JP2002090117A - Wide angle distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the distance measurement to an object within a wide spatial area and to ensure high reliability. SOLUTION: The image of the object within the whole circumferential area is taken by use of an electronic camera 26 as one reflected image. The reflected image is formed on the electronic camera 26 by a main lens 22 and a focus variable lens unit 24. The subject field depth of the main lens 22 is formed shallow, and the focus variable lens unit 24 changes its focal distance, whereby the distance to the object where it is focused on the reflected image is changed. An image processing part 6 gains focal distance information through a focus variable lens unit control part 4 and detects the area where the reflected image from the electronic camera 26 is in focus. The measurement distance determined from the focal distance is determined to the focused area. The focal distance is changed and focused on each area, whereby the distance to the object reflected to each point of the reflected image is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-angle distance measuring apparatus capable of measuring a distance from a wide area in a wide range in all directions by being installed at one place.

[0002]

2. Description of the Related Art With the recent development of ITS technology, importance has been placed on obstacle detection technology in safe driving support, automatic driving control, and the like.

[0003] As a conventional technique used for obstacle detection,
Radar technology using ultrasonic waves, infrared rays, millimeter waves, etc.
There is a stereo image method for detecting an obstacle from a perspective judgment based on a triangulation method using a stereo camera. In addition, a method using advanced artificial intelligence has been proposed in which a monocular image is image-processed, a region is divided into a background and an obstacle by image recognition, and an obstacle is determined based on its apparent size. I have.

[0004]

The radar technology has a problem that it is difficult to obtain the spatial resolution and the synchronism / immediateness, and a problem that the reliability may be reduced due to competition with other radar waves. Was. In addition, the stereo image method has a problem in robustness such as a correspondence point problem and a mismatch point.

Further, the monocular image method has a problem that it requires an enormous amount of calculation and a problem that it requires complicated knowledge for automatic recognition. In addition, an edge is detected based on a difference in contrast appearing in an image, and the image is divided into regions such as a road surface and a structure.
For example, if the lighting conditions are poor and the contrast is low, or if the background is the same color, it is difficult to discriminate the areas. Conversely, for example, when the shade and the hinata make a contrast on the road surface, they are different areas. May be erroneously recognized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to measure the distance between a wide area and a peripheral area by installing the apparatus at one place, and to detect an obstacle or the like in the peripheral area. It is an object of the present invention to provide a wide-angle distance measuring device to be used.

[0007]

According to the present invention, there is provided a wide-angle distance measuring apparatus comprising: a conical mirror having a conical outer surface reflecting light; and a reflection image of the conical mirror viewed from a central axis direction of the conical mirror. Imaging means for imaging the reflected image, imaging means for imaging the reflected image, and a distance measuring means for measuring the distance to the object around the conical mirror reflected in the reflected image, the imaging means is Focus variable means for changing an object point distance to the in-focus object, the distance measuring means includes a focus detection means for detecting the focused area in the reflected image, Focusing area measuring means for determining a measurement distance of the object reflected in the focusing area based on the optical condition for focusing.

According to the present invention, the conical mirror is positioned around the central axis.
By reflecting light from 60 ° in the direction of the central axis,
The reflection image of the conical mirror viewed from the central axis direction shows a wide-angle and wide-range object around the conical mirror. The generatrix constituting the side surface of the conical mirror may be a straight line or a curve, and the angle of view in the reflected image can be increased or decreased according to the generatrix. The image forming means forms objects at different distances (object point distances) from the conical mirror at different positions in the optical axis direction. Therefore, the reflection image on the imaging surface of the imaging unit may include an in-focus area (in-focus area) and an out-of-focus area. The focus changing unit changes an object point distance corresponding to a focused area on the imaging surface. In a preferred aspect of the present invention, the variable focal length unit has a variable focal length lens unit capable of changing a focal length, and a focal length control unit configured to change the focal length of the variable focus lens unit. It is. In this aspect, while the imaging surface is fixed in the optical axis direction, the position where an object located at a certain object distance forms an image is displaced in the optical axis direction,
The object point distance corresponding to the focused area changes. However, in the present invention, the focus changing means may move the position of the imaging means itself in the optical axis direction to change the object distance corresponding to the focused area. The distance from the conical mirror of the object reflected in the focusing area depends on the shape of the reflecting surface of the conical mirror, the optical parameters of the imaging means, and the positional relationship between the conical mirror, the imaging means, and the imaging means. Can be determined based on optical conditions for focusing on the object, and thereby a measurement distance to the object is determined.

