Movement direction presentation device, movement direction presentation method, program, and movement direction presentation system

Abstract

A first movement calculation unit 30 calculates a first movement direction v1 and a first movement amount q1 of an object X from a first frame f1 and a second frame f2 in a first video α1. A superimposition unit 40 generates a superimposed image p in which an image indicating the direction of the first movement direction v1 is superimposed on the image of the first frame f1. A second movement calculation unit 70 calculates a second movement direction v2 and a second movement amount q2 of a user's predetermined portion Y from a third frame f3 and a fourth frame f4 in a second video β obtained by imaging the predetermined portion Y moving along the superimposed image p. When the first movement direction v1 and the second movement direction v2 match and the first movement amount q1 and the second movement amount q2 satisfy a predetermined relationship, a control unit 80 updates a frame next to the first frame f1 to a new first frame f1, updates a frame next to the second frame f2 to a new second frame f2, and causes the superimposition unit 40 to generate the superimposed image p.

Description

Motion direction presentation device, motion direction presentation method, program, and motion direction presentation system

[0001] The present disclosure relates to technology for creating tactile illusions.

[0002] Humans use their hands to create, assemble, and repair things. However, mastering these techniques is not easy. One way to learn these techniques is to use video. By watching the video, you can learn how an expert moves their hand and the results of their movements. However, there is a problem with just watching the video: it is difficult to understand the appropriate amount and direction of hand movement, or the texture that results from the movement. To solve this problem, it is necessary to convey the texture of the hand or object to the user by linking the movement of the hand or object in the video with the user's own movements.

[0003] To achieve this, a user, typically a beginner, is given information about the hand movements of an expert in previously recorded footage (amount and direction of movement), and the user moves their hands in accordance with that information, and the system evaluates whether the user moved their hands correctly in accordance with that information.

[0004] For example, in Non-Patent Document 1, a video of a user's hand movements is captured in real time by a camera. While presenting the captured video to the user, another video of the hand that is ahead of or behind the actual position during the hand movement is also presented to the user. By superimposing the video on the captured video, the video of the hand that is ahead of or behind the actual hand position is presented to the user, proposing a method of presenting a pseudo-tactile impression to the user.

[0005] Taro Maeda et al., "Super Body Sensation," Journal of the Virtual Reality Society of Japan, Vol. 14, No. 2, 2009, pp. 99-103, June 2009

[0006] In the technology of the above-mentioned Non-Patent Document 1, for example, when a delayed image is superimposed, the user merely feels that the hand is heavy, and does not give the user the feeling that they are controlling the hand, which is the object in the already-recorded image.

[0007] Therefore, the present disclosure has been made to solve the above problem, and aims to provide a technology that gives the feeling of controlling an object in a previously shot video.

[0008] In order to solve the above problem, a movement direction presentation device according to one aspect of the present disclosure includes a first movement calculation unit that calculates a first movement direction and a first movement amount of an object from a first frame and a second frame in a first video; a superimposition unit that generates a superimposed image in which an image indicating the first movement direction is superimposed on an image of the first frame; a second movement calculation unit that calculates a second movement direction and a second movement amount of a specified part from a third frame and a fourth frame in a second video that captures an image of a specified part of a user moving in accordance with the superimposed image; and a control unit that, if the first movement direction and the second movement direction match and the first movement amount and the second movement amount satisfy a specified relationship, updates the frame following the first frame in the first video to a new first frame, updates the frame following the second frame to a new second frame, and causes the superimposition unit to generate a superimposed image.

[0009] According to the present disclosure, it is possible to give the feeling of controlling an object in a previously captured video.

