JPH1144635A - Dry/moisture moisture detection system of object surface in which two cameras of same visual field are used - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the necessary place for water scattering by finding an average value of each pixel of a threshold value subtraction image found by subtracting a threshold value image from a subtraction image obtained by image processing for a pair of horizontal and vertical polarization images taken in by a plurality of cameras, and judging dryness and moisture of an object. SOLUTION: Reflection light from an object surface by a light source is condensed by a lens 1, and a part of a converted parallel beam is taken in as an image in a first camera 4 through a polarization filter 3 transmitting horizontal oscillating light through a translucent mirror 2. The other part of the horizontal beam is taken in as an image in a second camera 7 through a polarization filter 6 transmitting vertical oscillation light through the translucent mirror 2 and a reflection plate 5. Vertical polarization image is subtracted from a pair of horizontal polarization images with regard to the brightness of the pixel of the same spot to obtain a subtraction image. If the average value of the brightness of the threshold value subtraction image obtained to subtract a corresponding threshold value image from the subtraction image is smaller than a reference value, water scattering is judged necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection system for detecting whether a surface of an object such as a large-scale concrete placing surface such as a concrete placing surface of a dam or a ground surface of a golf course is dry or wet. About.

[0002]

2. Description of the Related Art When a large-scale concrete such as a dam is cast, water is sprinkled on the concrete surface to promote heat radiation to prevent the occurrence of cracks and the like due to heat generated by the hardening after the casting. Cured while softening evenly. This watering is done manually or by a sprinkler, but tends to be done in places that are moist and do not require watering to keep the concrete surface dry.

On the other hand, Japanese Patent Application No. 7-316781 discloses a system for detecting dryness and humidity of an object surface. According to this system, the location where watering is required can be accurately detected,
There is no excessive watering, and there is no possibility of overlooking a dry spot and neglecting watering. Furthermore, if it is mounted on a watering vehicle, automatic watering is also possible, which saves manpower and costs.

However, in Japanese Patent Application No. Hei 7-316781, a dry / wet detecting unit is obliquely irradiated by a light source 9 onto the surface of an object 10 such as concrete, and the reflected light is condensed by a camera 13 through a polarizing filter 11 and the computer 12 And its attachments. The polarizing filter 11 was continuously rotated by 90 °, and the horizontally polarized light and the vertically polarized light were alternately sent to the camera 13.

FIG. 1 is a conceptual diagram of the system of Japanese Patent Application No. 7-316781.

[0006]

[Problems to be Solved by the Invention] Here, Japanese Patent Application No. 7-316781
Had the following problems.

In order to mechanically rotate the polarizing filter, there are movable parts, which complicates the configuration of the system.

Further, a mechanism for synchronizing the angle between the camera shutter and the polarizing filter is also required.

Further, since one camera sequentially captures the horizontal and vertical polarization images, there is a time difference between the two images used for the calculation. When the system is mounted on a moving body, two images are used. Images were no longer at the same point, causing errors in the detection system.

In order to solve these problems, the present invention uses two cameras having the same field of view and improves the camera mechanism.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a system for real-time detecting the dryness and wetness of the surface of an object by using such an image processing system by a computer, which is designed to solve the above-mentioned problems. It is.

That is, the present invention provides (A) a light source that irradiates an object surface obliquely, (B) a lens that converts reflected light from the object surface into parallel light, and (C) a light that has been made parallel by a lens in two directions. A semi-transparent mirror or a prism (D) that changes the direction of light; (E) a polarizing filter that transmits only light having an oscillating component in a specific direction of the split light; (F) a light that passes through a polarizing filter. Two cameras for capturing images (G) Computer for performing image processing of images captured by cameras and arithmetic processing for determining wet / dry (H) Display for displaying the results of image processing and arithmetic processing, and recording unit for recording these results And (I)
At the same time, captured from two cameras with the same field of view,
A pair of horizontal polarization image and vertical polarization image having a brightness value for each pixel is obtained by image processing to obtain a subtraction image obtained by subtracting the vertical polarization image from the horizontal polarization image, and a threshold prepared in advance from the subtraction image. A threshold subtraction image obtained by subtracting the value image is obtained, and an average value of the brightness of each pixel of the threshold subtraction image is obtained.
An arithmetic operation for judging whether the object is wet or dry based on the average value, and displaying and / or recording these results. And

When the dry / humidity detection system of the present invention is mounted on a traveling vehicle, the vehicle travels on the surface to be detected, and when a dry portion is detected, water may be sprinkled by another watering vehicle or manually. It is preferable that the system is mounted on an automatic watering vehicle, and when a drying unit is detected, watering is performed automatically or by a key operation of a passenger. A system in which part or all of a computer is installed at a base, and a part of or all of arithmetic processing and image processing are performed by a computer at the base by wirelessly communicating with a traveling vehicle, and a command is issued to the traveling vehicle. Needless to say, this may be done.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of a conventional system, in which one polarizing filter has to be rotated by 90 degrees.

In the present invention, the reflected light from the surface of the object is divided into two directions using a translucent mirror or prism, and the light path is changed by a reflector if necessary, and each light is separated into nine directions.
Through a polarizing filter arranged in a direction different by 0 degrees, a horizontal polarization image and a vertical polarization image are simultaneously obtained by two cameras.

FIG. 2 is a table illustrating the steps of computer pixel processing of an image leading to the determination of the state of the object surface based on the input polarization.

The system of the present invention is based on the principle that reflected light from a wet surface is more oscillating than reflected light from a dry surface, where an image with horizontal polarization is brighter than an image with vertical polarization. Utilize a phenomenon.

