Imaging device, control method thereof, and program

Abstract

To provide an imaging apparatus capable of precisely specifying a position of a photogenic subject, thereby providing an image with enhanced visibility.SOLUTION: A network camera 101 comprises a position specification unit 212-1 that specifies a relative position of a photogenic subject 106 viewed from the network camera 101 based on an incoming direction of a radio wave received from a wireless device 103 that the photogenic subject 106 has, a position determination unit 212-2 that determines whether or not the photogenic subject 106 is positioned within a blind zone 501 on a captured image based on the position of the photogenic subject 106 specified by the position specification unit 212-1, and a PTZ control unit 212-3 that based on the position of the photogenic subject 106 specified by the position specification unit 212-1, if the photogenic subject 106 is not positioned within the blind zone 501, changes an imaging direction, and if the photogenic subject 106 is positioned within the blind zone 501, performs control such that the imaging direction is not changed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an imaging device, a control method thereof, and a program.

Background Art

[0002] A network camera that performs pan-tilt-zoom control (hereinafter referred to as PTZ control) is known. Some network cameras of this type have an automatic tracking function that changes the shooting direction according to the position of the subject so as to continuously capture the subject within the screen. Patent Document 1 discloses that when it is determined that the position of the subject to be tracked is within the dead zone range, the shooting direction of the camera is not moved, and when it is determined that the position of the subject to be tracked is outside the dead zone range, the shooting direction of the camera is moved in the direction of tracking the subject. Thereby, even if the subject moves slightly within the screen, the shooting direction of the camera does not move, and the subject can be automatically tracked with an easy-to-view video.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Normally, video analysis is used to identify the position of a person who is the subject. However, when using video analysis, depending on the shooting environment and the state of the objects shown in the video, such as color changes due to illumination fluctuations, the orientation and posture of the person, there is a risk that the position of the person cannot be accurately identified. In Patent Document 1, the position of the subject is identified based on the difference image between frames, but there is also a risk that the position of the subject cannot be accurately identified depending on the shooting environment and the state of the objects shown in the video.

[0005] The present invention has been made in view of the above points, and an object thereof is to be able to accurately identify the position of a subject and provide an image with improved visibility.

Means for Solving the Problems

[0006] The imaging device of the present invention is an imaging device capable of changing the shooting direction and performing wireless communication, and includes a position specifying means for specifying the position of the subject based on radio waves received from a wireless device possessed by the subject, and based on the position of the subject specified by the position specifying means, the shooting direction is changed on the condition that the subject is not located within a predetermined region on the captured image. either in a first control mode that enables [operation] or On the condition that the subject is located within the predetermined region, the shooting direction is changed. control the shooting direction in a second control mode that does not enable [operation], control means when the position specifying means specifies that the subject has moved out of the predetermined area after being located within the predetermined area, a measuring means for measuring the time during which the subject is located outside the predetermined area; and when the time measured by the measuring means is equal to or longer than a predetermined time, the control means switches from the second control mode to the first control mode is characterized by.

Effects of the Invention

[0007] According to the present invention, the position of the subject can be accurately specified, and an image with improved visibility can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. [First Embodiment] FIG. 1 is a diagram showing the configuration of a network system according to an embodiment. The network system according to the embodiment includes a network camera 101, a client device 102, a wireless device 103, a network 104, and a wireless network 105.

[0010] The network camera 101 can perform video distribution and camera control via a wired or wireless network. In the present embodiment, the network camera 101 functions as an imaging device to which the present invention is applied. The client device 102 is connected to the network camera 101 via the network 104. The client device 102 controls the network camera 101 and outputs information via a browser. The wireless device 103 is connected to the network camera 101 via the wireless network 105. The wireless device 103 incorporates a wireless communication module compliant with the 5.1 specification of Bluetooth (registered trademark). The wireless device 103 is possessed by the subject 106 photographed by the network camera 101 (if the subject 106 is a person, the wireless device 103 is possessed), and is used to automatically track the subject 106 with the network camera 101 as will be described in detail below.

[0011] Network 104 is a network for delivering the video captured by network camera 101 to an external recording server or the like, and enables mutual communication between network camera 101 and client device 102. In this embodiment, the communication form of network 104 is a wired LAN, but it may also be a wireless LAN. Wireless network 105 enables mutual communication between network camera 101 and wireless device 103. In this embodiment, wireless network 105 complies with Bluetooth (registered trademark), but it may also comply with wireless communication standards such as Z-Wave (registered trademark) and Zigbee (registered trademark).

