JP2008226185A - Road monitoring system and road monitoring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road monitoring system and method for maintaining environmental performance of the road monitoring system with a far-infrared camera, without using a compensating means, such as, weather indicator or visible camera. <P>SOLUTION: An attenuation measurement apparatus 6 measures the attenuation of a far-infrared ray between a far-infrared ray projector 5 and a far-infrared camera 1, and image processor 2 is used for amplifying a video signal according to the attenuation, to adjust a threshold for determining the signal intensity, according to the attenuation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a road monitoring system and a road monitoring method, and more particularly to a road monitoring system and a road monitoring method for detecting a vehicle using a far-infrared camera.

Many conventional road monitoring systems use a far-infrared camera or a visible camera as a camera for monitoring a traveling vehicle on the road.
However, there is a difference in the environmental performance between the two, and it is not uniform which camera is used for monitoring work if the system is configured.
For example, as described on page 4 of Patent Document 1, a configuration using a far-infrared camera is effective in an environment with low illuminance and visibility (such as at night), and a visible camera in a rainy or high temperature environment. The configuration by is effective. This is because, first of all, far infrared rays have physical characteristics that are easily absorbed by water droplets. Second, since the far-infrared radiation has a physical characteristic that it correlates with the temperature of the object, the contrast between the monitoring object and the background in the monitoring image becomes small in a high-temperature environment.

  For this reason, the invention described in Patent Document 1 includes both a far-infrared camera and a visible camera, and selects a more appropriate camera image by measuring the environment of the monitoring area using a weather measurement device. The method of monitoring is taken. This constitutes a road monitoring system that reinforces the shortcomings of far-infrared cameras.

  In addition to this, for example, as disclosed in Patent Document 2, both a far-infrared camera and a visible camera are provided, and the peripheral area of the monitoring target on the monitoring video is grasped by the visible camera, By observing the temperature distribution in the region with a far-infrared camera and setting a threshold value for detecting the monitoring target according to the temperature distribution, deterioration of the detection performance of the monitoring target is prevented. This constitutes a road monitoring system that reinforces the shortcomings of far-infrared cameras.

  Further, as disclosed in Patent Document 3, both a far-infrared camera and a visible camera are provided, and the sunlight (background of the road surface, etc.) on the surveillance video is observed with the visible camera, and infrared rays from the background are observed. By setting a threshold value for correcting the amount of reflection, deterioration of the detection performance of the monitoring target is prevented. This constitutes a road monitoring system that reinforces the shortcomings of far-infrared cameras.

In addition, as disclosed in Patent Document 4, an object to be monitored is irradiated with an infrared projector, and reflected light is photographed and monitored with an infrared camera.
JP 2003-162895 A Japanese Patent Laid-Open No. 10-255019 JP-A-2005-249529 JP 2002-114097 A

  By the way, the first problem of a road monitoring system using a far-infrared camera according to the prior art is that it is not always possible to configure a road monitoring system that maintains sufficient environmental performance for road monitoring work with only a far-infrared camera. This means that a system with advanced compensation means must be constructed.

  For example, in the invention described in Patent Document 1, a meteorological measurement device and a visible camera must be added to the system configuration requirements in addition to the far-infrared camera, which increases the system scale and optimizes these systems. Since the parameters for operation vary depending on the weather characteristics of the observation point, there is a problem that it is difficult to adjust the system.

  In addition, for example, the invention described in Patent Document 2 requires a condition that the monitoring control can be taken with a visible camera, and lighting with a lamp or street light is indispensable. It is necessary to set and maintain the parameters so that there is no hindrance to the operation.

  Furthermore, as disclosed in, for example, Patent Document 3, far infrared radiation from a background in a monitoring image is also used for removing a reflection amount from a far infrared background included in solar radiation only by observing with a visible camera. The amount depends not only on the sunshine conditions but also on the climatic conditions, road surface conditions (dry, wet, freezing, etc.). It is necessary to use a means capable of measuring the far-infrared radiation amount. Thus, it is difficult to compensate the environmental conditions of the far-infrared camera by using the visible camera as described in this example.

  A second problem of a road monitoring system using a far-infrared camera is a method of simply reducing a threshold value for signal strength determination when extracting a monitoring target from a video signal in accordance with the degree of attenuation of the video signal. This means that the detection performance of the monitoring target is easily deteriorated due to the influence of the background of the video signal and the fluctuation of the signal intensity distribution of the monitoring target. For example, in the invention described in Patent Document 2, when the temperature distribution in the vicinity of the monitoring target is low, the monitoring target is extracted by lowering the threshold value for signal strength determination for extracting the monitoring target.

