JPWO2019017328A1 - Calibration apparatus and calibration method - Google Patents

Abstract

The calibration device 50 provides a technique for facilitating acquisition of an accurate distance between the imaging device and the calibration subject when performing the calibration process of the imaging device, and for providing a technique for reducing the work involved in the calibration process. A plurality of calibration subjects 51, 52, a subject connecting member 53, a photographing device fixing member 56, and a gap fixing member 57 are provided. The calibration subjects 51 and 52 are juxtaposed with each other with a space therebetween. The subject connecting member 53 connects the calibration subjects 51 and 52 and fixes the interval between the calibration subjects 51 and 52. The image capturing device fixing member 56 positions and fixes the plurality of image capturing devices 54 and 55, which are arranged side by side in a direction intersecting the direction in which the plurality of calibration subjects 51 and 52 are arranged side by side with a gap therebetween. The distance fixing member 57 fixes the distance between the calibration subject 51, 52 and the photographing device 54, 55.

Description

The present invention relates to a technique related to calibration of a photographing device.

By using the image captured by the image capturing device, information on each length of the captured image in the horizontal direction and the vertical direction orthogonal to each other and the information in the direction orthogonal to the captured image (depth direction) are acquired. Various three-dimensional measurement techniques have been proposed.

In order to obtain accurate length information by such three-dimensional measurement, calibration of the image capturing device is necessary.

Patent Document 1 discloses a configuration of a three-dimensional measuring device in which a stereo camera and a measuring device that measures a distance to a survey target point and its direction are integrated. Further, in the configuration of the three-dimensional shape detection device disclosed in Patent Document 2, a mounting table on which a subject is mounted is arranged on one end side, and a photographing section for photographing the subject is arranged on the other end side. Patent Document 2 discloses a technique related to the calibration of the three-dimensional shape detection device having such a configuration.

JP, 2007-147422, A JP, 2007-212159, A

In order to calibrate the photographing device with high accuracy, it is necessary to accurately measure the distance between the photographing device and a subject photographed by the photographing device for calibration.

By the way, in order to observe a fish and the like, a fish may be photographed by a photographing device in the water such as undersea, and the length of the fish may be measured using the photographed image. In such a case, for example, a fish to be observed is photographed by a stereo camera which is a photographing device including a digital video camera, and a photographed image including length information is acquired. The length of the fish and the like are measured using this captured image. In order to improve the accuracy of measurement values such as fish body length, it is necessary to calibrate the stereo camera with high accuracy.

In this case, the stereo camera is calibrated by arranging the stereo camera and a calibration subject (for example, a plate member such as a checkerboard) in water with a space therebetween, and based on a captured image of the calibration subject captured by the stereo camera. Done. However, the distance between the stereo camera and the calibration subject is an interval according to the size of the area to be captured by the stereo camera, and may be, for example, about 2 m. When the stereo camera and the calibration subject are separated from each other in this way, when different people hang the stereo camera and the calibration subject in water from the ship and the distance between the stereo camera and the calibration subject is measured. There is. In such a case, it is difficult to obtain an accurate distance between the stereo camera and the calibration subject. Further, in water such as undersea, the calibration subject may be displaced by wave force, which also makes it difficult to obtain an accurate distance between the stereo camera and the calibration subject.

As described above, since it is difficult to obtain an accurate size of the distance between the underwater imaging device such as a stereo camera and the calibration subject, it is difficult to increase the accuracy of the calibration process of the underwater imaging device.

Furthermore, the change in transparency (degree of visibility) in water such as the sea and lake due to changes in seasons and weather is larger than that in the atmosphere, so it is possible to adapt to changes in seasons without changing the shooting device or shooting location. It is necessary to perform the calibration process of the imaging device at an appropriate timing. Therefore, the imaging device used in the sea or the like has a higher frequency of calibration processing than in the case of being used in the atmosphere. As described above, each time the calibration process is performed, it is necessary to suspend the imaging device and the calibration subject in water from the ship and measure the distance between the imaging device and the calibration subject, which is troublesome.

The present invention has been devised to solve the above problems. That is, a main object of the present invention is to facilitate acquisition of an accurate dimension of the distance between the image capturing device and the calibration subject when performing the image capturing device calibration process, and to reduce the work involved in the calibration process. It is to provide the technology that can.

In order to achieve the above object, the calibration device of the present invention comprises:
A plurality of calibration subjects arranged side by side with an interval between each other,
A subject connecting member that connects the calibration subjects and fixes the interval between the calibration subjects,
An image pickup device fixing member for positioning and fixing a plurality of image pickup devices, which are arranged in parallel with each other in a direction intersecting the direction in which the plurality of calibration subjects are arranged in parallel,
An interval fixing member that fixes an interval between the calibration subject and the imaging device is provided.

