JP2024063309A - Distance measuring camera system, mobile device equipped with same, calibration method, and program - Google Patents

Abstract

[Problem] To provide a distance measurement camera system capable of distance measurement calibration while using a moving device such as a vehicle. [Solution] A distance measurement camera system (1) installed on a moving object and performing distance measurement by photographing the surroundings of the moving object includes a reference object (110), a distance measurement camera unit (20) that photographs the reference object and calculates the reference object distance using distance measurement parameter values, a focusing optical unit (109, 115) having a reflecting unit (111) that reflects light emitted from the reference object and directs it to the distance measurement camera unit, and a distance measurement calibration unit (30) that calibrates the distance measurement parameter values, the reflecting unit being disposed within the photographing angle of view of the distance measurement camera unit, the distance measurement camera unit photographs the reference object via the focusing optical unit to calculate the reference object distance using the distance measurement parameter values, and the distance measurement calibration unit calibrates the distance measurement parameter values based on the reference object distance and a reference optical path length, which is the length of the optical path from the reference object to the point where the light emitted from the reference object is incident on the distance measurement camera unit. [Selected Figure] Figure 1

Description

The present invention relates to a distance measuring camera system.

A distance measuring camera system that uses the principle of triangulation is known as a device for measuring the distance to a subject. Distance measuring camera systems are mounted on vehicles and used to measure the distance to obstacles around the vehicle.

Examples of distance measuring camera systems include stereo camera systems and image plane phase difference measuring camera systems. In a stereo camera system, two cameras are arranged in parallel at a specified distance apart. A stereo camera system detects the shift caused by parallax of the subject in the images captured by each camera, and estimates the distance to the subject based on this. An image plane phase difference measuring camera system takes images using a single camera equipped with an image sensor called an image plane phase difference sensor. An image plane phase difference measuring camera system detects the shift in the image signal generated when light that has passed through an imaging optical system is incident on multiple pixels on the image sensor, and estimates the distance to the subject based on this.

The distance measurement accuracy of these distance measurement camera systems is affected by misalignment in the optical axis direction between the imaging optical system and the image sensor, and in the case of a stereo camera, the distance between the two cameras, misalignment in the optical axis direction, and misalignment in the optical axis direction. For this reason, Patent Document 1 proposes a method for calibrating the parameter values used in calculating distance measurements before product shipment of these distance measurement camera systems or during regular inspections.

JP 2004-132870 A

However, while the calibration method for the ranging camera system described in Patent Document 1 can be performed in a facility such as a factory where the ranging camera system is assembled and installed in a vehicle, it is difficult to perform the method while a user is using the vehicle or outside the facility. A ranging camera system mounted on a vehicle may be deformed due to vibrations and shocks caused by the vehicle's travel, temperature fluctuations due to the outside air and solar radiation, and over time. For this reason, the ranging accuracy of the ranging camera system may decrease while the user is using the vehicle.

The present invention aims to provide a distance measurement camera system that allows distance measurement calibration while using a moving device such as a vehicle.

A distance measuring camera system according to one aspect of the present invention is a distance measuring camera system that is installed on a moving body and measures distance by photographing the surroundings of the moving body, and includes a reference object, a distance measuring camera unit that photographs the reference object and calculates a reference object distance to the reference object using a distance measuring parameter value, a focusing optical unit having a reflecting unit that reflects light emitted from the reference object and directs it to the distance measuring camera unit, and a distance measuring calibration unit that calibrates the distance measuring parameter value, the reflecting unit being disposed within the photographing angle of view of the distance measuring camera unit, the distance measuring camera unit photographs the reference object via the focusing optical unit and calculates the reference object distance using the distance measuring parameter value, and the distance measuring calibration unit calibrates the distance measuring parameter value based on the reference object distance and a reference optical path length, which is the length of the optical path from the reference object to the point where the light emitted from the reference object enters the distance measuring camera unit.

Other objects and features of the present invention are described in the following embodiments.

According to the present invention, it is possible to provide a distance measuring camera system that can perform distance measurement calibration while the mobile device is in use after mounting the distance measuring camera system on the mobile device such as a vehicle.