  However, in this method, the difference between the signal intensity of the monitored object and the background and the threshold value is small, so that the intensity signal near the threshold value affected by the fluctuation of the signal intensity distribution of the background or monitored object is erroneously detected. The probability of detection increases, and the detection performance of the monitoring target tends to deteriorate.

The invention described in Patent Document 4 is inconvenient for monitoring a fixed point because infrared rays are projected from a headlight or the like of a moving vehicle and photographed by an infrared camera.
Therefore, an object of the present invention is to provide a road monitoring system and a road monitoring method capable of maintaining the environmental performance of a road monitoring system using a far-infrared camera without using compensation means such as a meteorological observation meter and a visible camera. There is to do.

  In order to solve the above problem, the invention according to claim 1 is a road monitoring system for detecting a vehicle traveling on a road using a far-infrared camera, comprising a far-infrared projector that lights the vehicle, and the far-infrared light It has a measurement means which measures the intensity | strength of the far-infrared detected from the said far-infrared projector using the camera.

  According to the first aspect of the present invention, the far-infrared camera has the far-infrared projector that lights the automobile, and the measuring means that measures the intensity of the far-infrared detected from the far-infrared projector using the far-infrared camera. It is possible to maintain the environmental performance of the road monitoring system using the system without using compensation means such as a meteorological observation meter or a visible camera.

  According to a second aspect of the present invention, in the first aspect of the invention, the image processing apparatus further includes an image processing device that amplifies a video signal that is an output of the far-infrared camera according to the intensity of the far-infrared light detected from the far-infrared projector. Features.

  According to a third aspect of the present invention, in the first aspect of the present invention, the threshold for extracting features from the video signal that is the output of the far-infrared camera according to the intensity of the far-infrared detected from the far-infrared projector. And an image processing device for adjusting the image.

  According to a fourth aspect of the present invention, in the road monitoring method for detecting a vehicle traveling on a road using a far-infrared camera, the far-infrared light is lit on the vehicle, and the intensity of the far-infrared is measured using the far-infrared camera. It is characterized by doing.

  According to invention of Claim 4, the environmental performance of the road monitoring system using a far-infrared camera can be maintained, without using compensation means, such as a meteorological observation meter and a visible camera.

  According to a fifth aspect of the invention, in the fourth aspect of the invention, the video signal which is an output of the far-infrared camera is amplified according to the intensity of the far-infrared ray.

  According to a sixth aspect of the invention, in the fourth aspect of the invention, a threshold value for extracting a feature from a video signal that is an output of the far-infrared camera is adjusted according to the intensity of the far-infrared ray. And

  A road monitoring system using a far-infrared camera according to the present invention extracts a monitoring target from a far-infrared projector and a signal obtained by amplifying a video signal input from the far-infrared camera according to the intensity of the far-infrared detected from the far-infrared projector. And an image processing apparatus having the function of

  The far-infrared attenuation during propagation from the far-infrared projector to the far-infrared camera is measured by the image processing device, and the video signal is amplified according to the attenuation, and this video signal is used for extraction of the monitoring target. . Further, the threshold value for signal strength determination when extracting the monitoring target is adjusted according to the attenuation amount. That is, since the video signal is amplified, the threshold value is set higher than the far-infrared intensity from the background so as to prevent the conventional threshold value from being determined to be “target”.

  The reason is that the video signal is amplified according to the amount of attenuation of far infrared rays from the monitoring target, and this video signal is used for extraction of the monitoring target, and the threshold value for signal intensity determination when extracting the monitoring target is set. By adjusting according to the amount of attenuation, the difference between the signal intensity of the monitored object and the background and the threshold value can be reduced, and it is possible to prevent erroneous determination of a signal having an intensity near the threshold value. is there.

  According to the present invention, a road using a far-infrared camera has a far-infrared projector that lights a vehicle, and has a measuring unit that measures the intensity of far-infrared detected from the far-infrared projector using a far-infrared camera. The environmental performance of the monitoring system can be maintained without using compensation means such as a meteorological observation meter or a visible camera.

Next, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of a road monitoring system according to the present invention.
Referring to FIG. 1, an embodiment of the present invention includes a far-infrared camera 1, an image processing device 2, a road monitoring device 3, an attenuation measurement device 6, and a far-infrared projector 5.

