JP4463388B2 - Visual status measurement device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measurement result indicating a visual recognition condition on a road or the like, for example, a visual recognition condition measuring apparatus that measures visibility or the like.
[0002]
[Prior art]
When the visibility becomes worse due to fog, rain, snow, etc. on roads, etc., traffic safety will be threatened. Measurement of the visual status is performed.
[0003]
Conventionally, as such a visual condition measuring device, a visibility measuring device using a transmittance meter (VI meter) composed of a projector and a light receiver arranged at a predetermined distance from each other has been used. In this visibility measuring device, the visibility is calculated from the transmittance obtained from the transmittance meter according to the following equation 1 called the Koschmieder equation.
[0004]
[Expression 1]
V = (L × logε) / logT
[0005]
In Equation 1, V is the visibility (unit is m), L is the distance between the projector and the light receiver constituting the transmittance meter (unit is m), and T is the transmittance obtained by the transmittance meter (VI meter). , Ε is a contrast value (usually 0.02 to 0.05 empirically) necessary for a human to identify an object.
[0006]
However, in a visibility measuring apparatus using a transmittance meter, it is necessary to provide a transmittance meter dedicated to visibility measurement.
[0007]
Therefore, in recent years, various traffic conditions on the road have been monitored using a television camera, so that a visibility measuring device using a television camera is used so that this television camera can also be used for visibility measurement. Came to be offered.
[0008]
A conventional visibility measuring device using a television camera is disclosed in Japanese Patent No. 266575739, and an index having a region with different brightness and darkness that is installed at a predetermined distance in the atmosphere is captured by the television camera. Based on the image signal from the camera, the contrast between the bright area and the dark area of the index at a position separated by the predetermined distance is detected by the light / dark contrast detecting means, and imaged at a distance not affected by atmospheric turbidity The visibility is calculated from the light / dark contrast and the light / dark contrast detected by the light / dark contrast detecting means.
[0009]
According to this conventional visibility measuring device, when fog or the like occurs, the contrast between the bright area and the dark area of the index imaged by the television camera is reduced according to the amount of fog, so the visibility can be calculated. . The conventional visibility measuring apparatus uses a television camera and does not use a transmittance meter. Therefore, the television camera can be used as a television camera for monitoring traffic conditions and the like. For this reason, cost reduction and reduction in the number of installations can be achieved.
[0010]
[Problems to be solved by the invention]
However, in the conventional visibility measuring device, the visibility is obtained by the change in contrast between the brightness and darkness of the index, and since brightness information (luminance information) is used, the brightness differs greatly between daytime (daytime) and nighttime. Since the brightness information is greatly different, visibility can only be determined appropriately only in one of daytime and nighttime, and visibility cannot be determined appropriately over day and night. That is, since the brightness of the light curtain changes due to the influence of ambient light, there is a difference in contrast between daytime and nighttime. Therefore, the conventional visibility measuring device cannot measure daytime and nighttime.
[0011]
FIG. 10 shows the result of an experiment conducted by the present inventor regarding this point. The experimental results were obtained as follows. The index 50 shown in FIG. 9 and a television camera (not shown) were set apart from each other by a predetermined distance, and the index 50 was imaged by the television camera. The index 50 includes a white area (bright area) 50A and a black area (dark area) 50B that are separately painted in white and black. The index 50 was illuminated with illumination light from an illuminating lamp installed near the index 50 at night. Based on the image signal from the television camera, the luminance L of the white area 50A_WAnd luminance L of the black area 50B_BAnd the luminance L_W, L_BThe contrast C was calculated according to the following formula 2.
[0012]
[Expression 2]
C = (L_B-L_W) / L_W
[0013]
In addition, using a transmittance meter (VI meter), the projector was installed in the vicinity of the index 50, and the receiver was installed in the vicinity of the television camera, and the transmittance was measured by this transmittance meter (VI meter). . Then, from this transmittance, the visibility was determined according to the equation 1. Contrast C and visibility were obtained by the above-described method for each generation amount while artificially generating fog between the TV camera and the index 50 and changing the generation amount at daytime and nighttime. FIG. 10 shows the relationship between the contrast C thus obtained and the visibility. In FIG. 10, line (1) shows the relationship between the contrast C and visibility obtained in the daytime (the sky illuminance at that time was 379 lux), and line (2) shows the night (the sky at that time). The illuminance was 2.34 lux.), And the relationship between the contrast C and the visibility obtained.