Further, the calibration method in the present invention is
By connecting the subject connecting member between a plurality of calibration subjects that are arranged in parallel with each other with a gap therebetween, the gap between the calibration subjects is fixed,
A plurality of photographing devices arranged side by side in a direction intersecting a direction in which the plurality of calibration subjects are arranged side by side are respectively fixed and fixed by a photographing device fixing member,
In a state in which the gap fixing member fixes the gap between the calibration subject and the photographing device,
The photographing device photographs the calibration subject,
The image capturing device is calibrated using the image captured by the image capturing.

According to the present invention, it is possible to easily obtain an accurate dimension of the distance between the image capturing device and the calibration subject when performing the calibration process of the image capturing device, and to reduce the work involved in the calibration process.

It is a perspective view which shows typically the structure of the calibration apparatus of 1st Embodiment which concerns on this invention. It is a figure explaining the structure of the mounting member which comprises the imaging device fixing member in 1st Embodiment. It is a figure explaining the structure of a mounting member with FIG. Furthermore, it is a figure explaining the structure of a mounting member with FIG. 2 and FIG. It is sectional drawing explaining one form example of the connection member which comprises an imaging device fixing member. It is a perspective view explaining an example of composition of a connecting part of an image pick-up device fixed member and a member for interval fixation. It is a perspective view which shows typically the structure of the calibration apparatus of 2nd Embodiment which concerns on this invention. It is a figure explaining other embodiment of a calibration device. It is a figure explaining another another embodiment of a calibration device. It is a figure explaining another another embodiment of a calibration device.

Embodiments according to the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a perspective view schematically showing a calibration device according to a first embodiment of the present invention. The calibration device 1 of the first embodiment is a device (appliance) used when calibrating a stereo camera. In the first embodiment, a stereo camera to be calibrated is composed of a plurality of similar photographing devices (here, digital video cameras) 10 and 11 arranged side by side at intervals, and is used in water such as the sea or lake. It is supposed to photograph fish etc.

The calibration device 1 according to the first embodiment includes a plurality of calibration subjects 2 and 3, a subject connecting member 4, a photographing device fixing member 5, and a gap fixing member 6.

The imaging device fixing member 5 is a member that fixes a plurality of imaging devices 10 and 11 in a state of being arranged side by side with a gap therebetween, and includes mounting members 13 and 14 on which the imaging devices 10 and 11 are installed, and a mounting member 13 and 14, respectively. The connecting member 15 for connecting the members 13 and 14 is provided.

The mounting member 13 and the mounting member 14 have the same structure. Therefore, here, the configuration of the mounting member 13 will be described, and the description of the configuration of the mounting member 14 will be omitted.

FIG. 2 is a perspective view schematically showing the configuration of the mounting member 13, and FIG. 3 is a perspective view schematically showing a state in which the imaging device 10 is mounted on the mounting member 13. The mounting member 13 has a substrate 20 on which the imaging device 10 is mounted, and the substrate 20 is provided with a configuration for positioning and fixing the imaging device 10. FIG. 4 is a diagram illustrating a configuration for positioning and fixing the imaging device 10 on the mounting member 13.

The photographing device 10 may be attached to a supporting tool such as a tripod or a monopod in order to perform stable photographing. In consideration of the attachment to the support tool, the photographing device 10 may be provided with a screw hole 17 and a positioning hole 18 as shown in FIG. In the first embodiment, it is assumed that the imaging device 10 provided with such screw holes 17 and positioning holes 18 is installed on the mounting member 13. Here, the mounting member 13 is provided with a configuration for positioning and fixing the imaging device 10 using the screw holes 17 and the positioning holes 18. That is, the mounting member 13 is provided with the insertion hole 21 at the position of the substrate 20 corresponding to the screw hole 17 of the imaging device 10 when the imaging device 10 is mounted at the set position, and the imaging device 10 has the insertion hole 21. Protrusions 22 are provided at positions on the substrate 20 corresponding to the positioning holes 18. The insertion hole 21 is a through hole that penetrates from the back surface to the front surface of the substrate 20 in FIG. 4, and has a hole diameter that allows a screw 23 that is screwed into the screw hole 17 of the imaging device 10 to be inserted. The protrusion 22 has a shape and a size that allow the protrusion 22 to be loosely fitted in the positioning hole 18 of the imaging device 10.

The imaging device 10 is represented in FIG. 3 by screwing the screw 23 inserted into the insertion hole 21 from the back surface side of the substrate 20 into the screw hole 17 and allowing the protrusion 22 to loosely fit in the positioning hole 18. So that it is installed at the set position on the substrate 20. The substrate 20 is provided with gripping members 24 and 25 in order to fix the imaging device 10 thus installed to the substrate 20.