In another wide-angle distance measuring apparatus according to the present invention, the in-focus area measuring means obtains the measuring distance for each point of the reflection image, and based on the measuring distance of each point, A distance image corresponding to the reflection image is generated.

According to the present invention, by changing the object point distance by the focus changing means, it is possible to focus on an arbitrary point of the reflected image, and to focus on the point at which the reflected image is in focus. Finds the measurement distance. As a result, a distance image is generated in which the measured distance of the object reflected at each point of the reflection image is used as image data.

In a wide-angle distance measuring apparatus according to another aspect of the present invention, the distance measuring means determines each point of the reflection image based on a distance to an existing object existing around the conical mirror. Reference distance determining means for determining a reference distance, and validity determining means for comparing the measured distance and the reference distance respectively corresponding to the same position in the reflected image to determine the validity of the measured distance. It is characterized by the following.

According to the present invention, each point of the reflection image is associated with each point in a predetermined direction about the conical mirror. Therefore, if the shape of the existing object existing around the conical mirror is known, the distance to the existing object in each direction centering on the conical mirror is determined, and the point of the reflection image corresponding to each direction will reach the existing object. The distance is associated. For example, when the existing object is a flat surface such as a road surface, the distance to the existing object is calculated geometrically from the height of the conical mirror and the direction of the existing object with respect to the conical mirror corresponding to a point in the reflection image. You can ask. The reference distance determining means determines the reference distance based on the distance to the existing object. The reference distance may be the distance to the existing object itself, or may be, for example, a value offset by a predetermined amount from the distance to the existing object. Here, when another object exists between the existing object and the conical mirror, the measurement distance and the reference distance do not basically match, and the present apparatus does not assume that these two distances match. Absent. However, even when the target object does not exist between the existing object and the conical mirror, a mismatch between the measured distance and the reference distance may occur. And the measurement distance in such a case may not be appropriate for use in detecting an object, etc.
This is determined by the validity determining means. The validity determination means is:
Based on the comparison between the measured distance and the reference distance, a predetermined validity determination regarding the measured distance is performed. For example, if the measured distance is larger than the reference distance, it simply means that the existing object has retreated, but if such a situation is not assumed, the validity determination means does not consider the measured distance to be valid. Is determined. In addition, when tilting or shifting from the state in which the conical mirror is installed, a systematic difference between the measurement distance and the reference distance may occur over the entire reflection image. The validity determining means may be configured to detect such a state.

In a wide-angle distance measuring apparatus according to another aspect of the present invention, the reference distance determining means determines the reference distance for each sub-frame image obtained by dividing the captured image of the reflected image, and The means obtains the measured distance for each of the sub-frame images.

According to the present invention, a captured image is divided into a relatively small number of sub-frame images, and processing such as determination of a reference distance and a measurement distance is performed in units of this sub-frame image. The processing load is reduced as compared with the case where the processing is performed for each of the pixels (for example, the pixels of the imaging element constituting the imaging unit).

In still another wide-angle distance measuring apparatus according to the present invention, the focus changing means changes the object point distance in a width corresponding to the depth of field of the imaging means.

In the width corresponding to the depth of field of the imaging means, it is determined that the object is focused even at different object point distances.
These differences in object point distance cannot be accurately detected. That is, this width becomes the resolution of the measurement distance. According to the present invention, the focus variable unit divides the object point distance into a finite number of ranges for each of the distance resolutions, and associates each range with one focus state (that is, one measurement distance). This simplifies the processing.

[0017]

Next, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic overall configuration diagram of a wide-angle distance measuring apparatus according to the present invention. This apparatus includes an optical system 2, a variable focus lens unit control unit 4, an image processing unit 6, a central control unit 8, and an output unit 10. FIG. 2 is a schematic diagram showing the configuration of the optical system 2. The optical system 2 includes a conical mirror 20, a main lens 22, a variable focus lens unit 24, and an electronic camera 26.

