JP5277600B2 - Overhead radiography system and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system and a method for photographing an overhead wire in proper size and direction. <P>SOLUTION: A laser device 28 calculates the distance and direction to a representative overhead wire, viewed from a video camera 10 by a selector 34 and a representative wire distance and direction calculator 36. A camera and mount controller 38 controls the focus and photographing direction of the camera 10, according to the output of the calculator 36. A line extractor 46 extracts a line image from the photographed image of the camera 10. An inclination calculator 48 calculates the inclination of the line image. A control target determination device 50 determines the control target of the optical zoom of the camera 10 and the control target of the photographing center from the information of the extracted line. In a tracking mode, the controller 38 controls the optical zoom of the camera 10, according to the control target of an optical zoom function, rotates the camera 10, so as to make the overhead wire horizontal in a photographic picture, according to the calculation result of the inclination calculator 48, and tilts the video camera 10, according to the control target of the photographing center, to pan the camera 10, according to the output of the calculator 36. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an overhead line imaging system and method, and more specifically, an overhead line in use such as an overhead transmission line and a grounding wire (ground wire) for preventing lightning strikes is photographed for the inspection. The present invention relates to an overhead radiography system and method.

  As a method for photographing an overhead line, Patent Document 1 discloses that a laser ranging device and a high-definition video camera are mounted on a helicopter, the helicopter is caused to fly along the overhead line, and the distance to the overhead line by the laser ranging device is A system for controlling the focus and shooting direction of a video camera according to the direction measurement results is described. By shooting and recording the overhead line while flying the helicopter along the overhead line, it is possible to track the overhead line and obtain a focused video image. It also describes that the displacement and inclination of the electric wire in the photographed image are detected, and the tilt angle and roll angle of the camera are controlled so that the overhead line is always positioned almost horizontally at the center of the screen.

  Patent Document 2 describes a technique for detecting a local high temperature part by measuring a temperature distribution by moving an infrared camera facing an overhead line at a constant speed in the longitudinal direction of the overhead line. The part where the corrosion of the coating of the steel core is proceeding utilizes the fact that the temperature is higher than the surroundings.

Patent Document 3 has an overhead wire surface observation device that has a rod shape that extends from the ground and hangs on an electric wire, and allows the surface of the overhead wire to be observed on the ground by installing a camera near the wire. Is described.
JP-A-10-003109 Japanese Patent Laid-Open No. 05-332962 JP 2004-242401 A

  In general, a plurality of transmission lines are connected in parallel to the transmission tower. With the method described in Patent Document 1, it is easy to photograph a single overhead line up. However, it is difficult to shoot a plurality of overhead lines with different shooting distances at the same time, and to take a picture so high that details can be confirmed.

  The methods described in Patent Documents 2 and 3 require a camera device to be hung on an overhead line, and are difficult to apply to, for example, an overhead line in a mountain or an overhead line installed at a very high position.

  An object of the present invention is to solve such a problem and to provide an overhead line imaging system and method capable of imaging a plurality of overhead lines simultaneously and up to the extent that they can be used for inspection of details. To do.

An overhead line imaging system according to the present invention is an overhead line imaging system for imaging an overhead line, which has an optical zoom function and an autofocus function, and is capable of manually controlling focus by an external control signal, Recording means for recording video image information of the video camera, zoom control means for controlling the optical zoom function of the video camera, shooting direction changing means for changing the shooting direction of the video camera, and shooting the video camera Representative from camera rotation means that rotates around the optical axis, distance / direction measurement means that measures the distance and direction to the overhead line, and a plurality of measurement values of the overhead line that are measured by the distance / direction measurement means selection means for selecting the measurement result of the line, and the line extracting means for extracting a line image from the photographed image of the video camera, the line extraction hand And inclination calculation means for calculating an inclination of in the extracted line image, and the possible line designating means a plurality of imaginary lines in the photographic image plane of the video camera, the extraction result of the line extracting unit and the line specifying means specified in accordance with, the plurality of imaginary lines specified by the line specifying means to be in the predetermined size and a predetermined position within the imaging screen, control of the optical zoom function of the video camera about the size of in the shooting screen Control target determination means for determining a control target of the shooting center of the video camera with respect to the target and the position in the shooting screen, and in the tracking mode, performs control to approach the control target of the optical zoom function. a control target determination means for instructing the zoom control means, said zoom control means, a control means for controlling the photographing direction changing means and the camera rotation means The tracking preparation phase, according to the measurement result of the distance and direction measuring means representative lines selected in the selecting means, to control the focus of the video camera, the photographing direction of the video camera by the shooting direction change means change the, in the tracking mode, to enable the optical zoom function and the auto-focus function of the video camera, in accordance with the calculation result of the inclination calculation means, the so the overhead wire is oriented in a predetermined direction in the shooting screen The camera rotation unit is controlled, and the video camera is controlled in the first direction by the shooting direction changing unit so as to approach the control target of the shooting center determined by the control target determination unit, and is selected by the selection unit. According to the measurement result of the distance / direction measuring means of the representative line, the video camera is hit by the shooting direction changing means. And a control means for controlling in a second direction orthogonal to the first direction.