FIG. 3 is a diagram showing an example of a camera mechanism using two cameras according to the present invention.

It is needless to say that it is preferable to use a high intensity monochromatic light such as a halogen lamp as a light source.
Light reflected from the object surface by the light source is condensed by the lens 1 and converted into a parallel light beam. Part of the parallel light passes through the polarizing filter 3 that transmits through the translucent mirror 2 and transmits light of horizontal vibration, and is captured by the first camera 4 as an image. Another part of the parallel light beam condensed by the lens 1 is reflected by the translucent mirror 2, the light direction is changed again by the reflection plate 5, and the light passes through the polarizing filter 6 which transmits the light of the vertical vibration, and the second camera 7
Is captured as an image.

The images captured by the first camera 4 and the second camera 7 are sent to a computer and its attached devices for processing.

That is, as shown in FIG. 2, on the dry surface, the horizontal polarization image (I) and the vertical polarization image (II)
There is almost no difference in brightness between the two. However, due to the polarization phenomenon on the wet surface, the brightness of the horizontal polarization image (I) increases and the brightness of the vertical polarization image (II) decreases on the contrary as compared with the dry surface. In addition, the polarization phenomenon also occurs on the surface of the puddle, and the brightness of the portion with the puddle increases in the horizontal polarization image (I) showing the puddle.

Here, the brightness values of the corresponding pixels of the pair of horizontal polarization image (I) and vertical polarization image (II) at the same point are converted from the horizontal polarization image (I) to the vertical polarization image (II).
Is subtracted to obtain a subtraction image (III). However, in the subtraction image (III), the dry state and the puddle can be distinguished on the image, but the average value (IV) of the brightness of the subtraction image used for the discrimination by the computer depends on the size of the puddle. Both values may be as small as the same, and cannot be distinguished as they are.

For this reason, the subtraction image on the surface which is dry to the extent that watering is necessary is recorded in advance in a computer as a threshold image (V), and the corresponding subtraction image (III) is used. This threshold image
By subtracting (V) by the same method, a threshold subtraction image (VI) is obtained. Average brightness of threshold subtracted image
(VII) can be clearly distinguished between the dry state and the water pool because they differ greatly. Of course, the wet state can also be determined from the average value (VII) of the brightness of the threshold subtraction image.

Therefore, a certain reference value is set for the average brightness value (VII) of the threshold-subtracted image, and the average brightness value (VII) of the threshold-subtracted image is higher than the reference value. If it is smaller, it is determined that watering is required. According to this determination, watering is performed automatically or manually.

FIG. 4 is a view showing an example in which the direction of light is changed by using a prism 8 instead of the translucent mirror 2 of FIG.

FIG. 5 is a diagram showing an example in which the light path is changed without using the reflection plate 5.

As described above, the present invention is not limited to the embodiment shown in FIG. 3, 4 or 5 as long as the optical path of the same field of view is divided by the translucent mirror or the prism and the optical path is changed by the reflecting mirror.

Depending on the number of reflections in the optical path, one of the two polarized images may be a mirror image. In this case, the computer performs coordinate transformation and then performs image processing calculations. .

[0030]

According to the present invention, the location where watering is required can be accurately detected, so that watering is not excessively performed, and a situation in which a dry spot is overlooked and watering is neglected does not occur. Furthermore, if it is mounted on a watering vehicle, automatic watering is also possible, which saves manpower and costs.

Further, compared with the conventional system for detecting dryness and humidity on the surface of an object, there is no movable part in the camera part, and the reliability of the system is improved. Further, since the two polarized images have the same field of view for the same time, the calculation error can be minimized, and water can be sprinkled by highly accurate detection.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a conventional system.

FIG. 2 is a table showing a process of computer image processing and calculation for determining a wet / dry state of an object surface from a polarization image captured by a camera.

FIG. 3 is a diagram showing an example of a camera mechanism using two cameras of the present invention.

4 is a diagram showing an example in which a prism 8 is used instead of the translucent mirror 2 in FIG. 3 to change the direction of light.

FIG. 5 is a diagram showing an example in which a reflection plate 5 is not used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lens 2 ... Translucent mirror 3 ... Polarizing filter which transmits light in the horizontal direction 4 ... First camera 5 ... Reflector 6 ... Polarizing filter which transmits light in the vertical direction ,
7 Second camera, 8 Prism, 9 Light source, 10
... An object such as concrete, 11 a polarizing filter having a rotating mechanism, 12 a computer, 13 a camera

Claims (1)

[Claims] (A) a light source for irradiating an object surface obliquely; (B) a lens that converts reflected light from the object surface into parallel light; Or a prism (D) that changes the direction of light, a reflecting mirror (E), and a polarizing filter (F) that transmits only light having a vibration component in a specific direction among the split light, and that captures light transmitted through a polarizing filter as an image 2 (G) A computer that performs image processing of images captured by the cameras (G) and arithmetic processing of wet / dry determination (H) A display that displays the results of image processing and arithmetic processing, and a recording unit that records these results , (I) a pair of horizontally and vertically polarized images with brightness values for each pixel captured from two cameras with the same field of view at the same time, By processing, a subtraction image obtained by subtracting the vertical polarization image from the horizontal polarization image is obtained, a threshold subtraction image obtained by subtracting a threshold image prepared in advance from the subtraction image is obtained, and each pixel of the threshold subtraction image is obtained. An average value of brightness is calculated, an operation for determining whether the object is wet or dry is performed based on the average value, and the results are displayed and / or recorded. Dry / wet detection system.