JP6138861B2 - Distance calculation device - Google Patents

Description

  The present invention relates to a distance calculation device and a distance calculation method, for example, a distance calculation device applied to an imaging system including a plurality of imaging units.

  Conventionally, in the automobile field and the like, various safety systems are equipped for the purpose of improving safety.

  In recent years, an object detection system for detecting an object such as a pedestrian or a vehicle using a plurality of cameras such as a stereo camera has been put into practical use as one of such safety systems.

  The object detection system described above calculates the positional deviation (parallax) of the same object on a plurality of images captured at the same time by a plurality of cameras (imaging devices) using, for example, template matching, and is known as the parallax. The object can be detected by calculating the position of the object in the real space using

  Such an object detection system for a stereo camera that recognizes an object by calculating the distance to the object using a pair of images captured by a plurality of cameras (imaging devices) is a vehicle safety system described above. In addition to the system, it can also be applied to a monitoring system that detects intrusion or abnormality of a suspicious person.

  A stereo camera target detection system applied to the safety system and the surveillance system is a pair of captured images captured by a plurality of cameras that are captured at a predetermined interval and captured by the plurality of cameras. Is a system that calculates the distance to an object by applying a triangulation technique.

  Specifically, the object detection system generally includes at least two imaging devices (cameras) and stereo image processing that applies triangulation processing to at least two captured images output from these imaging devices. LSI (Large Scale Integration), and this stereo image processing LSI superimposes pixel information included in a pair of captured images captured by a plurality of cameras and shifts the matching position of the two captured images. Triangulation processing is executed by performing calculation processing for calculating the quantity (parallax). In such an object detection system, there is a difference in optical characteristics and signal characteristics for each imaging device so that a shift other than parallax does not occur between a pair of captured images captured by a plurality of cameras. It is necessary to make adjustments so that the distance between the imaging devices is not necessary, or to obtain the distance between the imaging devices in advance.

  FIG. 7 illustrates the principle of the object detection system using the above-described stereo camera. In the figure, δ is parallax (the amount of deviation of the position where a pair of captured images match), and Z is the distance to the object. The measurement distance, f represents the focal length of the imaging device, and b represents the base length (distance between the imaging devices), respectively, and the relationship represented by the following equation (1) is established between them.

  By the way, in the object detection system using a stereo camera, since the parallax δ decreases as the measurement distance to the object increases, the accuracy of the distance measurement to the object decreases as the calculation performance of the parallax δ decreases. There is a problem such as.

  With respect to such a problem, Patent Document 1 discloses a technique for complementing the drawbacks of both the stereo camera and the monocular camera.

  A three-dimensional coordinate acquisition device disclosed in Patent Document 1 calculates a three-dimensional coordinate of an object from images captured by a monocular camera and a stereo camera, and simply switches or integrates the calculation results of both. It is. Moreover, when integrating both calculation results, it is an apparatus which changes both weight according to the distance from the camera of a target object, a vehicle speed, the number of flows, and precision.

JP 2007-263657 A

  According to the three-dimensional coordinate acquisition device disclosed in Patent Document 1, by using images captured by a monocular camera and a stereo camera, the distance to an object in both the monocular camera and the stereo camera is determined. By being able to measure and weighting the three-dimensional coordinates of the object calculated from the images captured by the monocular camera and the stereo camera according to the distance to the object or the vehicle speed, The accuracy of distance measurement to the object can be increased.

  However, in the three-dimensional coordinate acquisition apparatus disclosed in Patent Document 1, the above-described weight distribution method is not mentioned. Moreover, when the reliability of the captured image of each camera falls, there exists a subject that the precision of the distance measurement with the target calculated from the image imaged with each of the monocular camera and the stereo camera falls.

  The present invention has been made in view of the above problems, and the object of the present invention is to perform distance measurement below the parallax resolution of a stereo camera, and the reliability of the captured images of each camera is reduced. Even if it is a case, it is providing the distance calculation apparatus which can measure the relative distance to a target object precisely.

  The present invention is an apparatus for calculating a distance of an imaging system including a plurality of imaging devices, wherein an estimated distance to an object is calculated based on a single image captured by a single imaging device among the plurality of imaging devices. A first estimated distance calculator that calculates, a second estimated distance calculator that calculates an estimated distance to an object based on images captured by at least two of the plurality of imaging devices, and The first estimated distance calculated by the first estimated distance calculator and the second estimated distance calculated by the second estimated distance calculator are weighted and output to the object And an output distance calculation unit for calculating the distance.

