JP3941790B2 - Moving object detection apparatus and method - Google Patents

Description

  The present invention relates to a moving object detection apparatus and method for detecting a moving object from a measurement result of a laser radar.

  Conventionally, detection of a moving object in a predetermined monitoring area is generally performed by performing predetermined image processing on an image obtained by photographing the monitoring area with a monitoring camera. Specifically explaining this detection method, a background image that does not move for a long time is previously captured using a monitoring camera, and a difference between this background image and a new image captured by the monitoring camera is taken, An object photographed with a pixel having a difference is detected as a moving object.

In recent years, in addition to the detection method using the monitoring camera, a moving object detection method using a laser radar has been devised. In this detection method, a laser beam is scanned in a monitoring area to be monitored, reflected light, diffracted light, or scattered light reflected by an object in the monitoring area is received and the temporal change is detected. It detects moving objects. For example, in Patent Document 1 below, a method has been devised in which a monitoring area is set as a pedestrian crossing and a pedestrian crossing the pedestrian crossing is detected.
JP 2002-140790 A

  By the way, the detection method using the monitoring camera has a problem that the detection performance is remarkably deteriorated in a place where the environment changes greatly, such as outdoors, and the moving object cannot be detected stably. For example, in a situation where clouds are scattered in the sky (a situation other than a situation where no clouds are present in the sky or a situation where the clouds cover the entire sky), the shadow of the building will remain as long as the clouds block the light from the sun. Will not appear, but if the sun comes out of the clouds, the shadow of the building will appear, so the newly appearing shadow will be falsely detected as a moving object. Furthermore, although it is possible to detect a vehicle or the like whose lights are on at night, it cannot accurately detect a moving object.

  Further, in the detection method using the laser radar disclosed in Patent Document 1, the height position of the ground that does not vary with time is set as a reference plane (height 0) and predetermined with respect to the reference plane. Is set as an object in the monitoring area (moving object). For this reason, if the ground surface is uneven, a moving object is erroneously detected. For example, when the bottom of the moving object is placed on the reference plane, even if the top position exceeds the height threshold, the moving object is placed in the concave portion of the ground and the top position of the moving object is If the height threshold value is lower than that, the moving object cannot be detected.

  The present invention has been made in view of the above circumstances, even under circumstances where the environment of the monitoring area fluctuates, or even under circumstances where the reference plane for detecting a moving object cannot be set to a plane. An object of the present invention is to provide a moving object detection apparatus and method capable of stably detecting a moving object.

In order to solve the above problems, a moving object detection device of the present invention includes a laser radar (10) that scans a detection region including at least a predetermined region (SR), distance information measured by the laser radar, and the laser. means for generating a background distance map from the information indicating the scanning position of the radar indicating the background distance of the entire detection area, the value of the singularity contained in the background distance map from the background distance in near the singularity A background distance map generating means (21) provided with a singular point removing means for removing the singular points by setting the average value of the remaining background distances except for those having the smallest difference from the value of the singular points ; by comparing the background distance of the background distance map at the distance information and the distance information detecting point and its surroundings were obtained as measured by the scanning of the laser radar of the predetermined It is characterized by comprising detecting means for detecting a moving object in the region (23).
According to the present invention, when there is no moving object in the detection area including the predetermined area, the background distance map showing the background distance of the entire detection area based on the measurement result of the laser radar in advance, the background from which the singular point is removed A distance map is generated, and the background distance map is compared with distance information measured by the laser radar to detect a moving object in a predetermined area.
Further, in the moving object detection device of the present invention, the background distance map generation means periodically updates the background distance map from distance information measured by the laser radar and information on the scanning direction of the laser radar. It is characterized by that.
According to the present invention, the background distance map is periodically updated by the background distance map generating means .
In order to solve the above-described problems, the moving object detection method of the present invention includes a measurement step (S12) of scanning a laser radar to measure a detection area including at least a predetermined area, and a distance measured by the laser radar. information and the background distance map generating step from the information indicating the scanning position of the laser radar generates a background distance map indicating the background distance of the entire detection area (S13, S14) and, near the singularity contained in the background distance map The average value of the remaining background distances, excluding those with the smallest difference from the value of the singular point from the background distance, and the singular point is removed by setting the value of the singular point to the average value a point removal step (S16), the background distance Ma in the distance information and the detection point and around thereof the distance information is obtained to be measured by scanning of the laser radar By comparing the background distance flop it is characterized by including a detection step of detecting a moving object in the predetermined area.