[0012] FIG. 2 is a diagram showing a configuration example of network camera 101 according to the embodiment. Network camera 101 includes an imaging unit 201, a lens control unit 202, and a pan-tilt unit 203. Network camera 101 also includes an A / D conversion unit 204, a camera signal processing unit 205, a storage unit 206, a bus 207, a video analysis unit 208, a compression / decompression unit 209, a wired communication processing unit 210, a wireless communication processing unit 211, and a CPU (Central Processing Unit) 212.

[0013] Imaging unit 201 includes a zoom lens, a focus lens, a diaphragm, and an imaging element. Lens control unit 202 controls the movement of the zoom lens and the focus lens along the optical axis and operates the diaphragm. In imaging unit 201, the imaging element photoelectrically converts the light that has passed through the zoom lens, the focus lens, and the diaphragm to generate an analog image signal. The analog image signal generated by the imaging element is output to A / D conversion unit 204 after being subjected to amplification processing by sampling. Pan-tilt unit 203 includes a pan drive unit and a tilt drive unit. By controlling pan-tilt unit 203 via an actuator (not shown), pan-tilt drive (hereinafter referred to as PT drive) for rotating imaging unit 201 in the horizontal and vertical directions is performed, and the shooting direction can be changed.

[0014] The A / D conversion unit 204 converts the analog image signal into a digital image signal and outputs it to the camera signal processing unit 205. The camera signal processing unit 205 performs various image processes on the digital image signal converted by the A / D conversion unit 204 to generate a video signal. The various image processes include, for example, offset processing, gamma correction processing, gain processing, RGB interpolation processing, noise reduction processing, color tone correction processing, and the like.

[0015] The storage unit 206 is composed of a RAM, a ROM, a storage device, etc. not shown in the figure. The RAM is a volatile memory such as an SRAM or a DRAM. The ROM is a non-volatile memory such as an EEPROM or a flash memory. The storage device is an HDD (hard disk drive), an SSD (solid state drive), or the like. Programs for realizing the functions described in this embodiment and data used when the programs are executed are stored in the ROM or the storage device. These programs and data are appropriately taken into the RAM via the bus 207 under the control of the CPU 212 and executed by the CPU 212. Thereby, the functions of the position specifying unit 212-1, the position determination unit 212-2, the PTZ control unit 212-3, the interval control unit 212-4, and the tracking system control unit 212-5 are realized.

[0016] The video analysis unit 208 analyzes the video signal and performs various detection processes such as human body detection, face detection, and moving object detection. For example, as an example of video analysis for specifying the position of the subject 106, human body detection for detecting a human body in the image frame can be mentioned, but face detection or moving object detection may be used depending on the use scene. The video analysis result by the video analysis unit 208 is notified to the CPU 212 via the bus 207. The compression / decompression unit 209 performs compression processing on the video signal to generate compressed data.

[0017] The wired communication processing unit 210 performs network communication processing with the client device 102 via the network 104. The wireless communication processing unit 211 performs wireless communication processing with the wireless device 103 via the wireless network 105. In this embodiment, it is assumed that the wireless communication processing unit 211 is included in a wireless communication module compliant with the Bluetooth (registered trademark) 5.1 specification, but it is not limited thereto. For example, a wireless communication module may be externally connected using a general-purpose interface such as USB.

[0018] The CPU 212 controls the entire network camera 101. Further, the CPU 212 functions as a position specifying unit 212-1, a position determination unit 212-2, a PTZ control unit 212-3, an interval control unit 212-4, and a tracking system control unit 212-5. The position specifying unit 212-1 specifies the relative position of the wireless device 103 as viewed from the network camera 101, that is, the subject 106 having the wireless device 103, based on the incoming direction of the radio wave received from the wireless device 103 (hereinafter referred to as the radio wave direction). The method for specifying the position of the subject 106 in the position specifying unit 212-1 is performed based on the direction detection function of wireless communication compliant with the Bluetooth (registered trademark) 5.1 specification, and the details will be described later with reference to FIG. 3.

[0019] The position determination unit 212-2 determines whether or not the subject 106 is located within a predetermined area on the captured image based on the position of the subject 106 specified by the position specifying unit 212-1. Hereinafter, the predetermined area is referred to as a dead zone. FIG. 5 schematically shows an example of an image frame of a captured image during automatic tracking processing. The dead zone 501 is a rectangular area set with a predetermined width and a predetermined height in the image frame, and is an area that does not include the outer edge of the image frame (an area away from the outer edge), and in this example, is the central area of the image frame. The dead zone 501 is an area that prevents the PT drive for automatically tracking the subject 106 from being performed when the subject 106 is captured inside it.