According to the distance calculation device of the present invention, in an imaging system including a plurality of imaging devices, for example, distance measurement below the parallax resolution of a stereo camera can be performed, and the reliability of the captured image of each camera decreases. Even so, the relative distance to the object can be precisely and stably measured.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an overall configuration diagram schematically showing an imaging system to which a first embodiment of a distance calculation apparatus according to the present invention is applied. The internal block diagram which shows the internal structure of the distance calculation apparatus of 1st Embodiment shown in FIG. The figure explaining the distance calculation method to the target object using a monocular camera. The figure which shows an example of the weight table according to the certainty factor used by the output distance calculation part shown in FIG. The internal block diagram which shows the internal structure of 2nd Embodiment of the distance calculation apparatus which concerns on this invention. The figure which shows an example of the weight table according to the certainty factor used by the output distance calculation part shown in FIG. The figure explaining the principle of the target object detection system using a stereo camera.

  Embodiments of a distance calculation device and a distance calculation method according to the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 schematically shows an imaging system to which a first embodiment of a distance calculation apparatus according to the present invention is applied.

  The illustrated imaging system 100 mainly includes two cameras (imaging devices) 101 and 102 arranged at a predetermined interval, a camera control device 103 that controls the cameras 101 and 102, and the cameras 101 and 102. A RAM 104 that is a temporary storage area for captured images and the like, a ROM 105 that stores programs and various initial values, and a communication system for notifying a control system such as a brake and the camera recognition state to the user. A certain external IF 106, a distance calculation device 107 that calculates the distance to the object, and a CPU 108 that controls the entire system are provided, each of which can exchange information via a bus 109. . In other words, the imaging system 100 is configured to be able to measure a distance from an object using a stereo camera by using two cameras 101 and 102.

  The cameras 101 and 102 are composed of imaging elements such as CCD (Charge Coupled Device Image Sensor) and CMOS (Complementary Metal Oxide Semiconductor) sensors, for example. Are controlled to be the same. In addition, the exposure of the cameras 101 and 102 is controlled to be the same so that the luminance values are the same when searching for corresponding points in the images captured by both the cameras 101 and 102.

  FIG. 2 shows an internal configuration of the distance calculation device 107 according to the first embodiment shown in FIG. The captured images captured by the cameras 101 and 102 are temporarily stored in the camera image storage units 104a and 104b of the RAM 104, respectively.

  The illustrated distance calculation device 107 mainly includes a monocular estimated distance calculation unit (first estimated distance calculation unit) 203, a stereo estimated distance calculation unit (second estimated distance calculation unit) 204, and an estimated distance comparison unit 205. The output distance calculation unit 206 and the HALT circuit 207 are provided.

  The monocular estimated distance calculation unit 203 calculates an estimated distance (first estimated distance) to an object based on image information captured by the camera 101 and stored in the camera image storage unit 104a, and the calculation result is calculated. It transmits to the estimated distance comparison unit 205.

  As the calculation method of the estimated distance described above, various conventionally known calculation methods can be applied. For example, a calculation method using the vehicle width of the vehicle can be given. Specifically, the vehicle region (position on the screen) is calculated from the image information obtained from the camera image storage unit 104a by pattern matching. Here, the pattern matching is a method of calculating the correlation value of the luminance value of the captured image, and if the luminance value is equal to or greater than a predetermined value, it is determined as “vehicle” and the region is set as “vehicle region”. It is. Thus, the vehicle width of the vehicle can be calculated from the image information obtained from the camera image storage unit 104a, and assuming that the imaging direction of the camera and the rear surface of the vehicle are substantially vertical, the vehicle width of the assumed vehicle Thus, the approximate distance from the vehicle to the target vehicle can be easily calculated.

  FIG. 3 illustrates a method for calculating the distance to the object using the camera 101. In the figure, W is the vehicle width of the preceding vehicle, Z is the distance to the preceding vehicle, and x is the vehicle width on the imaging surface. , F represents the focal length of the camera 101, and since the relationship represented by the following formula (2) is established between them, the distance W to the preceding vehicle can be calculated.