According to the present invention, since the moving object is detected from the difference between the distance when there is no moving object (background distance) and the distance when there is a moving object in front of the background, the illuminance change due to the presence or absence of sunlight irradiation Even if there is an environmental change such as this, there is an effect that a moving object can be detected stably. Further, since the moving object is detected based on the change in distance from the background distance, there is an effect that the moving object can be detected stably regardless of the positional relationship between the background and the moving object.
Further, according to the present invention, since the background distance map is periodically updated, there is an effect that when the background changes due to construction or the like, the construction location is not erroneously detected as a moving object, By automatically updating the background, there is an effect that no new adjustment is required when the background changes.
In addition, according to the present invention, the value of the singular point in the background distance map is set to the average value of the background distance around it, so that it is erroneously detected when a moving object is detected by a change in distance from the background distance. There is an effect that can be prevented.
Further, according to the present invention, when detecting a moving object, the distance information measured at a certain detection point is compared with the background distance of the background distance map at the detection point and its surroundings. Even when the scanning error occurs, a stable moving object can be detected.

  Hereinafter, a moving object detection apparatus and method according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a moving object detection apparatus according to an embodiment of the present invention. As shown in FIG. 1, the moving object detection device of the present embodiment includes a laser radar 10 and a detection device body 20. The laser radar 10 is housed integrally in a predetermined housing to form a sensor unit, and is installed at a predetermined height such as a wall surface of a building or a utility pole. For example, monitoring for detecting a moving object as shown in FIG. It arrange | positions so that the whole area | region (predetermined area | region) may be looked down on.

  FIG. 2 is a diagram illustrating an example of a mounting state of the laser radar 10. In the example shown in FIG. 2, the laser radar 10 is arranged so as to look down on the road surface R passing between the building BL1 and the building BL2. In the present embodiment, it is assumed that the monitoring area SR is on the road surface R between the building BL1 and the building BL2. The laser radar 10 scans the monitoring region SR and a region (detection region) including a part of the buildings B1 and B2.

  The laser radar 10 is provided with a main scanning motor 12 that drives the polyhedral mirror 11 to rotate at a constant speed, and a rotation axis of the polyhedral mirror 11 within a predetermined angular range. And a sub-scanning motor 13 that swings the rotating surface of the polyhedral mirror 11 at a predetermined speed. The laser radar 10 is provided with a laser light source 14, and the polyhedral mirror 11 is irradiated with pulsed laser light emitted from the laser light source 14 via the half mirror 15. The detection region including the monitoring region SR is irradiated according to the rotation and inclination of the lens. In addition, the reflected light from the region including the monitoring region of the pulse laser light is received by the light receiver 17 from the polyhedral mirror 11 via the condenser lens 16.

  That is, the laser radar 10 deflects and scans the irradiation direction of the pulsed laser beam in the main scanning direction (x direction) at high speed by rotating and swinging the polyhedral mirror 11, while scanning the scanning surface in the sub scanning direction (y direction). ), Thereby scanning the entire detection region including the monitoring region SR as illustrated in FIG. In addition, the reflected light from various objects in the detection area is received in synchronization with the irradiation of the pulsed laser light, and the object from the light receiving timing (the elapsed time from the pulsed laser light irradiation timing to the reflected light receiving timing). The distance information to (reflection point) is obtained.

  The scanning range by the laser radar 10 is set to 60 degrees in the main scanning (horizontal) direction and 30 degrees in the sub-scanning (vertical) direction, for example. In addition, the laser radar 10 is configured to sequentially apply information of reflected light by irradiating pulse laser light every time the scanning direction changes by 0.1 degrees and receiving the reflected light, for example. Therefore, in the detection area including the monitoring area SR, 600 detection points are provided in the x direction and 300 detection points are provided in the y direction.

