JP2004172828A - Night vision device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a night vision device for a vehicle, which controls the display of a night vision image according to the illumination environment in a driving direction. <P>SOLUTION: A visual camera images a visible picture in front of a vehicle, the night vision device extracts the border of a lane from the imaged image (S3), and calculates the length of the extracted border (S4). Further, the night vision device assumes the missing point of the lane from the extracted border (S5), calculates the length of the border up to the missing point, and calculates a reference length (S6). The night vision device calculates the rate of the calculated length as an index for discriminating the illuminance environment in the drive direction (S7), and discriminates whether or not the index is a prescribed value or over (S8) to control ON / OFF of display of a night vision image (S9, S10). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a night vision device for a vehicle that assists a driver with night visibility by night vision images using infrared light.
[0002]
[Prior art]
A night vision device for a vehicle, which provides a driver with night vision information in a dark and invisible range during night driving, has an effect of effectively assisting the driver's night visibility. On the other hand, the fact that a night-vision image with high luminance is always displayed irrespective of the driving situation adversely affects the driver's forward gaze behavior. Therefore, as a night vision device for a vehicle that presents appropriate information according to a traveling situation, there is a device that determines the possibility of an obstacle and controls the display of a night vision image in accordance with the determination. In this night vision device for a vehicle, the determination of the possibility of the presence of an obstacle is performed based on the result of determining the traveling environment of the vehicle based on map information, information obtained by road-to-vehicle communication, or various sensor information.
When it is determined that the possibility of the presence of the obstacle is low, the display intensity is reduced, the display area is reduced, and the like (see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-285394
[Problems to be solved by the invention]
In the conventional example, the display of the night-vision image is controlled based on the possibility of the presence of the obstacle. However, the situation where the night-vision image is required is not limited to the case where the obstacle exists. For example, when traveling on a mountain road where the road alignment is meandering, the likelihood of the presence of obstacles is low, but the visibility is poor due to insufficient illuminance environment in the traveling direction. Sex is higher.
[0005]
The present invention provides a vehicular night-vision device that determines the quality of a field of view in a traveling direction, limits display of a night-vision image when the field of view is good, and displays a night-vision image when the field of view is poor. Things.
[0006]
[Means for Solving the Problems]
A night vision apparatus for a vehicle according to the invention of claim 1 irradiates a visible light to the front of the vehicle, and captures an infrared image of the front of the vehicle, and at least a range of the front of the vehicle farther than the irradiation range of the irradiation means. Image capturing means including an image capturing range, a display means for displaying the captured infrared image, a visible image capturing means for capturing a visible image in front of the vehicle, and a view based on the brightness of the traveling environment in front of the vehicle. The infrared image is displayed on the display means when the visibility is determined to be poor by the determination means for determining whether the visibility is good, and the infrared image is displayed on the display means when the visibility is determined to be good. Display control means not to be provided.
[0007]
【The invention's effect】
According to the present invention, whether the visibility is good or bad is determined based on the brightness of the traveling environment ahead of the vehicle, and based on the determination result, a night vision image of the front of the vehicle captured by the infrared camera when the visibility is poor is displayed. With this configuration, it is possible to provide appropriate visual information according to the nighttime driving situation.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
--First Embodiment--
FIG. 1 shows a first embodiment of a night vision device for a vehicle according to the present invention mounted on a vehicle 100. The headlamp 6 emits visible light and infrared light toward the front of the vehicle 100. The visible light is radiated as a low beam and reaches a distance B in front of the vehicle 100 to form an irradiation range 61 shown by hatching. On the other hand, the infrared light reaches the distance A in front of the vehicle 100 and forms an irradiation range 62 including the irradiation range 61 of the visible light.