  However, the monocular estimated distance calculation unit 203 may not be able to accurately calculate the distance to the preceding vehicle when the imaging direction of the camera, such as a road surface with a gradient or a curve, and the rear surface of the vehicle are not substantially perpendicular. There is. In addition, since the distance to the preceding vehicle is calculated using the assumed vehicle width or the like, if the vehicle width of the target vehicle is unknown, there is a possibility that an error will occur in the distance to the vehicle. is there.

  Therefore, the estimated stereo distance calculation unit 204 shown in FIG. 2 is based on the respective image information captured by the cameras 101 and 102 and stored in the camera image storage units 104a and 104b. Estimated distance) is calculated. Specifically, the corresponding pixel is searched from the image information obtained from the camera image storage units 104a and 104b, the parallax is calculated, the estimated distance to the target is calculated (see FIG. 7), and the calculation result is It transmits to the estimated distance comparison unit 205.

  More specifically, as a method of searching for corresponding points in images captured by the cameras 101 and 102 in order to calculate parallax, for example, a method of calculating the sum of absolute differences (SAD). Apply a specific part of one image as a template, search for the corresponding position in the image, calculate the sum of the absolute value differences of the luminance values of each pixel, and handle the sum as the highest correlation Position. Thereby, the position shift of one image and the other image can be made parallax. Here, for efficient processing by hardware, the vertical positions of both images are aligned in advance (referred to as “parallelizing”), and a specific part of one image is set to about 4 × 4 pixels and the other is Search the image only in the horizontal direction. An image created by performing this process on one entire image is referred to as a “distance image”. Next, in order to detect the vehicle as the object from the “distance image” created in this way, a plane having the same distance is searched from the “distance image” group, and the width of the object in the plane seems to be a vehicle. If it is a width, it is searched as “vehicle”. Then, the distance to the vehicle as the object is calculated by calculating the average value of the distances of the plurality of “vehicle” areas detected in this way.

  The estimated stereo distance calculation unit 204 includes an estimated distance accuracy calculation unit 202, and the estimated distance accuracy calculation unit 202 calculates the degree of dispersion (variance) of the parallax value of the “vehicle” area detected by the above method. The calculation result is output to the output distance calculation unit 206 as the certainty factor (Confidence) of the stereo estimated distance calculation unit 204. The estimated distance accuracy calculation unit 202 calculates the degree of blur of the entire captured image (for example, using the contrast level as a determination index), and uses the calculation result as the certainty factor of the stereo estimated distance calculation unit 204. good. In addition, if the “distance image” is created by dividing the “distance image” by a fixed value such as about 4 × 4 pixels in order to be efficiently processed by hardware, the distance to the object including the background at the boundary between the vehicle position and 4 × 4 pixels is included. This error is likely to occur. In particular, when the object is located far away, the parallax value decreases and the size of the vehicle also decreases, so it is considered that the error in the distance to the object further increases. Therefore, the estimated distance accuracy calculation unit 202 uses the estimated distance to the object calculated by the stereo estimated distance calculation unit 204, and is large when the distance to the object is short, for example, and small when the distance to the object is far. A certain confidence level may be set. In the present embodiment, the certainty factor is normalized from 0 to 100.

  Here, although it is desirable that the calculation results (estimated distances) calculated by the monocular estimated distance calculation unit 203 and the stereo estimated distance calculation unit 204 are the same, both of them are caused by the difference in the calculation method as described above. The calculation results of are not necessarily the same.

  Therefore, the estimated distance comparison unit 205 that has received the calculation results from the monocular estimated distance calculation unit 203 and the stereo estimated distance calculation unit 204 described above, and the monocular estimated distance calculation unit 203 determine whether or not the distance measurement is illegal. Both estimated distances calculated by the stereo estimated distance calculation unit 204 are compared. When the difference between the estimated distances of the monocular estimated distance calculation unit 203 and the stereo estimated distance calculation unit 204 is equal to or greater than a predetermined threshold, the abnormality is notified to the HALT circuit 207. The predetermined threshold value is stored in the ROM 105 in advance and is transmitted to the estimated distance comparison unit 205 as necessary.