  On the other hand, the detection apparatus main body 20 is constituted by a personal computer, for example, and includes a background distance map generation unit 21, a background distance map memory 22, a moving object detection unit 23, and an output control unit 24 as shown in FIG. The From the reflected light information obtained by using the laser radar 10 described above, the background distance map generation unit 21 determines the distance from the laser radar 10 to the reflection point set in the detection area when there is no moving object in the detection area ( A background processing map indicating the background distance is generated.

  FIG. 3 is a diagram illustrating a configuration of the background distance map generation unit 21. As shown in FIG. 3, the background distance map generation unit 21 includes a laser pulse scanning unit 21a, a reflected light measurement unit 21b, a distance information conversion unit 21c, and a singular point removal unit 21d. The laser pulse scanning unit 21a drives the laser light source 14, and also drives the main scanning motor 12 and the sub-scanning motor 13 to control the scanning of the pulse laser light by the rotation of the polyhedral mirror 11 and its swing. The laser pulse scanning unit 21a outputs a synchronization signal indicating a main scanning angle and a sub scanning angle when the main scanning motor 12 and the sub scanning motor 13 are scanned.

  The reflected light measurement unit 21b receives the synchronization signal output from the laser pulse scanning unit 21a and measures the light reception timing of the reflected light by the object of the pulse laser beam. The distance information conversion unit 21c converts the light reception timing (time) measured by the reflected light measurement unit 21b into a distance. The distance here is a distance from the laser radar 10 to each reflection point in the detection region.

  The background distance map is a map showing distance information from the laser radar 10 to each reflection point in the detection region, and is a distance obtained through measurement of the light reception timing in the reflected light measurement unit 21b and conversion processing in the distance information conversion unit 21c. The information is created by sequentially mapping the information on the background distance map memory 22 according to the information indicating the main scanning angle and the sub-scanning angle obtained from the laser pulse scanning unit 21a. That is, the background distance map memory is written by writing the distance information obtained at that time to the coordinates (address of the background distance map memory 22) specified by the main scanning angle and the sub scanning angle indicating the scanning direction of the pulse laser beam. A laser radar image for three-dimensionally specifying the reflection point of the pulse laser beam on the above-described monitoring region SR is created on 22.

  The singular point removing unit 21d reads the background distance map stored in the background distance map memory 22, and removes the singular points included in the background distance map. Here, the singular point is a point where the background distance in the background distance map shows an abnormal value due to noise or measurement omission. Since the background distance map indicates the distance from the laser radar 10 at each detection point, it cannot normally occur that the distance is “0” for a certain point. However, there is no possibility that the background distance becomes “0” when dust is temporarily attached to the laser radar 10 when the background distance map is created using the laser radar 10 or when electrical noise occurs. is not. Therefore, the singular point removal unit 21d is provided to remove such singular points. Details of the process of removing singular points will be described later.

  Returning to FIG. 1, the moving object detection unit 23 extracts the difference between the distance information at each detection point obtained by using the laser radar 10 described above and the content of the background distance map stored in the background distance map memory 22. Extraction data is generated to detect a moving object in the detection area. Here, if there is no moving object in the detection area, the distance from the laser radar 10 to each reflection point at each detection point is equal to the background distance map. On the other hand, if there is a moving object in the detection area, the distance from the laser radar 10 to the moving object is shorter than the distance (background distance) when there is no moving object. In this embodiment, this principle is used to detect that a moving object is present at a detection point at which the background distance is shortened.

  The output control unit 24 reads the background distance map stored in the background distance map memory 22, converts the distance information indicated by the background distance map into, for example, light and dark information that becomes darker as the distance increases, and outputs it to the monitor 30. To do. In the present embodiment, an example is shown in which the output control unit 24 converts the background distance map into shading information in which the density becomes deeper as the distance increases. However, color conversion is performed so that the color changes stepwise according to the distance. Also good.

