes a three-dimensional position measurement system having a plurality of optical imaging means such as cameras. Based on images (two-dimensional images) obtained from the cameras whose shooting position and shooting angle are determined, this input device calculates the three-dimensional position, the coordinates on three axes (X, Y and Z axes) and the like of an object (input body) of interest by computation to output the coordinate values thereof to a control means (such as a computer) of a display device and the like (with reference to Patent Literatures 1 and 2, for example).
For example, an input device for detecting the coordinates of an input body (hand H) in the directions of three axes (X, Y and Z axes) orthogonal to each other as shown in
However, the three-dimensional position measurement system for use in the aforementioned conventional input device necessarily involves the need for a plurality of cameras, which results in large-scale and costly facilities in many cases. In addition, the cameras are not always disposed in positions optimum for shooting, depending on the ambient environment and the device structure thereof, but are disposed in positions which give a feeling of strangeness to an operator. Further, when the cameras come into a field of view recognizable by the operator, there is apprehension that the motion of a hand of the person unskilled in manipulation is unnatural or is not smooth.
In view of the foregoing, it is therefore an object of the present invention to provide a method for detecting the motion of an input body, the method being capable of detecting the three-dimensional motion of a human hand from image analysis using a single image sensor, and an input device for instruction manipulation using the method for detecting the motion.
To accomplish the aforementioned object, a first aspect of the present invention is intended for a method for detecting the three-dimensional motion of a hand used for input of coordinates in an input device by means of a single image sensor. The method comprises the steps of: projecting light from a light source disposed above or below a hand including a fist toward the hand; disposing an image sensor on the same side of the hand as the light source to acquire the reflection of the light from the hand as a two-dimensional image on a virtual imaging plane; allocating coordinates on two axes orthogonal to each other to the two-dimensional image to recognize and extract the shape of the fist and the position of a fingertip protruding from the fist from the two-dimensional image, thereafter calculating the coordinates of the center of gravity of the area distribution of the fist and the coordinates of the fingertip by computation; and repeating the step of projecting the light, the step of acquiring the two-dimensional image and the step of calculating the center of gravity coordinates of the fist and the fingertip coordinates to compare distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after the repetition, thereby making a determination that the hand including the fist has made a sliding movement along the virtual imaging plane when there is no change between the distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after the repetition, and a determination that the fingertip has pivoted upwardly or downwardly about the wrist of the hand or an elbow when there is a change between the distance between the center of gravity coordinates of the fist and the fingertip coordinates before and after the repetition.
To accomplish the same object, a second aspect of the present invention is intended for an input device which comprises: a light source disposed above or below a hand including a fist used as an input body for the device; an image sensor disposed on the same side of the hand as the light source; a controller for controlling the light source and the image sensor; a shape recognizer for acquiring the reflection of light projected from the light source toward the hand as a two-dimensional image to calculate coordinates corresponding to the center of gravity of the area distribution of the fist and coordinates corresponding to the position of a fingertip protruding from the fist from the two-dimensional image; and a motion determinator for comparing distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after a predetermined time interval to make a determination that the motion of the hand is an upward or downward motion of a finger with respect to a virtual imaging plane of the image sensor when there is a decrease or an increase between the distances before and after the time interval.
The present inventor has diligently made studies to solve the aforementioned problem, and has verified the motion (image) of a hand when it is shot with a single camera in detail. The present inventor has found that there is a difference in the way of motion between a fingertip portion and a fist (palm) portion of the hand, and has focused attention on this fact to make further studies. As a result, the present inventor has found that the motion of the fingertip including a vertical direction component (i.e. “upward or downward motion”) with respect to an imaging plane of the camera is detected by tracking the motion of the coordinates of the fingertip which moves greatly when the hand is inclined with respect to the center of gravity coordinates (the center of gravity point of the dot distribution on an image or a substantially fixed point close to the pivot axis of a wrist) of the fist which moves a little even when the hand is inclined. Hence, the present inventor has attained the present invention.
The present invention has made based on the aforementioned findings. The method for detecting the motion of an input body according to the present invention includes the steps of: projecting light toward a hand including a fist; acquiring the reflection of the light from the hand as a two-dimensional image by means of a single image sensor; recognizing the coordinates of the center of gravity of the area distribution of the fist and the coordinates of a fingertip in this image; repeating the aforementioned steps to compare distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after the repetition, thereby determining the motions of the fingertip and the fist from the result of comparison. Thus, the method for detecting the motion of an input body according to the present invention makes a determination that the whole hand including the fist has made a sliding movement along an imaging plane (virtual plane) of the image sensor when there is no change between the distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after the repetition, and makes a determination that the fingertip has pivoted upwardly or downwardly with respect to the imaging plane about the wrist of the hand or an elbow when there is a change between the distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after the repetition. Therefore, the method for detecting the motion of an input body according to the present invention is capable of detecting the three-dimensional motion of a human hand from image analysis by using only the single image sensor.