[0010] Fig. 1 is a diagram showing an example of the functional configuration of a motion direction presentation device according to the first embodiment. Fig. 2 is a diagram showing an example of the processing flow of a motion direction presentation method according to the first embodiment. Fig. 3 is a diagram showing an example of the functional configuration of a motion direction presentation device according to a first modified example of the first embodiment. Fig. 4 is a diagram showing an example of the processing flow of a motion direction presentation method according to the first modified example of the first embodiment. Fig. 5 is a diagram showing an example of the functional configuration of a motion direction presentation device according to a second modified example of the first embodiment. Fig. 6 is a diagram illustrating the functional configuration of a computer.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Components having the same functions are designated by the same numbers, and redundant explanations will be omitted.

[0012] 1 , a motion direction presentation device 1 according to a first embodiment includes a first image capture unit 10, a frame rate adjustment unit 20, a first motion calculation unit 30, a superimposition unit 40, a display unit 50, a second image capture unit 60, a second motion calculation unit 70, a control unit 80, a video database (video DB) D1, a motion direction database (motion direction DB) D2, and a motion amount database (motion amount DB) D3. The motion direction presentation device 1 performs the motion direction presentation method of this embodiment by implementing the processing flow illustrated in FIG. 2 . The first image capture unit 10, the frame rate adjustment unit 20, the display unit 50, the second image capture unit 60, the video database D1, the motion direction database D2, and the motion amount database D3 may be provided within the motion direction presentation device 1 or may be provided separately from the motion direction presentation device 1.

[0013] (First Image Capture Unit 10) The first image capture unit 10 generates a first video α capturing the movement of object X, which is the object of image capture (step S10). In this embodiment, object X is described as a human hand; however, object X is not limited to a human hand. Object X may be another part of a human body, such as a foot. Alternatively, object X may be a part of a robot, as long as it can accurately reproduce the movements of, for example, a skilled person. The first image capture unit 10 is, for example, a camera capable of capturing images at a high frame rate. While a higher frame rate is desirable for the first image capture unit 10, as an increase in frame rate may result in blurring of the image or a decrease in image brightness, the first image capture unit 10 captures the image at, for example, the highest frame rate available depending on the intended use. The captured image, that is, the first video α, is transmitted to the frame rate adjustment unit 20.

[0014] (Frame Rate Adjustment Unit 20) The frame rate adjustment unit 20 adjusts the frame rate so that the motion direction presentation device 1 can operate appropriately (step S20). For example, if the first video α has a frame rate of 200 to 300 frames per second, the frame rate is adjusted to 30 frames per second. The adjusted first video α (hereinafter also referred to as "first video α1") is stored in the video database D1.

[0015] (First movement calculation unit 30) The first movement calculation unit 30 calculates the movement direction of the object X (hereinafter also referred to as the "first movement direction v1") and the movement amount of the object X (hereinafter also referred to as the "first movement amount q1") from one frame in the first moving image α1 and the next frame (step S30). If the total number of frames in the first moving image α1 is N, the first movement direction v1 and the first movement amount q1 are calculated using the image of the ith frame (i=1, 2, 3, ..., N-1) and the image of the (i+1)th frame.

[0016] Step S30 is performed for all frames in the first moving image α1. Therefore, if the first moving image α1 is composed of N image frames, the data length of the first movement direction v1 and the first movement amount q1 is a maximum of N-1 frames each. Furthermore, to identify the frame from which the first movement direction v1 and the first movement amount q1 were generated, they may be referred to as the first movement direction vi1 (i = 1, 2, 3, ..., N-1) and the first movement amount qi1 (i = 1, 2, 3, ..., N-1). For example, when i = 5, the first movement direction calculated from the fifth and sixth frames may be referred to as the "first movement direction v51," and the first movement amount calculated from the fifth and sixth frames may be referred to as the "first movement amount q51."

[0017] The method of calculating the first movement direction v1 and the first movement amount q1 in the first movement calculation unit 30 is not limited to a specific method. For example, any method may be used, such as using an existing optical flow calculation algorithm. The calculated first movement direction v1 is stored in a movement direction database D2. The calculated first movement amount q1 is stored in a movement amount database D3.