[0020] The PTZ control unit 212-3 executes PTZ control using the lens control unit 202 and the pan-tilt unit 203 based on the position of the subject 106 specified by the position specifying unit 212-1 and the result determined by the position determination unit 212-2. By controlling the PT drive so that the PTZ control unit 212-3 changes the shooting direction to the position of the subject 106, automatic tracking of the subject 106 becomes possible. In this embodiment, it will be described that the PT drive is controlled to perform automatic tracking. Also, the PTZ control unit 212-3 switches the setting of whether to permit or prohibit the PT drive based on whether the subject 106 is located within the dead zone 501. The PTZ control unit 212-3 performs the PT drive in conjunction with the position of the subject 106 in the permitted state of the PT drive, and controls so as not to perform the PT drive even if the position of the subject 106 changes in the prohibited state of the PT drive.

[0021] The interval control unit 212-4 controls the transmission interval of the radio wave that the wireless device 103 transmits to the network camera 101. By transmitting the instruction data indicating the transmission interval to the wireless device 103 by the interval control unit 212-4, the wireless device 103 changes the transmission interval of the radio wave to the network camera 101. If the transmission interval is shortened, the position of the subject 106 can be specified one by one by the network camera 101, but the battery consumption of the wireless device 103 becomes severe. On the other hand, if the transmission interval is lengthened, the battery consumption of the wireless device 103 can be reduced, but the interval for specifying the position of the subject 106 by the network camera 101 becomes long, and it becomes difficult to specify the position of the subject 106.

[0022] The tracking system control unit 212-5 controls the overall process of automatic tracking and performs initial settings of the automatic tracking process and the like.

[0023] FIG. 3 is a diagram for explaining the principle of detecting the radio wave direction from the wireless device 103 by the network camera 101. In the direction detection function of wireless communication compliant with the 5.1 specification of Bluetooth (registered trademark), the radio wave direction is detected by utilizing the phase difference of radio waves caused by the different locations of each antenna using an antenna array having a plurality of antennas. There are the following two methods for detecting the radio wave direction. The first method is called Angle Of Arrival (AoA) and calculates the reception angle of the radio wave on the receiving device side. The second method is called Angle Of Departure (AoD) and calculates the radiation angle on the transmitting device side and transmits it to the receiving device. In the present embodiment, the wireless device 103 is positioned as the transmitting device and the network camera 101 is positioned as the receiving device, and the direction is detected by AoA, but the same effect can be obtained by using AoD.

[0024] As shown in FIG. 3, the network camera 101, which is a receiving device, includes a receiver 301 and a plurality of antennas 302 arranged at equal intervals. Further, the wireless device 103, which is a transmitting device, includes a transmitter 303 and a single antenna 304. The wireless device 103 transmits, from the antenna 304, a radio wave 305 including a special direction detection signal by the transmitter 303, and the network camera 101 receives this radio wave 305 with the plurality of antennas 302. At this time, each of the plurality of antennas 302 arranged at equal intervals receives the radio wave 305. As a result, a distance difference between the antenna 304 and each antenna 302, such as distance D1 and distance D2, is generated, and the network camera 101 can detect signals with different phases for each antenna 302. Then, while switching the active antenna, the network camera 101 acquires a modulation signal (IQ modulation signal) having an in-phase component and a quadrature phase component as the phase information of the radio wave, and calculates the incident angle θ, which is the relative direction of the signal, based on the IQ modulation signal. The calculation of the incident angle θ is performed using the wavelength of the radio wave, the distance between the antennas, and the phase difference, but the method is well-known, so the description thereof is omitted. And in the network camera 101, the current orientation of the camera in the three-dimensional space can be grasped by calibration performed at the time of installation. Therefore, the network camera 101 can specify the relative position of the wireless device 103 as seen from the network camera 101 based on the direction of the radio wave from the wireless device 103.

[0025] Next, with reference to the flowchart shown in FIG. 4, the flow of the automatic tracking process of the network camera 101 in the first embodiment will be described. Further, FIG. 5 schematically shows an example of an image frame of a captured image during the automatic tracking process. In step S401, the tracking system control unit 212-5 reflects the initial settings related to the operation of the automatic tracking process. The contents of the initial settings are determination of the subject 106 to be tracked, information regarding the size and arrangement of the dead zone 501, and the like. Note that the contents of the initial settings may be determined in advance or may be determined according to an input from the client device 102.

