Measuring device

Abstract

When measuring the surface condition of an object while it is in motion, both the shape and color information of the object's surface are checked simultaneously. [Solution] The measuring device attached to a mobile body includes a first measuring unit that measures the shape of the surface of an object by light section method based on an image captured by a first camera after irradiating a measurement point on the surface of the object with a first light, and a second measuring unit that measures the state of the surface of the object based on an image captured by a second camera after irradiating the measurement point with a second light having a different wavelength from the first light, wherein the second camera captures an image through a filter that blocks the wavelength of the first light, and the first camera captures an image through a filter that transmits light corresponding to the wavelength of the first light.

Description

[Technical Field]

[0001] The present invention relates to a measuring device. [Background Art]

[0002] Patent Document 1 describes an apparatus that surveys the surface of a road structure, is mounted on a vehicle, includes a first road surface irradiation means and a first road surface imaging means, wherein the first road surface imaging means generates a visible image, includes a second road surface irradiation means and a second road surface imaging means, wherein the second road surface irradiation means irradiates a laser beam, the second road surface imaging means is a high-speed 3D measurement camera system, and an analysis image obtained by the second road surface imaging means is combined with a visible image (an image obtained by the first road surface imaging means).

[0003] Patent Document 2 describes an apparatus that monitors the presence or absence of obstacles or the like on a road via an image, includes a visible light imaging element and an infrared light imaging element, wherein a bandpass filter that allows only passage of so-called visible light with a wavelength of 390 nm to 770 nm is added to the surface of each element of the visible light light-receiving element, and a bandpass filter that allows only passage of a limited wavelength band within so-called infrared light, such as a wavelength of 3 µm to 5 µm or 8 µm to 12 µm, is added to the infrared light light-receiving element.

[0004] Patent Document 3 describes an apparatus that detects flaws on the surface of a material to be inspected, wherein the same position on the surface of the material to be inspected is simultaneously irradiated with two light sources, a one-dimensional light source and a two-dimensional light source, each having a different peak wavelength, wavelength components of the two light sources are optically selectively separated from reflected light from the irradiated position on the surface to be inspected, the components are formed as two-dimensional images on two different imaging elements, and image processing based on the light section method is applied to a reflected light image obtained by the one-dimensional light source.

[0005] Patent Document 4 describes a device capable of detecting the surface shape of an object surface, comprising: a first light-emitting means for irradiating the object surface with widespread light; a second light-emitting means for irradiating a slit-shaped linear light ray with a single emission wavelength; a first light-receiving means for capturing an image of the object when irradiated by the widespread first light-emitting means, with only the light in the wavelength range of the linear light ray cut off via a cut filter; and a second light-receiving means for capturing an image of the object when irradiated by the second light-emitting means with a slit-shaped linear light ray that selectively transmits only the wavelength range of the linear light ray via an interference filter. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6068099 [Patent Document 2] Japanese Patent Publication No. 2001-189926 [Patent Document 3] Japanese Patent Application Publication No. 09-152322 [Patent Document 4] Japanese Patent Application Publication No. 07-071931 [Overview of the project] [Problems that the invention aims to solve]

[0007] When evaluating pavement damage, for example, cracks in the pavement do not change color; rather, they are recognized by the shadows they cast. In such cases, it is impossible to detect cracks in color images in shadowless environments such as coaxial incident illumination.

[0008] Furthermore, while 3D measurement based on the light section method allows us to see the shape, it is usually impossible to acquire color information because lasers have a single wavelength. Color information is valuable in pavement inspections; pumping, where sand is ejected from the pavement surface, can be easily identified if the color is known, but in monochrome it may appear as uneven coloring of the pavement. Also, the condition of rust on steel joints of bridges cannot be identified as rust without color information.

[0009] Therefore, the present invention aims to simultaneously confirm both the shape and color information of the surface of an object when measuring the surface condition of an object in motion. [Means for solving the problem]

[0010] A first aspect of the present invention is a measuring device attached to a moving body, comprising: a first measuring unit that measures the shape of the surface of an object by light section method based on an image captured by a first camera after irradiating a measurement point on the surface of the object with a first light; and a second measuring unit that measures the state of the surface of the object based on an image captured by a second camera after irradiating the measurement point with a second light having a different wavelength from the first light, wherein the second camera captures an image through a filter that blocks the wavelength of the first light, and the first camera captures an image through a filter that transmits light corresponding to the wavelength of the first light.

[0011] A second aspect of the present invention, in the first aspect, includes a first measuring unit that acquires the measurement results from the first measuring unit and the measurement results from the second measuring unit in a synchronized manner, and a combining unit that combines the measurement results from the first measuring unit and the measurement results from the second measuring unit.