[0018] In the present disclosure, among the frames in the first moving image α1, a frame having an image that serves as the basis for a superimposed image p (described below) to be displayed on the display unit 50 will be referred to as the "first frame f1." The frame following the first frame f1 will be referred to as the "second frame f2." Therefore, it can be said that the first movement calculation unit 30 calculates the first movement direction v1 and the first movement amount q1 of the object X from the first frame f1 of the first moving image α1 and the second frame f2, which is the frame following the first frame f1.

[0019] (Superimposition Unit 40) The superimposition unit 40 generates a superimposed image p by superimposing an image indicating the first movement direction v1 on the image (still image) of the first frame f1 (step S40). For example, assume that the frame to be displayed on the display unit 50 is the first frame (i = 1) in the first moving image α1. In this case, the superimposition unit 40 receives the image of the first frame f1 from the video database D1. The superimposition unit 40 receives information on the first movement direction v11 from the movement direction database D2 as the first movement direction v1. The superimposition unit 40 generates an image (hereinafter also referred to as a "superimposed image p") by superimposing an image indicating the first movement direction v11 (e.g., an arrow image) on the image of the first frame f1. The generated superimposed image p is transmitted to the display unit 50.

[0020] Although it has been described that an "arrow image" is superimposed as an image indicating the first movement direction v1, instead, an image in which an "image of words" indicating the direction of the first movement direction v1, such as "Please move your hand diagonally to the right," is superimposed may be generated as the superimposed image p. The superimposing unit 40 may generate an image in which both an image of an arrow indicating the direction of the first movement direction v1 and an image of words indicating the direction of the first movement direction v1 are superimposed on the image of the first frame f1 as the superimposed image p. In other words, the image indicating the direction of the first movement direction v1 is an image showing at least one of an image of an arrow indicating the direction of the first movement direction v1 and an image of words indicating the direction of the first movement direction v1.

[0021] (Display Unit 50) The display unit 50 displays the received image of the superimposed image p (Step S50). The display unit 50 is, for example, a display device such as a liquid crystal display. A user (described later) moves the predetermined part Y of his or her own hand along the direction indicated by the first movement direction v1 while viewing the superimposed image p output from the display unit 50 without looking at his or her own hand. That is, the user moves the predetermined part Y along the superimposed image p.

[0022] (Second Image Capturing Unit 60) The second image capturing unit 60 generates a second video β, which is a video capturing a predetermined part Y moved by the user (step S60). If the object X is a person's hand, the predetermined part Y is the user's hand. That is, the second image capturing unit 60 generates the second video β capturing an image of the predetermined part Y of the user moving in accordance with the superimposed image p. In this example, the second image capturing unit 60 captures an image of the user's hand in real time.

[0023] The second image capturing unit 60 is an image capturing device similar to the first image capturing unit 10, for example, a camera capable of capturing images at a high frame rate. The generated second video β is sequentially transmitted for each generated frame to the second movement calculation unit 70. When the second image capturing unit 60 captures the predetermined part Y, it is preferable that the size of the predetermined part Y in the second video β be matched to the size of the object X in the first video α.

[0024] (Second Movement Calculation Unit 70) The second movement calculation unit 70 calculates the movement direction of the predetermined part Y (hereinafter also referred to as the "second movement direction v2") and the movement amount of the predetermined part Y (hereinafter also referred to as the "second movement amount q2") from an image of one frame (hereinafter also referred to as the "third frame f3") in the received second moving image β and an image of the frame following the third frame f3 (hereinafter also referred to as the "fourth frame f4") (step S70). In the calculation by the second movement calculation unit 70, the second movement calculation unit 70 adjusts which of the frame images received from the second image capture unit 60 to calculate the second movement direction v2 and the second movement amount q2 for, taking into account synchronization with the superimposed image p, for example, by setting the image of the frame immediately before the most recent frame received from the second image capture unit 60 as the third frame f3 and the most recent frame as the fourth frame f4. That is, the second movement calculation unit 70 calculates the second movement direction v2 and the second movement amount q2 of the predetermined part Y being moved by the user in real time. The method of calculating the second movement direction v2 and the second movement amount q2 in the second movement calculation unit 70 is not limited to a specific method. The calculated second movement direction v2 and second movement amount q2 are transmitted to the control unit 80. Note that the second movement calculation unit 70 calculates the second movement direction v2 and the second movement amount q2 without depending on the frame rate of the second video β or the relative frame rates between the second video β and the first video α. Therefore, the frame rate of the second video β generated by the second image capture unit 60 does not necessarily have to be the same as the frame rate of the first video α1 stored in the video database D1.