The input device according to the present invention includes: a light source; an image sensor disposed on the same side as the light source; a controller; a shape recognizer for calculating the coordinates of the center of gravity of the shape distribution of the fist and the coordinates of the tip of a finger from a two-dimensional image acquired by the image sensor; and a motion determinator for comparing distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after a predetermined time interval. Thus, when there is a decrease or an increase between the distances between the center of gravity coordinates of the fist and the fingertip coordinates before and after the time interval, a determination is made that the motion of the hand is an upward or downward motion (vertical motion with respect to the image sensor) of the finger with respect to a virtual imaging plane of the image sensor. Therefore, the input device according to the present invention is capable of detecting the three-dimensional motion of a human hand from image analysis by using the single image sensor provided in the input device.
Additionally, the input device according to the present invention requires only the single image sensor as described above. Thus, the input device for detecting the three-dimensional motion is provided with simple facilities at low costs. Further, the flexibility of the placement of the aforementioned image sensor (camera or the like) is improved, so that the camera or the like may be disposed (hidden) in a position of which an operator is unconscious. Therefore, the input device according to the present invention is an intuitive user-friendly device on which even a beginner of manipulation performs an input operation easily.
Next, an embodiment according to the present invention will now be described in detail with reference to the drawings. It should be noted that the present invention is not limited to the embodiment.
The input device according to the present embodiment is provided for detecting the three-dimensional motion of the hand H including a fist used as an input body for the device by means of the single optical imaging means (camera C). The input device includes a camera unit disposed below (substantially vertically under) the aforementioned hand H, as shown in
In this input device, the shape recognition means (not shown) acquires the reflection (image) of light projected from the aforementioned light sources L toward the hand H as the two-dimensional image H′ on the virtual imaging plane P having coordinate axes extending in X and Y directions, as shown in
Further, the aforementioned input device repeats the projection of light from the aforementioned light sources L, the acquisition of the two-dimensional image H′ by means of the camera C and the calculation of the center of gravity coordinates G of the fist and the fingertip coordinates T based on the two-dimensional image. In addition, when a distance between the center of gravity coordinates G of the fist and the fingertip coordinates T is changed before and after the aforementioned repetition (with reference to
The aforementioned input device and the detection method for use in the detection of the motion of the input body (hand H) will be described in further detail. The camera unit disposed below the aforementioned hand H includes the camera C, and the plurality of (in this example, three) light sources L disposed around this camera C, as shown in
Examples of the aforementioned light sources L include illuminators such as infrared LEDs, and lamps. It is desirable that the aforementioned light sources L used herein are illuminators which emit light having a range other than that of visible light so as not to hinder the field of vision of an operator who performs an input operation. The aforementioned camera unit may be disposed in an inclined attitude with respect to the hand H below the input body (hand H) (with reference to
The method for detecting the motion of the hand H inserted into a sensing region of the aforementioned input device will be described in a step-by-step manner.
For the detection of the motion of the aforementioned hand H, light is initially projected from the light sources L disposed below (or above) the hand H including the fist toward the hand H, as shown in
Next, the aforementioned acquired two-dimensional image H′ is binarized, based on the threshold value. Thereafter, as shown in
Thereafter, the step (light projecting step) of projecting the aforementioned light, the step (imaging step) of acquiring the two-dimensional image and the step (coordinate specifying step) of calculating the center of gravity coordinates G of the fist and the fingertip coordinates T are repeated at determined time intervals. The center of gravity coordinates G of the fist and the fingertip coordinates T after the repetition are measured again (measuring step).