The gripping members 24 and 25 are plate-shaped small piece members, respectively, and have contact surfaces 24A and 25A that contact the side surface of the image capturing apparatus 10 installed at the set position on the substrate 20. Further, the gripping members 24 and 25 are provided with through holes 26 and 27 penetrating from the front surface side to the back surface side shown in FIG. 2 and the like (in the first embodiment, the through holes 26 and 27). Are provided one by one). The through holes 26, 27 allow the screws 30, 31 to be screwed into screw holes (not shown) for attaching a gripping member provided in the substrate 20 to be inserted, and the flanges of the screws 30, 31 have through holes 26, 27. It has a size to be locked to the opening edge of 27. In addition, in the first embodiment, the through holes 26 and 27 are formed in a long hole shape that extends in a direction approaching and approaching the contact surfaces 24A and 25A. By thus forming the through holes 26 and 27 in the elongated shape, it is possible to adjust the distance between the contact surfaces 24A and 25A of the gripping members 24 and 25 fixed to the substrate 20.

As described above, the photographing device 10 is installed at the set position of the substrate 20, and the contact surfaces 24A and 25A of the gripping members 24 and 25 press the side face of the photographing device 10 as shown in FIG. While holding the screws 30, 31, the grip members 24, 25 are screwed to the substrate 20. As a result, the gripping members 24 and 25 positionally fix the imaging device 10 on the substrate 20 by gripping the imaging device 10. Note that, in the examples of FIGS. 2 to 4, the substrate 20 and the gripping members 24 and 25 of the mounting member 13 (14) and the imaging device 10 are simplified and shown, and the substrate 20 and the gripping members 24 and 25 are illustrated. Alternatively, the shape of the photographing device 10 is not limited to the example shown in the figure. For example, the portions of the substrate 20 and the gripping members 24 and 25 that come into contact with or face the image capturing device 10 (11) are improved in the shape of the image capturing device 10 (11), the workability of attaching the image capturing device 10 (11), and the mounting accuracy. It is preferable to have a shape in consideration of the above.

The connection member 15 is a member that connects the mounting members 13 and 14 and fixes the interval between the mounting members 13 and 14. For example, the connecting member 15 is made of a rod-shaped rigid body (for example, metal such as aluminum). In the first embodiment, the material forming the connecting member 15 is mechanically strong, and because it is assumed to be used in water (for example, in the sea), it is corroded by seawater and easily transported. It is selected in consideration of its lightness and workability. Further, the rod-shaped connecting member 15 may be solid, but may have a hollow structure in consideration of weight reduction. Further, for example, the connecting member 15 may have a rod shape whose cross-sectional shape is shown in FIG. Also in this case, the connecting member 15 can be made lighter than a solid member. The connection member 15 and the mounting members 13 and 14 are connected to each other by, for example, screws.

It is assumed that the interval between the mounting members 13 and 14 fixed by the connecting member 15 is the viewing angle of the image capturing devices 10 and 11 mounted on the mounting members 13 and 14 and the subject to be imaged from the image capturing devices 10 and 11. This is an interval that is appropriately set in consideration of the distance to the area to be processed.

The attachment member 33 is connected to the connection member 15. The attachment member 33 functions as a portion to which the rope 35 used when suspending the calibration device 1 in water is attached. The attachment member 33 is also a rod-shaped member made of the same material as the connection member 15.

A stereo camera is configured by mounting the photographing devices 10 and 11 on the photographing device fixing member 5 including the mounting members 13 and 14 and the connecting member 15 as described above.

The calibration subjects 2 and 3 are subjects whose images (feature points) used for calibration of the imaging devices 10 and 11 are included in the captured images. In the first embodiment, the calibration subjects 2 and 3 are quadrangular frames 2A and 3A, and reinforcements provided inside the quadrangular frames 2A and 3A to reinforce and prevent distortion of the frames 2A and 3A, respectively. A frame structure having frames 2B and 3B is provided. The rectangular frame 2A (3A) and the reinforcing frame 2B (3B) are arranged along a virtual plane. The virtual plane in this example is the xy plane of the three-dimensional orthogonal coordinate system in FIG. Further, the materials forming the frames 2A and 3A and the reinforcing frames 2B and 3B are similar to the connecting member 15 in mechanical strength, corrosion due to seawater, lightness for easy transportation, and processing. It is selected in consideration of ease of use.

Further, the frame 2A of the calibration subject 2 is formed larger than the frame 3A of the calibration subject 3 (for example, the frame 2A is a square with one side of 100 cm, and the frame 3A is a square with one side of 70 cm). .. The calibration subjects 2 and 3 are arranged in parallel with each other in the perspective direction with respect to the photographing devices 10 and 11 so that the smaller calibration subject 3 is closer to the photographing devices 10 and 11 than the larger calibration subject 2. Is set up. The distance between the calibration subjects 2 and 3 and the size of the calibration subjects 2 and 3 are the size of the imaging area determined based on the performance of the imaging devices 10 and 11 and the size of the imaging target (for example, fish). It is set in consideration of the above. In the configuration in which the frame 2A of the calibration subject 2 is larger than the frame 3A of the calibration subject 3, the size of the object in the captured image decreases as the distance from the imaging devices 10 and 11 increases, and the size of the object in the imaging devices 10 and 11 decreases. This is because the viewing angle is taken into consideration.