[0025] (Control Unit 80) In addition to the second movement direction v2 and second movement amount q2 received from the second movement calculation unit 70, the control unit 80 also receives the first movement direction v1 from the movement direction database D2 and the first movement amount q1 from the movement amount database D3. Based on these, the control unit 80 determines whether the movement of the user's predetermined part Y satisfies a predetermined criterion (step S80-1). In this example, step S80-1 determines whether the first movement direction v1 of the object X and the second movement direction v2 of the predetermined part Y coincide with each other, and whether the second movement amount q2 of the predetermined part Y exceeds the first movement amount q1 of the object X. Note that, in the present disclosure, the coincidence of the first movement direction v1 and the second movement direction v2 may include not only a case where the direction indicated by the first movement direction v1 and the direction indicated by the second movement direction v2 completely coincide with each other, but also a case where the difference between the two directions is within a predetermined range. In this case, the predetermined range may be changed as appropriate depending on the actual usage situation.

[0026] If the control unit 80 determines that the first movement direction v1 and the second movement direction v2 do not match, or if it determines that the second movement amount q2 does not exceed the first movement amount q1 (N in step S80-1), it returns to the processing of step S70, sets the image of the frame just before the most recent frame received at that time as the third frame f3, and sets the most recent frame as the fourth frame f4, and then performs the processing of step S70.

[0027] If the control unit 80 determines that the first movement direction v1 and the second movement direction v2 are the same and that the second movement amount q2 exceeds (has exceeded) the first movement amount q1 (Y in step S80-1), it determines whether or not processing of all frames in the first moving image α1 has been completed (step S80-2). That is, it determines whether or not the image of the N-1th frame in the first moving image α1 has been used for the superimposed image p on the display unit 50. In other words, it determines whether or not i≧N-1.

[0028] If it is determined that processing of all frames in the first moving image α1 has not been completed (i<N-1) (N in step S80-2), i is incremented (i=i+1), the frame following the first frame f1 in the first moving image α1 is updated to the new first frame f1, and the frame following the second frame f2 in the first moving image α1 is updated to the new second frame f2 (step S80-3). Then, the process returns to step S40, and the superimposing unit 40 generates a new superimposed image p. That is, the superimposing unit 40 generates a new superimposed image p by superimposing an image indicating the new first movement direction v1 (i.e., the first movement direction v(i+1)1) calculated by the first movement calculation unit 30 onto the image of the new first frame f1. This process is repeated until i=N-1. That is, the control unit 80 causes the superimposition unit 40 to set the (i+1)th frame in the first video α1 as the new first frame f1, and the (i+2)th frame in the first video α1 as the new second frame f2 (step S80-3), and then perform processing from step S40 onwards.

[0029] When the control unit 80 determines that i≧N-1, that is, when the above-mentioned processing has been completed for all frames in the first video α1 (Y in step S80-2), the movement direction presentation method by the movement direction presentation device 1 ends.

[0030] Through the above-described processing, by moving a specific part Y (in this example, the "hand") of the user's own body in the direction indicated by the superimposed image p displayed on the display unit 50, the user can have the sensation that the movement of the specific part Y (hand) is controlling the object X (in this case, the "hand") in the first video α. Therefore, the motion direction presentation device 1 can give the user the sensation of controlling an object in a previously captured video. In other words, the motion direction presentation device 1 can induce the illusion that the user is controlling the object X. In this sense, the motion direction presentation device of the present disclosure can also be described as a tactile sensation induction device.