  Further, the output distance calculation unit 206, when the difference between the estimation distances of the monocular estimation distance calculation unit 203 and the stereo estimation distance calculation unit 204 is smaller than a predetermined threshold, the monocular estimation distance calculation unit 203 and the stereo estimation distance calculation unit Based on both the estimated distances 204 and the certainty of the stereo estimated distance calculation unit 204 calculated by the estimated distance accuracy calculation unit 202, an output distance (for output to a control system such as a brake, a display system, etc.) Final distance) is calculated. At this time, the output distance is calculated using a weight table corresponding to the certainty factor stored in the ROM 105 in advance.

  FIG. 4 shows an example of a weight table corresponding to the certainty factor used in the output distance calculation unit 206 shown in FIG. In the figure, monocular is the weight (usage) of the estimated distance (monocular estimated distance) calculated by the monocular estimated distance calculating unit 203, and stereo is the estimated distance (stereo estimated distance) calculated by the stereo estimated distance calculating unit 204. Represents the weight of.

  For example, when the certainty factor (Confidence) of the stereo estimated distance calculation unit 204 is 80, the output distance calculation unit 206 can calculate the output distance (final distance) based on the following equation (3).

  In addition, about the intermediate value of reliability shown in FIG. 4, it can complement linearly from the value before and behind the intermediate value.

  By adopting such a configuration, even when the accuracy of distance measurement of the stereo estimated distance calculation unit 204 decreases due to, for example, variations in parallax values, blurring of the entire image, and the like, regardless of the distance to the target object The distance can be measured stably and accurately.

  If the difference between the estimated distances of the monocular distance calculation unit 203 and the stereo distance calculation unit 204 is large, dirt is attached to the camera lens, measurement is difficult due to bad weather, or the camera sensor There is a high possibility that an abnormality has occurred. Therefore, when the HALT circuit 207 receives an abnormal signal from the estimated distance comparison unit 205, the HALT circuit 207 transmits a stop signal to the output distance calculation unit 206, stops the distance calculation, and stops the system. In addition, the user is notified that the system is not operating normally, and the malfunction is suppressed.

[Second Embodiment]
FIG. 5 shows the internal configuration of the second embodiment of the distance calculation apparatus according to the present invention. The distance calculation device 107A according to the second embodiment illustrated in FIG. 5 analyzes the camera image captured by each camera with respect to the distance calculation device 107 according to the first embodiment illustrated in FIG. The other points are almost the same as the distance calculation device 107 of the first embodiment. Therefore, the same components as those of the distance calculation device 107 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The illustrated distance calculation device 107A includes a monocular estimated distance calculation unit (first estimated distance calculation unit) 203A, a stereo estimated distance calculation unit (second estimated distance calculation unit) 204A, an estimated distance comparison unit 205A, and an output. A distance calculation unit 206A and a HALT circuit 207A are provided, and an estimated distance (first first) to an object based on image information captured by the camera 102 (see FIG. 1) and stored in the camera image storage unit 104Ab. (Estimated distance) is calculated by analyzing the image information stored in the monocular estimated distance calculating unit (first estimated distance calculating unit) 208A and each of the camera image storage units 104Aa and 104Ab, and calculating the reliability of each camera image. Reliability calculation units 201Aa and 201Ab.

The monocular estimated distance calculation unit 208A executes the same calculation as the monocular estimated distance calculation unit 203 of the first embodiment, and calculates the estimated distance to the object based on the image information stored in the camera image storage unit 104Ab. The calculation result is transmitted to the estimated distance comparison unit 205A.

  Further, the reliability calculation units 201Aa and 201Ab analyze the contents of the images stored in the camera image storage units 104Aa and 104Ab, respectively, and determine whether or not the distance from each camera image to the object is accurately measured. The reliability is calculated, and the calculation result is transmitted to the estimated distance comparison unit 205A.

  Various calculation methods can be applied as the reliability calculation method in the reliability calculation units 201Aa and 201Ab described above. For example, when the contrast of an image is calculated and the calculated contrast is low, for example. Is a method of decreasing the reliability and increasing the reliability when the contrast is high. Moreover, it is good also as a reliability of each camera image by detecting a raindrop, mud, etc., and the imaging state of a camera.