[0009]
The visible camera 1 and the infrared camera 2 capture an image in front of the vehicle. For this, for example, a CCD camera or the like is used. The visible camera 1 has sensitivity in the visible light region and captures a visible image. Here, the sensitivity of the visible camera 1 is determined by human vision so that a visible image suitable for determining whether the visibility based on the brightness of the driving environment, that is, the illuminance in front of the vehicle is equal to or greater than a predetermined value, can be captured. The sensitivity is set as close as possible to the sensitivity. The infrared camera 2 captures an infrared image, and the imaging range is set to cover the irradiation range 62 of the infrared light, including a range farther than the irradiation range 61 of the visible light. The image captured by the visible camera 1 is output to the image processing circuit 3. The image processing circuit 3 performs various processes described later on the basis of the image captured by the visible camera 1, and controls the display changeover switch 5 according to the processing result. The image processing circuit 3 includes, for example, a CPU, a DSP, and its peripheral circuits. The display changeover switch 5 controls display of an image captured by the infrared camera 2 on the display monitor 4. The display monitor 4 is provided near a driver's seat (not shown) of the vehicle 100, and provides a night vision image of the infrared camera 2 to the driver as needed. For this purpose, for example, a head-up display is used.
[0010]
The processing performed by the image processing circuit 3 will be described with reference to FIG. FIG. 2 illustrates an example of an image captured by the visible camera 1, and a hatched area 20 irradiated with visible light by the headlamp 6 is displayed as an image. Since the illuminance is low, the portion other than the display range 20 is not imaged by the visible camera 1, and the white line indicated by the broken line, the target 9, and the like are not displayed as images.
[0011]
The image processing circuit 3 extracts white lines 21 and 22 indicating the boundaries of the lane where the vehicle 100 is located within the display range 20 from the image shown in FIG. 2 by a known processing method. Next, a first length M1 of _one of the extracted white lines 21 and 22 on the image of the white line (white line 21 in FIG. 2) is obtained, and a length corresponding to a visible distance in front of the vehicle by visible light. Is calculated. Which of the white lines is the first length is determined based on a preset condition. For example, the shorter white line is always selected.
[0012]
Further, an intersection point when the white lines 21 and 22 are extended is determined, and this is assumed to be a vanishing point 23 of the lane. Next, a second length L when the white lines 21 and 22 are extended to the vanishing point 23 is obtained, and a reference length corresponding to an ideal visual recognition distance in front of the vehicle is calculated.
[0013]
Thereafter, the ratio of the first length to the calculated second length is calculated. When the calculation result is equal to or more than the predetermined value, it is determined that the night vision image is unnecessary because the visibility of the traveling environment ahead of the vehicle is good, that is, the brightness (illuminance) is equal to or more than the predetermined value, and the display switching is performed. Open switch 5. At this time, the image captured by the infrared camera 2 is not displayed on the display monitor 4. Conversely, when the calculation result is less than the predetermined value, it is determined that the night vision image needs to be displayed because the visibility of the traveling environment ahead of the vehicle is poor, that is, the brightness (illuminance) is less than the predetermined value. Then, the display changeover switch 5 is closed. At this time, the image captured by the infrared camera 2 is output to the display monitor 4 and displayed as shown in FIG.
[0014]
The predetermined value of the ratio used in this determination is set to a value of the ratio in a situation where the field of view is sufficiently far away from the range 20 irradiated with the visible light and a night vision image is not required. Here, the example of the image shown in FIG. 2 is a situation in which a visual field farther than the range 20 irradiated with visible light is not secured, and visual assistance using a night-vision image is required. Therefore, the calculated ratio of the first length to the second length is less than the set predetermined value, and it is determined that the display of the night vision image is necessary.
[0015]
FIG. 3 shows an example of an image displayed on the display monitor 4. Compared with the image of FIG. 2, in addition to the display range 20 by the visible camera 1, a range 30 (a range surrounded by an ellipse) in which only the infrared light is irradiated without the visible light from the headlamp 6 being irradiated. Displayed as an image. In the example of FIG. 3, the target 9 is displayed and can be recognized.