Further, here, the orientations of the calibration subjects 2 and 3 are arranged such that the imaginary plane on which the quadrangular frames 2A and 3A are arranged is the imaging device 10 mounted on the mounting members 13 and 14. It is oriented so as to be orthogonal to the optical axis of 11. The arranging direction of the calibration subjects 2 and 3 is a direction (z direction in FIG. 1) orthogonal to the arranging direction of the imaging devices 10 and 11 (x direction in FIG. 1). Further, the center lines of the calibration subjects 2 and 3 and the optical axes of the photographing devices 10 and 11 are arranged on the same plane.

When such calibration subjects 2 and 3 are displayed in the images captured by the image capturing devices 10 and 11, for example, the corners of the frames 2A and 3A are used for the calibration process as feature points. The calibration subjects 2 and 3 are provided with a configuration that makes it easy to determine the feature points of the calibration subjects 2 and 3 used for such calibration processing in the captured image. That is, in the first embodiment, the calibration subjects 2 and 3 are composed of the frame members (also referred to as vertical members) along the y direction in FIG. (Also referred to as a lateral member). For example, one of the vertical member and the horizontal member is black, and the other is yellow, so the color combination of the vertical member and the horizontal member is a color combination that makes the difference between the vertical member and the horizontal member clear. ing. The color combination of the vertical member and the horizontal member in the calibration subject 2 may be different from or the same as the color combination of the vertical member and the horizontal member in the calibration subject 3. However, when the color combinations of the calibration subjects 2 and 3 are the same, for example, even if the color combinations are the same, the colors of the vertical members of the calibration subjects 2 and 3 are made different so that It is preferable to make it easy to distinguish the subjects 2 and 3.

The subject connecting member 4 is a member configured by a rod-shaped rigid body for connecting the calibration subjects 2 and 3 and fixing the spacing between the calibration subjects 2 and 3 to the preset spacing as described above. In the first embodiment, the calibration subject 2, 3 is connected by the four subject connecting members 4. The subject connecting member 4 and the calibration subjects 2 and 3 are fixed by, for example, screws. The connection position between each subject connection member 4 and the calibration subjects 2 and 3 is appropriately set in consideration of suppressing the distortion of the calibration subjects 2 and 3 and the deviation of the interval between the calibration subjects 2 and 3. It By using a plurality of subject connecting members 4 as in the first embodiment, the distortion of the calibration subjects 2 and 3 and the calibration subject 2 and 3 are more increased than in the case where there is one subject connecting member 4. It becomes easy to prevent the deviation of the intervals.

The material forming the subject connecting member 4 is also similar to the connecting member 15 described above in terms of mechanical strength, corrosion due to seawater, lightness for easy transportation, and easy processing. Is a material (for example, a metal such as aluminum) appropriately selected in consideration of the above.

For example, ropes 36 and 37 are attached to the calibration subjects 2 and 3 connected by the subject connection member 4, and the calibration subjects 2 and 3 are suspended in water by the ropes 36 and 37. As described above, the calibration subjects 2 and 3 have a frame structure. Therefore, when suspended in water such as in the sea, the calibration subjects 2 and 3 can suppress distortion, positional displacement, and the like due to the pressing force of the water flow.

The distance fixing member 6 is a rigid member that fixes the distance between the calibration subjects 2 and 3 and the photographing devices 10 and 11. In other words, in order to perform accurate calibration of the image capturing devices 10 and 11, it is desirable to obtain information on the correct length between the calibration subjects 2 and 3 and the image capturing devices 10 and 11. In consideration of this, the distance fixing member 6 has a distance between the calibration subjects 2 and 3 and the photographing devices 10 and 11 (specifically, a distance between the calibration subject 3 and the photographing device fixing member 5). The distance between the calibration subject 3 and the imaging device fixing member 5 is fixed so that the set value is obtained. That is, in the first embodiment, the interval fixing member 6 has a configuration in which a plurality of rod-shaped rigid members are juxtaposed and integrated. The interval fixing member 6 has one end side connected to the setting position of the calibration subject 3 with, for example, a screw, and the other end side connected to the setting position of the connection member 15 of the imaging device fixing member 5 with, for example, a screw, thereby performing calibration. The space between the subject 3 and the photographing device fixing member 5 is fixed. Thus, the distance between the calibration subject 3 and the photographing device fixing member 5 is fixed by the distance fixing member 6, and the distance between the photographing devices 10 and 11 is fixed by the connecting member 15 as described above. The distance between the subjects 2 and 3 is fixed by the subject connecting member 4. As a result, the distance between the calibration subjects 2 and 3 and the imaging devices 10 and 11 is fixed.

For example, it is assumed that the calibration subject and the image capturing device are in a separated state, and the calibration subject and the image capturing device are separately suspended from the ship to the water for calibration of the image capturing device. In this case, since the distance between the calibration subject and the photographing device is different each time the calibration process is performed, it is necessary to measure the distance between the calibration subject and the photographing device each time the calibration process is performed. .. The measurement is performed by an operator on the ship after suspending the calibration subject and the imaging device from the ship to the water. Therefore, the measurement work is troublesome and it is difficult to obtain a highly accurate measurement value.