An overhead line imaging method according to the present invention includes an optical zoom function and an autofocus function, a video camera capable of manually controlling focus by an external control signal, and a recording means for recording captured video information of the video camera, Zoom control means for controlling the optical zoom function of the video camera, photographing direction changing means for changing the photographing direction of the video camera, camera rotating means for rotating the video camera around its photographing optical axis, and photographing A method of photographing an overhead line with an overhead line radiographing system comprising a distance / direction measuring means for measuring a distance and direction to an object, and measuring a plurality of the overhead lines measured by the distance / direction measuring means a selection step of selecting the measurement results of the representative line from the value, the distance and direction meter the representative line selected in the selection step According measurement result means, to control the focus of the video camera, a tracking preparation step of changing the photographing direction of the video camera by the shooting direction change means, in accordance with instruction to shift to the tracking mode, of the video camera A step of enabling the optical zoom function and the autofocus function, a line extraction step of extracting a line image from a captured image of the video camera, and an inclination calculation for calculating an inclination of the line image extracted in the line extraction step In accordance with the step, a line designation step for designating a plurality of overhead lines on the video camera screen, the extraction result of the line extraction step, and the designation at the line designation step, The shooting screen to ensure that the overhead line is at a predetermined size and position within the shooting screen A control target of the optical zoom function of the video camera about the size of, the control target determination step of determining a control target of the imaging center of the video camera on the position in the photographing screen, determined in the control target determination step is Ru controls the optical zoom function to approach the control target of the optical zoom function, the video camera by the shooting direction change means so as to approach the control target of the imaging center is determined by the control target determination step A zoom / direction control step for controlling in the first direction, and a camera rotation control step for controlling the camera rotation means so that the overhead line is directed in a predetermined direction in the imaging screen according to the calculation result of the tilt calculation step; according measurement results of those the distance and direction measuring means selected the representative line in the selection means, the imaging direction change And a shooting direction changing step of controlling the video camera in a second direction orthogonal to the first direction by means.

  According to the present invention, one or a plurality of overhead lines can be photographed and recorded in an appropriate size and direction without the need for an operator to manually adjust the optical zoom and focus. With the recorded video, it is possible to easily find an overhead line fault, and maintenance and inspection of the overhead line becomes easy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic block diagram of an embodiment of the present invention, which is used by being mounted on a helicopter or the like. A video camera 10 that captures an overhead wire is fixed to a camera mount 12 having a function of preventing vibration caused by a helicopter. The camera mount 12 can rotate the mounted video camera 10 around its optical axis, and in a horizontal plane parallel to the horizontal scanning line of the video camera 10 (for the sake of convenience, in the pan direction) and on the horizontal scanning line. In an orthogonal vertical plane (for convenience, a total of three axes in the tilt direction can be rotated. However, a pan frame and a tilt frame are mounted on a frame that rotates the video camera 10 about the photographing optical axis. Yes.

  The video camera 10 outputs the current zoom value and focus value, can control the focus by an external focus control signal, and can control the optical zoom by an external zoom control signal.