  The estimated distance comparing unit 205A calculates the estimated distance (monocular estimated distance) transmitted from the monocular estimated distance calculating units 203A and 208A, the estimated distance (stereo estimated distance) transmitted from the stereo estimated distance calculating unit 204A, and the reliability calculation. Based on the reliability transmitted from the units 201Aa and 201Ab, the estimated distances calculated by the monocular estimated distance calculating units 203A and 208A and the stereo estimated distance calculating unit 204A are compared. Specifically, the estimated distance comparison unit 205A selects a monocular estimated distance calculation unit that calculates an estimated distance to an object based on a highly reliable camera image, and estimates transmitted from the monocular estimated distance calculation unit The distance is compared with the estimated distance transmitted from the stereo estimated distance calculation unit 204A. Similarly to the first embodiment, when the difference between the estimated distances of the monocular estimated distance calculation unit and the stereo estimated distance calculation unit 204A is equal to or greater than a predetermined threshold, an abnormality is notified to the HALT circuit 207A. To do.

  Note that the estimated distance comparison unit 205A is stored in each of the camera image storage units 104Aa and 104Ab instead of selecting a monocular estimated distance calculation unit that calculates an estimated distance to the object based on a highly reliable camera image. The results of the estimated distances calculated by the monocular estimated distance calculation units 203A and 208A may be merged according to the reliability ratio of each camera image. By adopting such a configuration, it is possible to prevent the monocular estimated distance calculation units 203A and 208A from being frequently switched during distance measurement and the calculation result of the monocular estimated distance becoming unstable.

  When the difference between the estimated distances of the monocular estimated distance calculating unit and the stereo estimated distance calculating unit is smaller than a predetermined threshold, the output distance calculating unit 206A includes the estimated distances transmitted from the monocular estimated distance calculating units 203A and 208A, The estimated distance transmitted from the estimated stereo distance calculation unit 204A, the certainty factor of the estimated stereo distance calculation unit 204A calculated by the estimated distance accuracy calculation unit 202A, the reliability transmitted from the reliability calculation units 201Aa and 201Ab, Based on the above, an output distance (final distance) for output to a control system such as a brake or a display system is calculated. At that time, the output distance is calculated using a weight table corresponding to the certainty factor stored in the ROM 105A in advance.

  FIG. 6 shows an example of a weight table corresponding to the certainty factor used in the output distance calculation unit 206A shown in FIG. In the figure, the monocular 1 is a weight (usage rate) of the estimated distance (monocular estimated distance) calculated by the monocular estimated distance calculating unit 203A, and the monocular 2 is the estimated distance weight calculated by the monocular estimated distance calculating unit 208A. Stereo represents the weight of the estimated distance (stereo estimated distance) calculated by the stereo estimated distance calculation unit 204A.

  As shown in the figure, in the second embodiment, the two estimated distances calculated by the monocular estimated distance calculating units 203A and 208A and the estimated distance calculated by the stereo estimated distance calculating unit 204A are confident. The relative distance to the object is calculated by weighting according to the degree.

  Specifically, for example, when the certainty factor of the stereo estimated distance calculation unit 204A is low, the weights of the estimated distances calculated by the monocular estimated distance calculation units 203A and 208A are increased, and distance measurement using a monocular camera is mainly performed. Thus, the distance to the object can be accurately and stably calculated. At that time, for example, even if the accuracy of distance measurement of one of the two cameras is reduced due to the influence of mud or raindrops, the effect of mud and raindrops can be achieved by combining the distance measurement with two monocular cameras. Robustness to the like can be improved. On the other hand, for example, when the certainty factor of the stereo estimated distance calculation unit 204A is high, the weight of the estimated distance calculated by the stereo estimated distance calculation unit 204A is increased, and the distance measurement using a stereo camera is mainly performed. The distance to the object can be calculated precisely and stably.

  In the illustrated example, the monocular 1 and the monocular 2 are shown to have the same value for each certainty factor of the stereo estimated distance calculation unit 204A. However, the reliability of the camera images stored in the camera image storage units 104Aa and 104Ab is shown. The weights of the estimated distances calculated by the monocular estimated distance calculating units 203A and 208A are calculated based on the degrees, and the estimated distances calculated by the monocular estimated distance calculating units 203A and 208A according to the reliability of each camera image are calculated. The weight may be variably set. For example, when one camera is soiled due to mud, raindrops, etc., the reliability of the stereo estimated distance calculation unit 204A is reduced, and the reliability of the camera image captured by the one camera is also reduced. Since the reliability of camera images captured with a clean camera is still maintained, mud and raindrops can be increased by increasing the weight of the estimated monocular distance calculated based on the camera image captured with a clean camera. The robustness against the influence of the above can be further improved.