[0012] A third aspect of the present invention is, in the first or second aspect, the first measuring unit irradiates the measurement location with laser light as the first light to form a marker, which is then photographed from an oblique direction by the first camera to measure the shape of the surface of the object.

[0013] A fourth aspect of the present invention is, in any one of the first to third aspects, the second measuring unit irradiates the measurement location with white light as the second light from an oblique direction, and the second camera captures a line image to measure the surface condition of the object.

[0014] A fifth aspect of the present invention is an embodiment of any one of the first to fourth aspects, wherein the moving body is a vehicle and the object is a road surface. Effects of the Invention

[0015] According to the present invention, when measuring the surface state of an object with a moving moving body, both the shape of the surface of the object and color information can be simultaneously checked. Brief Description of the Drawings

[0016] [Figure 1] It is a functional block diagram showing a measuring device. [Figure 2] It is a side view of a vehicle incorporating the measuring device. [Figure 3A] It is a side view for explaining a measuring method applied to the measuring device. [Figure 3B] It is a front view for explaining a measuring method applied to the measuring device. [Figure 3C] It is a top view for explaining a measuring method applied to the measuring device. [Figure 4] It is a diagram showing an example of information stored in a recording device 50. [Figure 5] It is a diagram showing an example of a color image to which crack information is added. [Figure 6A] It is a side view for explaining a measuring method applied to a measuring device according to a modification. [Figure 6B] It is a front view for explaining a measuring method applied to a measuring device according to a modification. [Figure 6C] It is a top view for explaining a measuring method applied to a measuring device according to a modification. Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the measuring device according to the present invention will be described with reference to the drawings.

[0018] (Summary of the Present Invention) High-performance pavement (drainage pavement) is used on expressways. This pavement uses open-graded aggregate, which makes it difficult to detect cracks in color images because it does not easily create shadows. Therefore, by using 3D shape measurement, which acquires the road surface shape using the light section method, cracks caused by aggregate scattering can be clearly detected.

[0019] However, in 3D shape measurement using the light section method, a laser is used as a line marker, so color information cannot be obtained, and usually only the reflected brightness of the laser can be acquired.

[0020] On highways, a phenomenon called "pumping" occurs, where sand is ejected from the road surface. This phenomenon involves soil and sand below the roadbed being ejected along cracks in the pavement, often accompanied by water.

[0021] While this pumping action is clearly visible in color images, it can be difficult to identify in monochrome images, as it can be confused with road surface dirt or other imperfections.

[0022] Therefore, in this embodiment, a measurement unit using a color line scan camera and a measurement unit using a 3D camera based on the light section method acquire color information and shape information from the same location and synchronize them.

[0023] To synchronize the shooting positions, the laser for the color line scan camera and the laser for the 3D camera must point to the same location. In color line scanning, the wavelength of a typical laser, 808nm, is in the sensitivity range and negatively affects the sensitivity to red light. Color line scanning requires white illumination, but this interferes with the laser being captured by the 3D camera. Therefore, in this embodiment, the color line scan camera and the 3D camera are configured to capture images through different filters.

[0024] (Configuration of the measuring device) Figure 1 is a functional block diagram showing the measuring device 100.

[0025] Figure 2 is a side view of vehicle 1 with the measuring device 100 incorporated into it.

[0026] The measuring device 100 includes a distance meter 20, a first measuring unit 30, a second measuring unit 40, and a recording device 50.

[0027] Vehicle 1 is a work vehicle used, for example, for road maintenance work, and a measuring device 100 is installed at the rear of Vehicle 1, facing the road surface 4.

[0028] The distance meter 20 measures the distance traveled by vehicle 1, for example, based on the wheel speed.

[0029] The first measurement unit 30 measures the shape of the road surface 4 by irradiating the measurement point on the road surface 4 with laser light from the slit laser oscillator 32 and based on the image captured by the first camera 34, using the light section method. Specifically, as shown in Figure 3A, the marker formed by irradiating the measurement point with laser light from the slit laser oscillator 32 is photographed from an oblique direction by the first camera 34.

[0030] Here, the slit laser oscillator 32 emits a slit laser. The slit laser oscillator 32 is mounted on the vehicle 1 so as to irradiate the road surface 4 perpendicularly from above with a slit-shaped slit laser that is perpendicular to the direction of travel of the vehicle 1. On the road surface 4, linear markers perpendicular to the direction of travel of the road surface are formed by the irradiation of the slit laser.

[0031] According to the principle of the light section method, the first camera 34 photographs the linear marker as a straight line if the road surface is flat in a direction perpendicular to the direction of travel, and photographs the linear marker as a distorted shape with irregularities if there are irregularities in the road surface in a direction perpendicular to the direction of travel.