The far-infrared projector 5 is installed with its relative position fixed so that the emitted light can be reflected in the far-infrared camera 1 and emits far-infrared light having a constant output.
The far-infrared camera 1 outputs a far-infrared video signal in the monitoring range.
The attenuation measuring device 6 measures the signal intensity in an arbitrary region from the input far-infrared image.
The image processing apparatus 2 includes a CPU, a RAM, a ROM, an I / F, and the like (not shown), and performs the following two processes. First, the signal intensity of the input far-infrared video is amplified according to the input attenuation amount information. Second, the monitoring target determined based on the signal intensity is extracted from the amplified far-infrared video signal, and information about the monitoring target (detection position, moving direction, moving speed, etc.) is output. At this time, the threshold value for determining the signal strength is appropriately adjusted based on the attenuation amount information.

  The road monitoring device 3 is composed of a CPU, RAM, ROM, I / F, etc. (not shown), analyzes input monitoring target information, and distributes information (congestion information, etc.) suitable for road monitoring work. Deliver and manage various information related to work, and manage the operation of the road monitoring system in general.

  1 may be transferred to the image processing apparatus 2 and configured as one functional module. Further, the road monitoring device 3 is not limited to the one described above, and may have any function / configuration as long as the function necessary for providing road monitoring work is realized with an appropriate configuration.

Next, the operation of the road monitoring system shown in FIG. 1 will be described.
FIG. 2 is an example of a flowchart for explaining the operation of the road monitoring system shown in FIG.
In the far-infrared camera 1, the image processing device 2 and the attenuation measurement are performed on the road monitoring video including the light emission of the far-infrared projector 5 (step S1), the shooting of the road including the monitoring target (step S2), and the monitoring target 4. To the device 6 (step S3).
The attenuation measuring device 6 separates and extracts the image of the far-infrared projector 5 from the input road monitoring image, measures the intensity of the far-infrared, and takes the difference from the light output of the far-infrared projector 5 to obtain the far-infrared projector 5. The attenuation of the path until the far infrared ray emitted from the infrared projector 5 reaches the far infrared camera 1 is measured (step S4).

This attenuation amount information is input to the image processing apparatus 2 (step S5).
The image processing apparatus 2 performs the following two processes. First, based on the attenuation amount information input from the attenuation amount measuring device 6, the attenuation amount of the far infrared ray in the route from the monitoring target to the far infrared camera is estimated, and the input road is accordingly input. The signal intensity of the monitoring video is amplified (step S6).

  Secondly, a monitoring target is extracted based on the signal strength of the amplified road monitoring video signal, and information (detection position, moving direction, moving speed, etc.) regarding the monitoring target is output to the road monitoring device 3 (step S7). ).

  At this time, the threshold value for determining whether or not to be monitored is set to an appropriate value based on information from the attenuation measuring device 6 (step S8).

  The road monitoring device 3 to be monitored analyzes the monitoring target information input from the image processing device 2 and distributes information (congestion information, etc.) according to the road monitoring work, as well as various information related to the monitoring work. Distribution / management, system operation management, and the like are performed (steps S9 and S10).

  In addition, when amplifying the signal intensity of the road monitoring video, which is the first operation of the image processing apparatus, it is not always necessary to linearly amplify the signal intensity. For example, a difference in the amplification factor between a weak signal and a strong signal is used. It may be provided. In this way, it is possible to obtain a road monitoring video in which the difference between the far-infrared projector and the monitoring target to be detected and the signal intensity between the background and the background is further emphasized.

  Next, the operation of the road monitoring system shown in FIG. 1 will be described with reference to changes in the signal intensity distribution of the road monitoring video signal shown in FIGS.

  FIG. 3A shows an example of the signal intensity distribution of the road monitoring video signal when the monitoring area of the far-infrared camera is in a favorable environment (such as when the weather is clear). FIG. 3B shows an example of the signal intensity distribution of the road monitoring video signal when the far-infrared camera monitoring area is in a bad environment (such as rainy weather). FIG. 3C shows an example of the signal intensity distribution when the road monitoring video signal in the state of FIG. 3B is amplified according to the amount of attenuation of far infrared rays. 3A to 3C, the left peak of the signal intensity distribution curve indicates the video signal of the far-infrared projector. The right peak of the signal intensity distribution curve indicates a video signal of a monitoring target (such as an automobile).