  FIG. 2 is an explanatory diagram of the shooting direction control of the video camera 10 by the camera mount 12. The pan actuator 14P of the camera mount 12 rotates the photographing direction of the video camera 10 in a plane parallel to the horizontal scanning line by an amount according to the pan control signal, and the angle detector 16P detects the rotation angle (position) α. . The tilt actuator 14T of the camera mount 12 rotates the shooting direction of the video camera 10 in a plane perpendicular to the horizontal scanning line by an amount according to the tilt control signal, and the angle detector 16T detects the rotation angle (position) β. . The rotation actuator 14R of the camera mount 12 rotates the video camera 10 about its photographing optical axis by an amount according to the camera rotation control signal, and the angle detector 16R detects the rotation angle γ.

  In this embodiment, a gantry rotated by the pan actuator 14P and a gantry rotated by the pan actuator 14T are placed on the gantry rotated by the rotary actuator 14R. With this configuration, while shooting a hanging overhead line so that it is horizontal in the screen, you can change the shooting direction of the video camera along the overhead line by pan control, and perpendicular to the overhead line by tilt control You can control the shooting direction of the video camera in any direction. That is, the shooting direction of the video camera 10 can be easily controlled. Of course, control values in two directions of the shooting direction of the camera may be calculated from the inclination of the overhead line.

  The output video signal of the video camera 10 is supplied to the high definition monitor 18 and the VTR 20. On the screen of the high-definition monitor 18, the photographing object and the range can be confirmed. The VTR 20 can record a captured video. The operator or pilot on board the helicopter can control the recording of the VTR 20 and its stop by the VTR control device 22.

  A GPS (Global Positioning System) receiver 24 receives radio waves from GPS satellites and measures the helicopter body position and time (GPS time). In addition, the attitude detection device 26 including a three-axis gyro apparatus or the like measures the aircraft attitude (or the direction of the aircraft) with respect to the three axes, and outputs a three-axis aircraft attitude value on the ground coordinates. The scanning laser distance measuring device 28 irradiates a laser pulse toward the overhead line, scans the overhead line so as to cross the overhead line, and reflects the reflected light from the overhead line within the scanning range from the body of the overhead line. The distance D and the direction θ are measured.

  The GPS receiver 24 outputs the measured body position and GPS time to the imaging line coordinate calculation device 30. The posture detection device 26 outputs angle information of the three-axis body posture to the imaging line coordinate calculation device 30. The laser distance measuring device 28 outputs the measured distance D and angle θ of each reflection point i, that is, {(D, θ) i}, to the imaging line coordinate calculating device 30. The imaging line coordinate calculation device 30 is based on the body position from the GPS receiver 24, the angle information of the 3-axis body posture from the posture detection device 26, and the measurement data {(D, θ) i} of the laser distance measuring device 28. Then, the three-dimensional position on the ground coordinates of each shooting line (that is, the overhead line that is the shooting target) is calculated. Since this calculation method is well known, detailed description thereof is omitted. The imaging line coordinate calculation device 30 uses the calculated coordinate value, the GPS time from the GPS receiver 24, and the original data used for the calculation (the body posture value, the body position, and {(D, θ) i}) as the VTR 20. To supply. The VTR 20 records the data from the photographing line coordinate calculation device 30 on the video tape together with the video signal as ancillary data of the video signal from the video camera 10. The VTR 20 also records the rotation angles α, β, γ of the camera mount 12. Of course, when the recording video can be synchronized, these measurement data may be recorded by a recording device different from the VTR 20.

  FIG. 3 shows the relationship between the scanning range of the laser distance measuring device 28 and the photographing range of the camera 10. A plurality of (for example, four overhead lines) are grouped between transmission lines, and a plurality of groups of overhead lines are hung. The laser distance measuring device 28 has a scanning capability capable of measuring the distance to these overhead lines in one scan. On the other hand, the camera 10 shoots a group of overhead lines together when shooting up.

  In this embodiment, the following functions are provided so that a plurality of overhead lines of one group can be photographed at the same time, and so as to be photographed as large as possible.

A representative line is selected from a group to be initially focused according to the measurement result of the laser distance measuring device 28. Specifically, the operator designates a representative line among the measured values of the laser distance measuring device 28 by the representative line designation device 32. The selection device 34 selects the measured value (D, θ) of the line designated by the representative line designation device 32 as the representative value (D, θ) _rep .