[0016]
In the above description, the case where there is no visible light irradiation other than the visible light irradiation from the vehicle in front of the vehicle has been described. Next, a case where visible light irradiation is present in front of the vehicle will be described.
[0017]
FIG. 4 shows a case where a road light 7 that emits visible light is present in front of the vehicle 100 in the first embodiment. 1 is the same as FIG. 1 except that the road light 7 forms the visible light irradiation range 71.
[0018]
FIG. 5 shows an example of an image captured by the visible camera 1 in the case of FIG. In addition to the range 20 where the headlamp 6 is irradiated with visible light, the range 50 where the road light 7 is irradiated with visible light is displayed as an image. In this case, the target 9 not displayed in FIG. 2 can be displayed as an image.
[0019]
The image output from the visible camera 1 to the image processing circuit 3 is subjected to the processing described with reference to FIG. 2 in the image processing circuit 3 to determine whether to display a night vision image. In the example of the image shown in FIG. 5, the field of view of the traveling environment ahead of the vehicle is sufficiently far away, and a wide range of white lines is extracted. Therefore, the ratio of the length of the extracted first white line to the length of the reference second white line is equal to or greater than the set predetermined value, and it is determined that the display of the night vision image is unnecessary. Therefore, the display changeover switch 5 is opened, and the image captured by the infrared camera 2 is not displayed on the display monitor 4.
[0020]
FIG. 6 shows an example of an image captured by the infrared camera 2 in the case of FIG.
Compared with the image by the visible camera 1 shown in FIG. 5, the range of the displayed image is not so different. Thus, in the case of FIG. 4, there is not so much difference between the range visible with visible light and the range of the night-vision image, and it is understood that the display of the night-vision image is unnecessary.
[0021]
FIG. 7 shows a flowchart of the process in the first embodiment. This is a processing flow based on a program executed by the image processing circuit 3. After the start of the process, it is determined in step S1 whether the headlamp 6 is on. If it is determined to be off, step S1 is repeated. If it is determined to be on, the process proceeds to the next step S2. In step S2, an image captured by the visible camera 1 is read.
[0022]
In step S3, white lines on both sides of the lane are extracted from the visible image read in step S2 by a known processing method. Next, in step S4, the length M of the white line extracted in step S3 is calculated. In step S5, the position of the intersection when the white line extracted in step S3 is extended is determined, and this is assumed to be the vanishing point of the lane.
In the next step S6, a reference length L when the white line is extended to the vanishing point obtained in step S5 is calculated.
[0023]
In step S7, the ratio M / L of the length M of the white line calculated in step S4 to the reference length L calculated in step S6 is determined, and this is determined as the visibility of the traveling environment, that is, the brightness (illuminance) in front of the vehicle. Is determined as a determination index EL. In step S8, EL obtained in step S7 it is determined whether a predetermined value EL ₀ or more field of view ahead of the vehicle traveling environment is considered good enough. If EL is equal to or greater than EL _0, it is determined that the visibility is good and the night vision image is unnecessary, and the process proceeds to step S9. If EL is less than EL _0, it is determined that the field of view is poor and a night-vision image needs to be displayed, and the process proceeds to step S10.
[0024]
In step S9, the display changeover switch 5 is opened so that the image captured by the infrared camera 2 is not displayed on the display monitor 4. In step S10, the display changeover switch 5 is closed, and the image captured by the infrared camera 2 is displayed on the display monitor 4. After step S9 or step S10, the process returns to step S1, and the above-described processing is repeated.
[0025]
According to the night vision device for a vehicle according to the first embodiment, the following operation and effect can be obtained. From the visible image captured by the visible camera, the visible distance of visible light and the length corresponding to the ideal visible distance are calculated, and the quality of the field of view of the running environment ahead of the vehicle is determined based on the ratio. On / off of the display of the night vision image ahead of the vehicle by the infrared light is controlled according to the determination result. As a result, it is possible to provide appropriate visual information according to night driving conditions.