[0026] In step S402, the PTZ control unit 212-3 sets the PT drive to the prohibited state. As a result, until the PT drive is set to the permitted state in step S407 described later, that is, until the prohibited state is explicitly released, the PT drive for automatic tracking is not performed.

[0027] In step S403, the position specifying unit 212-1 specifies the position of the subject 106 based on the radio wave direction from the wireless device 103 of the subject 106. When the position of the subject 106 is specified, the process proceeds to step S404. When the position of the subject 106 is not specified, the process returns to step S403.

[0028] In step S404, the PTZ control unit 212-3 determines whether the PT drive is in the prohibited state. If the PT drive is in the prohibited state, the process proceeds to step S405. If the PT drive is not in the prohibited state, that is, in the permitted state, the process proceeds to step S410.

[0029] In step S405, the position determination unit 212-2 determines whether the subject 106 is located within the dead zone 501 based on the position of the subject 106 specified in step S403. If the subject 106 is located within the dead zone 501, the process proceeds to step S406. If the subject 106 is not located within the dead zone 501, that is, is located outside the dead zone 501, the process proceeds to step S407.

[0030] In step S406, the interval control unit 212-4 instructs the wireless device 103 to set the transmission interval of the radio wave from the wireless device 103 to an interval longer than a predetermined interval. Thereby, the battery consumption of the wireless device 1 can be reduced.

[0031] In step S407, the PTZ control unit 212-3 sets the PT drive to the permitted state. As a result, until the PT drive is set to the prohibited state in step S402 next, the PT drive for automatic tracking is performed.

[0032] In step S408, the interval control unit 212-4 instructs the wireless device 103 to set the transmission interval of the radio wave from the wireless device 103 to be shorter than a predetermined interval. Thereby, the position of the subject 106 can be identified one by one.

[0033] In step S409, the PTZ control unit 212-3 instructs PT drive at a predetermined speed toward the position of the subject 106 identified in step S403. Here, the shooting direction is changed so that the subject 106 is displayed at the central position 504 within the dead zone 501. Specifically, the driving amounts in the pan direction and the tilt direction are obtained and PT drive is performed. Since the method of obtaining the driving amounts is well-known, the description thereof is omitted here. Also, the predetermined speed is a speed at which the background objects can be visually recognized on the captured image so that the background does not appear to flow, and may be adjustable according to the use case.

[0034] In step S410, the position determination unit 212-2 determines whether or not the subject 106 has reached the central position 504 of the dead zone 501 based on the position of the subject 106 identified in step S403. If the subject 106 has not reached the central position 504 of the dead zone 501, the process proceeds to step S409 and the PT drive continues. If the subject 106 has reached the central position 504 of the dead zone 501, the process returns to step S402. In this way, when the subject 106 is displayed at the central position of the dead zone 501 by changing the shooting direction, it will switch to not changing the shooting direction. Note that in this embodiment, an example is given in which the shooting direction is changed so that the subject 106 is displayed at the central position 504 within the dead zone 501, but it may be a predetermined position within the dead zone 501. The predetermined position can be adjusted according to the use case and may be determined by the initial setting in step S401.

[0035] Here, with reference to FIG. 5, a specific example of the automatic tracking process of the flowchart in FIG. 4 will be described. Reference numeral 501 indicates a dead zone, reference numeral 502 indicates the position of the subject 106 (wireless device 103), reference numeral 503 indicates an arrow representing the movement of the subject 106 itself, and reference numeral 504 indicates the central position within the dead zone 501. First, with reference to FIGS. 5(a) and 5(b), a process of not interlocking the PT drive with the movement of the subject 106 will be described. In FIG. 5(a), the PT drive is in a prohibited state, and the position 502 of the subject 106 specified by the position specifying unit 212-1 is within the dead zone 501. In FIG. 4, the position of the subject 106 is specified (Yes in step S403), and it is determined that the PT drive is in a prohibited state (Yes in step S404). Then, it is determined that the subject 106 is located within the dead zone 501 (Yes in step S405). Then, although not shown, the wireless device 103 is instructed to set the transmission interval of the radio wave from the wireless device 103 to be longer than a predetermined interval (step S406), and the process returns to step S403. The processes from step S403 to step S406 are repeated while the subject 106 is located within the dead zone 501 (until No in step S405). For example, in FIG. 5(b), although the subject 106 is moving from near the center to near the boundary of the dead zone 501, since it is located within the dead zone 501, the same process flow as in FIG. 5(a) occurs.