[0014]
As can be seen from FIG. 10, the contrast C differs greatly between daytime and nighttime. For this reason, when it is attempted to obtain the visibility based on the contrast C, it is possible to obtain the visibility only in one of daytime and nighttime, and it is not possible to obtain the visibility over day and night.
[0015]
The present invention has been made in view of such circumstances, and can measure the visual status using the imaging means without using the transmittance meter, and appropriately measure the visual status over day and night. An object of the present invention is to provide a visual condition measuring device capable of performing the above-mentioned.
[0016]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the visual condition measuring device according to the first aspect of the present invention is an image pickup unit that picks up an indicator having at least two regions having different chromaticities installed at positions separated by a predetermined distance in the atmosphere. And an acquisition means for obtaining a degree of difference in chromaticity between the at least two regions of the index at a position separated by the predetermined distance based on an image signal from the imaging means, and substantially influence of atmospheric turbidity Calculation means for obtaining a measurement result indicating a visual recognition status based on the degree of difference between the chromaticities of the at least two regions of the indicator in a state not received automatically and the degree obtained by the acquisition means; It is provided.
[0017]
The chromaticity indicates the whole of the three elements of the color excluding lightness (luminance). In the present invention, not only the visible region but also the region other than the visible region such as the near infrared region. Including the wavelength. Further, when the visual recognition state is measured even at night, the at least two areas of the indicator are self-luminous areas or illuminated areas illuminated by illumination light at night. The above point is the same also about each aspect mentioned later.
[0018]
In the daytime, when atmospheric turbidity such as fog, rain, and snow occurs, light from the index is scattered by fog and the scattered light does not reach the imaging means. Moreover, sunlight is scattered by fog etc. For this reason, the color of the image of each region of the index imaged by the imaging unit becomes whitish due to the scattered light, and the degree of whitishness depends on the amount of fog or the like between the imaging unit and the index. Therefore, since the chromaticity of each area of the index is different, the degree of difference in chromaticity of the image of each area of the index imaged by the imaging means is large unless atmospheric turbidity such as fog occurs. When atmospheric turbidity such as fog occurs, the image of each area of the index imaged by the imaging means becomes whitish and approaches the same chromaticity according to the amount of fog or the like. In this way, in the daytime, when atmospheric turbidity such as fog, rain, and snow occurs, the chromaticity of the image of each area of the index imaged by the imaging means becomes uniform (that is, the degree of chromaticity difference). The degree of uniformity depends on the amount of fog or the like, that is, the transmittance (and thus visibility).
[0019]
On the other hand, if there is no ambient light such as illumination light between the imaging means and the index at night, light from the index is scattered by the fog or the like when turbidity of the atmosphere such as fog, rain, or snow occurs. The scattered light does not reach the imaging means. Therefore, since the chromaticity of each area of the index is different, the degree of difference in chromaticity of the image of each area of the index imaged by the imaging means is large unless atmospheric turbidity such as fog occurs. On the other hand, when atmospheric turbidity such as fog occurs, the image of each area of the index imaged by the imaging means becomes dark and approaches the same chromaticity according to the amount of fog or the like. In this way, even when ambient light such as illumination light does not exist between the image pickup means and the index at night, the image is picked up by the image pickup means when turbidity of the atmosphere such as fog, rain, and snow occurs. The chromaticity of the image in each region of the index is made uniform (that is, the degree of chromaticity difference is reduced), and the degree of uniformity depends on the amount of fog or the like, that is, the transmittance (and thus visibility). White and black differ only in lightness (luminance) and have the same chromaticity.