Normally, the center optical axis of scanning of the laser distance measuring device 28 and the imaging optical axis of the video camera 10 do not coincide with each other, so that the distance and direction of the overhead line measured by the laser distance measuring device 28 can be viewed from the video camera 10. It is necessary to convert or correct to the distance and direction when The representative line distance / direction calculation device 36 is responsible for this conversion or correction, converts the distance D _rep and direction θ _rep of the representative line from the selection device 34 into the distance and direction when viewed from the video camera 10, The converted distance value and direction value are supplied to the camera / base control device 38.

  Although details will be described later, initially, the camera / base control device 38 follows the direction value from the representative line distance / direction calculation device 36 so that the representative line falls within the shooting range of the camera 10 and tilt. Control signals are generated and applied to the pan actuator 14P and the tilt actuator 14T of the camera mount 12, respectively. As a result, the representative line designated by the representative line designating device 32 comes to be positioned substantially at the center of the shooting range of the video camera 10.

  The camera / base control device 38 also causes the focus control device 40 to control the focus of the camera 10 in accordance with the direction value from the representative line distance / direction calculation device 36. In other words, at this time, the camera / base control device 38 instructs the target focus value to the focus control device 40, and the focus control device 40 sets the focus value of the designated focus control value of the video camera 10. Control the focus.

  After such control, the operator can instruct the camera / mount control device 38 to shift to the tracking mode by the operation device 42. In the tracking mode, as will be described later, the camera / base control device 38 enables the control of leveling the captured overhead line on the shooting screen, the autofocus control of the video camera 10, and the zoom control of the video camera 10. To do. Before entering the tracking mode, the operator can manually operate the optical zoom and focus of the video camera 10 and the rotation angles of the three axes of the camera mount 12 via the camera / mount control device 38 by the operation device 42.

  The frame memory 44 temporarily stores a video signal output from the video camera 10 in order to confirm the number and position of the captured overhead lines. Although it is preferable to store all frames, frames may be thinned out appropriately. The line extraction device 46 extracts a line image from the frame image stored in the frame memory 44 according to a known line extraction algorithm. For example, the frame image stored in the frame memory 44 is binarized by its luminance or color, and the outer edge of each line element is detected by Hough transform or the like. From this detection result, a function indicating the line width and the center line, or both Determine the function that represents the outer edge line. The line extraction device 46 outputs a linear function expression or a quadratic function expression indicating each extracted line (center line and width thereof, or outer edges on both sides) on the coordinates of the frame image.

  The inclination calculation device 48 calculates the average inclination value of all the lines extracted by the line extraction device 46 (or the inclination value of the representative line such as the center of the screen) and supplies it to the camera / base control device 38. In the tracking mode, the camera / table control device 38 slightly rotates the video camera 10 around the photographing optical axis in the direction in which the tilt value from the tilt calculating device 48 approaches the horizontal on the photographing screen. Is generated. The generated camera rotation control signal is supplied to the camera rotation actuator 14R of the camera mount 12. The camera rotation actuator 14R rotates the video camera 10 about its photographing optical axis by the rotation angle according to the camera rotation control signal. As a result of such gradual control, the inclination of the shooting line is relaxed in the shooting screen of the video camera 10, and finally becomes almost horizontal in the shooting screen.

  Of course, in the range where the inclination value from the inclination calculating device 48 can be regarded as substantially horizontal in the photographing screen, the camera / mount control device 38 stops the control of the camera rotation actuator 14R, and when it is off the horizontal, the camera rotation actuator The control of 14R is resumed.

  By such control, it is possible to take an image while maintaining the overhead line substantially horizontal. For example, the transmission line is bent in the middle between the transmission line towers. Regardless of this bending, the transmission line can always be captured horizontally and photographed.