[0026]
――Second embodiment――
A second embodiment of the night vision device for a vehicle according to the present invention will be described. In the first embodiment, a reference length corresponding to an ideal viewing distance is calculated from an image captured by a visible camera. In the second embodiment, a reference length is calculated from an image captured by an infrared camera.
[0027]
FIG. 8 shows a second embodiment of the vehicular night vision device according to the present invention mounted on the vehicle 100. The second embodiment is the same as the first embodiment except that an infrared image output from the infrared camera 2 is also input to the image processing circuit 3.
[0028]
FIG. 9 shows a flowchart of the process according to the second embodiment. This is a processing flow based on a program executed by the image processing circuit 3 as in the first embodiment. Steps S1 to S4 perform the same processing as in the first embodiment.
[0029]
In step S21, an image captured by the infrared camera 2 is read. In the next step S22, white lines on both sides of the lane are extracted from the image read in step S21 by a method similar to that performed in step S3. In step S23, it calculates a third length of the white line extracted at the step S22, and the length L ₁ of the reference. In step S7A, the length M of the white line calculated in step S4, obtains a ratio M / L ₁ with respect to the reference length L ₁ calculated in step S23, a determination index EL visibility of running environment this .
[0030]
After step S8, the same processing as in the first embodiment is performed. After step S9 or step S10, as in the first embodiment, the process returns to step S1, and the processing described above is repeated.
[0031]
According to the night vision device for a vehicle according to the second embodiment described above, instead of the reference length calculated from the visible image in the first embodiment, the vehicle is extracted from the infrared image captured by the infrared camera. Obtain the length of the white line and use it as the reference length. Then, the quality of the field of view of the traveling environment ahead of the vehicle is determined, and on / off of the display of the night vision image ahead of the vehicle by infrared light is controlled according to the determination result. As a result, the same functions and effects as those of the first embodiment can be obtained.
[0032]
In the first and second embodiments described above, since the position of the white line on the visible image changes depending on the traveling position of the vehicle, the length of the extracted white line is the same even in the same traveling environment. Not constant. Therefore, the relationship between the traveling position of the vehicle and the position of the white line is determined from the visible image, and accordingly, the determination index for determining the visibility of the traveling environment, that is, the predetermined value of the length of the white line with respect to the reference length is changed. It is desirable.
[0033]
--Third embodiment--
Third Embodiment A night vision device for a vehicle according to a third embodiment of the present invention will be described. FIG. 10 shows a third embodiment in which a road light 7 for irradiating visible light is distant from the front of the vehicle 100. The configuration of the third embodiment is the same as that of the first embodiment.
[0034]
FIG. 11 shows an example of an image captured by the visible camera 1 in the case of FIG. A range 20 where the visible light is emitted from the headlamp 6 and a range 50 where the visible light is emitted from the road light 7 at a slightly distant position are displayed as images. In this case, the target 9 indicated by the broken line is not displayed as an image because it is in a range where visible light is not irradiated. When a white line is extracted from such an image in the same manner as in the first embodiment, the white line is extracted as a continuous white line between the range 20 and the range 50 and not actually displayed. Could be At this time, the first length of the white line in the visible range is incorrectly calculated as the length M3 shown in the drawing, and the ratio of the reference white line to the second length increases. If this ratio is equal to or greater than a predetermined value, it is determined that the visibility of the traveling environment ahead of the vehicle is good, and no night vision image is displayed. As a result, the target 9 cannot be recognized.
[0035]
In the third embodiment, a brightness determination area 10 including areas 10a to 10d is set in a part of an image, and the brightness of the image in each area is detected. It is determined whether or not these brightnesses are equal to or greater than a predetermined value. Only when the brightness of all areas is equal to or greater than the predetermined value, it is determined that the visibility of the traveling environment ahead of the vehicle is good. If there is at least one area whose brightness is less than the predetermined value, it is determined that the visibility of the traveling environment ahead of the vehicle is poor, and a night-vision image is displayed.