[0031] <First Modification> A motion direction presentation device according to a first modification of the first embodiment will be described below. FIG. 3 is a diagram showing an example of the functional configuration of a motion direction presentation device according to a first modification of the first embodiment. The above-described motion direction presentation device 1 may be configured as a motion direction presentation device 1B shown in FIG. 3. The motion direction presentation device 1B of FIG. 3 differs from the motion direction presentation device 1 of FIG. 1 in that a weighting unit 90 and a weight database (weight DB) D4 are added. Accordingly, step S90 is added between step S30 and step S40 in the processing flow of FIG. 2, as shown in FIG. 4. The weight database D4 may be provided within the motion direction presentation device 1B or separately from the motion direction presentation device 1B.

[0032] (Weighting Unit 90) The weighting unit 90 performs a weighting process of multiplying the first movement amount q1 calculated by the first movement calculation unit 30 in step S30 and stored in the movement amount database D3 by a predetermined magnification (magnification k) (step S90). The magnification k is stored in advance as a candidate value in the weight database D4. The magnification k is a type of weight to be multiplied by the first movement amount q1.

[0033] As a result, if the first movement direction v1 and the second movement direction v2 are the same and the second movement amount q2 exceeds k times the first movement amount q1 (step S80-1 in Figure 4), and processing of all frames in the first video α1 has not been completed (N in step S80-2), the frame is updated (step S80-3) and processing then returns to step S40.

[0034] If the object X is a "hand," then by setting the magnification k to a value greater than 1 (k>1), the user will perceive the hand in the first video α1 as heavy, or the material the hand is touching in the first video α1 as heavy or sticky.

[0035] On the other hand, by setting the magnification k to a value smaller than 1 (k<1), the hand in the superimposed image p can be felt light, or the material the hand is touching in the superimposed image p can be felt light, or a smooth (silky) feel can be felt.

[0036] As shown in this modified example, by adjusting the relationship between the second movement amount q2 and the first movement amount q1 using a weighting factor k, it is possible to induce, for example, an illusion of the weight of the hand in the user's hand or an illusion of the texture of the object the hand is touching in the first video α1.

[0037] <Second Modification> A motion direction presentation device according to a second modification of the first embodiment will be described below. FIG. 5 is a diagram showing an example of the functional configuration of a motion direction presentation device according to a second modification of the first embodiment. The above-described motion direction presentation device 1B may be configured as the motion direction presentation device 1C shown in FIG. 5. The motion direction presentation device 1C of FIG. 5 differs from the motion direction presentation device 1B of FIG. 3 in that the weight database D4 is replaced by a weight database D4'. The magnification k in the weight database D4' receives information about the first moving image α1 from the frame rate adjustment unit 20, and a different value is set for each frame in the first moving image α1. In other words, the magnification k is set to change over time.

[0038] In general, the amount of hand movement (speed) per unit time when manipulating an object (hereinafter referred to as "object Z") that is operated by touching object X changes depending on the physical properties of object Z. For example, when tightening a screw using object Z as object Z, the force required for tightening increases with each tightening of the screw, and the tightening action often gradually slows down. When loosening a screw, a large force is required at first, but the force required thereafter decreases, and the hand movement often gradually speeds up.

[0039] In this way, in order to simulate a situation in which the speed of the object X changes over time based on the object Z, the value of the magnification k is changed over time in the motion direction presentation device 1C.

[0040] In the movement direction presentation device 1C, the weighting unit 90 performs a weighting process of multiplying the first movement amount q1 calculated by the first movement calculation unit 30 in step S30 and stored in the movement amount database D3 by a predetermined magnification factor (magnification factor k) (step S90 in FIG. 4). The magnification factor k is stored in advance in the weighting database D4′ as the magnification factor k corresponding to the frame.