[0036] Next, with reference to FIGS. 5(c) to 5(f), the process of interlocking the PT drive with the movement of the subject 106 will be described. In FIG. 5(c), the subject 106 has moved outside the dead zone 501 from the state of FIG. 5(b), and the position 502 of the subject 106 identified by the position specifying unit 212-1 is outside the dead zone 501. In FIG. 4, the position of the subject 106 is specified (Yes in step S403), and it is determined that the PT drive is in the prohibited state (Yes in step S404). Then, it is determined that the subject 106 is located outside the dead zone 501 (No in step S405), and the PT drive is set to the permitted state (step S407). Although not shown, the wireless device 103 is instructed to set the transmission interval of the radio wave from the wireless device 103 to be shorter than the predetermined interval (step S408). Then, as shown in FIG. 5(d), PT drive at a predetermined speed is instructed so that the subject 106 is displayed at the central position 504 within the dead zone 501 (step S409), and the process returns to step S403. From FIG. 5(d) through FIG. 5(e), until the subject 106 is displayed at the central position 504 within the dead zone 501 as shown in FIG. 5(f), the processes of steps S403, S404, S410, and S409 are repeated. Note that until the subject 106 is displayed at the central position 504 within the dead zone 501, since the PT drive is in the permitted state, as shown in FIG. 5(e), even if the subject 106 is captured within the dead zone 501, the PT drive continues. This is because if the PT drive is prohibited as soon as the subject 106 enters the dead zone 501, the subject 106 will move out of the dead zone 501 with just a slight movement. FIG. 5(f) shows a state where, after passing through FIGS. 5(d) and 5(e), the subject 106 is displayed at the central position 504 within the dead zone 501 (Yes in step S410). As a result, the PT drive is set to the prohibited state (step S402), and the process returns to the state of FIG. 5(a).

[0037] As described above, the position of the subject 106 is specified based on the direction of the radio wave from the wireless device 103 possessed by the subject 106. Therefore, unlike the case of using video analysis, the position of the subject 106 can be accurately specified without being affected by color changes due to illumination fluctuations, the state of the shooting environment such as the orientation and posture of a person, or the state of the objects shown in the video.

[0038] Also, on the condition that the subject 106 is located within the dead zone 501, the PT drive is prohibited and the shooting direction is not changed. Therefore, the PT drive is not linked to the minute movement of the subject 106 one by one, so that screen shaking and the like can be suppressed, and the phenomenon that the viewer gets motion sickness can be suppressed. On the other hand, on the condition that the subject 106 is not located within the dead zone 501, the PT drive is permitted, the shooting direction is changed, and the subject 106 is tracked. At this time, the shooting direction can be changed at a speed at which the background object can be visually recognized, and it is possible to suppress the image from looking like the background is flowing. As a result, it is possible to provide a video with improved visibility.

[0039] Also, the transmission interval of the radio wave from the wireless device 103 when the subject 106 is located within the dead zone 501 is made longer than the transmission interval when the subject 106 is not located within the dead zone 501. Therefore, the battery consumption can be reduced while the subject 106 is located within the dead zone 501. On the other hand, while the subject 106 is located outside the dead zone 501, the position of the subject 106 can be specified one by one. In this way, while power saving of the wireless device 103 is achieved, it is possible to change the shooting direction so as to quickly capture the subject 106 when necessary.

[0040] In this embodiment, only the PT drive by the PTZ control unit 212-3 has been described. However, for example, the distance to the wireless device 103 (the distance to the subject 106) may be estimated according to the radio wave intensity from the wireless device 103, and zoom control may be performed as necessary. In this case, it is preferable to expand and contract the dead zone 501 according to the zoom ratio so as to maintain the relationship between the size of the subject 106 and the dead zone 501. This is to avoid the subject 106 going out of the dead zone 501 when zooming in.

[0041] Also, although the PT drive has been described as being performed at a predetermined speed, the speed does not necessarily have to be constant. For example, when it is detected that the subject 106 itself is moving in the direction toward the dead zone 501, the speed may be made slower than the speed when the subject 106 is not moving. As a method for detecting the movement of the subject 106 itself, there is a method of temporarily stopping the PT drive at a predetermined timing and detecting using the motion vector of the subject 106 or the like. In this case, it is preferable to make the transmission interval instructed in step S408 relatively longer than the current transmission interval.