1 is a cross-sectional view showing a configuration of a distance measuring camera system according to a first embodiment. FIG. 1 is a block diagram of a distance measuring camera system according to a first embodiment. FIG. 13 is a diagram showing an example of a color pattern of a chart. FIG. 1 is a top view of a light guide member of a distance measuring camera system according to a first embodiment; 13 is a flowchart showing a procedure of a calibration process. 4 is a graph illustrating a distance measurement calibration method of the distance measurement camera system according to the first embodiment. FIG. 13 is a top view of a light guide member of a distance measuring camera system according to a second embodiment; 13 is a graph illustrating a distance measurement calibration method of the distance measurement camera system according to the second embodiment.

The following describes in detail an embodiment of the present invention with reference to the drawings. In each drawing, the same components are given the same reference symbols, and duplicate descriptions are omitted.

The following describes the distance measuring camera system 1 according to the first embodiment.

Figure 1 is a cross-sectional view showing the schematic configuration of a distance measuring camera system 1 according to this embodiment. Figure 2 is a block diagram showing the configuration of a distance measuring camera system 1 according to this embodiment.

The distance measuring camera system 1 of this embodiment is installed on a moving object, and captures images of the surroundings of the moving object to measure distances. The distance measuring camera system 1 includes an optical system 101, an image sensor 102, a signal processing circuit 104, a memory 105, a light source 106, and a light guide member 109. The distance measuring camera system 1 also includes a housing 112 that houses these components. The distance measuring camera system 1 is mounted on a vehicle (not shown), which is a moving device equipped with a front windshield 114. In FIG. 1, the left direction (positive Y-axis direction) is the front of the vehicle, the upward direction (positive Z-axis direction) is above the vehicle, and the direction toward the front of the paper is the left of the vehicle (positive X-axis direction).

The optical system 101 is composed of multiple lenses (not shown) and a cylindrical lens barrel (not shown) that holds these lenses. The optical system 101 forms an optical subject image (optical image) from external light, and projects the formed optical image onto the imaging surface (light receiving surface) (not shown) of the imaging sensor 102. The optical axis OA of the optical system 101 is positioned so as to be approximately horizontal and facing forward of the vehicle (positive direction of the Y axis).

The image sensor 102 is a so-called image sensor having a light receiving surface on which pixels made of multiple photoelectric conversion elements are arranged in a matrix. The image sensor 102 converts the optical image formed on the light receiving surface into an electrical signal and outputs an image signal and an image surface phase difference signal. The image surface phase difference signal is a signal obtained from two photoelectric conversion elements at different positions and contains information about the distance to the subject. The light receiving surface of the image sensor 102 is arranged approximately perpendicular to the optical axis OA of the optical system 101 and at a position where an optical image of the subject is formed behind the optical system 101. The image sensor 102 is mounted on a sensor circuit board 103, which is a PCB (Printed Circuit Board).

The signal processing circuit 104 is an integrated circuit such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). As shown in FIG. 2, the signal processing circuit 104 includes an image processing unit 116, a distance measurement calculation unit 117, an output unit 118, a chart brightness calculation unit 121, a distance measurement calibration parameter value calculation unit 123, and a control unit 130, which will be described later. The control unit 130 is a system controller that controls these components.

The memory 105 is a non-volatile, rewritable semiconductor memory such as a flash EEPROM (Electrically Erasable Programmable Read-Only Memory). As shown in FIG. 2, the memory 105 includes a ranging parameter value storage unit 119, a ranging calibration parameter value storage unit 120, and a reference optical path length storage unit 124, which will be described later.

The light source 106 is a light-emitting element such as an LED (Light Emitting Diode), and is supplied with a predetermined voltage and current by a light source driving unit 122, which is a power supply circuit, to illuminate a chart (reference object) 110, which will be described later.

The signal processing circuit 104, memory 105, light source 106, and light source driving unit 122 are mounted on a main circuit board 107, which is a PCB. The sensor circuit board 103 and the main circuit board 107 are electrically connected by a connection cable 108 such as an FPC (Flexible Printed Circuits).

The chart 110 is made of an opaque material such as resin or metal, and is the object to be photographed for correcting the optical system 101. The chart 110 has a planar chart pattern formed by providing areas of different colors on its surface by painting, printing, plating, or the like. The chart 110 is placed near the light source 106 in a position where it is illuminated by the white light emitted by the light source 106.

Figure 3 is a diagram showing an example of the chart pattern of chart 110. The chart pattern of chart 110 is formed by a combination of areas of different colors, that is, black and white areas, and has characteristic points. For example, chart 110 has a color pattern on its surface that has areas of different colors, such as a cross, stripes, or a grid pattern.

The magnifying optical element (magnifying optical system) 115 is a lens made of a transparent material such as glass or polycarbonate resin. The magnifying optical element 115 is positioned facing the chart pattern of the chart 110.