[0032] The calculation unit 36 ​​measures the shape of the road surface based on linear markers represented by the image captured by the first camera 34. Specifically, the calculation unit 36 ​​calculates brightness information indicating the peak brightness of the laser beam and information on the centroid position of the laser beam for each position perpendicular to the direction of travel on the road surface 4, based on the linear markers represented by the image captured by the first camera 34.

[0033] In this embodiment, the first camera 34 captures an image through a filter 34A that transmits light corresponding to the wavelength of the laser light. The filter 34A is, for example, a bandpass filter with a central wavelength range of 808 nm. This eliminates the influence of white light in the first camera 34.

[0034] The second measurement unit 40 irradiates the same measurement location as the first measurement unit 30 with light of a different wavelength from the laser light from the illumination unit 42, and measures the condition of the road surface 4 based on the image captured by the second camera 44. Specifically, as shown in Figure 3B, the second measurement unit 40 irradiates the measurement location with white light from the illumination unit 42 from an oblique direction, captures a line image with the second camera 44, and outputs RGB information for each pixel in a direction perpendicular to the direction of travel of the road surface 4. For example, an LED light is used as the illumination unit 42. However, it is not limited to LED light; any light source that emits white light other than LED light may be used as the illumination unit 42.

[0035] In this embodiment, the second camera 44 captures an image through a filter 44A that blocks the wavelength of the laser light. The filter 44A is, for example, a high-cut filter that blocks light of 800 nm or higher. As a result, the laser light does not appear in the image captured by the second camera 44. Since the first camera 34 is free from the influence of white light and the image captured by the second camera 44 does not show the laser light, the first camera 34 and the second camera 44 can acquire information from the same location.

[0036] The first measuring unit 30 synchronizes and acquires the measurement results from the first measuring unit 30 and the measurement results from the second measuring unit 40, and includes a combining unit 38 that combines the measurement results from the first measuring unit 30 and the measurement results from the second measuring unit 40.

[0037] The synthesis unit 38 stores the result of combining the measurement results from the first measurement unit 30 and the measurement results from the second measurement unit 40 in the recording device 50.

[0038] Specifically, the synthesis unit 38 synthesizes the luminance information and centroid position information calculated by the first measurement unit 30 with the RGB information obtained by the second measurement unit 40 and stores it in the recording device 50.

[0039] As shown in Figure 4, the information stored in the recording device 50 synchronizes the RGB information of a color image with high-resolution shape information (luminance information, position information). Figure 4 shows an example in which the recording device 50 stores RGB information, luminance information, and position information for each position on the road surface 4 perpendicular to the direction of travel.

[0040] Furthermore, in this embodiment, a line sensor camera is used as the second camera 44 to acquire color images, so an LED line illumination unit 42 is placed near the second camera 44 for imaging (see Figures 3A to 3C). Normally, adding LED line illumination near a camera results in shadowless illumination similar to coaxial incident illumination, making it unsuitable for crack detection. However, in this embodiment, where the shape can be acquired simultaneously, cracks can be detected as described above. In addition, since there is no need to illuminate at an angle, the reflected light from the illumination unit 42 is easily captured by the second camera 44, and the output of the illumination unit 42 itself can be kept low.

[0041] Figures 3A and 3B show an example where, viewed from the side and top of vehicle 1, the slit laser oscillator 32, illumination unit 42, and second camera 44 are arranged side by side facing the road surface 4, and the first camera 34 is photographing the road surface 4 from an oblique angle. Figure 3C shows an example where, viewed from the rear of vehicle 1, the slit laser oscillator 32 and illumination unit 42 are irradiating the road surface 4 with laser light and white light in a range extending perpendicular to the direction of travel, and the second camera 44 is capturing a line image extending perpendicular to the direction of travel of the road surface 4.

[0042] (Operation of the measuring device) Next, the operation of the measuring device 100 described above will be explained.

[0043] First, when the vehicle 1 equipped with the measuring device 100, specifically, a patrol vehicle used for daily patrol work, is driving on the road surface 4, the measuring device 100 is instructed to start measuring.

[0044] When measurement begins, the distance meter 20 inputs triggers to the first camera 34 and the second camera 44 according to the distance traveled on the road surface 4. For example, a trigger is input to the first camera 34 and the second camera 44 each time the road surface moves 1 mm.

[0045] In the first measurement unit 30, for each time a trigger is input from the distance meter 20, the marker formed on the road surface by the irradiation of the slit laser oscillator 32 is photographed from an oblique direction by the first camera 34 via the filter 34A.

[0046] Furthermore, in the second measurement unit 40, white light is shone from the illumination unit 42 as a second light source onto the measurement point from an oblique direction, and for each time a trigger is input from the distance meter 20, a line image is captured by the second camera 44 via the filter 44A.