  Further, the output control unit 24 simplifies the shape of the moving object based on the extracted data generated by the moving object detection unit 23, converts it into spatial coordinates, and outputs it to the monitor 30. Further, a frame-shaped identification mark surrounding the detected moving object is displayed so as to be superimposed on the image displayed on the monitor 30, thereby highlighting the moving object and enhancing the distinguishability. Further, the output control unit 24 appropriately records the image displayed on the monitor 30 in the image recording device 31 connected to the detection device main body 20. In particular, when a moving object enters the monitoring area SR by the moving object described above, it is used for specifying the moving object that has entered the monitoring area SR by recording it in the image recording device 31 together with the laser radar image described above. You may do it.

  Next, a moving object detection method using the moving object detection apparatus having the above configuration will be described. In the present embodiment, in order to detect a moving object in the detection region, a process of creating a background distance map is performed when there is no moving object in the detection region including the monitoring region SR in advance. FIG. 4 is a flowchart showing a background distance map creation method. The process shown in FIG. 4 is performed by the background distance map generation unit 21. When the processing is started, the background distance map generation unit 21 sets all the contents of the background distance map memory 22 to “0” and initializes the background distance map (step S10). That is, in this process, the distance from the laser radar 10 to the reflection point at all detection points is set to 0 meter.

  When the initialization of the background distance map is finished, the background distance map generation unit 21 determines whether or not the creation of the background distance map is finished (step S11). Here, since the distance is not measured for any of the detection points, the determination result is “NO”. Next, the laser pulse scanning unit 21 a provided in the background map generation unit 21 drives the laser light source 14 and the main scanning motor 12 and the sub scanning motor 13 to start scanning in the detection region.

  When the scanning is started, the reflected light measuring unit 21b receives the synchronization signal output from the laser pulse scanning unit 21a and measures the light reception timing of the reflected light by the object of the pulse laser beam. Next, the distance information conversion unit 21c converts the light reception timing (time) measured by the reflected light measurement unit 21b into a distance. In this way, measurement data at the first detection point is acquired (step S12: measurement step).

  When the measurement data is acquired, the background distance map generation unit 21 reads the distance information (background distance) at the first detection point from the background distance map memory 22, and the distance indicated by the measurement data acquired in step S12 is read. It is determined whether or not the distance is longer than the background distance (step S13: background distance map generation step). Here, since the content of the background distance map memory 22 is initialized in step S10, the determination result is “YES”, and the background distance at the detected point is updated to the distance measured in step S12 ( Step S14: Background distance map generation step). When the update process ends, the process returns to step S11. The process also returns to step S11 if the determination result in step S13 is “NO”.

  When the process returns to step S11, it is determined again whether or not the creation of the background distance map is completed. When the determination result is “NO”, measurement data at the next detection point is acquired (step S12), and it is determined whether or not the distance indicated by the measurement data is longer than the background distance at the next detection point. (Step S13) When it is determined that the length is long (when the determination result is “YES”), the background distance at the detected point is updated (Step S14). Similarly, when the determination result of step S11 is “NO”, the processes of steps S12 to S14 are repeated.

  When the measurement at all the detection points is performed by the above processing and the creation of the background distance map is completed, the determination result in step S11 is “YES”. When the creation of the background map is completed, the invalid background distance is replaced (step S15). Here, the invalid background distance refers to a background distance equal to or greater than a predetermined distance included in the background distance map. For example, if the detection area of the radar laser 10 includes sky, measurement is not possible because there is no reflection point at this detection point. Therefore, at this detection point, a process of replacing the background distance with a preset virtual far distance (for example, 200 m) is performed.

Next, the singularity removing unit 21d performs processing for removing singularities included in the background distance map (step S16 : singularity removing step ). FIG. 5 is a diagram for explaining processing for removing singular points included in the background distance map. In order to remove the singularity, the singularity removal unit 21d first performs a process of determining the singularity included in the background distance map. In this process, a detection point whose difference from the background distance at the surrounding detection points in the background distance map is equal to or greater than a predetermined threshold is determined as a singular point.