The light guide member 109 is a polyhedron formed of a transparent material such as polycarbonate resin, and has a light exit side reflecting portion (reflecting portion) 111 and light reflecting portions (reflecting surfaces) 125 and 125' (not shown in FIG. 1) described later. Furthermore, the light guide member 109 has a light incident surface 128 that causes light from the magnifying optical member 115 to enter the inside of the light guide member 109. The light guide member 109 and the magnifying optical member 115 are collectively called the focusing optical portion. The light guide member 109 is disposed below the optical axis of the optical system 101. The light exit side reflecting portion 111 reflects light emitted from the chart 110 to guide it to the optical system 101. The light exit side reflecting portion 111 is disposed within the shooting angle of view 100 of the distance measuring camera unit 20 described later, which includes the optical system 101, the image sensor 102, etc., and is disposed in front of the optical system 101. This allows the distance measuring camera unit 20 to shoot the chart 110. At the photographing angle of view 100, the horizontal angle of view is larger than the vertical angle of view. The distance measuring camera unit 20 photographs the chart 110 at a peripheral position of the photographing angle of view 100. Preferably, the distance measuring camera unit 20 photographs the chart 110 at a position lower than the center of the photographing angle of view 100. The light emitting units (reflecting surfaces) 125, 125' are provided between the chart 110 and the light emitting side reflecting unit 111 on the optical path. The light incident surface 128 is disposed near the magnifying optical member 115 and on the opposite side of the chart 110 with respect to the magnifying optical member 115. The magnifying optical member 115 is disposed between the chart 110 and the light emitting side reflecting unit 111 on the optical path.

Figure 4 is a view of the light-guiding member 109 as seen from above (positive direction of the Z axis). The light reflecting portions 125 and 125' are light reflecting surfaces formed of aluminum vapor deposition film on some surfaces of the light-guiding member 109. The light reflecting portion 125 reflects light incident from the light incident surface 128 toward the light reflecting portion 125'. The light reflecting portion 125' reflects light from the light reflecting portion 125 toward the light exit side reflecting portion 111.

The white light emitted by the light source 106 is diffusely reflected by the surface of the chart pattern of the chart 110, and then passes through the magnifying optical member 115 and enters the light incident surface 128 of the light guide member 109. The light that enters the light incident surface 128 travels inside the light guide member 109 and is guided by the light reflecting units 125 and 125' toward the light emitting side reflecting unit 111, and is further guided by the light emitting side reflecting unit 111 to the optical system 101. The optical path is controlled by the magnifying optical member 115, the light emitting side reflecting unit 111, and the light reflecting units 125 and 125'. As a result, an apparent chart 129 with the same chart pattern as the chart 110, a predetermined distance away from the optical system 101, and a predetermined size can be photographed by the image sensor 102.

In this embodiment, the optical path length of the optical path (first optical path) from the chart 110 to the optical system 101 is the sum of the solid arrows a, b, c, and d shown in FIG. 1 and FIG. 4, and is the length R1. By forming an optical path that is reflected multiple times by the light reflecting parts 125 and 125', the optical path length R1 can be secured while forming the light guide member 109 in a small size. In this way, the reflecting parts 125 and 125' of the light guide member 109 function as an optical path extension part that extends the optical path and enables the distance measuring camera unit 20 to take a picture of the chart 110 in a focused state. The value of this optical path length R1 is stored in the reference optical path length storage unit 124 described later as the reference optical path length (the length of the optical path from the light emitted from the chart 110, which is the reference object, to the distance measuring camera unit 20). Note that, if an optical system different from that in this embodiment is used for the optical system 101, the relationship between the optical path length and R1 is not limited to this.

The housing 112 is made of an opaque material such as a metal such as an aluminum alloy or a resin such as ABS, and as shown in FIG. 1, houses components such as the optical system 101, the sensor circuit board 103, the main circuit board 107, the light guide member 109, and the chart 110. The housing 112 is provided with a housing opening (opening) 113 so that the light emitted from the light-emitting side reflector 111 can reach the optical system 101.

The front windshield 114 is a three-layer laminated glass made of two sheets of tempered glass sandwiched with a transparent resin film, and is a transparent windshield installed in front of the driver's seat of a vehicle (not shown). The front windshield 114 is positioned in front of the optical system 101 and tilted downward.

