JPH0336696A - Visual range state detecting device - Google Patents

Abstract

PURPOSE:To prevent the generation of invalid visual range decision due to a drop in the brightness ratio obtained when recognition plates are shadowed by projecting the vertical direction of the white part of each recognition plate and checking whether the projected result of only the white part is reduced or not. CONSTITUTION:Image information including two recognition plates 52, 53 is stored in a multi-level image memory part 13 through a television camera 11 (51) and an A/D conversion part 12. A vertical direction projecting part 14 projects the vertical direction of the recognition plate 53 stored in the memory part 13 and decides whether the plate 53 is influenced by a shadow or not as compared with a previously set value. At the time of recognizing the influence of the shadow, an output is generated to a visual range validity deciding part 17, while generating the output to a brightness ratio calculating part in the other case. The calculation part 15 finds out the brightness ratio of white and black parts of both the plates 52, 53. On the other hand, the decision part 17 outputs an invalid visual range decision to the post stage when the visibility distance is smaller than a previously set one in accordance with the output from the projection part 14 or a visibility distance calculation part 16, while outputting a valid visual range decision in the other case.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a visibility state detection device used to determine poor visibility due to snowstorms.

(Prior Art) FIG. 5 shows the usage status of a conventional visibility state detection device of this type. In FIG. 5, 51 is a television camera, 52.
53 is a recognition board. FIG. 6 shows an example of the design of the recognition plates 52 and 53. No. 7 @ shows the configuration of a conventional visibility state detection device. In Fig. 7, 71 is a television camera;
72 is an A/D conversion section, 73 is a multivalued image memory section, 74 is a brightness ratio calculation section, 75 is a visibility distance calculation section, and 76 is a poor visibility determination section.

Next, the operation of the above conventional example will be explained. The conventional visibility state detection device connects a television camera 51 to two recognition plates 52.
53 will fit on the same screen. The brightness ratio calculation unit 74 cuts out a region including the white and black portions of the recognition plate 52, 53 from the multivalued image memory unit 73, and calculates the brightness ratio thereof. FIG. 8 is an example showing how to obtain the brightness ratio. As shown in Figure 8, from the luminance values of the specified horizontal area including the white and black parts of the recognition board, its minimum value e
, the maximum value e in the area to the left of 81 of order 0
From xt and the maximum value 81m in the region on the right side, the average e, = (a□1+01□)/2 is determined. From this, the brightness ratio Q = (e-e0)/e is determined. The visibility distance calculation unit 75 calculates the visibility distance from the brightness ratio C□pct of the two recognition plates 52, 53 calculated by the brightness ratio calculation unit 74 and the distance between the two recognition plates using the following equation.

That is, L=Q-a/Q n (ct/ax) ・
=■. Here, a is a constant determined from the brightness ratio at which a person cannot identify the object.

In this way, even in the conventional visibility state detection device described above, the visibility distance at which visibility is determined to be poor is set in advance in the poor visibility determining section 76, and compared with the output from the visibility distance calculation section 75, the visibility distance is determined as poor visibility. Visibility conditions can be detected by outputting judgments such as whether or not visibility is good to the subsequent stage.

(Problem to be Solved by the Invention) In a state of poor visibility, the ability to discern distant objects is lost, so of the two recognition plates 52 and 53, the brightness ratio of 53 is smaller. Visibility distance power is calculated to be 1 shorter. In the above-mentioned conventional visibility state detecting device, when there is a snowstorm, the brightness of the black part of the recognition board approaches the brightness of the white part, as shown in FIG.

Since the brightness ratio is smaller than when the visibility is good in FIG. 9, the visibility distance is calculated to be short. However, as shown in Figure 11, when the shadow of a tree falls on the white part of the recognition board, the brightness of the white part of the recognition board approaches the brightness of the black part, so the brightness ratio becomes smaller. Visibility was sometimes judged to be poor even though visibility was actually good. The present invention solves these conventional problems and makes it possible to accurately detect poor visibility due to a snowstorm without being affected by the shadows of trees near the recognition board. The object is to provide an excellent visibility state detection device.

(Means for Solving Problem a) In order to achieve the above object, the present invention provides a vertical projection section between the multilevel image memory section and the brightness ratio calculation section, so that the white portion of the recognition plate is This is designed to determine whether or not there is a shadow.

(Function) The present invention has the following effects due to the above configuration. In other words, the vertical projection result of the white-only part of the recognition board will be an almost constant value depending on the number of vertical pixels in the area of the recognition board, regardless of Lf and good or poor visibility, even if there is no shadow effect. As the value becomes smaller, it can be determined whether or not the white part of the recognition board is being affected by the force S.

(Embodiment) FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 11 is a television camera, 12 is a ±A/D converter, 13 is a multivalued image memory section, 14 is a vertical projection section, 15 is a brightness ratio calculation section, 16 is a visibility distance calculation section, and 17 is a This is the poor visibility determination section.