[0041] If the first movement direction v1 and the second movement direction v2 match and the second movement amount q2 exceeds k times the first movement amount q1 (step S80-1 in FIG. 4 ), and if processing of all frames in the first moving image α1 has not been completed (N in step S80-2 in FIG. 4 ), the frame is updated (step S80-3 in FIG. 4 ), and the process returns to step S40. In the movement direction presentation device 1C, since the magnification k is determined for each frame, the value of the magnification k is also updated in accordance with the frame update in step S80-3. In other words, the movement direction presentation device 1C can adjust the magnification k to match the frame in the first moving image α1.

[0042] In the first video α1, when the magnification k is set to increase over time, the user's hand movement gradually feels heavier. In addition, the weight and stickiness felt in the material of object Z that object X is touching also increases.

[0043] In the first video α1, when the magnification k is set to decrease over time, the user's hand movement gradually becomes lighter. Also, the weight and stickiness felt in the material of object Z that object X is touching decreases.

[0044] The above describes the movement direction presentation device according to the present disclosure. As an example of a situation in which the movement direction presentation device according to the present disclosure can be used, it is effective in a situation in which a user learns how to move their hands while watching a video.

[0045] For example, a case can be taken where a user, who is a beginner, is being taught surgical procedures. Utilizing the motion direction presentation device of the present disclosure, it is possible to present the texture of organs and surgical instruments while showing the beginner how to move their hands. A video of the surgical procedure is captured in advance by the first image capture unit 10. By moving the beginner's hands in the video captured by the second image capture unit 60 in accordance with the instructions of the superimposed image p of the motion direction presentation device of the present disclosure, the beginner can learn appropriate hand movements and how to operate the instruments.

[0046] Another example is its use in calligraphy. It can convey to the user, the learner, how to move the brush in calligraphy and the weight of the brush when sweeping. The first image capture unit 10 captures a scene of the master writing characters in advance. The second image capture unit 60 captures the learner's hand in the video, and the learner can learn the proper way to move the brush by moving the learner's hand in accordance with the instructions of the superimposed image p of the motion direction presentation device of the present disclosure.

[0047] Another example is online shopping. In online shopping, the feel and weight of a product can be visually conveyed. For example, a video of the product being touched is captured in advance by the first image capture unit 10. The weight and softness of the product can be communicated in a non-contact manner by moving the hand in the video captured by the second image capture unit 60 in accordance with the instructions of the superimposed image p of the motion direction presentation device of the present disclosure.

[0048] The above describes the embodiments and modifications of the present disclosure. The various processes in the above-described embodiments may not only be executed in chronological order as described, but may also be executed in parallel or individually depending on the processing capabilities of the devices that execute the processes or as needed. It goes without saying that other modifications are possible without departing from the spirit of the present disclosure.

[0049] The present disclosure may further include a device (terminal) for using the device of the present disclosure or the method of the present disclosure via a network (telecommunications line). The "device (terminal) for use" may be provided with functions (e.g., control function, decoding function, restoration function, input / output function, etc.) necessary to obtain the effects of implementing the device of the present disclosure or the method of the present disclosure.

[0050] [Processor, Program, Recording Medium] The functions performed by the components described herein may be implemented in circuitry or processing circuitry, including general-purpose processors, application-specific processors, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (a Central Processing Unit), conventional circuits, and / or combinations thereof, programmed to perform the described functions. A processor includes transistors and other circuits and is considered to be circuitry or processing circuitry. A processor may also be a programmed processor that executes a program stored in a memory.

[0051] In this specification, a circuitry, unit, or means is hardware that is programmed to realize or performs the described functions, which may be any hardware disclosed herein or any hardware known to be programmed to realize or perform the described functions.

[0052] If the hardware is a processor considered to be a type of circuitry, the circuitry, means, or unit is a combination of the hardware and software used to configure the hardware and / or processor.

[0053] The various processes described above can be implemented by loading a program that executes each step of the above method into the recording unit 2020 of the computer 2000 shown in Figure 6, and operating the control unit 2010, input unit 2030, output unit 2040, display unit 2050, etc.