[0042] Also, in step S406 and step S408, it has been described that the interval control unit 212-4 issues an instruction to change the radio wave transmission interval to the wireless device 103, but it is not necessarily required to issue an instruction every time. For example, in step S406, when the radio wave transmission interval from the wireless device 103 is longer than a predetermined interval, the process may be skipped. Similarly, in step S408, when the radio wave transmission interval from the wireless device 103 is shorter than a predetermined interval, the process may be skipped.

[0043] [Second Embodiment] In an actual use scenario, after the subject 106 moves out of the dead zone 501 and then immediately returns into the dead zone 501. For example, it is a situation where a person who is the subject 106 opens or closes a window or a door and then immediately returns to the original position. Therefore, in the second embodiment, a form in which the PT drive is kept in a prohibited state when the subject 106 temporarily moves out of the dead zone 501 will be described. The configuration and basic processing operations of the network camera 101 are the same as those in the first embodiment. Hereinafter, the same components and processing operations as those in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted, and the description will focus on the differences from the first embodiment.

[0044] Referring to the flowchart shown in FIG. 6, the flow of the automatic tracking process of the network camera 101 in the second embodiment will be described. Note that the processes overlapping with those in the flowchart shown in FIG. 4 are denoted by the same reference numerals, and the description thereof will be omitted. In addition, FIG. 7 schematically shows an example of an image frame of a captured image during the automatic tracking process. If it is determined in step S405 that the subject 106 is located outside the dead zone 501, the process proceeds to step S601. In step S601, the position determination unit 212-2 determines whether or not a predetermined time has elapsed while the subject 106 is located outside the dead zone 501. If the predetermined time has elapsed, the process proceeds to step S407 to set the PT drive to the permitted state. If the predetermined time has not elapsed, the process returns to step S403. The predetermined time is determined, for example, at the initial setting in step S401. The staying time during which the subject 106 is located outside the dead zone 501 is measured using a timer function or the like inside the camera, starting from when it is specified that the subject 106 is located outside the dead zone 501.

[0045] Here, referring to FIG. 7, a specific example of the automatic tracking process in the flowchart of FIG. 6 will be described. FIG. 7 is a diagram schematically showing an example of an image frame of a captured image during the automatic tracking process, similar to FIG. 5. First, referring to FIGS. 7(a) and 7(b), the process of maintaining the prohibited state of the PT drive when the subject 106 temporarily moves outside the dead zone 501 will be described. In FIG. 7(a), the PT drive is in the prohibited state, showing a state where the position 502 of the subject 106 specified by the position specifying unit 212-1 has moved outside the dead zone 501 from a state where it is within the dead zone 501, and the staying time outside the dead zone 501 is measured from this point. If the predetermined time has not elapsed (No in step S601), the process returns to step S403. FIG. 7(b) shows a state where the position 502 of the subject 106 specified by the position specifying unit 212-1 has returned to within the dead zone 501 again before the predetermined time has elapsed (Yes in step S405). Thus, when the subject 106 returns within the dead zone 501 before the predetermined time has elapsed, the PT drive is maintained in the prohibited state.

[0046] Next, with reference to FIGS. 7(c) and 7(d), a process of permitting PT driving when the subject 106 moves outside the dead zone 501 and a predetermined time has elapsed will be described. In FIG. 7(c), the PT driving is in a prohibited state, and a state is shown where it is specified that the position 502 of the subject 106 specified by the position specifying unit 212-1 has moved outside the dead zone 501 from a state where it is within the dead zone 501. The staying time located outside the dead zone 501 is measured from this point. When a predetermined time has elapsed (Yes in step S601), the PT driving is set to an enabled state (step S407). Then, although not shown, the wireless device 103 is instructed to set the transmission interval of the radio wave from the wireless device 103 to be shorter than the predetermined interval (step S408). Then, as shown in FIG. 7(d), PT driving at a predetermined speed is instructed so that the subject 106 is displayed at the central position 504 within the dead zone 501 (step S409), and the process returns to step S403.

[0047] As described above, when it is specified that the subject 106 is not located within the dead zone 501, the PT driving is prohibited until a predetermined time elapses while the subject 106 stays outside the dead zone 501, and after the predetermined time has elapsed, the PT driving is permitted to change the shooting direction. Therefore, when the subject 106 temporarily moves outside the dead zone 501, in addition to reducing the processing load by reducing unnecessary PT driving, it is possible to suppress screen shaking and the like caused by the PT driving. As a result, it is possible to provide an image with improved visibility. In addition, since the state where the transmission interval of the radio wave from the wireless device 103 is lengthened can be continued, the battery consumption of the wireless device 103 can be reduced.