[0020]
In addition, when ambient light such as illumination light exists between the imaging means and the index at night, light from the index is scattered by the fog or the like when atmospheric turbidity such as fog, rain, or snow occurs. The scattered light does not reach the imaging means. In addition, ambient light is scattered by fog or the like. Therefore, since the chromaticity of each area of the index is different, the degree of difference in chromaticity of the image of each area of the index imaged by the imaging means is large unless atmospheric turbidity such as fog occurs. On the other hand, when atmospheric turbidity such as fog occurs, the image of each area of the index imaged by the imaging means approaches the color of ambient light and approaches the same chromaticity according to the amount of fog or the like. . In this way, even when ambient light such as illumination light is present between the imaging means and the index at night, when the atmospheric turbidity such as fog, rain, snow, etc. occurs, the image is taken by the imaging means. The chromaticity of the image in each region of the index is made uniform (that is, the degree of chromaticity difference is reduced), and the degree of uniformity depends on the amount of fog or the like, that is, the transmittance (and thus visibility).
[0021]
Therefore, as in the first aspect, the turbidity of the atmosphere is obtained by obtaining the degree of difference between the chromaticities of at least two regions of the index located at a predetermined distance based on the image signal from the imaging means. A measurement result indicating a visual recognition state is obtained based on a degree of difference in chromaticity between the at least two regions of the indicator in a state substantially not affected by the above and the degree obtained by the acquisition unit. Can do it.
[0022]
And in the said 1st aspect, since it uses chromaticity instead of using contrast of light and dark like the conventional visibility measuring device, it is not influenced by the surrounding brightness, and it is day and night. The visual status can be measured appropriately.
[0023]
In the first aspect, since the imaging means is used and the transmittance meter is not used, the imaging means for monitoring traffic conditions and the like can also be used as the imaging means. For this reason, cost reduction and reduction in the number of installations can be achieved.
[0024]
The visual condition measuring device according to the second aspect of the present invention is the first indicator having the at least two regions having different chromaticities installed at positions separated by a first predetermined distance in the atmosphere in the first aspect. A second index having at least two regions with different chromaticities installed at a position separated by a second predetermined distance in the atmosphere different from the first predetermined distance, Based on image signals from the second imaging means for imaging and the first imaging means, the chromaticities of the at least two regions of the first index at positions separated by the first predetermined distance Colors of the at least two regions of the second index at positions separated by the second predetermined distance based on image signals from a first acquisition unit for obtaining a degree of difference and the second imaging unit The degree of difference between degrees And an arithmetic means for obtaining a measurement result indicating a visual recognition state based on the degree obtained by the first obtaining means and the degree obtained by the second obtaining means. Is.
[0025]
In the first aspect, only one index is used, and the measurement result indicating the visual recognition status based on the degree of difference between the chromaticities of the respective areas of the index in a state where the index is not substantially affected by atmospheric turbidity. On the other hand, in the second mode, two indicators set at different distances are used, and the visual status is determined from the relative relationship between the chromaticities of the areas of the two indicators. Although the measurement result shown is obtained, the same advantage as the first aspect can be obtained by the second aspect.
[0026]
The visual condition measuring device according to the third aspect of the present invention is the visual condition measuring apparatus according to the second aspect, wherein the first and second imaging means are combined with a single television camera or a digital still camera.
[0027]
In the second aspect, separate television cameras or digital still cameras may be used as the first and second imaging means. However, as in the third aspect, a single television camera or digital still camera is used. If the camera is also used, the cost can be reduced, which is preferable.
[0028]
The visual condition measuring device according to a fourth aspect of the present invention is the visual status measurement device according to any one of the first to third aspects, wherein the degree of difference between the chromaticities of the at least two regions is the chromaticity diagram. This is a value corresponding to the distance between the coordinates when expressed as the upper coordinates.
[0029]
In this fourth aspect, a value corresponding to the distance between coordinates on the chromaticity diagram is given as an example of the degree of difference between chromaticities, but the degree of difference between chromaticities is limited to this example. Is not to be done. Examples of the chromaticity diagram include, but are not limited to, an xy chromaticity diagram based on the XYZ color system, a chromaticity diagram based on the RGB color system, and a chromaticity diagram based on the HVC color system. It is not a thing.
[0030]
In the visual status measurement device according to the fifth aspect of the present invention, in any one of the first to fourth aspects, the calculation means obtains visibility or transmittance as the measurement result.
[0031]
Although the fifth aspect is an example of the form of the measurement result, the form of the measurement result indicating the visual recognition state is not limited to these.