  The control target determining device 50 determines the control target of the optical zoom magnification and the tilt target of the camera mount 12. First, the control target determination device 50 calculates the number of lines on the vertical line at the center of the photographing screen and the position and width of each line from the output of the line extraction device 46. The user can specify by the line specifying device 52 whether one or a plurality of overhead lines being photographed is positioned at the center of the screen. When one overhead line is designated, it means that the designated one overhead line is positioned at the center of the photographing screen, and the designated one overhead line is placed on the designated range on the screen (for example, This means that the image is enlarged and photographed within 20 to 30% of the photographing screen. In addition, when a plurality of overhead lines are specified, it means that the center position of the specified plurality of overhead lines is located at the center of the shooting screen, and the specified plurality of overhead lines are displayed on the shooting screen. This means that the image is enlarged and photographed within a specified range (for example, about 60 to 70% in the photographing screen).

  The control target determining device 50 determines the control target of the optical zoom magnification of the video camera 10 and the tilt target of the camera mount 12 in accordance with the designation of the line designating device 52. Then, the control target determination device 50 instructs the zoom control device 54 to control the optical zoom magnification slightly closer to the control target of the optical zoom, and performs the tilt control in the direction approaching the tilt target of the camera mount 12 with the camera / mount control. Instruct the device 38. The zoom control device 54 slightly controls the optical zoom of the video camera 10 in the telephoto direction or the wide-angle direction in accordance with an instruction from the control target determination device 50. The camera / base control device 38 supplies a tilt control signal for slightly changing the tilt angle β to the tilt actuator 14T of the camera base 12 in accordance with an instruction from the control target determination device 50.

  As a result of these controls, the one or more overhead lines designated by the line designation device 52 are positioned from the center in the photographing screen, and the size in the photographing screen also approaches an appropriate size. Reflecting this change, the control target determining device 50 supplies a new instruction signal for instructing the change of the optical magnification to the zoom control device 54, and sends a new instruction signal for instructing the change of the tilt angle to the camera / base control device. 38. As a result of such gradual control, one or a plurality of overhead lines designated by the line designating device 52 can be photographed at an appropriate size almost at the center in the photographing screen.

  When the number of lines extracted by the line extraction device 46 is smaller than the target number of lines, the control target determination device 50 instructs the zoom control device 54 to change in the wide angle direction. In accordance with this instruction, the zoom control device 54 generates a zoom control signal that instructs zooming in the wide-angle direction, and supplies the zoom control signal to the video camera 10.

  As described above, in this embodiment, a line image indicating an overhead line is extracted from a captured image of the video camera 10, and the rotation angle γ around the shooting optical axis of the video camera 10 is controlled so that it is horizontal. At the same time, the optical zoom of the video camera 10 and the tilt angle of the video camera 10 are controlled so that the necessary number of overhead lines fit within a single screen.

  The focus detection device 56 extracts the high frequency component of the video signal output from the video camera 10 to detect the focus level, and supplies the detection result to the focus control device 40. In the autofocus mode, the focus control device 40 feedback-controls the focus of the video camera 10 so that the signal indicating the degree of focus output from the focus detection device 56 is maximized.

  Even in the tracking mode, the camera / base control device 38 controls the pan angle of the camera base 12 in accordance with the direction information from the representative line distance / direction calculation device 36.

  In the configuration shown in FIG. 1, the focus control device and the zoom control device are arranged outside the video camera 10 for easy understanding. However, the video camera incorporating these may be externally controlled. it is obvious.

  FIG. 4 shows a flowchart of the control operation of this embodiment. FIG. 5 shows a schematic diagram of a transition example of the shooting screen. In this embodiment, an overhead line is photographed while a helicopter equipped with the photographing system shown in FIG. 1 is made to fly along the overhead line to be photographed.

  First, at the start, the optical zoom of the video camera 10 is set to appropriate initial values, the pan angle α, the tilt angle β, and the rotation angle γ of the camera mount 12 are set to appropriate initial values, and the focus control device 40 is manually set. Control is set (S1).

  The distance and direction to the overhead line are measured by the laser distance measuring device 28 (S2). The camera / base control device 38 controls the pan / tilt angle of the camera base 12 via the pan actuator 14P and the tilt actuator 14T according to the distance / direction information from the representative line distance / direction calculation device 36, and the focus control device 40. The focus of the video camera 10 is controlled via (S3). Thereby, the overhead line to be photographed can be captured within the photographing field of view of the video camera 10.

  Steps S2 and S3 are repeated until the operator instructs the operation device 42 to shift to the tracking mode (S4).