On the other hand, in the first embodiment, as described above, the calibration subjects 2 and 3 and the photographing devices 10 and 11 are underwater while the distance between the calibration subjects 2 and 3 and the photographing devices 10 and 11 is fixed. Can be entered. Therefore, the distance between the calibration subjects 2 and 3 and the photographing devices 10 and 11 can be measured, for example, on the ship, so that the calibration device 1 can easily measure the distance between the calibration subjects 2 and 3 and the photographing devices 10 and 11. Yes Work load can be reduced and accurate measurement values can be obtained. Further, since it is assumed that the distance between the calibration subjects 2 and 3 and the photographing apparatuses 10 and 11 does not substantially change, the calibration apparatus 1 once measures the distance between the calibration subjects 2 and 3 and the photographing apparatuses 10 and 11. If this is done, the subsequent measurement can be omitted and the work load can be further reduced.

The spacing fixing member 6 as well as the connection member 15 is appropriately selected in consideration of mechanical strength, corrosion due to seawater, lightness for easy transportation, and easy processing. It is made of a selected material (for example, a metal such as aluminum). In addition, the rod-shaped members forming the space fixing member 6 may have a shortenable structure, for example, in consideration of ease of transportation.

By the way, as described above, the imaging device fixing member 5 including the mounting members 13 and 14 and the connecting member 15 constitutes a stereo camera by mounting the imaging devices 10 and 11 on the mounting members 13 and 14. .. As a result, the connection member 15 of the photographing device fixing member 5 and the gap fixing member 6 are fixed from the connection member 15 so that the stereo camera and the calibration subjects 2 and 3 can be separated. The member 6 has a configuration in which it is easy to remove (detachable).

Various configurations are conceivable for the configuration for connecting the connection member 15 and the interval fixing member 6 in a state in which they can be easily removed, and any configuration may be adopted. For example, a protruding portion that projects toward the distance fixing member 6 side is provided at the connection position of the connection member 15 that is set to the distance fixing member 6, and the protrusion portion is provided on the end surface of the distance fixing member 6. Is formed into a recess. Further, there is provided a structure for holding (locking) the state in which the protruding portion of the connecting member 15 is fitted in the concave portion of the gap fixing member 6.

Alternatively, for example, the connection member 15 and the interval fixing member 6 may be connected using an L-shaped metal fitting. In this case, for example, as shown in the perspective view of FIG. 6, one piece 42B of the two pieces 42A and 42B forming the L-shaped metal fitting 40 is slid on the connecting member 15. A slide groove 41 that movably fits is formed. Further, the connecting member 15 and the piece 42B of the L-shaped metal fitting 40 communicate with each other while the piece 42B of the L-shaped metal fitting 40 is fitted in the slide groove 41 of the connection member 15. An insertion hole (not shown) is provided. The L-shaped metal fitting 40 is fixed to the connection member 15 by inserting the positioning and fixing pins through these pin insertion holes. When the L-shaped metal fitting 40 is fixed to the connection member 15 in this manner, the piece 42A of the L-shaped metal fitting 40 is projected from the connection member 15. A fitting portion (not shown) into which the piece 42A of the L-shaped metal fitting 40 is fitted is formed on the end surface of the interval fixing member 6. Further, the space fixing member 6 and the piece 42A of the L-shaped metal fitting 40 communicate with each other in a state where the space fixing member 6 and the piece 42A of the L-shaped metal fitting 40 are fitted to each other. A pin insertion hole (not shown) is provided. By inserting the positioning and fixing pins through these pin insertion holes, the L-shaped metal fitting 40 and the interval fixing member 6 are connected. With such a configuration, the connection member 15 and the interval fixing member 6 are connected by the L-shaped metal fitting 40.

The calibration device 1 of the first embodiment is configured as described above. The calibration device 1 can obtain the following effects. That is, in the first embodiment, the distance between the plurality of calibration subjects 2 and 3 is fixed by the subject connecting member 4, and the distance between the calibration subjects 2 and 3 and the imaging device fixing member 5 is fixed. It is fixed by the member 6. For this reason, the distance between the photographing devices 10 and 11 and the calibration subjects 2 and 3 becomes a set value, and it is possible to acquire information on the accurate dimension of the distance between the photographing devices 10 and 11 and the calibration subjects 2 and 3. .. Thereby, the calibration device 1 of the first embodiment can improve the accuracy of the calibration process of the imaging devices 10 and 11. This effect can be exerted especially in water. Further, the calibration device 1 can suppress variations in the accuracy of the calibration process. In other words, the calibration device 1 can improve the repeat accuracy of the calibration process.