  In FIG. 3A, the far-infrared projector and the signal intensity to be monitored (abbreviated as Pi1 and Po1 respectively) to be detected by the far-infrared camera are equal to or higher than the threshold value Ps1 set in the image processing apparatus in this embodiment. The background signal intensity Pu1 is equal to or lower than Ps1. In FIG. 3B, this is because the far-infrared projector, the monitoring target, and the background signal intensity (abbreviated as Pi2, Po2, and Pu2 respectively) are attenuated as shown in FIG. ing.

Therefore, in order to identify the far-infrared projector and the monitoring target in this state, it is necessary to lower the threshold value to Ps2 in accordance with the attenuation amount.
However, when the threshold value is simply lowered as in the prior art, the difference between the signal intensity of the monitoring target and the background and the threshold value is smaller than that in FIG. That is, it is expressed by the formula (1) and the formula (2).

  (Po2-Ps2) <(Po1-Ps1) (1)

  (Pu2-Ps2) <(Pu1-Ps1) (2)

It becomes. For this reason, it becomes easy to erroneously determine a signal having an intensity near the threshold.

  Therefore, as shown in FIG. 3C, the attenuated video signal is amplified according to the attenuation amount. For example, by amplifying the video signal by the same amount as the attenuation, the signal intensity of the monitored object and the background (abbreviated as Po3 and Pu3, respectively) after amplification is Po3 = Po1 and Pu3 = Po1. Therefore, it is possible to set the threshold value Ps3 for identifying the monitored object and background after amplification to the same value as Ps1, and to extract the monitored object with the same threshold value as in a favorable environment. At this time, Equations (3) and (4) are

  (Po3-Ps3) = (Po1-Ps1) (3)

  (Pu3-Ps3) = (Pu1-Ps1) (4)

Therefore, the difference between the signal intensity of the monitoring target and the background and the threshold value is also maintained at the same level as in a favorable environment.

In the above, the attenuation amount of the far infrared ray in the monitoring region of the far infrared camera is directly measured, and the monitoring target is extracted using the signal obtained by amplifying the video signal of the infrared camera according to the attenuation amount, and the monitoring target is extracted. By adjusting the threshold value, the environmental performance of the road monitoring system using the far-infrared camera can be maintained without using compensation means such as a meteorological observation meter or a visible camera.
〔The invention's effect〕
The first effect of the present invention is that the environmental performance of a road monitoring system using a far-infrared camera can be maintained without depending on sophisticated compensation means such as a visible camera or a meteorological observation meter.

  This is because the amount of attenuation can be easily measured by using an infrared projector and also using a far-infrared camera for monitoring the monitoring target for measuring the amount of attenuation of the far-infrared from the monitoring target.

  The second effect is that, according to the attenuation level of the video signal, a threshold value for signal strength determination in the past when a monitoring target is extracted from a video signal, which has been conventionally used in a road monitoring system using a far infrared camera, The detection performance of the monitoring target can be maintained better than the method of simply reducing.

  The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there.

1 is a block diagram showing an embodiment of a road monitoring system according to the present invention. It is an example of the flowchart for demonstrating operation | movement of the road monitoring system shown in FIG. (A)-(c) is a figure which shows the change of the signal strength distribution of a road monitoring video signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Far-infrared camera 2 Image processing device 3 Road monitoring device 4 Vehicle 5 Far-infrared projector 6 Attenuation measuring device

Claims (6)

In a road monitoring system that detects a car traveling on a road using a far-infrared camera,
A road monitoring system comprising a far-infrared projector for lighting the automobile, and measuring means for measuring the intensity of the far-infrared detected from the far-infrared projector using the far-infrared camera.   The road monitoring system according to claim 1, further comprising an image processing device that amplifies a video signal that is an output of the far-infrared camera in accordance with a far-infrared intensity detected from the far-infrared projector.   2. The image processing apparatus according to claim 1, further comprising: an image processing device that adjusts a threshold value for extracting a feature from a video signal that is an output of the far-infrared camera in accordance with an intensity of far-infrared detected from the far-infrared projector. The described road monitoring system. In a road monitoring method for detecting a car traveling on a road using a far-infrared camera,
A road monitoring method characterized in that far-infrared light is lit on the automobile and the intensity of the far-infrared light is measured using the far-infrared camera.   5. The road monitoring method according to claim 4, wherein a video signal which is an output of the far-infrared camera is amplified in accordance with the intensity of the far-infrared ray.   5. The road monitoring method according to claim 4, wherein a threshold value for extracting a feature from a video signal which is an output of the far infrared camera is adjusted according to the intensity of the far infrared ray.

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