  When the operator instructs the camera / mounting control device 38 to shift to the tracking mode by the operation device 42 (S4), the camera / mounting control device 38 enables autofocus on the focus control device 40 (S5). Accordingly, the focus control device 40 automatically controls the focus of the video camera 10 so that the subject (mainly the overhead line of the shooting target) becomes sharp in the captured image of the video camera 10 according to the output of the focus detection device 56. To do. In this state, for example, as shown in FIG.

  As described above, the camera / table control device 38 rotates the video camera 10 around its photographing optical axis by the camera rotation actuator 14R according to the calculation result of the tilt calculation device 48, as illustrated in FIG. 5B. Next, the imaged overhead line is leveled (S6).

  Further, the camera / base control device 38 controls the tilt angle of the camera base 12 via the tilt actuator 14T according to the target tilt angle from the control target determination device 50, and the zoom control device 54 receives the control target determination device 50 from the control target determination device 50. According to the target zoom value, the optical zoom of the video camera 10 is controlled to the wide angle side or the telephoto side (S7). Thereby, as illustrated in FIG. 5C, the overhead line to be photographed is photographed with an appropriately enlarged size.

  If any error is detected, the process returns to step S1 (S9). This may be performed automatically or manually by an operator. This error is, for example, when the overhead line to be photographed suddenly deviates from the field of view of the video camera 10 due to a gust of wind or the like, and automatic tracking becomes impossible.

  Steps S6 to S9 are repeated until the operator turns off the tracking mode (S10). For the sake of explanation, steps S6, S7, and S9 are executed sequentially. However, it is obvious that these steps may be executed simultaneously.

  In the above-described embodiment, the focus control device 40, the zoom control device 54, and the focus detection device 56 are illustrated outside the video camera 10 so that the optical zoom control and focus control modes or operations of the video camera 10 can be easily understood. However, in many video cameras, functions corresponding to the focus control device 40, the zoom control device 54, and the focus detection device 56 are built in the video camera. That is, the video camera according to the present invention includes one incorporating any of the focus control device 40, the zoom control device 54, and the focus detection device 56.

  In the above embodiment, as with the overhead line shooting (recording), the shooting line coordinate calculation device 30 calculates the three-dimensional coordinates of the overhead line measured by the laser distance measuring device 28. You may do it.

It is a schematic block diagram of one Example of this invention. It is explanatory drawing which shows the rotation direction of the video camera 10 by the camera mount frame 12. 3 is a schematic diagram showing a relationship between a scanning range of a laser distance measuring device and a photographing range of a video camera. It is a control flowchart of a present Example. It is the example of a change of the picked-up image of a present Example.

Explanation of symbols

10: Video camera 12: Camera mount 14P: Pan actuator 14T: Tilt actuator 14R: Camera rotation actuators 16P, 16T, 16R: Angle detector 18: High-definition monitor 20: VTR
22: VTR control device 24: GPS receiver 26: attitude detection device 28: scanning laser range finder 30: imaging line coordinate calculation device 32: representative line designation device 34: selection device 36: representative line distance / direction calculation device 38 : Camera / frame control device 40: Focus control device 42: Operation device 44: Frame memory 46: Line extraction device 48: Tilt calculation device 50: Control target determination device 52: Line designation device 54: Zoom control device 56: Focus detection apparatus

Claims (5)