Further, as described above, since the interval between the image capturing devices 10 and 11 and the calibration subjects 2 and 3 is a set value, the interval between the image capturing devices 10 and 11 and the calibration subjects 2 and 3 is set at every calibration process. Since it is not necessary to perform the measurement, it is possible to reduce the work of the calibration process.

Further, in the first embodiment, since the calibration subjects 2 and 3 have the frame structure, the wave force received in water becomes weaker than in the case where the calibration subjects 2 and 3 are plate-shaped. Therefore, the calibration device 1 can suppress the distortion and displacement of the calibration subjects 2 and 3 in water.

Further, since the calibration subjects 2 and 3 have the frame structure, the weight can be reduced. Further, the calibration subjects 2 and 3 are planar, and the planar calibration subjects 2 and 3 can be arranged in parallel to include three-dimensional information in a captured image. Therefore, the calibration subjects 2 and 3 can include the three-dimensional information necessary for the calibration process in the captured image without using a cubic solid as the calibration subject, and the volume is suppressed. be able to. Due to the above weight reduction and bulk reduction, the calibration subjects 2 and 3 are easily transported.

Furthermore, since the calibration subjects 2 and 3 have the frame structure, it is possible to reduce the portion of the calibration subject 2 on the far side of the photographing device 10 that is hidden in the shadow of the calibration subject 3 on the near side. It is possible to increase the number of feature points used for processing. Further, the sizes of the calibration subjects 2 and 3 are different, which also contributes to an increase in feature points.

Further, in the first embodiment, the mounting members 13 and 14 of the photographing device fixing member 5 are provided with a configuration for positioning and fixing the photographing devices 10 and 11. For this reason, the mounting members 13 and 14 can install the photographing devices 10 and 11 at the set positions even when the photographing devices 10 and 11 are repeatedly attached and detached, whereby the calibration process is performed each time they are attached and detached. It will not be necessary. That is, the mounting members 13 and 14 can reduce the trouble of performing the calibration process every time the imaging devices 10 and 11 are attached and detached for maintenance or the like.

<Second Embodiment>
The second embodiment according to the present invention will be described below. In the description of the second embodiment, components having the same names as those of the components configuring the calibration device of the first embodiment are designated by the same reference numerals, and duplicate description of the common components will be omitted.

FIG. 7 is a perspective view schematically showing the configuration of the calibration device according to the second embodiment. The calibration apparatus 1 according to the second embodiment includes a calibration subject 8 in addition to the configuration of the first embodiment. The calibration subject 8 is different in size from the calibration subjects 2 and 3. The configuration other than the size of the calibration subject 8 is the same as that of the calibration subjects 2 and 3. That is, the calibration subject 8 is formed smaller than the calibration subject 3 (for example, the calibration subject 2 is a square with a side of 100 cm, the calibration subject 3 is a square with a side of 70 cm, and Subject 8 is a 40 cm square. Further, the calibration subject 8 is arranged between the calibration subjects 2 and 3 (for example, an intermediate position between the calibration subjects 2 and 3) so as to be parallel to the calibration subjects 2 and 3. Further, the position of the center line of the calibration subject 8 matches the position of the center line of the calibration subjects 2 and 3.

The calibration subject 2 and the calibration subject 8 and the calibration subject 3 and the calibration subject 8 are connected by a subject connecting member 4, respectively. In addition, the subject connection member 4 fixes the distance between the calibration subjects 2 and 8 and the distance between the calibration subjects 3 and 8 to set values.

The size of the calibration subject 8 is such that, when the calibration subjects 2, 3 and 8 are photographed by the photographing devices 10 and 11 installed on the mounting members 13 and 14, the corner portions of the calibration subject 8 are photographed images. Is set so as not to overlap the corners of the calibration subjects 2 and 3. That is, the corners of the calibration subjects 2, 3 and 8 in the images captured by the image capturing devices 10 and 11 are used as feature points when performing the calibration process. The provision of the calibration subject 8 in addition to the calibration subjects 2 and 3 increases the number of feature points used in the calibration process in the images captured by the imaging devices 10 and 11. Note that the calibration subject 8 may have a function as a measuring ruler (having a length serving as a reference of a measurement target).

Since the calibration device 1 of the second embodiment has the same configuration as that of the first embodiment, the same effect as that of the first embodiment can be obtained, and the feature points used in the calibration process can be increased. This makes it possible to further improve the accuracy of calibration of the imaging devices 10 and 11.

In the second embodiment, the calibration subject 8 is arranged between the calibration subjects 2 and 3. On the other hand, the calibration subject 8 may be arranged closer to the photographing devices 10 and 11 than the calibration subject 3, for example. However, by disposing the calibration subject 3 larger than the calibration subject 8 on the side closer to the imaging devices 10 and 11, the area to be calibrated in the calibration process can be increased.

<Other embodiments>
The present invention is not limited to the first and second embodiments, and can take various aspects. For example, in the second embodiment, the calibration device 1 includes three calibration subjects. Alternatively, the calibration device 1 may include four or more calibration subjects. That is, if the number of calibration subjects constituting the calibration device 1 is plural, the viewing angles of the imaging devices 10 and 11, the accuracy required for the calibration process, the size of the region for the calibration process, and the like are considered. The appropriate number may be used.