As shown in FIG. 2, the distance measurement camera system 1 has a distance measurement camera unit 20, a distance measurement calibration unit 30, a chart unit 40, and a control unit 130. The distance measurement camera unit 20 captures an image of a chart 110, which is a reference object, via a focusing optical unit, and calculates a reference object distance to the reference object using distance measurement parameter values. The distance measurement camera unit 20 includes an optical system 101, an image sensor 102, an image processing unit 116, a distance measurement calculation unit 117, an output unit 118, a distance measurement parameter value storage unit 119, and a distance measurement calibration parameter value storage unit 120. The distance measurement calibration unit 30 calibrates the distance measurement parameter values, and includes a reference optical path length storage unit 124 and a distance measurement calibration parameter value calculation unit 123. The chart unit 40 includes a light source 106, a light guide member 109, a chart brightness calculation unit 121, and a light source drive unit 122.

When the calibration process described below has not been performed, the imaging sensor 102 in the distance measurement camera system 1 captures an image, receives light from around the vehicle via the optical system 101, and outputs an image signal to the image processing unit 116 and an image plane phase difference signal to the distance measurement calculation unit 117.

The image processing unit 116 is an image signal conversion unit that performs corrections such as distortion correction, brightness correction, and color correction on the image signal, generates image data, and outputs the image data to the output unit 118 described below. The image processing unit 116 also calculates a vehicle surroundings brightness value, which is the brightness of the captured range around the vehicle equipped with the distance measuring camera system 1, based on the image signal, and outputs the vehicle surroundings brightness value to the output unit 118.

The distance measurement calculation unit 117 is a distance measurement value calculation means that calculates the distance value to the subject around the vehicle using the image plane phase difference signal, the distance measurement parameter values stored in the distance measurement parameter value storage unit 119, and the distance measurement calibration parameter values stored in the distance measurement calibration parameter value storage unit 120. The distance measurement calculation unit 117 outputs the distance measurement data to the output unit 118 described later.

The output unit 118 is a data output means that outputs image data and distance measurement data to an ECU (Electronic Control Unit) that controls the vehicle equipped with the distance measurement camera system 1 (not shown).

The ranging parameter value storage unit 119 is a storage unit that stores ranging parameter values, and outputs the ranging parameter values to the ranging calculation unit 117. The ranging parameter values are parameter values required to obtain distance information from the image plane phase difference signal obtained by the imaging sensor 102, and are set before the ranging camera system 1 is shipped, and are written and stored in the ranging parameter value storage unit 119.

The ranging calibration parameter value memory unit 120 is a memory unit that stores ranging calibration parameter values, and outputs the ranging calibration parameter values to the ranging calculation unit 117. The ranging calibration parameter values are parameter values for calibrating the above-mentioned distance information to correct values, and initial values are set in the adjustment process before the product shipment of the ranging camera system 1, and are written and stored in the ranging calibration parameter value memory unit 119.

The chart luminance calculation unit 121 is a luminance calculation means that calculates the chart luminance value required to clearly capture the chart 110 when photographing the chart 110 based on the vehicle surroundings luminance value, and outputs the required chart luminance value to the light source driving unit 122.

The light source driving unit 122 is a light source power supply means that determines the current and voltage for driving the light source 106 based on the required chart brightness value and outputs the current and voltage to the light source 106 to drive and light the light source 106.

The ranging calibration parameter value calculation unit 123 is a ranging calibration parameter value calculation means that compares the reference optical path length stored in the reference optical path length memory unit 124 with the distance value to the chart 110 calculated by the ranging calculation unit 117 to calculate the ranging calibration parameter value. The ranging calibration parameter value calculation unit 123 outputs the ranging calibration parameter value to the ranging calibration parameter value memory unit 120. In this embodiment, the process of calculating and updating the ranging calibration parameter value is called a calibration process.

The reference optical path length memory unit 124 is a memory unit that stores the reference optical path length and outputs the reference optical path length to the ranging calibration parameter value calculation unit 123. The reference optical path length is a value equal to the predetermined distance R1 at which the chart 110 is formed, and is written and stored in the reference optical path length memory unit 124 during an adjustment process before the range-finding camera system 1 is shipped.

The control unit 130 controls the operation of each part of the distance measuring camera system 1, such as image capture by the image sensor 102, image data generation by the image processing unit 116, reading from the memory 105, and output from the output unit 118.

Figure 5 is a flowchart showing the procedure for the calibration process of the distance measuring camera system 1 according to this embodiment.