[0032]
In the first to fifth aspects, for example, a television camera or a digital still camera may be used as the imaging unit.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a visual condition measuring device according to the present invention will be described with reference to the drawings.
[0034]
[First Embodiment]
[0035]
FIG. 1 is a schematic perspective view showing a visual condition measuring device according to a first embodiment of the present invention. FIG. 2 is a schematic block diagram showing the configuration of the processing apparatus 3 in FIG. FIG. 3 is a schematic flowchart illustrating an example of processing at the time of installation and operation of the processing device 3. FIG. 4 is an xy chromaticity diagram of the CIE 1931XYZ color system for explaining the operating principle of the visual condition measuring apparatus according to the present embodiment. FIG. 5 is a diagram showing experimental results related to the operating principle of the visual condition measuring apparatus according to the present embodiment.
[0036]
As shown in FIG. 1, the visual status measurement device according to the present embodiment processes a television camera 1 as an imaging means for imaging the index 2 and an image signal from the television camera 1 to show a measurement result indicating the visual status. And a processing device 3 for outputting the visibility. In the present embodiment, the index 2 is configured exclusively for visibility measurement, and has two regions having different chromaticities (in this embodiment, red and blue, but the chromaticity is not limited). It consists of a plate member having A and B. Although not shown in the drawing, the index 2 is illuminated by illumination light at night. The areas A and B may be configured as self-luminous areas. In this case, for example, a large number of light emitting elements such as LEDs may be provided, or a fluorescent lamp may be provided inside so that the colored translucent plate emits light. The areas A and B may be spot-like areas with a remarkably small area, but the areas of a certain size are used so that the accuracy can be improved by averaging when determining the chromaticity as will be described later. It is preferable to have.
[0037]
The television camera 1 is supported by a column 5 erected on the shoulder of the road 4 and is installed at a position away from the index 2 by a predetermined distance across the atmosphere. In this embodiment, a so-called full-color camera is used as the television camera 1, but it is not always necessary to be full-color.
[0038]
The processing device 3 includes an A / D converter 10 that performs A / D conversion on an image signal from the TV camera 1, and image data that has been A / D converted by the A / D converter. Image memory 11R, 11G, and 11B that are stored separately, CPU 12, memory 13 that stores programs and data for causing CPU 12 to perform operations necessary to perform processing described later, and processing results And an output unit 14 for outputting the visibility.
[0039]
The operation of the visual condition measuring apparatus according to the present embodiment will be described with reference to FIG. Steps S1 to S5 in FIG. 3 are preprocessing performed only when the apparatus is installed. After installing the television camera 1, the index 2 and the processing device 3, first, the position of the image of the area A and the position of the image of the area B in the image captured by the television camera 1 are set (steps S1 and S2). This is the setting of the position for extracting the images of the areas A and B from the image by using a mask. The image is taken by the installer on the monitor (not shown) and the input device (not shown). This is done by specifying the position of.
[0040]
Thereafter, in response to the command from the input device, the processing device 3 performs the image of the regions A and B based on the image data obtained from the television camera 1 in a state where it is not substantially affected by atmospheric turbidity. Are respectively calculated (steps S3 and S4). As an image used for this processing, an image acquired in a state where there is no air turbidity such as fog, rain or snow between the TV camera 1 and the index 2 in the installation state as shown in FIG. Even if an image obtained using the index 2 in a state in which the index 2 is sufficiently close to the TV camera 1 (that is, at a distance that is not substantially affected by atmospheric turbidity) before the index 2 is installed at a predetermined installation location may be used. Good.
[0041]
Here, calculation of the chromaticity of the area A in step S3 will be described. In the present embodiment, the average value of the R value, the average value of the G value, and the average value of the B value of each pixel in the region A in the image are obtained, and the XYZ color system is used as the chromaticity of the region A from these values. The x value and y value at are obtained according to a well-known conversion formula. The x value and the y value indicate the coordinates of the xy chromaticity diagram in the XYZ color system. Point A in FIG.₀Indicates an initial value of the chromaticity of the region A. Similarly, in step S4, an average value of R values, an average value of G values, and an average value of B values in the region B in the image are obtained, and from these values, the chromaticity of the region B is determined in the XYZ color system. Find the x and y values. Point B in FIG.₀Indicates an initial value of the chromaticity of the region B.