Then, a change in distance between the center of gravity coordinates G of the aforementioned fist and the fingertip coordinates T is calculated using the values of the center of gravity coordinates G(Xm,Yn) of the fist and the fingertip coordinates T(Xp,Yq) before and after the lapse of the aforementioned repetition. From the result of calculation, a determination is made as to which one of the two patterns to be described later the motion of the aforementioned hand H has, i.e. whether the motion of the aforementioned hand H has a fist pattern (with reference to
An instance where the hand (input body) has made a horizontally sliding movement (H0→H1) as shown in
For the determination of the motion of the aforementioned hand H, an identification region in which the motion (T0→T1) of the aforementioned fingertip coordinates T is allocated on an area-by-area basis to four directions [X(+), X(−), Y(+) and Y(−)] may be defined on the virtual imaging plane P having the coordinate axes extending in the X and Y directions, as shown in
Next, in an instance where the hand (input body) has made an upward or downward motion (H0→H2) as shown in
The method for detecting the upward or downward motion of the aforementioned hand H in the Z-axis direction, i.e. the motion of the aforementioned fingertip coordinates T approaching the center of gravity coordinates G in the binary image (a procedure of image processing) will be described in further detail. First, infrared radiation is projected from the light sources L (infrared LEDs) disposed below the hand H including the fist as mentioned above. The reflection (two-dimensional image) from the hand H is shot with the camera C disposed similarly below the hand H. The coordinate axes extending in the X and Y directions are al located to this two-dimensional image. Next, the shape recognition means (program) optimally sets the threshold value of brightness for binarization, and performs a binarization process on the aforementioned two-dimensional image. Then, the shape recognition means (program) performs a thinning process to sharpen the outside shape of the hand H, as shown in
Next, by using the aforementioned sharpened two-dimensional image, the shape recognition means (program) identifies the site of a finger to calculate the coordinates [fingertip coordinates T(Xp,Yq)] corresponding to the tip of the finger. Next, a similar program is used to identify the shape of the fist of the aforementioned hand H (with reference to the portion shaded with solid diagonal lines in
During this calculation, Equation (1) to be described below is used for the computation of an X-axis coordinate among the center of gravity coordinates G.
Xm among the center of gravity coordinates G=(the sum of X coordinate values of pixels present inside the shape of the fist)/(the number of pixels present inside the shape of the fist) (1)
Equation (2) to be described below is used for the computation of a Y-axis coordinate among the center of gravity coordinates G.
Yn among the center of gravity coordinates G=(the sum of Y coordinate values of pixels present inside the shape of the fist)/(the number of pixels present inside the shape of the fist) (2)
Next, after the fingertip coordinates T (Xp, Yq) and the center of gravity coordinates G(Xm,Yn) of the fist are specified, the step (light projecting step) of projecting the aforementioned light, the step (imaging step) of acquiring the two-dimensional image and the step (coordinate specifying step) of calculating the center of gravity coordinates G of the fist and the fingertip coordinates T are repeated as mentioned above. As shown in
A method for comparing distances d between the center of gravity coordinates G of the fist and the fingertip coordinates T with each other will be described in further detail.
In making a determination that the hand H has made an upward or downward motion by comparing the distances d between the center of gravity coordinates G of the fist and the fingertip coordinates T with each other, another condition is set in this example in addition to the setting of the threshold value (lower limit) of the difference between the distances d. As shown in
As described above, when the distance between the center of gravity coordinates G of the aforementioned fist and the aforementioned fingertip coordinates T is decreased or increased before and after the measurement, the method for detecting the motion of the input body according to the present invention is capable of making a determination that the motion of the hand H at that time is an upward or downward motion of a finger with respect to the virtual imaging plane P of the aforementioned optical imaging means (camera C).
Also, the input device according to the present invention which uses the method for detecting the motion of the aforementioned input body is capable of detecting the motion of the human hand H in the Z-axis direction, i.e. the three-dimensional motion, from an image analysis by using only the single camera C disposed below or above the aforementioned hand H.
Further, because of the capability of detecting the motion in the Z-axis direction, the aforementioned input device is capable of allocating the motion of the hand H in a horizontal direction (X and Y directions), for example, to a cursor movement manipulation of the display device and the like while allocating the motion in the aforementioned Z-axis direction to a decision (click) manipulation.
Another manipulation method may be employed such that the motion of the hand H in the X-axis (leftward or rightward) direction and in the Z-axis (upward or downward) direction is allocated to the manipulation of moving an object on the display device while the motion thereof in the Y-axis (forward or backward) direction is allocated to the manipulation of expanding and contracting the aforementioned object. In this manner, the input device according to the present invention achieves the manipulation corresponding to essential three-dimensional (three axes of X, Y and Z) information for three-dimensional (3D) video pictures and the like. Also, the input device according to the present invention has the advantage of achieving more intuitive manipulations by approaching the same manipulation environment as in a real three-dimensional space.
As mentioned above, the method for detecting the motion of the input body according to the present invention is capable of similarly detecting the three-dimensional motion of the human hand H even when the aforementioned camera unit is disposed in an inclined attitude below the input body (hand H) (
Also, when the camera unit is disposed above the hand H as shown in
Although a specific form in the present invention has been described in the aforementioned examples, the aforementioned examples should be considered as merely illustrative and not restrictive. It is contemplated that various modifications evident to those skilled in the art could be made without departing from the scope of the present invention.
The method for detecting the motion of the input body, and the input device using the same according to the present invention are capable of detecting the three-dimensional motion of a human hand by using the single camera without using a plurality of cameras. This achieves more intuitive manipulations for three-dimensional (3D) video pictures and the like as in a real three-dimensional space.
Number | Date | Country | Kind |
---|---|---|---|
2011-194938 | Sep 2011 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/JP2012/071456 | 8/24/2012 | WO | 00 | 3/4/2014 |