In step S1, when the calibration process is started in response to a user instruction, the image sensor 102 captures an image, receives light from around the vehicle via the optical system 101, outputs an image signal to the image processing unit 116, and outputs an image plane phase difference signal to the distance measurement calculation unit 117.

In step S2, the image processing unit 116 calculates a vehicle surroundings luminance value, which is the luminance around the vehicle equipped with the distance measuring camera system 1, based on the image signal, and outputs the calculated value to the output unit 118. The output unit 118 outputs the vehicle surroundings luminance value to the chart luminance calculation unit 121.

In step S3, the chart luminance calculation unit 121 calculates the required chart luminance value for clearly capturing the chart 110 when capturing the chart 110 based on the vehicle surroundings luminance value, and outputs the required chart luminance value to the light source driving unit 122.

In step S4, the light source driving unit 122 determines and outputs the current and voltage for driving the light source 106 based on the required chart brightness value so that the chart 110 has the required brightness. This illuminates the chart 110 so that it has the optimum brightness for calibration.

In step S5, the image sensor 102 captures an image of the chart 110 via the light-guiding member 109, and outputs an image signal to the image processing unit 116 and an image plane phase difference signal to the distance measurement calculation unit 117.

In step S6, the light source driving unit 122 stops driving the light source 106 and stops illuminating the chart 110.

In step S7, the distance measurement calculation unit 117 uses the image plane phase difference signal, the stored distance measurement parameter value, and the stored distance measurement calibration parameter value to calculate the apparent display distance of the chart 129. The distance measurement calculation unit 117 then outputs the apparent display distance of the chart 129 (chart display distance value, reference object distance) to the output unit 118. The output unit 118 outputs the chart display distance value to the distance measurement calibration parameter value calculation unit 123.

In step S8, the ranging calibration parameter value calculation unit 123 compares the input chart display distance value with the reference optical path length stored in the reference optical path length memory unit 124 to calculate the ranging calibration parameter value and outputs it to the ranging calibration parameter value memory unit 120.

In step S9, the ranging calibration parameter value storage unit 120 updates the ranging calibration parameter value to the value input in step S8. This completes the calibration.

Figure 6 is a graph that explains the distance measurement calibration method of the distance measurement camera system 1. The horizontal axis of the graph is the correct distance, which means the true distance from the optical system 101 to the subject. The vertical axis of the graph is the measured distance, which means the distance to the subject calculated by photographing the subject with the distance measurement camera system 1.

The solid line 625 is a line segment that indicates the distance measurement result by the distance measurement camera system 1 in a correctly calibrated state. In other words, the solid line 625 indicates a state in which the correct distance and the measured distance match. The point 626 is a point on which the chart display distance value calculated in step S7 is plotted when calibrating the distance measurement camera system 1 in a state in which the distance measurement accuracy has decreased. In other words, since the apparent chart 129 is formed with an optical path length R1, the correct distance is R1, but the measured distance is different, r1.

Dotted line 627 is a line segment that estimates the distance measurement result by distance measurement camera system 1 when the distance measurement accuracy has decreased, has the same slope as solid line 625, and passes through point 626. In other words, the distance measurement result by distance measurement camera system 1 when the distance measurement accuracy has decreased is a value that is shifted by r1-R1 from the correct distance.

To make this estimated measured distance equal to the correct distance, the measured distance is corrected by subtracting r1-R1 from the measured distance. That is, in steps S8 and S9 of the calibration process, the value r1-R1 is calculated as the distance measurement calibration parameter value, the distance measurement calibration parameter value is updated to this value, and the calibration process is terminated. Thereafter, when the distance measurement calculation unit 117 calculates the distance to an obstacle around the vehicle, the value r1-R1 is read from the distance measurement parameter value storage unit 119 as the distance measurement calibration parameter value, and subtracted from the measured distance.

In this embodiment, the chart 110 and the magnifying optical member 115 are formed separately from the light-guiding member 109, but this is not limited to the above. The chart 110 and the magnifying optical member 115 may be formed integrally with the light-guiding member 109. In addition, the magnifying optical member 115 may be replaced by controlling the curvature of the light reflecting portions 125, 125' and the exit side reflecting portion 111.

The chart 110, the magnifying optical member 115, and the light guide member 109 may be disposed below, in front of, or to the side of the main circuit board 107. In this embodiment, the chart 110, the light guide member 109, the chart brightness calculation unit 121, and the distance measurement calibration parameter value calculation unit 123, which are only necessary for performing the calibration process, are housed in the housing 112 and formed as a single body. However, these may be configured as separate entities and installed when performing the calibration process.