The outer surface of the conical mirror 20 is a mirror, and can reflect light from all directions around the central axis in the direction of the central axis. The conical surface may be a straight line having a generatrix, but here, by using a conical surface convex in an elevation direction formed by an outwardly convex generatrix (for example, a parabola),
The angle of view in the elevation direction reflected on the reflection image of the conical mirror 20 as viewed from the central axis direction is enlarged. The portion near the periphery of the reflection image of the conical mirror 20 is an image of a portion near the bottom surface of the conical mirror 20, and the portion near the center of the reflection image of the conical mirror 20 is an image of a portion near the vertex of the conical mirror 20. is there. As shown in FIG. 2, when the conical surface is convex in the elevation direction, a straight line connecting the actual position of the object reflected in the reflection image and the conical mirror 20 and the central axis of the conical mirror 20 The angle (hereinafter referred to as the elevation angle ψ) increases as the position of the reflection image of the object approaches the circumference of the reflection image of the conical mirror 20.

Main lens 22 and variable focus lens unit 2
Numeral 4 is arranged so that each optical axis coincides with the central axis of the conical mirror 20, and constitutes an image forming means for forming a reflection image of the conical mirror 20 viewed from the central axis direction. In this device,
The distance to the object around the conical mirror is measured based on the focus of the captured reflected image. Therefore, in order to obtain high distance resolution, the imaging means is configured to have a shallow depth of field. Here, in order to make the depth of field shallow, a bright lens having a small F value is used as the main lens 22, and no iris diaphragm is provided. Variable focus lens unit 24
Is a lens unit used as an auxiliary lens of the main lens 22, and can change the focal length of the imaging means. By changing the focal length of the imaging means, the distance (object point distance) to the focused object on the imaging surface of the electronic camera 26 changes. That is, by changing the focal length of the variable focus lens unit 24, a reflected image focused on an object at a different distance from the conical mirror 20 is projected on the imaging surface of the electronic camera 26.

The electronic camera 26 is constituted by using a solid-state image pickup device, and converts a reflection image formed on the image pickup device into an electric video signal and outputs it. As the solid-state imaging device, for example, a device having a large dynamic range such as a CMOS image sensor of a type capable of taking out an incident light as an output signal obtained by logarithmically converting the amount of incident light is suitable. The reason why the wide dynamic range is preferable is that the aperture which is a means for controlling the amount of incident light is eliminated in order to improve the distance resolution as described above, and that the present apparatus can be used both indoors and outdoors. In addition, it can be used outdoors even on a sunny day or at night. When processing using a sub-frame image to be described later is performed, it is desirable to be able to access each sub-frame image obtained by dividing one frame image. Therefore, a solid-state imaging device such as a CMOS image sensor that can randomly access pixels is used. Can be

The variable focus lens unit control section 4 generates a variable focal length control signal, and controls the focal length of the variable focus lens unit 24 based on the signal. The variable focus lens unit 24 notifies the variable focal length lens unit achieved by the signal to the variable focal length lens unit controller 4, and the variable focal length lens unit controller 4 transmits this to the image processor 6 as focal length information. Further, the variable focus lens unit control unit 4 notifies the central control unit 8 of the control state. The control state is, for example, whether or not the variable focus lens unit 24 can be controlled and a response state.

The image processing unit 6 receives a video signal from the electronic camera 26 and outputs a signal to the focus variable lens unit control unit 4.
, And generates a distance image based on the focal length information, which uses the distance to the object reflected at each point of the reflected image as image data. This distance image generation processing will be described later. The generated distance image is output to the output unit 10 such as an image display device. When performing the sub-frame processing, the image processing unit 6 outputs the sub-frame control information to the electronic camera 26 and acquires the video signal of the sub-frame image to be processed from the electronic camera 26.