  For example, as shown in FIG. 5A, the difference between the background distance of a detection point P1 in the background distance map and the background distances of eight detection points P2 to P9 around the detection point P1 is obtained. In the example shown in FIG. 5, the background distance of the detection point P1 is 10 meters, and the background distance of the detection points P2 to P9 is 50 to 54 meters. In this example, for example, when the predetermined threshold is set to 5 meters, the difference between the detection point P1 and each of the surrounding detection points P2 to P9 exceeds the threshold. The unit 21d determines that the detection point P1 is a singular point. The above processing is performed for all detection points in the background distance map. In addition, at the end of the background distance map, there are cases where there are 3 or 5 detection points in the surroundings. In this case, the difference from the background distance at these 3 or 5 detection points is calculated. Ask.

  When the determination of the singular point is completed, the singular point removing unit 21d obtains an average value of the background distances at the detection points around the detection point determined to be the singular point, and the average value is determined to be the singular point. Singularity is removed by setting the background distance at the point. At this time, when obtaining the average value of the background distances at the detection points around the detection point determined to be a singular point, except for the detection point having the smallest distance difference from the detection point determined to be a singular point The average value is calculated from

  Referring to FIG. 5A, among the eight detection points P2 to P9 around the detection point P1, the detection point P2 has the smallest difference from the background distance of the detection point P1. Therefore, an average value (52.28) of the background distances of the detection points P3 to P9 excluding the detection point P2 is obtained, and a value “52” obtained by rounding off the average value is detected as shown in FIG. The background distance is P1. Here, the average value is calculated after removing the detection point having the smallest distance from the detection point determined to be a singular point because one of the detection points around the detection point determined to be a singular point is singular. This is in order to eliminate the influence of points.

  A background distance map is created by the above processing. In the above description, after the background distance map is initialized in step S10, if only one measurement is performed for all detection points, it is determined in step S11 that the background distance map has been created. However, it may be determined that the creation of the background distance map is completed when the measurement is performed several times for all the detection points. In addition, since the background may change due to construction or the like, the process of creating (updating) the background distance map by performing the writing in steps S11 to S16 without performing the initialization in step S10 may be performed periodically. desirable. Update the background distance map, for example, every few hours, every day, every week, or every month. If the update interval is more than one day, for example, it should be done at midnight when there is little traffic, for example Is preferred.

  When the creation of the background distance map is completed, processing for detecting a moving object in the detection region is performed. The details of this process are as follows. That is, when distance information at a detection point where the laser radar 10 scans the detection area is measured, the measured distance information is input to the detection apparatus main body 20. The moving object detection unit 23 reads the background distance at the detection point where the input distance information is obtained and the detection points around it.

  FIG. 6 is a diagram for explaining a process of extracting a moving object. As shown in FIG. 6, it is assumed that the distance information of a certain detection point P11 measured by the laser radar 10 is 20 meters. Further, the background distances of the detection point P11 and the surrounding detection points P12 to P19 are read from the background distance map memory 22. In the example shown in FIG. 6, the background distances of the detection points P11 to P19 read from the background distance map memory 22 are 12 to 14 meters and 50 to 52 meters.

  In order to extract a moving object, the difference between the measured distance information and each of the background distances read from the background distance map memory 22 is obtained, and when the difference is not equal to or less than a predetermined threshold value is not included Then, it is extracted that a moving object is arranged at the detection point. In the example shown in FIG. 6, 20 meters that is the measurement distance is subtracted from the background distance of each of the detection points P11 to P19 read from the background distance map memory 22. For example, when the threshold is set to 3 meters, in the example shown in FIG. 6, none of the subtraction results is less than or equal to the threshold, so that a moving object is arranged at the detection point P11.

  FIG. 7 is a diagram illustrating a state where moving objects are arranged. In the example shown in FIG. 7, the distance from the laser radar 10 to the building BL2 is the background distance. The distance from the laser radar 10 to the moving object MO is distance information measured by scanning with the laser radar 10. In this embodiment, the presence or absence of a moving object is detected by detecting a change in the distance from the laser radar 10. Of the subtraction results obtained by the above processing, the smallest value is the distance (L2-L1) between the background and the moving object.