  In the first and second embodiments described above, the embodiment using two cameras (imaging devices) has been described. However, at least two imaging devices are provided, and distance measurement with an object using a stereo camera is possible. If possible, the radix of the imaging device can be changed as appropriate.

  In the first and second embodiments described above, the mode in which one or both of the two cameras (imaging devices) constituting the stereo camera are used for the monocular camera has been described. For example, the camera constituting the stereo camera And a monocular camera may be provided separately.

  In addition, this invention is not limited to above-described embodiment, Various deformation | transformation forms are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files that realize each function can be stored in a storage device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  Further, the control lines and information lines are those that are considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

100 Imaging System 101, 102 Camera (Imaging Device)
103 Camera control device 104 RAM
104a, 104b Camera image storage unit 105 ROM
106 External IF
107 Distance calculation device 108 CPU
109 Bus 202 Estimated Distance Accuracy Calculation Unit 203 Monocular Estimated Distance Calculation Unit (First Estimated Distance Calculation Unit)
204 Stereo estimated distance calculation unit (second estimated distance calculation unit)
205 Estimated distance comparison unit 206 Output distance calculation unit 207 HALT circuit

Claims (9)

A distance calculation device for an imaging system including a plurality of imaging devices,
A first estimated distance calculation unit that calculates an estimated distance to an object based on a single image captured by a single imaging device among the plurality of imaging devices;
A second estimated distance calculation unit that calculates an estimated distance to an object based on images captured by at least two of the plurality of imaging devices;
Weighting is performed on the first estimated distance calculated by the first estimated distance calculating unit and the second estimated distance calculated by the second estimated distance calculating unit, and the distance to the target object is calculated. An output distance calculation unit for calculating the output distance,
The output distance calculating unit (1) increases the weight of the first estimated distance when the certainty factor for the second estimated distance is low, and (2) the certainty factor for the second estimated distance is When the distance is high, at least one of increasing the weight of the second estimated distance is performed.   The distance calculation apparatus according to claim 1, wherein the first estimated distance calculation unit calculates the first estimated distance by pattern matching. The output distance calculating unit (1) increases the weight of the first estimated distance when the certainty factor for the second estimated distance is low, and (2) the certainty factor for the second estimated distance is The distance calculation apparatus according to claim 1, wherein when it is high, the weight of the second estimated distance is increased.   The distance calculating device includes a plurality of the first estimated distance calculating units that calculate an estimated distance to an object based on an image captured by a single imaging device among the plurality of imaging devices, and the output The distance calculating unit includes a plurality of first estimated distances calculated by the plurality of first estimated distance calculating units, a second estimated distance calculated by the second estimated distance calculating unit, and the at least 2 Weights of the plurality of first estimated distances and the second estimated distances determined according to the certainty factor of the second estimated distance calculation unit calculated based on images captured by one imaging device; The distance calculation device according to any one of claims 1 to 3, wherein the output distance is calculated on the basis of.   5. The distance calculation device according to claim 4, wherein the weight of each of the plurality of first estimated distances is calculated based on a reliability of each image used in each first estimated distance calculation unit. .   The certainty factor is the degree of variation in the parallax value of the object in the images taken by the at least two imaging devices, the degree of blurring of the images taken by the at least two imaging devices, and the imaging by the at least two imaging devices. 6. The distance calculation device according to claim 3, wherein the distance calculation device is calculated based on at least one of estimated distances to an object calculated based on the obtained image. An estimated distance comparison unit that compares the first estimated distance and the second estimated distance;
A HALT circuit that receives an abnormal signal from the estimated distance comparison unit when a difference between the first estimated distance and the second estimated distance compared by the estimated distance comparison unit is equal to or greater than a predetermined threshold; The distance calculation device according to any one of claims 1 to 6, further comprising:   The HALT circuit, when receiving an abnormal signal from the estimated distance comparison unit, transmits a stop signal to the output distance calculation unit and stops the output distance calculation by the output distance calculation unit. 8. The distance calculation device according to 7.   9. The distance calculation according to claim 7, wherein the HALT circuit notifies the user that the imaging system is not operating normally when receiving an abnormal signal from the estimated distance comparison unit. apparatus.

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