[0036]
FIG. 12 schematically shows the brightness of the areas 10a to 10d in FIG. The lightness in the areas 10a to 10d is represented by Ga to Gd, respectively, and the difference in lightness is represented by a step-like graph. The closer the graph is to the left side of the figure, the lower the brightness is, that is, the darker, and the closer the graph is to the right side, the higher the brightness is, that is, the brighter.
[0037]
Here, determines the quality of the field of view of the traveling environment ahead of the vehicle, the predetermined value G ₀ of the brightness, shown by a broken line. Since the Gc is below the predetermined value G _0, the field of view of the front of the vehicle traveling environment is determined to be bad, the night vision image shown in FIG. 13 is displayed. The target 9 can be recognized by the night vision image.
[0038]
The processing according to the third embodiment will be described using still another image example. In an image example in which there is no visible light irradiation in front of the vehicle as shown in FIG. 14, the brightness of the areas 10a to 10d is expressed as shown in FIG. In this case, since the Gc and Gd is below the predetermined value G _0, the field of view of the front of the vehicle traveling environment is determined to be bad, the night vision image in FIG. 13 is displayed. On the other hand, in an example of an image in which a wide range in front of the vehicle is irradiated with visible light as shown in FIG. 16, the brightness of the areas 10a to 10d is represented as shown in FIG. In this case, since all Ga~Gd is the predetermined value G ₀ or more, the field of view of the front of the vehicle traveling environment is determined to be good, the night vision image is not displayed.
[0039]
FIG. 18 shows a flowchart of the process according to the third embodiment. This is a processing flow based on a program executed by the image processing circuit 3 as in the first and second embodiments. Steps S1 and S2 perform the same processing as in the first and second embodiments.
[0040]
In step S31, the grayscale gradation average value of the image for each area is calculated, and the calculated values are defined as lightness Ga to Gd respectively corresponding to the areas 10a to 10d. In the next step S32, for each Ga~Gd obtained in step S32, it determines whether less than a predetermined value _{G 0.} All Ga~Gd advances to step S9 if not less than G _0, if even one was less than G ₀ proceeds to step S10, in the same manner as in the first and second embodiments, the display monitor 4 is controlled. After step S9 or step S10, as in the first and second embodiments, the process returns to step S1, and the above-described processing is repeated.
[0041]
According to the night vision device for a vehicle according to the third embodiment described above, a part of the visible image captured by the visible camera is divided into a predetermined number of areas, the brightness of each area is detected, and the brightness in front of the vehicle is detected. The visibility of the driving environment is determined. On / off of the display of the night vision image ahead of the vehicle by the infrared light is controlled according to the determination result. As a result, in addition to the same functions and effects as the first and second embodiments, it is possible to provide more appropriate visual information according to the nighttime driving situation.
[0042]
――Fourth embodiment―
FIG. 19 shows a fourth embodiment of the vehicular night vision device according to the present invention mounted on the vehicle 100. The configuration is the same as that of the second embodiment except that an alarm device 13 and a steering control device 14 are provided. The warning device 13 notifies the driver of the departure from the lane by a signal from the image processing circuit 3 by, for example, a warning sound. When the vehicle deviates from the lane, the steering control device 14 controls the steering of the vehicle 100 under the control of the image processing circuit 3 to change the traveling direction of the vehicle 100 to return to the lane before the departure.
[0043]
FIG. 20 is a flowchart of the process according to the fourth embodiment. This is a processing flow based on a program executed by the image processing circuit 3 as in the first to third embodiments. Note that this processing and the processing shown in FIG. 9 may be performed in parallel. Steps S1 to S3 perform the same processing as in the first and second embodiments.
[0044]
In step S41, it is determined whether the vehicle 100 has crossed the white line extracted in step S3. This determination is made based on, for example, whether or not the position of the white line with respect to the entire image is within a predetermined range. If it is determined that the vehicle has deviated from the lane beyond the white line, the process proceeds to step S42. If it is determined that the vehicle does not exceed the white line, the process returns to step S1.