The central control unit 8 controls the variable focus lens unit control unit 4 and the image processing unit based on the control signal output to the variable focus lens unit control unit 4 and the image processing control signal output to the image processing unit 6. 6 Controls initialization, start / stop, etc. In addition, based on a control state signal from the variable focus lens unit control unit 4, the controllability of the variable focus lens unit 24 is detected, and the system operation state is monitored.

Next, the operation of the present apparatus will be described. FIG.
FIG. 3 is a schematic diagram illustrating the principle of distance measurement in the present device. FIG. 3 is a schematic diagram showing a vertical plane including the conical mirror 20, and the conical mirror 20 is disposed at a point S having a height h above a plane 30 such as a road surface, with a central axis directed vertically. FIG. 4 is a schematic diagram of a reflection image of the conical mirror 20 output from the electronic camera 26. In FIG. 4, the circular image reflected in the rectangular image 32 is the reflection image 34 of the conical mirror 20.

Which point on the reflection image 34 corresponds to an arbitrary point P on the conical mirror 20, and the conical mirror 2 at the corresponding point
Since the direction of the mirror surface of 0 is known in each case, it is possible to specify in which direction the object reflected at the point P is located with respect to the conical mirror 20. That is, the azimuth angle θ of the object is specified from the direction of the line segment OP connecting the center point O and the point P of the reflection image 34, and the elevation angle of the object 物
Is determined according to the length L of the line segment OP. For example, the azimuth angle θ is defined based on the upper part of the screen.

As described above, the present apparatus changes the focal length of the variable focal length lens unit 24, and changes the focal length of the variable focal length lens unit 24 to the object reflected at each point in the reflection image 34 based on the optical condition in which the focal length is in focus. Distance can be measured. Here, the distance to the object is in focus, which is determined according to the focal length of the variable focus lens unit 24 and xi] _F. Variable focus lens unit controller 4, for example, alter the xi] _F from the minimum value to the maximum value, the image processing unit 6, for each reflection image 34 obtained from the electronic camera 26 for each xi] _F, in focus Part (in-focus area) is detected. Then, the image processing unit 6, to the point of focus areas, the xi] _F at that time and the measured distance of the object reflected in the point. Here, the measured distance to the target existing in the direction Θ≡ (θ, ψ) corresponding to the point P is represented by ξΘ.

On the other hand, if the shape of the existing object around the conical mirror 20 is known, the distance to the existing object existing in the direction 対 応 corresponding to the point P can be calculated. For example,
FIG. 3 shows a plane 30 such as a road surface as an existing object. In this case, the distance ξ _SB to the existing point B on the road surface corresponding to the point P can be obtained by a simple geometric calculation. Here, the distance (reference distance) to the existing object existing in the direction Θ, which is obtained based on the shape information of the existing object, is expressed as ξΘ ′. The distance ξΘ ′ may be configured to be calculated by the image processing unit 6 based on the given existing object shape information, or the distance ξΘ ′ calculated in advance may be stored in the image processing unit 6. Can also be configured.

The image processing section 6 can determine the validity of the measured distance ξΘ by comparing the measured distance ξΘ with the reference distance ξΘ ′. For example, if ξΘ> ξΘ ', it simply means that existing structures such as a collapsed road or a lost building have receded. However, if the possibility of occurrence of an error in the focus detection process is higher than the possibility of such a situation, for example, the image processing unit 6 is configured to determine that the measurement distance ξΘ is not appropriate. .

On the other hand, if ξΘ <ξΘ ', it is generally considered that another object exists between the existing object and the conical mirror 20. Therefore, in this case, the image processing unit 6 can be configured to determine that the measurement distance ξΘ is appropriate.

Also, when the device is inclined or shifted from the initial installation state, for example, when something hits the device, if the existing horizontal road surface is based on the measured distance, It can be observed as tilting, or as a whole raised or subsided. Therefore, a pattern of a difference between the measured distance and the reference distance in these assumed abnormal states is registered in the image processing unit 6 in advance,
The image processing unit 6 may be configured to determine that the measured distance is not appropriate when the patterns match.