[0054] The program describing the processing contents can be recorded on a computer-readable recording medium, which may be, for example, a magnetic recording device, an optical disk, a magneto-optical recording medium, a semiconductor memory, or any other suitable recording medium.

[0055] The program may be distributed by, for example, selling, transferring, lending, etc. portable recording media such as DVDs and CD-ROMs on which the program is recorded. Furthermore, the program may be stored in a storage device of a server computer, and then transferred from the server computer to other computers via a network, thereby distributing the program.

[0056] A computer that executes such a program may first temporarily store the program recorded on a portable recording medium or transferred from a server computer in its own storage device. Then, when executing a process, the computer reads the program stored on its own recording medium and executes the process in accordance with the read program. Alternatively, the computer may read the program directly from a portable recording medium and execute the process in accordance with the program. Furthermore, the computer may execute the process in accordance with the received program each time a program is transferred from a server computer to the computer. Alternatively, the server computer may not transfer the program to the computer, but may instead execute the process through a so-called ASP (Application Service Provider) service, which realizes the processing function by issuing an execution instruction and obtaining the results. Furthermore, the server computer may execute the process at the terminal using a so-called SaaS (Software as a Service) service, which allows users to use part of a server computer along with the program. In this embodiment, the program includes information used for processing by an electronic computer that is equivalent to a program (such as data that is not a direct instruction to a computer but has properties that dictate computer processing).

[0057] Furthermore, in this embodiment, the device is configured by executing a predetermined program on a computer, but at least a part of the processing contents may be realized by hardware.

Claims

1. A movement direction presentation device comprising: a first movement calculation unit that calculates a first movement direction and a first movement amount of an object from a first frame and a second frame in a first video; a superimposition unit that generates a superimposed image by superimposing an image indicating the first movement direction on an image of the first frame; a second movement calculation unit that calculates a second movement direction and a second movement amount of a specified part of a user from a third frame and a fourth frame in a second video that captures the specified part of the user moving in accordance with the superimposed image; and a control unit that, when the first movement direction and the second movement direction match and the first movement amount and the second movement amount satisfy a specified relationship, updates the frame following the first frame in the first video to a new first frame, updates the frame following the second frame to a new second frame, and causes the superimposition unit to generate the superimposed image.

2. The motion direction presentation device according to claim 1, wherein the predetermined relationship is a relationship in which the second motion amount exceeds the first motion amount.

3. The movement direction presentation device according to claim 1, wherein the predetermined relationship is a relationship in which the second movement amount exceeds a movement amount obtained by multiplying the first movement amount by a predetermined magnification.

4. The motion direction presentation device according to claim 3, wherein the predetermined magnification is set to a different value for each frame in the first video.

5. A movement direction presentation device as described in any one of claims 1 to 4, wherein the image indicating the direction of the first movement direction is an image showing at least one of an image of an arrow indicating the direction of the first movement direction and an image of text indicating the direction of the first movement direction.

6. A movement direction presentation method, in which a first movement calculation unit calculates a first movement direction and a first movement amount of an object from a first frame and a second frame in a first video; a superimposition unit generates a superimposed image by superimposing an image indicating the first movement direction on an image of the first frame; a second movement calculation unit calculates a second movement direction and a second movement amount of a specified part of a user from a third frame and a fourth frame in a second video that captures the specified part of the user moving in accordance with the superimposed image; and a control unit, when the first movement direction and the second movement direction match and the first movement amount and the second movement amount satisfy a specified relationship, updates the frame following the first frame in the first video to a new first frame and updates the frame following the second frame to a new second frame, and causes the superimposition unit to generate the superimposed image.

7. A program for causing a computer to function as the motion direction presentation device according to any one of claims 1 to 4.

8. A motion direction presentation system comprising: a motion direction presentation device according to any one of claims 1 to 4; and a device for using the motion direction presentation device via a network.

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