[0042]
Thereafter, in step S5, the processing device 3 determines the initial chromaticity distance as the degree of difference between the initial chromaticity value of the area A acquired in step S3 and the initial chromaticity value of the area B acquired in step S4. A value is calculated and stored in the memory 13. The chromaticity distance is a distance between the coordinates when the two chromaticities are expressed as coordinates on the chromaticity diagram. In step S5, specifically, point A in FIG.₀And point B₀Initial value K of chromaticity distance which is the distance between₀Is obtained according to Equation 3 below. However, point A₀The coordinates of (x₀₁, Y₀₁), Point B₀The coordinates of (x₀₂, Y₀₂).
[0043]
[Equation 3]
K₀= {(X₀₁-X₀₂)²+ (Y₀₁-Y₀₂)²}^1/2
[0044]
After the preprocessing of steps S1 to S5 described above, the main measurement processing of steps S6 to S11 is performed. New images are sequentially obtained from the television camera 1.
[0045]
First, when a new image is obtained from the television camera 1, the processing device 3 calculates the chromaticities of the images of the regions A and B of the image, respectively, similarly to steps S3 and S4 (steps S6 and S7). Point A in FIG.₁Shows an example of the chromaticity of the region A obtained in step S6, and point B in FIG.₁Shows an example of the chromaticity of the region B obtained in step S7. Point A shown in FIG.₁And point B₁This example shows a state in which fog is generated between the TV camera 1 and the index 2 to some extent. Due to the occurrence of fog, the chromaticity of the region A and the chromaticity of the region B are made uniform to some extent, and the point A₁And point B₁The distance between the two (chromaticity distance) is point A₀And point B₀It is shorter than the distance between (the chromaticity distance initial value).
[0046]
Next, as in step S5, the processing device 3 determines the point A in FIG. 4 as the degree of difference between the chromaticity of the area A calculated in step S6 and the chromaticity of the area B calculated in step S7.₁And point B₁Chromaticity distance K, which is the distance between₁Is calculated (step S8).
[0047]
Next, the processing device 3 determines the chromaticity distance K calculated in step S8.₁And the chromaticity distance K previously calculated in step S5₀Ratio K₁/ K₀Is calculated (step S9).
[0048]
Thereafter, the processing device 3 converts the ratio calculated in step S9 into the visibility according to an expression or table obtained experimentally in advance (step S10), and outputs the visibility obtained in step S10 to the outside (step S11). Returning to step S6, the processing of steps S6 to S11 is repeated.
[0049]
Here, the experimental results shown in FIG. 5 obtained by the present inventor will be described as support that the visibility can be appropriately obtained by the above operation. The experimental results were obtained as follows. In the same configuration as in FIG. 1, a transmittance meter (VI meter) is used as in the case of obtaining the experimental result shown in FIG. 10, the projector is installed in the vicinity of the index 2, and the receiver is connected to the TV camera 1. The transmittance was measured with this transmittance meter (VI meter). Then, from this transmittance, the visibility was determined according to the equation 1. Also, a color luminance meter is installed in the vicinity of the television camera 1, and the x and y values in the XYZ color system of the areas A and B of the index 2 are respectively measured by this color luminance meter. The chromaticity distance between the chromaticity and the chromaticity of the region B was calculated. Then, while the fog is artificially generated between the TV camera 1 and the index 2 in the daytime and at night, and the generation amount is changed, the visibility and chromaticity distance are obtained by the above-described method for each generation amount. It was. FIG. 5 shows the relationship between the visibility and the chromaticity distance thus obtained. In FIG. 5, line (3) shows the relationship between visibility and chromaticity distance obtained in the daytime (the sky illuminance at that time was 264 lux), and line (4) shows the night (at that time) The sky illuminance was 2.34 lux.), Showing the relationship between the visibility and chromaticity distance obtained. In FIG. 5, K₀Indicates the chromaticity distance between the chromaticity of the region A and the chromaticity of the region B measured in a state where there is no air turbidity such as fog, rain, and snow.