Note that the case where ξΘ <に 'is generally the case where another object exists between the existing object and the conical mirror 20 as described above. That is, the present apparatus not only measures the distance to an object existing in a certain direction, but also allows the image processing unit 6 to compare the measured distance with the reference distance.
It can be determined whether the measured object is an existing object or not. That is, it is possible to detect, for example, an obstacle on a road by using the distance measuring device.

FIG. 5 is a schematic diagram of an example of an image showing the measured distance when the object is a plane. In this example, one of the object point distances (3 m, 5 m, 10 m, 20 m, and 40 m) quantized in five steps is obtained as the measurement distance according to the depth of field of the main lens 22. As in the case of FIG. 3, the conical mirror 20 is arranged with the central axis directed in the vertical direction, so that the focusing regions corresponding to the respective object point distances form concentric circles. Originally, it is the reflected image 3 that exactly matches each object point distance.
There is only one point on the radius of 4. However, in practice, since the main lens 22 has a depth of field, it is determined that focus is achieved within a certain range in the radial direction. Therefore, the focal region corresponding to each object point distance is a circle having a width like a donut. Therefore, the object point distance is discretely determined so that the reflection image 34 is divided by the doughnut-shaped focusing region. By discretizing the object point distance into a finite number instead of a continuous one, the process of determining the measurement distance is simplified. Here, the object point distance is quantized into five steps. If the depth of field of the main lens 22 is smaller, the object point distance can be obtained in more steps, and the resolution of the measurement distance can be improved. Can be. Conversely, if the depth of field is larger, the object point distance is quantized to a smaller number, and the processing load is further reduced. In FIG. 5, the focus areas 35 to 39 have object distances of 3 m, 5 m, 10 m, respectively.
It corresponds to 20m and 40m.

FIGS. 6 and 7 are schematic diagrams of reflection images for explaining a specific example of processing when another object is present on a plane. The object point distance is adjusted to 10 m and 5 m, respectively. It is an image at the time. 6 and 7 show a flat road surface 40 and a structure 42 as existing objects, respectively, and an image of an obstacle 44 as foreign matter other than the existing objects. The variable focus lens unit control unit 4 operates the focal length of the variable focus lens unit 24 to set the object distance in order from the smaller object distance. The image processing unit 6 captures the image of the electronic camera 26 at each object point distance, and checks the focus of the captured image within a donut-shaped focusing area with respect to a plane at the set object point distance. In FIG. 6, 1
Road surface portion 5 in the focused area corresponding to the object point distance of 0 m
At 0, focus is achieved, but in the image area of the obstacle 44, focus is not achieved even though it is on the donut area.
The image processing unit 6 determines the object point distance at that time as a measurement distance in the focused area. On the other hand, information indicating the defocus (for example, a foreign matter flag) is added to the area where the focus is not achieved. When the processing is completed for all object point distances in this way, the next step is to focus on the area where the foreign object flag is set, and search for an object point distance that is in focus on this area. FIG. 7 shows the result, for example, the obstacle 44
Is detected to be in focus at an object point distance of 5 m, and this object point distance is used as the measured distance of the obstacle 44. At this time, the donut-shaped region 52 corresponding to the object point distance of 5 m is also focused. In this way, the measurement distance corresponding to each point in the reflection image is determined, and a distance image is formed. The above is the outline of the process of forming a distance image, and will be described in more detail below.

FIGS. 8, 9 and 10 are flow charts of the process of forming a distance image by the present apparatus. FIG. 8 shows the main routine. FIG. 9 is an area check process for determining the focus in the in-focus area of each object point distance ξ _F when the object is a plane. Defined as the measurement distance. FIG. 10 shows a foreign matter measurement distance determination process that determines a measurement distance for a point determined to be out of focus in each focusing area with respect to the plane, that is, a point considered to be foreign matter on the plane.

[0036] The device in operation at the start, variable focus lens unit controller 4 controls the variable focus lens unit 24, sets the object distance xi] _F to 3m minimum value (S
60). In this state, the image processing section 6 captures the image of the reflection image of the conical mirror 20 captured by the electronic camera 26 (S6).
2), the object and determines focus at 3m area is focus area obtained in correspondence with the xi] _F = 3m when a plan (3m area check) (S64). This ξ _F =
When the processing for 3 m is completed, the process returns to step S60,
ξ Increment _F to the next quantization value 5m (S6
0), an image is captured (S62), and a 5m area check is performed (S64). Similarly, in the same manner, ξ _F is incremented in order (S60), an image is fetched (S62), and an area check process corresponding to the ξ _F is repeated (S64).