[0047] The calculation unit 36 ​​calculates brightness information indicating the peak brightness of the laser beam and information on the centroid position of the laser for each position on the road surface 4 perpendicular to the direction of travel, based on the linear markers represented by the image captured by the first camera 34.

[0048] The synthesis unit 38 synthesizes the brightness information and centroid position information calculated by the calculation unit 36 ​​with the RGB information obtained by the second camera 44 and stores it in the recording device 50.

[0049] The above process is repeated each time a trigger is input from the rangefinder 20 to the first camera 34 and the second camera 44, respectively.

[0050] An external computer displays an image as shown in Figure 5 and performs analysis based on the information stored in the recording device 50. At this time, crack information extracted from the shape information measured by the first measuring unit 30 can be added to the color image, making it possible to confirm cracks on a clear color image. Pumping can also be confirmed on the color image.

[0051] As described above, the measuring device 100 according to this embodiment includes a first measuring unit that measures the shape of the road surface by light sectioning based on an image captured by a first camera after irradiating a measurement point on the road surface with laser light, and a second measuring unit that measures the condition of the road surface based on an image captured by a second camera after irradiating the measurement point with white light. The second camera captures an image through a filter that blocks the wavelength of the laser light, and the first camera captures an image through a filter that transmits light corresponding to the wavelength of the laser light. This makes it possible to simultaneously check both the shape and color information of the road surface when measuring the condition of the road surface in a moving vehicle.

[0052] Furthermore, it facilitates the detection of deformations that use color information, such as pumping and crack sealing. It can also detect red rust that occurs not only on pavement surfaces but also on bridge joints.

[0053] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and applications are possible without departing from the spirit of the invention.

[0054] For example, the above explanation described a case where the slit laser oscillator 32, first camera 34, illumination unit 42, and second camera 44 are arranged as shown in Figures 3A to 3C, but the explanation is not limited to this. As shown in Figures 6A to 6C, the illumination unit 42 may be arranged to irradiate the road surface with white light from an oblique angle. Figures 6A and 6B show an example where, viewed from the side and top of the vehicle 1, the slit laser oscillator 32 and second camera 44 are arranged side by side facing the road surface 4, the illumination unit 42 irradiates the road surface 4 with white light from a slightly oblique angle, and the first camera 34 photographs the road surface from an oblique angle. Figure 6C shows an example where, viewed from the rear of the vehicle 1, the slit laser oscillator 32 and illumination unit 42 irradiate the road surface 4 with laser light and white light in a range extending perpendicular to the direction of travel, and the second camera 44 photographs a line image extending perpendicular to the direction of travel of the road surface 4.

[0055] The example given uses a vehicle as the moving object and the road surface condition as the object being measured, but it is not limited to this. Any surface of an object that is continuous in the direction of the moving object's movement may be used, other than the road surface.

[0056] Furthermore, although the explanation described an example where a trigger is input from the rangefinder 20 to the first camera 34 and the second camera 44, it is not limited to this. For example, the first camera 34 or the second camera 44 may generate a frequency to trigger the shutter and synchronize the images using the capture time. [Explanation of Symbols]

[0057] 1 vehicle 4 Road surface 20 Rangefinder 30 1st measurement section 32 Slit laser oscillator 34. Camera 1 34A filter 36 Arithmetic section 38 Synthesis section 40 Second measuring section 42 Lighting Section 44. Second Camera 44A filter 50 Recording device 100 measuring devices

Claims

1. In a measuring device attached to a mobile body, A first measuring unit measures the shape of the surface of an object by light sectioning based on an image captured by a first camera after irradiating a measurement point on the surface of the object with a first light, A second measuring unit measures the surface condition of the object based on an image captured by a second camera after irradiating the measurement location with a second light having a different wavelength from the first light, Includes, The second camera captures an image through a filter that blocks the wavelength of the first light, The first camera is a measuring device that captures an image through a filter that transmits light corresponding to the wavelength of the first light.

2. The measuring apparatus according to claim 1, wherein the first measuring unit acquires the measurement results from the first measuring unit and the measurement results from the second measuring unit in a synchronized manner, and the first measuring unit includes a synthesis unit that synthesizes the measurement results from the first measuring unit and the measurement results from the second measuring unit.

3. The measuring device according to claim 1, wherein the first measuring unit irradiates the measurement location with laser light as the first light to form a marker, and the first camera photographs the marker from an oblique direction to measure the shape of the surface of the object.

4. The measuring device according to claim 1, wherein the second measuring unit irradiates the measurement location with white light as the second light from an oblique direction, and the second camera captures a line image to measure the surface condition of the object.

5. The aforementioned moving object is a vehicle, The measuring device according to claim 1, wherein the object is the road surface.

Images