[0050]
As can be seen from FIG. 5, the chromaticity distance is almost the same between daytime and nighttime, and the chromaticity distance changes according to the visibility, and the visibility can be appropriately determined from the chromaticity distance. Therefore, according to the present embodiment, the visibility can be appropriately obtained over the day and night by the above-described operation.
[0051]
In the present embodiment, as described above, the chromaticity distance K₁Instead of converting directly to visibility, ratio K₁/ K₀This ratio K₁/ K₀Therefore, even if the chromaticities of the areas A and B of the index 2 are variously different, visibility can be appropriately obtained without special calibration.
[0052]
Moreover, according to this Embodiment, since the television camera 1 is used and the transmittance meter is not used, the television camera 1 can also be used for monitoring traffic conditions and the like. For this reason, cost reduction and reduction in the number of installations can be achieved.
[0053]
By the way, the visibility on the horizontal axis in FIG. 5 is obtained by converting the transmittance measured by the transmittance meter (VI meter) according to the equation 1 as described above.₁/ K₀To transmittance. Accordingly, the processing device 3 can output the transmittance as a measurement result indicating the visual recognition status instead of outputting the visibility. Thus, since it is also possible to output the transmittance as a measurement result, the device according to the present embodiment can be used not only as a visual condition measurement device, but also for fire detection, smog measurement, etc. It can also be used as a transmittance measuring device for measuring transmittance for other applications.
[0054]
In the present embodiment, the index 2 dedicated to measuring the visual status is used. However, for example, instead of the index 2, any traffic sign, signboard, or other areas having different chromaticities may be used. Any of them can be used as an indicator as appropriate. As an example of what can be used as an index instead of the dedicated index 2, a traffic guide sign is shown in FIG. In FIG. 6, the area is a green area and the area is a white area, and the chromaticities of the two areas are different from each other.
[0055]
[Second Embodiment]
[0056]
FIG. 7 is a schematic perspective view showing a visual condition measuring apparatus according to the second embodiment of the present invention. 7, elements that are the same as or correspond to those in FIG. 1 are given the same reference numerals, and redundant descriptions thereof are omitted. FIG. 8 is a schematic flowchart showing an example of processing at the time of installation and an operation of the processing device 3 in the visual condition measuring device according to the present embodiment.
[0057]
The difference between the present embodiment and the first embodiment is that in this embodiment, two indices 22, 23 are used instead of a single index 2, as shown in FIG. The only difference is that the processing at the time of installation and the operation of the processing device 3 are as shown in FIG.
[0058]
The distance between the index 22 and the TV camera 1 is different from the distance between the index 23 and the TV camera 1, and the index 23 is arranged closer to the TV camera 1 than the index 22. . In the present embodiment, both indexes 22 and 23 are included in the visual field of the television camera 1 at the same time. Of course, the indices 22 and 23 may be imaged by separate television cameras.
[0059]
The indicators 22 and 23 have the same configuration as the indicator 2. The index 22 has two regions 22A and 22B having different chromaticities. The index 23 has two regions 23A and 23B having different chromaticities. The areas 22A and 23A are the same as the area A of the index 22, and the areas 22B and 23B are the same as the area B of the index 2. However, the indicators 22 and 23 do not necessarily have the same configuration.
[0060]
The operation of the visual condition measuring device according to the present embodiment will be described with reference to FIG. Steps S21 to S24 in FIG. 8 are preprocessing performed only when the present apparatus is installed. After installing the television camera 1, the index 2, and the processing device 3, first, the positions of the images of the regions 22A, 22B, 23A, and 23B in the image captured by the television camera 1 are set (steps S21 to S24). This is a position setting for extracting the images of the regions 22A, 22B, 23A, and 23B from the image by using a mask, and the input device (not shown) is used while viewing the image taken by the installer on the monitor (not shown). )) To specify their position.
[0061]
After the preprocessing of steps S21 to S24 described above, the main measurement processing of steps S25 to S33 is performed.
[0062]
First, when a new image is obtained from the television camera 1, the processing device 3 calculates the chromaticities of the images 22A, 22B, 23A, and 23B of the image as in steps S6 and S7 in FIG. (Steps S25 to S28).