[0045]
In step S42, a signal is output to the alarm device 13 to activate it. In step S43, the steering control device 14 is controlled to return the traveling direction of the vehicle 100 to the lane before departure.
[0046]
In step S44, it is determined whether the vehicle 100 has returned to the original lane. This determination is made based on, for example, whether or not the position of the white line with respect to the entire image is within a predetermined range, as in step S41. If it is determined that the vehicle has returned to the original lane, the process proceeds to step S45. If it is determined that the vehicle has not returned to the original lane, the process returns to step S43. In step S45, the operation of the alarm device 13 is released. Then, the process returns to step S1.
[0047]
According to the night vision system for a vehicle according to the above-described fourth embodiment, it is determined whether or not the vehicle has passed the white line extracted from the infrared image captured by the infrared camera, and the vehicle has deviated from the lane beyond the white line. When it is determined that the vehicle is in the normal lane, the steering device of the vehicle is controlled to return to the original lane. As a result, it is possible to prevent deviation from the lane even during night driving. When it is determined that the vehicle has deviated from the lane beyond the white line, only the alarm device may be operated, or only the steering of the vehicle may be controlled.
[0048]
In the above description, the visible light and the infrared light are emitted from the headlamp 6. However, the visible light and the infrared light may be emitted from different headlamps. Alternatively, in the first and third embodiments, the irradiation of the infrared light may not be performed. In this case, a camera that detects far infrared rays, such as a thermal imager, is used as the infrared camera 2. In addition, although the boundary of the lane on the road extracted from the images captured by the visible camera 1 and the infrared camera 2 is described as a white line, the boundary is not limited to the white line. Anything, such as a yellow line or a road pavement break, can be used as long as it can be determined from the image that it is a lane boundary. Further, in the third embodiment, a part of the image captured by the visible camera 1 is divided into four areas 10a to 10d, but the number of divided areas may be changed. Further, the grayscale gradation average value for each area is calculated and used as the lightness of each area. However, a value calculated by another method may be used as the lightness.
[0049]
In the above embodiment, for example, the irradiating means is the headlamp 6, the visible image capturing means is the visible camera 1, the infrared image capturing means is the infrared camera 2, the determining means is the image processing circuit 3, the display means is the display monitor 4, The display control means is realized by the display changeover switch 5, respectively. Further, the alarm means is realized by the alarm device 13 and the steering control means is realized by the steering control device 14. However, these are merely examples, and each component is not limited to the above-described embodiment as long as the features of the present invention are not impaired.
[Brief description of the drawings]
FIG. 1 is a view showing a first embodiment of the present invention mounted on a vehicle. FIG. 2 is a view showing an image captured by a visible camera when there is no visible light irradiation from outside the vehicle in front of the vehicle. FIG. 3 is a diagram showing an example of a night-vision image displayed on a display monitor when the image example of FIG. 2 is taken. FIG. FIG. 5 shows an example of an image captured by a visible camera in the case of FIG. 4; FIG. 6 shows an example of an image captured by a visible camera in the case of FIG. 4; FIG. 7 is a diagram showing an example of an image picked up by FIG. 7. FIG. 7 is a flowchart of a process in the first embodiment. FIG. 8 is a diagram showing a second embodiment of the present invention mounted on a vehicle. FIG. 10 is a flowchart of a process according to the second embodiment. FIG. 11 is a diagram showing a case in which visible light from a road light is emitted away from the front of the vehicle. FIG. 11 is an example of an image captured by a visible camera in the case of FIG. 10 and brightness set in a part of the image. FIG. 12 is a diagram showing a determination area. FIG. 12 is a diagram schematically showing the brightness of each area of the brightness determination area in FIG. 11. FIG. 13 is displayed on a display monitor when an image example in FIG. 11 is captured. FIG. 14 is a diagram illustrating an example of a night-vision image. FIG. 14 is a diagram illustrating an example of a visible image when there is no visible light irradiation from outside the vehicle in front of the vehicle, and a brightness determination area set in a part of the image. 15 is a diagram schematically showing the brightness of each area of the brightness determination area in FIG. 14. FIG. 16 is an example of a visible image when a wide range in front of the vehicle is irradiated with visible light, and a part of the image. FIG. 17 is a diagram showing a brightness determination area set in FIG. 17; FIG. 18 is a diagram schematically showing the brightness of each area in FIG. 18; FIG. 18 is a flowchart of a process in a third embodiment; FIG. 19 is a diagram showing a fourth embodiment of the present invention mounted on a vehicle; FIG. 20 is a flowchart of a process according to the fourth embodiment.