The above-mentioned loop has ξ _F = 3 m, 5 m, 10 m,
Performed on 20 m, when completed also further xi] _F maximum 40m of (S66), foreign matter measuring distance determination process for determining the measurement distance for pixels determined to be a foreign body in the area check is made (S68). In each area check, a measurement distance is determined for a pixel that is in focus, and a measurement distance is determined for a pixel that is determined to be out of focus by the area check and is determined to be a foreign object, in a foreign object measurement distance determination process,
Therefore, when step S68 is completed, the measurement distance of each point of the reflection image is determined, and a distance image is obtained. The image processing unit 6 outputs this distance image to the output unit 10 (S7).
0). The above is the processing of generating a distance image of one frame. If there is no stop instruction, the present apparatus starts generating a distance image of the next frame (S72).

The area check for each エ リ ア_F will be described with reference to FIG. The azimuth θ in the reflection image is set to an initial value 0 (S90). Also setting the distance r from the center of the reflected image to the initial value r _{MI N} (S92). This r _MIN is the radius of the inner boundary circle of the doughnut-shaped focusing area corresponding to the set ξ _F. It is checked whether or not there is a defocus area in the area specified by the coordinates (r, θ) (S94).
The coordinates of the area are specified (S96), and a foreign matter flag is set for the area (S98). This processing is sequentially performed by r
Is incremented (S100), and is repeated until r reaches the upper limit r _MAX (S102). The r _MAX is the radius of the outer boundary circle of the toroidal focus region corresponding to the set xi] _F. Performed in steps S92 to S102,
The processing from the inner end to the outer end of the donut performed for a certain azimuth θ is sequentially repeated by incrementing θ (S104), and is performed for all azimuths (S10).
6), to complete the area check corresponding to the xi] _F.
In the area is determined not to be out of focus in this area check, the xi] _F is defined as the measured distance.

Next, the foreign matter measurement distance determination processing will be described with reference to FIG. Based on the foreign matter flag set in the area check processing, the area check determines that the image is out of focus, and selects an area of interest from an area where the measurement distance has not been determined (S120). ξ Set _F to the initial value 3m (S
122), an image of the reflection image is obtained. As this image, an image acquired for each _{F in} order to perform an area check may be stored, read out and used, or an image captured anew may be used. ξ _F = 3
In the image for m, focus determination is performed on the attention area (S124, S126). If the ξ _F is out of focus, ξ _F is incremented to the next value (S128), and focus determinations S124 and S126 are performed. Then, when focus is achieved (S126), the xi] _F at that time as a measurement distance of the region of interest (S130).
If there is an area for which the measurement distance has not yet been determined (S1)
32), and a new attention area is selected from among them (S13).
4), the processes of steps S122 to S130 are performed. on the other hand,
If the measurement distance has been determined for all the regions for which the foreign object flag has been set (S132), the foreign object measurement distance determination processing ends.

[Second Embodiment] In the above embodiment, the measurement distance is determined for each pixel of the image sensor of the electronic camera 26. On the other hand, in the present embodiment, one frame image of the reflection image is divided into sub-frame images, and the measurement distance is determined for each sub-frame image. Since the configuration of the device is basically the same as that shown in FIGS. 1 and 2 of the above embodiment, these will be referred to as needed in the following description.

FIG. 11 is a schematic diagram for explaining a sub-frame image. This FIG illustrates an image of one frame including a reflection image which is divided into a donut-shaped focus area (focus matching region) for each xi] _F is shown. For example, the one frame image is vertically and horizontally divided into a matrix as shown by a dotted line in the figure, and the partial regions formed by the division are each set as a sub-frame image 150. For example, 1
The image of the frame is divided into 16 vertical and 16 horizontal sub-frame images.