The following describes a distance measuring camera system 2 according to Example 2. Note that parts similar to those in Example 1 are given the same reference numbers and descriptions thereof are omitted.

Figure 7 is a view of the light guide member 109 and the light guide member 209 of the distance measuring camera system 2 according to this embodiment, viewed from above (positive Z-axis direction). The distance measuring camera system 2 has charts 110 and 210, magnifying optical members 115 and 215, and light guide members 109 and 209.

Chart 210 has a chart pattern similar to chart 110 and is illuminated by a light source (not shown).

The magnifying optical element 215 is a magnifying optical element similar to the magnifying optical element 115, and is positioned facing the chart pattern of the chart 210.

The light guide member 209 is a polyhedron made of a transparent material such as polycarbonate resin, and has a light exit side reflecting portion (reflecting portion) 211 and light reflecting portions (reflecting surfaces) 225, 225', 225'', and 225''', which will be described later. The light exit side reflecting portion 211 is arranged within the shooting angle of view 100 of the distance measuring camera unit 20, similar to the light exit side reflecting portion 111. Furthermore, the light guide member 209 has a light incident surface 228 that causes light from the magnifying optical member 215 to enter the inside of the light guide member 209. The light guide members 209 are arranged in line to the left of the light guide member 109 (positive direction of the X-axis), and the light exit side reflecting portion 211 is formed on the side near the light exit side reflecting portion 111 of the light guide member 109. As a result, the distance measuring camera unit 20 photographs the charts 110 and 210, which are reference objects, at different positions within the shooting angle of view 100.

Light from the light source that is diffusely reflected by the surface of the chart pattern of the chart 210 passes through the magnifying optical member 215 and enters the light incident surface 228 of the light guide member 209. The light that enters the light incident surface 228 travels inside the light guide member 209 and is guided toward the light emitting side reflecting portion 211 by the light reflecting portions 225, 225', 225'', and 225''', and is further guided to the optical system 101 by the light emitting side reflecting portion 211. The optical path is controlled by the magnifying optical member 215, the light emitting side reflecting portion 211, and the light reflecting portions 225, 225', 225'', and 225'''. As a result, an apparent chart 229 that has the same chart pattern as the chart 210, is a predetermined distance away from the optical system 101, and has a predetermined size can be photographed by the image sensor 102.

The optical path length of the optical path (second optical path) from the chart 210 to the optical system 101 is the sum of the solid arrows a, e, f, g, h, and q shown in Figures 1 and 7, and is length R2. This optical path length R2 is set to a value different from the optical path length R1. The value of this optical path length R2 is stored as the reference optical path length in the reference optical path length memory unit 124, together with the value of the optical path length R1.

Figure 8 is a graph explaining the distance measurement calibration method of the distance measurement camera system 2.

Points 826 and 827 are points where the chart display distance values of the apparent charts 129 and 229 calculated in step S7 of FIG. 5 are plotted when calibrating the distance measuring camera system 2 in a state where the distance measuring accuracy has decreased. That is, the apparent chart 129 is formed with an optical path length R1, and the apparent chart 229 is formed with an optical path length R2, so the correct distances are R1 and R2, respectively. However, these measured distances are r1 and r2, which are different from R1 and R2, respectively. The dashed line 828 is a line segment that estimates the distance measuring result by the distance measuring camera system 2 in a state where the distance measuring accuracy has decreased, and is a line segment that passes through points 826 and 827.

In other words, the distance measurement result by the distance measurement camera system 2 when the distance measurement accuracy has decreased is a value that is shifted from the correct distance by r1-R1 at the position of the correct distance R1, and the slope is shifted by (r2-r1)/(R2-R1)-1.

To make this estimated measured distance match the correct distance, the difference between the dashed line 828 and the solid line 625 is calculated as a function of the measured distance or as a table value, and the measured distance is corrected by subtracting it from the measured distance according to the value of the measured distance.

As described above, more accurate calibration can be achieved by photographing multiple charts 110, 210 through different optical path lengths.

In this embodiment, multiple charts 110 and 210 are used, but this embodiment may also be configured using only one chart (e.g., 110) and a light source that illuminates it.

In addition, the distance between the distance measuring camera system mounted on the vehicle and obstacles around the vehicle becomes closer to the distance measuring camera unit 20 as it moves downward within the shooting angle of the distance measuring camera system. Therefore, by setting the optical path length of a chart photographed below the center of the shooting angle of view to a smaller value and performing calibration, more accurate distance measurement can be achieved.