[0048] [Third Embodiment] In the first embodiment, when the subject 106 is located within the dead zone 501, the transmission interval of the radio wave from the wireless device 103 is set to be longer than the predetermined interval to reduce the battery consumption. On the other hand, when the transmission interval of the radio wave becomes longer, the timing for specifying the position of the subject 106 is delayed, and for example, there is a possibility that the detection of the movement of the subject 106 outside the dead zone 501 is delayed. Therefore, in the third embodiment, a form in which the transmission interval of the radio wave of the wireless device 103 is changed according to the position when the subject 106 is located within the dead zone 501 will be described. Specifically, the transmission interval when the subject 106 is located in the region near the boundary within the dead zone 501 is made shorter than the transmission interval when it is not. Hereinafter, the same components and processing operations as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted, and the description will be centered on the differences from the first embodiment.

[0049] With reference to the flowchart shown in FIG. 8, the flow of the automatic tracking process of the network camera 101 in the third embodiment will be described. Note that the same reference numerals are given to the processes that overlap with the processes of the flowchart shown in FIG. 4, and the description thereof is omitted. FIG. 9 schematically shows an example of an image frame of a captured image during the automatic tracking process. If it is determined in step S405 that the subject 106 is located within the dead zone 501, the process proceeds to step S801. In step S801, the position determination unit 212-2 determines whether the subject 106 is located in the region 901 near the boundary. If the subject 106 is located in the region 901 near the boundary, the process proceeds to step S802. If the subject 106 is not located in the region 901 near the boundary, the process proceeds to step S406. Here, two patterns are assumed as methods for determining whether the subject 106 is located in the region 901 near the boundary. One is a method of specifying the position of the subject 106 based on the radio wave direction from the wireless device 103. In this case, it can be determined using an existing mechanism. However, since the transmission interval of the radio wave from the wireless device 103 is long, the timing for specifying the position of the subject 106 is delayed, and a situation may occur in which the subject 106 moves outside the dead zone 501 before determining whether it is located in the region 901 near the boundary. The other is a method that utilizes the video analysis unit 208. By supplementarily using moving object detection and human body detection in the video analysis unit 208, the timing for specifying the position of the subject 106 is not delayed, and it is determined whether the subject 106 is located in the region 901 near the boundary.

[0050] In step S802, the interval control unit 212-4 instructs to shorten the transmission interval of the radio wave from the wireless device 103 by a predetermined amount. Thereafter, the process returns to step S403. The predetermined amount is set to a value that is longer than the transmission interval set in step S408 and shorter than the transmission interval set in step S406.

[0051] Here, with reference to FIG. 9, a specific example of the automatic tracking process of the flowchart in FIG. 8 will be described. FIG. 9 is a diagram schematically showing an example of an image frame of a captured image during the automatic tracking process, similar to FIG. 5. FIG. 9(a) shows a state where the subject 106 is located at the central position 504 within the dead zone 501. In this case, it is determined that the subject 106 is located within the dead zone 501 (Yes in step S405), and it is determined that it is not in the region 901 near the boundary (No in step S801). Therefore, the wireless device 103 is instructed to set the transmission interval of the radio wave from the wireless device 103 to be longer than a predetermined interval (step S406), and the process returns to step S403.

[0052] FIG. 9(b) shows a state where the subject 106 has moved from the state in FIG. 9(a) and is located in the region 901 near the boundary within the dead zone 501. In this example, by additionally using moving object detection or human body detection in the video analysis unit 208, it is determined whether the subject 106 is located in the region 901 near the boundary. In this case, it is determined that the subject 106 is located within the dead zone 501 (Yes in step S405), and it is determined that it is in the region 901 near the boundary (Yes in step S801). Therefore, the wireless device 103 is instructed to shorten the transmission interval of the radio wave from the wireless device 103 by a predetermined amount (step S802), and the process returns to step S403.

[0053] As described above, even while the subject 106 is located within the insensitive zone 501, when the subject 106 is located in the region 901 near the boundary, the transmission interval of the radio wave from the wireless device 103 is shortened by a predetermined amount. Thereby, the timing for specifying the position of the subject 106 is not delayed, and for example, it is possible to prevent the delay in detecting that the subject 106 has moved outside the insensitive zone 501. Therefore, since the distance to be PT-driven becomes short, it is possible to suppress screen shaking and the like due to PT driving. As a result, it is possible to provide a video with improved visibility.