DESCRIPTION OF SYMBOLS 1 Visible camera 2 Infrared camera 3 Image processing circuit 4 Display monitor 5 Display changeover switch 6 Headlamp 7 Road light 10 Brightness judgment area 13 Warning device 14 Steering control devices 21 and 22 White line 23 showing the boundary of lane 23 Assumed point 100 vehicle

Claims (8)

Irradiating means for irradiating visible light to the front of the vehicle,
An infrared image capturing unit that captures an infrared image in front of the vehicle and includes a range farther than the irradiation range of at least the irradiation unit in the imaging range,
Display means for displaying the captured infrared image,
A visible image capturing means for capturing a visible image in front of the vehicle,
Determining means for determining whether the visibility is good or bad based on the brightness of the traveling environment in front of the vehicle;
A display control unit that displays the infrared image on the display unit when the visibility is determined to be poor by the determination unit and does not display the infrared image on the display unit when the visibility is determined to be good And a night vision device for a vehicle. The night vision device for a vehicle according to claim 1,
The determination unit extracts, from the captured visible image, boundaries on both sides of a lane in which the vehicle is located,
Calculating a first length of the extracted boundary line;
Assuming the intersection point when the extracted boundary line is extended as the vanishing point of the lane,
Calculating a second length when the extracted boundary line is extended to the vanishing point, and a ratio of the first length to the second length;
A night vision apparatus for a vehicle, wherein the visibility is determined to be poor when the ratio is less than a predetermined value, and the visibility is determined to be good when the ratio is equal to or more than a predetermined value. The night vision device for a vehicle according to claim 1,
The determination unit extracts, from the captured visible image and the infrared image, boundary lines on both sides of the lane where the vehicle is located,
Calculate a first length of the boundary line extracted from the visible image, a third length of the boundary line extracted from the infrared image, and a ratio of the first length to the third length. And
A night vision apparatus for a vehicle, wherein the visibility is determined to be poor when the ratio is less than a predetermined value, and the visibility is determined to be good when the ratio is equal to or more than a predetermined value. The night vision device for a vehicle according to any one of claims 1 to 3,
The determining means divides a part of the captured visible image into a predetermined number of areas having a direction toward a distant front of the vehicle as a dividing direction,
Detecting the brightness of each area,
A night vision device for a vehicle, wherein the visibility is determined to be poor when at least one of the brightnesses is less than a predetermined value, and the visibility is determined to be good when all of the brightnesses are equal to or more than a predetermined value. The night vision device for a vehicle according to claim 2 or 3,
The night vision device for a vehicle, wherein the determination means determines that the vehicle has deviated from the lane when the vehicle crosses any of the extracted boundary lines. A night vision device for a vehicle according to claim 5,
When the determining means determines that the vehicle has deviated from the lane, there is provided a notifying means for notifying the user of the determination. A night vision device for a vehicle according to claim 5,
The lane return device further comprising a steering control unit that controls a traveling direction of the vehicle so as to return to the lane before departure when the determination unit determines that the vehicle deviates from the lane. A lane departure warning device according to claim 6,
The lane return device further comprising a steering control unit that controls a traveling direction of the vehicle so as to return to the lane before departure when the determination unit determines that the vehicle deviates from the lane.

Images