Other Examples
The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

The above-described embodiments are merely representative examples, and various modifications and variations are possible when implementing the present invention.

The disclosure of each embodiment includes the following configurations and methods:

(Configuration 1)
A distance measuring camera system that is provided on a moving body and captures an image of an area around the moving body and measures distances,
A reference object;
a distance measuring camera unit that captures an image of the reference object and calculates a reference object distance to the reference object using distance measuring parameter values;
a focusing optical unit including a reflecting unit that reflects light emitted from the reference object and directs it to the distance measuring camera unit;
a ranging calibration unit that calibrates the ranging parameter value;
the reflecting unit is disposed within a photographing angle of view of the distance measuring camera unit,
the distance measuring camera unit photographs the reference object via the focusing optical unit, and calculates the reference object distance using distance measuring parameter values;
A ranging camera system characterized in that the ranging calibration unit calibrates the ranging parameter value based on the reference object distance and a reference optical path length, which is the length of the optical path from the reference object to when light emitted from the reference object is incident on the ranging camera unit.
(Configuration 2)
the optical path includes a first optical path and a second optical path different from the first optical path,
The distance measuring camera system of configuration 1, characterized in that the distance measuring camera unit photographs the reference object at different positions within a shooting angle of view of the distance measuring camera unit using light passing through the first optical path and light passing through the second optical path.
(Configuration 3)
3. The distance measuring camera system according to configuration 2, wherein an optical path length of the first optical path and an optical path length of the second optical path are different from each other.
(Configuration 4)
4. The distance measuring camera system according to any one of configurations 1 to 3, wherein the focusing optical unit has an optical path extension unit that enables the distance measuring camera unit to photograph the reference object in a focused state.
(Configuration 5)
5. The distance measuring camera system according to any one of configurations 1 to 4, wherein the focusing optical unit includes a plurality of reflecting surfaces provided on the optical path between the reference object and the reflecting unit.
(Configuration 6)
6. The distance measuring camera system according to any one of configurations 1 to 5, wherein the focusing optical unit includes a magnifying optical system provided on the optical path between the reference object and the reflecting unit.
(Configuration 7)
7. The distance measuring camera system according to any one of configurations 1 to 6, wherein the distance measuring camera unit photographs the reference object at a peripheral position of the photographing angle of view.
(Configuration 8)
In the photographing angle of view of the distance measuring camera unit, a horizontal angle of view is larger than a vertical angle of view,
8. The distance measuring camera system according to any one of configurations 1 to 7, wherein the distance measuring camera unit photographs the reference object at a position lower than a center of the photographing angle of view.
(Configuration 9)
9. The distance measuring camera system according to any one of configurations 1 to 8, wherein a color pattern made up of areas of different colors is formed on the surface of the reference object.
(Configuration 10)
10. The distance measuring camera system according to any one of configurations 1 to 9, further comprising a light source that illuminates the reference object.
(Configuration 11)
a housing that houses the reference object, the distance measuring camera unit, the focusing optical unit, and the distance measuring calibration unit;
11. The distance measuring camera system according to any one of configurations 1 to 10, wherein the housing has an opening formed therein for passing light that has passed through the optical path and been reflected by the reflecting portion.
(Configuration 12)
12. The distance measuring camera system according to any one of configurations 1 to 11, wherein the distance measuring camera unit includes a storage unit that stores the distance measuring parameter values.
(Configuration 13)
A ranging camera system according to any one of configurations 1 to 12, characterized in that the ranging parameter values are parameter values necessary to obtain distance information from an image plane phase difference signal obtained by an imaging sensor of the ranging camera unit.
(Configuration 14)
14. The distance measuring camera system according to any one of configurations 1 to 13, wherein the reference object distance is an apparent display distance of the reference object.
(Configuration 15)
15. A mobile device comprising the distance measuring camera system according to any one of configurations 1 to 14, and capable of moving while holding the distance measuring camera system.
(Method 1)
A distance measuring camera system that is provided on a moving body and captures an image of an area around the moving body and measures distances,
A reference object;
A distance measuring camera unit that photographs the reference object;
a focusing optical unit including a reflecting unit that is arranged within a photographing angle of view of the distance measuring camera unit and reflects light emitted from the reference object and directs it to the distance measuring camera unit, the method comprising:
capturing an image of the reference object via the focusing optical unit;
calculating a reference object distance to the reference object using the ranging parameter values;
a step of calibrating the distance measurement parameter value based on the reference object distance and a reference optical path length, which is the length of the optical path from the reference object to the point where light emitted from the reference object is incident on the distance measurement camera unit.
(Configuration 16)
A program for causing a computer to execute the method for calibrating a distance measuring camera system according to the first method.