[0054] As described above, the present invention has been described together with the embodiments. However, the above embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its technical idea or its main features. In the above-described embodiment, wireless communication conforming to the Bluetooth (registered trademark) version 5.1 specification has been cited. However, as long as the direction detection function operates, the version does not matter. That is, even if it is Bluetooth (registered trademark) version 5.2 or later, as long as the direction detection function operates, it satisfies the conditions as the wireless communication standard to which the present invention is applied. (Other Embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. Further, it can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Explanation of Reference Numerals

[0055] 101: Network camera, 103: Wireless device, 105: Wireless network, 106: Subject, 212: CPU (Central Processing Unit), 212-1: Position specifying unit, 212-2: Position determination unit, 212-3: PTZ control unit, 212-4: Interval control unit, 212-5: Tracking system control unit

Claims

1. An imaging device capable of changing the shooting direction and capable of wireless communication, a position specifying means for specifying the position of the subject based on radio waves received from a wireless device carried by the subject; a control means for controlling the photographing direction in either a first control mode in which the photographing direction can be changed on the condition that the subject is not located within a predetermined area on the captured image, based on the position of the subject identified by the position identification means, or a second control mode in which the photographing direction cannot be changed on the condition that the subject is located within the predetermined area; a measuring means for measuring a time during which the subject is located outside the predetermined area when the position specifying means specifies that the subject is located outside the predetermined area after being located within the predetermined area; Equipped with When the time measured by the measuring means is equal to or longer than a predetermined time, the control means switches from the second control mode to the first control mode.

2. 2. The imaging device according to claim 1, wherein the control means, when controlling the imaging direction in the first control mode, changes the imaging direction so that the subject is displayed at a predetermined position within the predetermined area.

3. 3. The imaging device according to claim 2, wherein the control means switches to not changing the imaging direction when the subject is displayed at the predetermined position by changing the imaging direction.

4. 4. The imaging device according to claim 1, wherein the control means changes the shooting direction at a speed at which background objects can be visually recognized on the captured image.

5. 5. The imaging device according to claim 1, further comprising an interval control means for controlling an interval at which the radio wave is transmitted from the wireless device.

6. 6. The imaging device according to claim 5, wherein the interval control means makes the transmission interval when the subject is located within the predetermined area longer than the transmission interval when the subject is not located within the predetermined area.

7. 7. The imaging device according to claim 5, wherein the interval control means changes the transmission interval depending on the position of the subject within the predetermined area when the subject is located within the predetermined area.

8. 8. The imaging device according to claim 7, wherein the interval control means shortens the transmission interval when the subject is located in an area near a boundary within the predetermined area compared to the transmission interval when the subject is not located in that area.

9. 9. The imaging device according to claim 8, wherein the determination of whether the subject is located in the area near the boundary within the predetermined area is performed by video analysis.

10. 10. The imaging device according to claim 1, wherein the predetermined area is a central area of the captured image.

11. 11. The imaging device according to claim 1, wherein the position specifying unit specifies the position of the subject based on a direction detection function of Bluetooth (registered trademark).

12. A control method for an imaging device capable of changing the imaging direction and wireless communication, comprising: a position specifying step of specifying the position of the subject based on radio waves received from a wireless device carried by the subject; a control step of controlling the photographing direction in either a first control mode in which the photographing direction can be changed on the condition that the photographing subject is not located within a predetermined area on the captured image, based on the position of the photographing subject identified in the position identification step, or a second control mode in which the photographing direction cannot be changed on the condition that the photographing subject is located within the predetermined area; a measuring step of measuring a time during which the subject is located outside the predetermined area when it is determined in the position specifying step that the subject is located outside the predetermined area after being located within the predetermined area; and A control method for an imaging apparatus, wherein, when the time measured in the measuring step is equal to or longer than a predetermined time, the control step switches from the second control mode to the first control mode.

13. A program for controlling an imaging device capable of changing the imaging direction and capable of wireless communication, a position specifying means for specifying the position of the subject based on radio waves received from a wireless device carried by the subject; Based on the position of the subject specified by the position specifying means, a first control mode in which the shooting direction can be changed on the condition that the subject is not located within a predetermined area on the captured image, and a second control mode in which the shooting direction cannot be changed on the condition that the subject is located within the predetermined area, and control means for controlling the shooting direction in either of the modes; When the position specifying means specifies that the subject has moved out of the predetermined area after being located within the predetermined area, measuring means for measuring the time during which the subject is located outside the predetermined area; Causing a computer to function, A program characterized in that when the time measured by the measuring means is equal to or longer than a predetermined time, the control means switches from the second control mode to the first control mode.

Images