Each of the subframes is mainly labeled based on which focus matching area is included. For example, the subframes 152 to 158 mainly include a 3m focus matching area 160, which is a 3m focus subframe. In this apparatus, the measurement distance is determined in subframe units. That is, one measurement distance is determined for one sub-frame, and a distance image is generated as if each sub-frame is one pixel. In order to perform processing in subframe units at high speed and efficiently, a solid-state imaging device of the electronic camera 26 that can be randomly accessed is used.

FIG. 12, FIG. 13, and FIG. 14 are processing flowcharts of the distance image formation of the present apparatus. FIG. 12 shows the main routine. Figure 13 is a xi] _F focus subframe processing that determines the measurement distance to xi] _F Pinto subframe labeling each object distance xi] _F. FIG. 14 shows the set ξ
_This is a focus inspection process for determining whether or not focus is achieved by _F.

When the processing is started, the image processing section 6 divides an image of one frame into sub-frames corresponding to each ξ _F (S170). Further, a sub-frame corresponding to the central blind spot of the reflection image of the conical mirror 20 is excluded (S172).
The label of the subframe to be processed is designated. Ξ _F is set to an initial value of 3 m (S174), and 3m focused subframe processing is performed on the 3m focused subframe (S1).
76). When the processing for ξ _F = 3 m is completed, ξ _F is incremented to the next quantization value of 5 m (S174).
A 5m focus subframe process is performed on the m focus subframe (S176). Similarly, 以下_F is incremented in order (S174), and ξ _F focus sub-frame processing is performed on each ξ _F focus sub-frame (S17).
6) When the processing for the maximum ξ _F is completed, the processing ends (S178).

The ξ _F focus subframe processing will be described with reference to FIG. When this process is started, among xi] _F Pinto subframe labeled at the set xi] _F,
One subframe is selected (S190). The object point distance ξ _F ′ determined in the focus inspection processing is set to the initial value 3 m (S192), and the focus inspection processing for ξ _F ′ = 3 m is performed (S194). If the foreign matter flag is not set in this inspection processing (S196), it means that the focus is in focus at 3 m, so the measurement distance of the subframe is 3 m
(S198), the next ξ _F focus subframe is selected, and the same processing is performed. On the other hand, when the processing for all the subframes corresponding to the set xi] _F is completed (S200), and ends the xi] _F focus subframe processing. If the object point distance ξ _F ′ = 3 m and the focus is not achieved (S196), the object point distance ξ _F ′ of the inspection target is set to 5
m is incremented (S192), and a focus inspection process is performed (S194). As described above, the object point distance ' _F ′ of the inspection target is sequentially incremented (S192), and the focus inspection process is performed (S194). If any of the ξ _F ′ does not set the foreign matter flag (S196), The ξ _F 'is set as the measurement distance of the subframe (S198). Note that ξ
If the foreign object flag is set in the focus inspection processing for the maximum value of _F ′ (S202), the processing for the subframe is ended without determining the measurement distance as an error.

The focus inspection process will be described with reference to FIG. This process is performed the specified sub-frame and the object point distance xi] _F 'is determined focus. That is, the designated object point distance ξ _F ′ is set as the inspection distance (S21).
0), the focus test is performed on the basis of the image at the object point distance xi] _F 'for the specified sub-frame (S212). If is in focus in this test (S214), the process ends by setting xi] _F 'as the object distance focus is achieved (S216), if were not in focus on the opposite ( (S214), a foreign object flag indicating that effect is set, and the process is terminated (S218).

In the present apparatus, the measurement distance is set to the main lens 2
The area that is discretized according to the depth of field of 2 and basically corresponds to one measurement distance on the image is a continuous area having a relatively large area. That is, even if the measurement distance is obtained for each pixel of the image sensor, it is highly possible that the value does not change in a certain range close to the image sensor. Therefore, the present apparatus reduces the load of the distance measurement process by dividing the image into subframes and determining the measurement distance in subframe units. Here, in order to ensure the accuracy of the distance image, it is basically desirable to set the size of the subframe so that the measurement distance does not change within one subframe.
For example, when the resolution of the measurement distance is high, the continuous range of the area corresponding to one measurement distance is small,
It is desirable to set the sub-frames accordingly small. Conversely, if the distance resolution is low, the sub-frames can be set large to reduce the processing load sufficiently.