An overhead line photographing system for photographing overhead lines,
A video camera (10, 40, 56) having an optical zoom function and an autofocus function and capable of manually controlling focus by an external control signal;
Recording means (20) for recording video image information of the video camera;
Zoom control means (54) for controlling the optical zoom function of the video camera;
Shooting direction changing means (14P, 14T) for changing the shooting direction of the video camera;
Camera rotating means (14R) for rotating the video camera around its photographing optical axis;
A distance / direction measuring means (28) for measuring the distance and direction to the overhead line;
Selection means (34) for selecting a measurement result of the representative line from a plurality of measurement values of the overhead line measured by the distance / direction measurement means;
A line extracting means (46) for extracting a line image from a photographed image of the video camera;
An inclination calculating means (48) for calculating the inclination of the line image extracted by the line extracting means (46);
A line designating means (52) capable of designating a plurality of overhead lines in the shooting screen of the video camera;
In accordance with the extraction result of the line extraction means (46) and the designation of the line designation means, the imaging is performed so that the plurality of overhead lines designated by the line designation means are at a predetermined size and a predetermined position in the imaging screen. Control target determining means (50) for determining a control target of the optical zoom function of the video camera related to the size in the screen and a control target of the shooting center of the video camera related to the position in the shooting screen ; In tracking mode, control target determining means for instructing the optical zoom control means to perform control that approaches the control target of the optical zoom function;
Control means (38) for controlling the zoom control means, the photographing direction changing means, and the camera rotating means, and in the tracking preparation stage, measurement of the distance / direction measuring means of the representative line selected by the selection means. according to the result, the controls the focus of a video camera, and change the photographing direction of the video camera by the shooting direction changing means, in the tracking mode, the optical zoom function and the auto-focus function of the video camera enable accordance calculation result of the inclination calculation means, and controls the camera rotation means so as to face in a predetermined direction the overhead line in the photographing screen, the control target of the imaging center is determined by the control target determination means by the shooting direction change means so as to approach to control the video camera in a first direction, selected by the selection means According measurement result of the distance and direction measuring means of the representative line, and characterized by a control means for controlling the video camera by the shooting direction changing means in a second direction perpendicular to the first direction Overhead radiography system. Further, a camera frame for supporting the video camera, the rotary frame capable of rotating the video camera around the optical axis of the video camera, and the video camera in a biaxial direction. The overhead line radiographing system according to claim 1 , further comprising a mount that directly supports the video camera.   3. The control target determining means, when the number of lines extracted by the line extracting means is smaller than a target number of lines, instructs the zoom control means to change in the wide angle direction. Overhead radiography system described in 1. A video camera (10, 40, 56) having an optical zoom function and an autofocus function and capable of manually controlling focus by an external control signal;
Recording means (20) for recording video image information of the video camera;
Zoom control means (54) for controlling the optical zoom function of the video camera;
Shooting direction changing means (14P, 14T) for changing the shooting direction of the video camera;
Camera rotating means (14R) for rotating the video camera around its photographing optical axis;
Distance / direction measuring means (28, 32, 34, 36) for measuring the distance and direction to the photographing object
A method for photographing an overhead line with an overhead line photographing system comprising:
A selection step of selecting a measurement result of the representative line from a plurality of measurement values of the overhead line measured by the distance / direction measurement means;
In accordance with the measurement result of the distance / direction measuring unit of the representative line selected in the selection step, the focus of the video camera is controlled, and the tracking direction of the video camera is changed by the shooting direction changing unit. Preparation steps,
In accordance with the instruction to shift to the tracking mode, enabling the optical zoom function and the autofocus function of the video camera;
A line extraction step of extracting a line image from a captured image of the video camera;
An inclination calculating step for calculating an inclination of the line image extracted in the line extracting step;
A line designating step for designating a plurality of overhead lines on the video camera screen;
In accordance with the extraction result of the line extraction step and the designation in the line designation step, the plurality of overhead lines designated in the line designation step are set at a predetermined size and a predetermined position in the photographing screen. A control target determining step for determining a control target of the optical zoom function of the video camera related to the size of the video camera, and a control target of the shooting center of the video camera related to the position in the shooting screen ;
Controls the optical zoom function to approach the control target of the control target determination step the optical zoom function that will be determined by, the photographing direction so as to approach the control target of the imaging center is determined by the control target determination step A zoom / direction control step for controlling the video camera in a first direction by a changing means ;
A camera rotation control step for controlling the camera rotation means so that the overhead line is directed in a predetermined direction in the shooting screen according to the calculation result of the tilt calculation step;
According measurement results of those the distance and direction measuring means selected the representative line in the selection means (28), controlled by the shooting direction changing means in a second direction perpendicular to the video camera to the first direction An overhead direction imaging method comprising: an imaging direction changing step. 5. The method according to claim 4, further comprising a step of instructing the zoom control means to change to the wide-angle direction when the number of lines extracted in the line extraction step is smaller than a target number of lines. Overhead radiography method.

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