[0063]
Next, similarly to step S8 in FIG. 3, the processing device 3 uses the chromaticity distance K between the chromaticities of the regions 22A and 22B of the index 22 obtained in steps S25 and S26.₂(Step S29), and the chromaticity distance K between the chromaticities of the areas 23A and 23B of the index 23 obtained in steps S27 and S28.₃Is calculated (step S30).
[0064]
Next, the processing device 3 determines the chromaticity distance K calculated in step S29.₂And the chromaticity distance K calculated in step S30.₃Ratio K₃/ K₂Is calculated (step S31).
[0065]
Thereafter, the processing device 3 converts the ratio calculated in step S31 into visibility according to an equation or table obtained experimentally in advance (step S32), and outputs the visibility obtained in step S32 to the outside (step S33). Returning to step S25, the processes of steps S25 to S33 are repeated.
[0066]
In the present embodiment, the initial value of the chromaticity distance obtained in step S5 in FIG. 3 is not obtained, but the chromaticity distance K of the indicators 22 and 23 installed at different distances.₂, K₃The ratio K which is the relative relationship of₃/ K₂The same advantages as those of the first embodiment can be obtained.
[0067]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.
[0068]
【The invention's effect】
As described above, according to the present invention, the visual status measurement device can measure the visual status using the imaging means without using the transmittance meter, and can appropriately measure the visual status over day and night. Can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a visual condition measuring device according to a first embodiment of the present invention.
FIG. 2 is a schematic block diagram showing a configuration of a processing device 3 in FIG.
FIG. 3 is a schematic flowchart showing an example of processing at the time of installation of the visual condition measuring device shown in FIG. 1 and operation of the processing device.
4 is an xy chromaticity diagram of a CIE 1931XYZ color system for explaining an operation principle of the visual condition measuring device shown in FIG.
FIG. 5 is a diagram showing experimental results related to the operation principle of the visual condition measuring apparatus shown in FIG. 1;
FIG. 6 is a diagram showing an example of a traffic guide sign that can be used as an index.
FIG. 7 is a schematic perspective view showing a visual condition measuring device according to a second embodiment of the present invention.
8 is a schematic flowchart showing an example of processing at the time of installation of the visual condition measuring device shown in FIG. 7 and operation of the processing device.
FIG. 9 is a diagram showing indices used in an experiment conducted in connection with a conventional visibility measuring device.
FIG. 10 is a diagram showing the results of an experiment conducted in connection with a conventional visibility measuring device.
[Explanation of symbols]
1 TV camera
2,22,23 indicators
3 processing equipment

Claims (5)

Imaging means for imaging an indicator having at least two regions with different chromaticities installed at positions separated by a predetermined distance in the atmosphere;
Obtaining means for obtaining a degree of difference between chromaticities of the at least two regions of the index at a position separated by the predetermined distance based on an image signal from the imaging means;
A measurement result indicating a visual recognition state based on the degree of difference between the chromaticities of the at least two regions of the indicator and the degree obtained by the acquisition means in a state substantially not affected by atmospheric turbidity Computing means for obtaining
A visual condition measuring device characterized by comprising: First imaging means for imaging a first index having at least two regions of different chromaticity that are installed at positions separated by a first predetermined distance in the atmosphere;
A second imaging means for imaging a second index having at least two regions with different chromaticities installed at positions separated by a second predetermined distance in the atmosphere different from the first predetermined distance;
First acquisition for obtaining a degree of difference between chromaticities of the at least two regions of the first index at a position separated by the first predetermined distance based on an image signal from the first imaging means. Means,
Second acquisition for obtaining a degree of difference between chromaticities of the at least two regions of the second index at a position separated by the second predetermined distance based on an image signal from the second imaging means. Means,
An arithmetic means for obtaining a measurement result indicating a visual recognition state based on the degree obtained by the first obtaining means and the degree obtained by the second obtaining means;
A visual condition measuring device characterized by comprising: 3. The visual condition measuring device according to claim 2, wherein the first and second imaging means are shared by a single television camera or a digital still camera. The degree of difference between chromaticities of the at least two regions is a value corresponding to a distance between the coordinates when the chromaticity is expressed as coordinates on a chromaticity diagram. 4. The visual condition measuring device according to any one of 3 above. The visual condition measuring device according to claim 1, wherein the calculation unit obtains visibility or transmittance as the measurement result.

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