  Here, in the above processing, when extracting the moving object, the difference between the measured distance information and each of the background distances read from the background distance map memory 22 is obtained by the main scanning of the laser radar 10. This is because an error may occur in the angle and the sub-scanning angle. In the example shown in FIG. 6, the distance information at the detection point P11 is measured as 20 meters by the laser radar 10, but this measurement result is the measurement result of the measurement point P19 having the smallest difference due to the above error. Can be considered.

  The above processing is performed at all detection points set in the detection area, and moving objects are extracted. When the moving object extraction process ends, the extraction result is output to the output control unit 24. The output control unit 24 reads the background distance map from the background distance map memory 22 and converts the background distance map into light / dark information that becomes darker as the distance increases, and based on the extraction result (extraction data) output from the moving object detection unit 23. Processing such as simplifying the shape of the moving object and converting it to spatial coordinates is performed, and these are combined and output to the monitor 30. When a recording instruction is given to the image recording device 31, the image displayed on the monitor 30 is output to the image recording device 31 for recording.

  As described above, in the present embodiment, the moving object is detected from the difference between the distance when there is no moving object (background distance) and the distance when there is a moving object in front of the background. A moving object can be detected stably even when there is an environmental change such as an illuminance change due to the presence or absence of irradiation. Further, unlike the prior art, the reference plane is not defined as the background, and the distance from the laser radar 10 to each reflection point is the background distance. Therefore, the moving object can be stably displayed regardless of the positional relationship between the background and the moving object. Detection can be performed.

  In the above embodiment, the case where a moving object on the road surface R is detected has been described as an example. However, in the present invention, the distance when there is no moving object (background distance) and the moving object before the background Since a moving object is detected from a difference from a certain distance, various moving objects such as a gondola moving in the air can be detected.

It is a block diagram which shows the structure of the moving object detection apparatus by one Embodiment of this invention. It is a figure which shows an example of the attachment state of the laser radar. 3 is a diagram showing a configuration of a background distance map generation unit 21. FIG. It is a flowchart which shows the preparation method of a background distance map. It is a figure for demonstrating the process which removes the singular point contained in a background distance map. It is a figure for demonstrating the process which extracts a moving object. It is a figure which shows a mode that a moving object is arrange | positioned.

Explanation of symbols

10 Laser Radar 21 Background Distance Map Generation Unit (Background Distance Map Generation Unit)
21d Singularity removal unit (singularity removal means)
23 Moving object detection unit (detection means)
SR monitoring area (predetermined area)

Claims (3)

A laser radar that scans a detection area including at least a predetermined area;
Means for generating a background distance map indicating the background distance of the entire detection region from the information indicating the scanning position of the distance information and the laser radar, which is measured by the laser radar, the singularity contained in the background distance map The singular point removing means for removing the singular point by setting the value of the average value of the remaining background distances by excluding the difference between the background distance around the singular point and the value of the singular point. A background distance map generating means comprising:
Detection means for detecting a moving object in the predetermined region by comparing the distance information measured by the scanning of the laser radar, the detection point from which the distance information is obtained, and the background distance of the background distance map around the detection point. And a moving object detection device.   2. The movement according to claim 1, wherein the background distance map generation means periodically updates the background distance map from distance information measured by the laser radar and information on a scanning direction of the laser radar. Object detection device. A measurement step of scanning a laser radar and measuring a detection area including at least a predetermined area;
  A background distance map generating step for generating a background distance map indicating a background distance of the entire detection area from distance information measured by the laser radar and information indicating a scanning position of the laser radar;
  An average value of the remaining background distances obtained by excluding those having the smallest difference from the value of the singular point from the background distance around the singular point included in the background distance map, and setting the value of the singular point as the average value A singularity removal step of removing the singularity by
  A detection step of detecting a moving object in the predetermined region by comparing the distance information measured by the scanning of the laser radar, the detection point where the distance information is obtained, and the background distance of the background distance map around the detection point. When
  A moving object detection method comprising:

Images