Distance measuring camera system 1, 2
Reference object 110, 210
Distance measuring camera section 20
Focusing optical unit 109, 115, 209, 215
Reflecting portion 111, 211
Distance measurement calibration unit 30

Claims (17)

A distance measuring camera system that is provided on a moving body and captures an image of an area around the moving body and measures distances,
A reference object;
a distance measuring camera unit that captures an image of the reference object and calculates a reference object distance to the reference object using distance measuring parameter values;
a focusing optical unit including a reflecting unit that reflects light emitted from the reference object and directs it to the distance measuring camera unit;
a ranging calibration unit that calibrates the ranging parameter value;
the reflecting unit is disposed within a photographing angle of view of the distance measuring camera unit,
the distance measuring camera unit photographs the reference object via the focusing optical unit, and calculates the reference object distance using distance measuring parameter values;
A ranging camera system characterized in that the ranging calibration unit calibrates the ranging parameter value based on the reference object distance and a reference optical path length, which is the length of the optical path from the reference object to when light emitted from the reference object is incident on the ranging camera unit. the optical path includes a first optical path and a second optical path different from the first optical path,
The distance measuring camera system according to claim 1, characterized in that the distance measuring camera unit photographs the reference object at different positions within a shooting angle of view of the distance measuring camera unit using light passing through the first optical path and light passing through the second optical path. The distance measuring camera system according to claim 2, characterized in that the optical path length of the first optical path and the optical path length of the second optical path are different from each other. The distance measuring camera system according to claim 1, characterized in that the focusing optical unit has an optical path extension unit that enables the distance measuring camera unit to photograph the reference object in a focused state. The distance measuring camera system according to claim 1, characterized in that the focusing optical unit includes a plurality of reflecting surfaces provided on the optical path between the reference object and the reflecting unit. The distance measuring camera system according to claim 1, characterized in that the focusing optical unit includes a magnifying optical system provided on the optical path between the reference object and the reflecting unit. The distance measuring camera system according to claim 1, characterized in that the distance measuring camera unit captures the reference object at a peripheral position of the shooting angle of view. In the photographing angle of view of the distance measuring camera unit, a horizontal angle of view is larger than a vertical angle of view,
2. The distance measuring camera system according to claim 1, wherein the distance measuring camera unit captures an image of the reference object at a position lower than a center of the photographing angle of view. The distance measuring camera system according to claim 1, characterized in that a color pattern formed of areas of different colors is formed on the surface of the reference object. The distance measuring camera system according to claim 1, further comprising a light source for illuminating the reference object. a housing that houses the reference object, the distance measuring camera unit, the focusing optical unit, and the distance measuring calibration unit;
2. The distance measuring camera system according to claim 1, wherein the housing has an opening through which the light that has passed through the optical path and is reflected by the reflecting portion passes. The distance measuring camera system according to claim 1, characterized in that the distance measuring camera unit includes a storage unit that stores the distance measuring parameter values. The distance measurement camera system according to claim 1, characterized in that the distance measurement parameter values are parameter values necessary to obtain distance information from an image plane phase difference signal obtained by an image sensor of the distance measurement camera unit. The distance measuring camera system according to claim 1, characterized in that the reference object distance is the apparent display distance of the reference object. A mobile device comprising the distance measuring camera system according to any one of claims 1 to 14, and capable of holding and moving the distance measuring camera system. A distance measuring camera system that is provided on a moving body and captures an image of an area around the moving body and measures distances,
A reference object;
A distance measuring camera unit that photographs the reference object;
a focusing optical unit including a reflecting unit that is arranged within a photographing angle of view of the distance measuring camera unit and reflects light emitted from the reference object and directs it to the distance measuring camera unit, the method comprising:
capturing an image of the reference object via the focusing optical unit;
calculating a reference object distance to the reference object using the ranging parameter values;
a step of calibrating the distance measurement parameter value based on the reference object distance and a reference optical path length, which is the length of the optical path from the reference object to the point where light emitted from the reference object is incident on the distance measurement camera unit. A program for causing a computer to execute the method for calibrating a distance measuring camera system according to claim 16.