Next, the operation of the above embodiment will be explained. In the above embodiment, image information including two recognition plates 52 and 53 (the recognition plates of the present invention and the conventional example are the same) is transmitted through the television camera 11 and the A/D converter 12. The image is stored in the multivalued image memory section 13. Vertical projection section 1
In step 4, the part of the recognition plate 53 of the multivalued image memory section 13 is projected in the vertical direction, and compared with the previously set value to determine whether there is an influence of the shadow. If it is recognized that there is an influence, the output is output to the poor visibility determination section 17, and if there is no influence, the output is output to the brightness ratio calculation section 15. In the brightness ratio calculation unit 15, the recognition plate 52 is
．． 53 areas are cut out and the brightness ratio of the white and black parts is determined. In the visibility distance calculation unit 35, two recognition plates 52.5
From the brightness ratio C□I 02 of 3 and the installation interval Q of the recognition plates 52.53, the visibility distance is calculated using the above equation (2) as in the conventional case. In the poor visibility determination unit 17, the vertical projection unit 1
4 or the output from the visibility distance calculation unit 16, a judgment such as poor visibility is output when the visibility distance is smaller than a preset value, and good visibility is output otherwise.

Figure 2 is an example of the vertical projection results when visibility is good and there is no shadow on the recognition board. Figure 3 is an example of the vertical projection results when visibility is poor due to a snowstorm. Figure 4 is when visibility is good. This is an example of the vertical projection result when the recognition board is shaded. The vertical projection result is divided into the following three areas according to the in-screen coordinates of the H kickboard. That is, it is divided into a white-only part on the left side of the recognition board from X-engine to x2, a part including a black area in the center of the recognition board from x2 to x3, and a white-only part on the right side of the recognition board from x3 to x4. The average value of the vertical projection results from xl to x2 and from X□ to x4 is PI3゜P3
4, this PI3. P34 has good visibility and visibility depending on the number of vertical pixels of the recognition object unless there is an influence of shadows.
It takes an almost constant value regardless of defectiveness. When the white part of the recognition board is shaded as shown in Fig. 4, the luminance of the shaded part is low, so the vertical projection result is also small by that part, and the average value P12. P34 is also smaller than when there is no influence of shadows. Therefore, in the 5 vertical direction projection section 14, the average value P12. By setting the comparison value with P34 in advance to a value that is considered to be affected by shadows and comparing the values, it is determined whether or not the recognition board is shadowed.

The effect of shadows means that the weather is so clear that shadows appear, so in this case, the output is sent to the poor visibility determination section 17 in the final stage, and the visibility is determined to be good without calculating the visibility distance based on the brightness ratio. It is determined that

As described above, according to the above embodiment, the vertical projection unit 14 projects the recognition plate portion in the vertical direction.

Since it is determined whether there is a shadow on the white part of the recognition plate, there is no need to judge whether visibility is poor due to a decrease in brightness ratio when a shadow is present.

In the above embodiment, when calculating the brightness ratio, the horizontal region including the white and black portions of the recognition board is used.

Although the direction of projection is vertical, when calculating the brightness ratio, L! Exactly the same result can be obtained by using the vertical area that includes the & signboard kickboard and the black part, and setting the projection direction horizontally.

(Effects of the Invention) As is clear from the above embodiments of the present invention, the present invention has the following effects.

(1) It is possible to judge whether there is a shadow effect by vertically projecting the part of the recognition board and seeing whether the projection result of the white-only part has decreased. A determination that visibility is poor due to a decrease in brightness ratio no longer occurs.

(2) The fact that the vertical projection unit can tell whether or not there is a shadow on the recognition plate means that it is sunny, so the visibility distance is calculated by finding the brightness ratio of the two recognition plates. You can judge whether the visibility is good without having to worry about it.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing an example of the vertical projection result when the recognition board is not shaded with good visibility, and FIG. 3 is a diagram showing an example of the vertical projection result when the recognition board is not shaded. , A diagram showing an example of the vertical projection results when visibility is poor due to a snowstorm. Figure 4 is for when visibility is good. A diagram showing an example of the vertical projection result when a shadow is cast on the recognition board, FIG. 5 is a diagram showing the usage status of a conventional visibility state detection device, and FIG. 6 is a diagram showing an example of the design of the recognition board. Fig. 7 is a diagram showing the configuration of a conventional visibility state detection device, Fig. 8 is a diagram showing an example of how to determine the brightness ratio, and Fig. 9 is an example of the brightness distribution in the horizontal area of the recognition board when visibility is good. Figure 10 is a diagram showing an example of the brightness distribution in the horizontal area of the recognition board during a snowstorm, and Figure 11 is a diagram showing an example of the brightness distribution in the horizontal area of the recognition board when visibility is good and there is a shadow effect. It is a figure showing an example. 11, 51.71--TV camera, 52.53
... recognition board, 12.72 ... A/D conversion section, 13,
73...Multi-valued image memory section, 14...Vertical direction projection section, 15.74... Brightness ratio calculation section. 16, 75... Visibility distance calculation unit, 17.76... Poor visibility determination unit.

Claims (1)

[Claims] Two recognition boards with the central part drawn in black and the other parts white, a multilevel image memory section that stores an image of the recognition board installed on the ground, and a recognition board area that is vertically drawn. A vertical projection unit that projects, a brightness ratio calculation unit that calculates the brightness ratio between the white and black parts of each recognition board, and a visibility that calculates the visibility distance from the brightness ratio of each recognition board and the installation interval of the recognition boards. This visibility state detection device includes a distance calculation section and a poor visibility determination condition setting section, compares the output of the visibility distance calculation section with the poor visibility determination condition, and determines that the visibility is poor when the conditions are satisfied.