[0048]

According to the wide angle distance measuring device of the present invention,
An image of a wide measurement target space area is acquired using a conical mirror. Then, the in-focus state on this image is changed by the focus changing means, and the distance to the object is measured based on the fact that the image is focused. By capturing a wide area as an image, there is an effect that it is easy to realize the simultaneousness / immediateness of distance measurement within the area. Since light is used,
This has the effect of being less affected by other sources than radio waves and ultrasonic waves. In addition, since the distance is measured depending on whether or not the subject is in focus, complicated calculation processing such as pattern recognition is unnecessary, and for example, the possibility of erroneously determining a pattern on the same plane as irregularities is low and reliability is low. high.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of a wide-angle distance measuring device according to the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of an optical system.

FIG. 3 is a schematic diagram illustrating the principle of distance measurement in the present device.

FIG. 4 is a schematic diagram of a reflection image of a conical mirror output from an electronic camera.

FIG. 5 is a schematic diagram of an example of an image showing a measurement distance when an object is a flat surface.

FIG. 6 is a schematic diagram of a reflection image for explaining a specific example of a process when another object exists on a plane.

FIG. 7 is a schematic diagram of a reflection image for explaining a specific example of a process when another object exists on a plane.

FIG. 8 is a processing flowchart of a main routine for forming a distance image of the apparatus.

FIG. 9 is a processing flowchart of an area check process in forming a distance image by the apparatus.

FIG. 10 is a process flowchart of a foreign matter measurement distance determination process in forming a distance image by the apparatus.

FIG. 11 is a schematic diagram illustrating a sub-frame image.

FIG. 12 is a processing flowchart of a main routine of a distance image formation based on a subframe of the apparatus.

FIG. 13 is a processing flowchart of a ξ _F focus sub-frame process for forming a distance image by the apparatus.

FIG. 14 is a processing flowchart of a focus inspection process for forming a distance image by the apparatus.

[Explanation of symbols]

2 optical system, 4 focus variable lens unit controller, 6
Image processing unit, 8 central control unit, 10 output unit, 20 conical mirror, 22 main lens, 24 variable focus lens unit, 26 electronic camera.

Claims (6)

[Claims] 1. A conical mirror having a conical outer surface reflecting light, an imaging unit for imaging a reflection image of the conical mirror viewed from a center axis direction of the conical mirror, and an image of the reflection image. Imaging means, and a distance measuring means for measuring a distance to the object around the conical mirror reflected in the reflected image, wherein the imaging means changes an object point distance to the focused object. A focusing variable means for causing the focus measuring unit to detect the focused focusing area in the reflected image; and A focusing area measuring unit for determining a measuring distance of the object reflected in a focal area; and a wide angle distance measuring apparatus. 2. The wide-angle distance measuring device according to claim 1, wherein the variable focal length means includes: a variable focal length lens unit capable of changing a focal length; and a focal length control for changing the focal length of the variable focus lens unit. Means, and a wide-angle distance measuring device, comprising: 3. The wide-angle distance measuring device according to claim 1, wherein the in-focus area measuring means obtains the measuring distance for each point of the reflection image, and performs the measurement of each point. Generating a distance image corresponding to the reflection image based on the distance. 4. The wide-angle distance measuring device according to claim 1, wherein the distance measuring unit is configured to determine the distance based on a distance to an existing object existing around the conical mirror in advance. Reference distance determining means for determining a reference distance for each point of the reflected image; comparing the measured distance and the reference distance, each corresponding to the same position in the reflected image, to determine the validity of the measured distance A wide-angle distance measuring device comprising: 5. The wide-angle distance measuring device according to claim 4, wherein the reference distance determining means determines the reference distance for each sub-frame image obtained by dividing the captured image of the reflection image, and the focus area measuring means. Calculating the measurement distance for each of the sub-frame images. 6. The wide-angle distance measuring device according to claim 1, wherein the focus varying unit sets the object point distance in a width corresponding to a depth of field of the imaging unit. A wide-angle distance measuring device.