Further, in the first embodiment, the calibration subjects 2 and 3 have different sizes, but the calibration subjects 2 and 3 may have the same size. Further, in the second embodiment, the sizes of the three calibration subjects 2, 3 and 8 are different from each other. Alternatively, for example, the calibration subjects 2 and 3 may have the same size, and the calibration subject 8 may be smaller than the calibration subjects 2 and 3. As described above, when the calibration device 1 includes three or more calibration subjects, the calibration subjects may have different sizes, and the calibration subjects having the same size are included. May be.

Further, although the calibration subjects 2, 3, 8 have a quadrangular shape, they may have other shapes.

Furthermore, in addition to the configurations of the first and second embodiments, the calibration subject has, for example, a light-emitting body such as an LED (Light Emitting Diode) or a visibility such that the calibration subject has a color or pattern with good coloring. A high mark or the like may be provided. For example, as shown in FIG. 8, the identification members 44 such as the light emitters and marks are installed at various places in the calibration subject 2, 3, 8. The identification member 44 can be a feature point used for the calibration process in the images captured by the image capturing devices 10 and 11. The identification member 44 can easily increase the number of feature points used in the calibration process.

Further, in addition to the configurations of the first and second embodiments, as shown in FIG. 10, a cord (for example, a fishing cord) 60 which is a filament material may be stretched between the calibration subjects 2 and 3. .. Furthermore, a mark (for example, a tape) 61 that is an identification member serving as a characteristic point used in the calibration process may be attached to the string 60 and the calibration subjects 2 and 3. In the example of FIG. 10, the calibration subjects 2 and 3 have the same size, and the subject connection member 4 connects the calibration subjects 2 and 3 at the four corners of the rectangular calibration subjects 2 and 3. doing.

Furthermore, in the first and second embodiments, the calibration device 1 is described as being supposed to be used underwater. However, the calibration device according to the present invention is used when calibrating an imaging device on the ground. May be used for.

Further, in the first and second embodiments, the calibration subjects 2, 3, 8 are arranged so that the center lines of the calibration subjects 2, 3, 8 and the optical axes of the photographing devices 10, 11 are on the same plane. 8 and photographing devices 10 and 11 are provided. Instead of this, the calibration subjects 2, 3 are arranged such that the optical axes of the image capturing devices 10, 11 are displaced to the lower side or the upper side in FIG. 1 and the like with respect to the center lines of the calibration subjects 2, 3, 8. , 8 and imaging devices 10, 11 may be provided.

Further, in the first and second embodiments, the calibration subjects 2, 3, 8 have a frame structure. Instead of this, for example, when there is little concern about distortion or displacement of the calibration subject due to wave force (or wind force when it is assumed to be used on the ground), the calibration subjects 2, 3, and 8 are It may be plate-shaped. However, in this case, there is a concern that the calibration subject 2 on the side far from the photographing device 10 becomes a shadow of the calibration subject 3 on the side closer to the photographing device 10 and is not photographed. In order to prevent such a situation, for example, it is preferable that at least the calibration subject 3 on the side closer to the imaging device 10 is configured by using a transparent member.

Further, in the first and second embodiments, the calibration subjects 2, 3 and 8 are connected by the four subject connecting members 4, but the number and connecting positions of the subject connecting members 4 are different from each other for calibration. It may be appropriately set in consideration of the size, strength, shape, etc. of the subjects 2, 3, 8. For example, in the second embodiment, the adjacent calibration subjects 2 and 8 and the adjacent calibration subjects 3 and 8 are connected by the subject connection member 4. Instead of this configuration, for example, the calibration subject 2 and the adjacent calibration subject 8 are connected by the subject connecting member 4, and the calibration subject 2 and the non-adjacent calibration subjects 2 and 3 are connected by the subject connecting member 4. , The calibration subjects 2, 3 and 8 may be connected with a fixed interval.

Further, in the first and second embodiments, the ropes 35, 36, 37 are connected to the calibration device 1 as suspending members for suspending the calibration device 1 in water. Instead of the ropes 35, 36, 37, the hanging member may be a rod-shaped member. In this way, when the hanging member is a rod-shaped member, the rod-shaped member may be arranged so as to pass between the hanging members, for example.

Further, in the first and second embodiments, the interval fixing member 6 has a configuration in which a plurality of rod-shaped members are fixed in a juxtaposed state, but it does not interfere with photographing and is easy to carry. Other forms may be used in consideration of the sheath mechanical strength and the like.

Furthermore, in the first and second embodiments, the connecting member 15 of the image capturing device fixing member 5 has a rod-like form. Alternatively, for example, the connecting member 15 may be a rectangular parallelepiped frame body, and the mounting members 13 and 14 are fixed inside the frame body to connect the mounting members 13 and 14 to each other. It may be configured to.

Furthermore, in each of the first and second embodiments, the mounting members 13 and 14 are disposed at the positions where the imaging devices 10 and 11 are arranged by using the screw holes 17 and the positioning holes 18 provided in the imaging devices 10 and 11. Is provided for positioning. Instead of this, the mounting members 13 and 14 may be provided with another configuration for positioning the imaging devices 10 and 11.

Furthermore, in the description of the second embodiment, it is stated that the calibration subject 8 may have a function as a measuring ruler (having a length serving as a reference of a measurement target). In addition to this, the calibration subjects 2 and 3, the subject connecting member 4, and the interval fixing member 6 in the first and second embodiments may similarly have a function as a measuring ruler.

Further, in the first and second embodiments, aluminum is used as a material forming the subject connecting member 4, the gap fixing member 6 and the connecting member 15, and the subject connecting member 4 and the calibration subjects 2 and 3 are screwed. An example of connecting by is given. Instead of this, for example, when the members 4, 6, 15 are made of stainless steel and are assumed not to be removed, the members 4, 6, 15 and the member to be connected (for calibration) The objects 2 and 3) may be connected by welding.

Furthermore, the calibration device according to the present invention may have a configuration as shown in FIG. 9 as another form. That is, the calibration device 50 in FIG. 9 includes a plurality of calibration subjects 51 and 52, a subject connection member 53, a photographing device fixing member 56, and a gap fixing member 57. The calibration subjects 51 and 52 are arranged in parallel with each other with a space therebetween. The subject connecting member 53 is a member that connects the calibration subjects 51 and 52 and fixes the interval between the calibration subjects 51 and 52. The image capturing device fixing member 56 is a member for positioning and fixing a plurality of image capturing devices 54 and 55, which are arranged in parallel with each other in a direction intersecting the direction in which the plurality of calibration subjects 51 and 52 are arranged side by side. The interval fixing member 57 is a member that fixes the interval between the calibration subjects 51 and 52 and the imaging devices 54 and 55.

In the calibration device 50, as in the first and second embodiments, the distance between the plurality of calibration subjects 51 and 52 is fixed by the subject connection member 53, and further, the calibration subjects 51 and 52 and the imaging device 54. , 55 are fixed by a gap fixing member 57. As a result, the same effects as those of the first and second embodiments can be obtained.

The present invention has been described above using the above-described embodiment as an exemplary example. However, the present invention is not limited to the above embodiment. That is, the present invention can apply various aspects that can be understood by those skilled in the art within the scope of the present invention.

This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2017-141663 for which it applied on July 21, 2017, and takes in those the indications of all here.

1,50 Calibration device 2,3,8,51,52 Calibration subject 4,53 Subject connection member 5,56 Imaging device fixing member 6,57 Interval fixing member

Claims (9)

A plurality of calibration subjects arranged side by side with an interval between each other,
A subject connecting member that connects the calibration subjects and fixes the interval between the calibration subjects,
An image pickup device fixing member for positioning and fixing a plurality of image pickup devices, which are arranged in parallel with each other in a direction intersecting the direction in which the plurality of calibration subjects are arranged in parallel,
A calibration device comprising a space fixing member that fixes a space between the calibration subject and the image capturing device. The calibration subject is a frame structure composed of frames arranged along a virtual plane,
The calibration device according to claim 1, wherein the calibration subject is arranged in a direction in which the virtual plane intersects an optical axis of the imaging device. The plurality of calibration subjects are juxtaposed in the perspective direction with respect to the imaging device fixing member,
The spacing fixing member connects the calibration subject close to the photographing device fixing member of the plurality of calibration subjects and the photographing device fixing member to each other, thereby connecting the calibration subject and the photographing device. The calibration device according to claim 1 or 2, wherein the interval is fixed. The photographing device fixing member is a member that also constitutes a stereo camera together with the plurality of photographing devices,
The calibration device according to claim 3, wherein the interval fixing member is detachably connected to the imaging device fixing member. The calibration device according to claim 1, wherein the plurality of calibration subjects have different sizes. The calibration device according to any one of claims 1 to 4, wherein the plurality of calibration subjects have the same size. The calibration device according to claim 1, wherein the calibration subject is provided with an identification member that is a feature point in a captured image used in a process of calibrating the imaging device. The calibration device according to claim 7, wherein a linear member is provided so as to pass between the calibration subjects, and the identification member is also provided on the linear member. By connecting the subject connecting member between a plurality of calibration subjects that are arranged in parallel with each other with a gap therebetween, the gap between the calibration subjects is fixed,
A plurality of photographing devices arranged side by side in a direction intersecting a direction in which the plurality of calibration subjects are arranged side by side are respectively fixed and fixed by a photographing device fixing member,
In a state in which the gap fixing member fixes the gap between the calibration subject and the photographing device,
The photographing device photographs the calibration subject,
A calibration method for calibrating the photographing device using a photographed image obtained by the photographing.

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