JP2005140537A - Shape-measuring device using line sensor and method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape-measuring device and a method for the same capable of simply, highly and precisely measuring the shape or the deformation of a measuring object, without being affected by the measurement environment, such as fluctuations in the reflectivity or the background light of the measuring object. <P>SOLUTION: Projectors 1, 2 which are inclined by equal angles with respect to the vertical line and projecting the light of a gradient luminance pattern and the light of constant luminance pattern to a relatively moving measuring object 6 respectively. Line sensors 3, 4, and 5 arranged in the moving direction are made to take images, under conditions of projecting of the light of the gradient luminance pattern, of a light of constant luminance pattern, and of no light projection . For the shape-measuring device using the line sensors and capable of measuring the luminance at the same place, a band-pass filter is applied to each of the line sensors, the angle of scatter of the projection light is made the same angle, respectively, the relation of the input light amount and its output of each line sensor is linearized, and the linear gain coefficient is set to be identical. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  This invention measures the shape of a measurement object by projecting a constant luminance light and a density gradient pattern light having a different luminance distribution and different brightness gradients onto the measurement object, and measuring and comparing the luminance with a line sensor. The present invention relates to a shape measuring apparatus using a line sensor to perform and a measuring method thereof.

  Railroad floor ballast and road surfaces are subject to deterioration over time such as wear and deformation when used for a long period of time, so it is necessary to perform maintenance and inspection work that monitors deformation and repairs in accordance with the situation. The current inspection method requires a lot of time to work and may limit the passage of vehicles, so a technology that can inspect ballast ballast and road surface shape quantitatively at a higher speed is required. There is a need to develop a non-contact method for roadbed ballast and road surface shape inspection from vehicles traveling on the road.

  Conventionally, as a method for measuring the shape of a roadbed ballast or road surface, a slit light is projected onto an object, the slit light distorted on the object surface is photographed with a two-dimensional CCD camera, and the shape of the object is calculated from the amount of distortion of the slit light. A technique using a light cutting method is known. In this measurement method, since a two-dimensional image is analyzed, there is a problem that it takes time for the analysis and the shape inspection cannot be performed at high speed. On the other hand, a method of measuring a shape in real time by continuously shifting the phase of a grating pattern projected onto a sample and obtaining a phase distribution image using a television camera such as a CCD camera is disclosed (for example, patents). Reference 1). However, in this shape measurement method, it is necessary to precisely adjust the pitch of parallel projection gratings for projection, and there is a problem that there is a practical inconvenience.

  As a shape measurement technique to eliminate such problems, measurement is performed by projecting light with a density gradient pattern onto a measurement object, photographing the reflected light with a two-dimensional CCD camera, and calculating the three-dimensional shape of the object. Methods have been proposed (see, for example, Non-Patent Documents 1 and 2). In this measurement method, two types of light having different luminance distribution patterns are alternately projected onto the object to be measured, and a calibration curve of the luminance ratio and distance obtained in advance is used based on the luminance ratio between the projection lights. The distance is calculated and the shape is measured.

JP 2001-4338 A ([0009] to [0014]) Takeo Miyasaka et al .: “Development of a real-time 3D measurement device using gradient gradient projection” (Proceedings of the 7th Image Sensing Symposium (2001 P.251-P.254)) Brian Carrihill and Robert Hummel: "Experiments with the Intensity Ratio Depth Sensor" (COMPUTER VISION, GRAPHICS, AND IMAGE PROCESSING, VOL.32 (1985), P.337-P.358

  However, in the shape measurement methods proposed in Non-Patent Documents 1 and 2, a CCD camera is used to capture an image with projection light projected onto a measurement object, and the brightness ratio in the captured image corresponding to the brightness ratio of the projection light is used. Measurement data is obtained by searching for a line sensor, but a line sensor capable of high-speed image capture is not used. Further, the luminance ratio in the image is affected by the reflectance of the measurement object, but no countermeasure is taken against this reflectance fluctuation. Further, Non-Patent Document 1 does not specifically describe the light source of the projection light onto the measurement object, and Non-Patent Document 2 examines the experimental results only when using monochromatic light. Therefore, in order to be able to use light sources other than monochromatic light, it is necessary to generalize the measurement technique.

  On the other hand, a measurement principle using a line sensor as shown in FIG. 7 has been proposed by one of the inventors of the present application. This measurement principle is to measure the shape of the measurement object 33 using two projectors 31 and 32 and three line sensors 34, 35 and 36 arranged at equal intervals in the moving direction of the measurement object 33. For the measurement object 33 that moves in the direction of the arrow on the reference surface, a constant luminance light is emitted from the projector 31, and a density luminance pattern light, that is, a density gradient pattern with a density pattern is given from the projector 32. In the state where light is sequentially projected in an oblique direction, nothing is projected, the state where constant luminance light is projected, and the state where density gradient pattern light is projected, the line sensor 34, 35, 36 causes the same object to be measured 33 to be measured. The shape is measured by photographing the position P, measuring the luminance, and calculating the luminance ratio at the same position P.

The luminance I _{1 at} the position P of the measurement object 33 measured in a state in which nothing is projected by the line sensor 34, and the luminance I ₂ at the position P measured in a state where constant light is projected by the line sensor 35, The brightness I ₃ at the position P measured with the density gradient pattern light projected is the light brightness at the height h in the line-of-sight direction of the line sensors 34, 35, 36, respectively, f ₁ (h), f ₂ (h ), F ₃ (h), where R _{1 is} the reflectance in the line-of-sight direction of the line sensor 34 at this position P, and R is the reflectance in the line-of-sight direction of the line sensors 35 and 36, the following can be expressed. .
Here, if the luminance ratio J is defined as follows, the luminance ratio J can be expressed as a function F (h) of the height h.
When F (h) has a monovalent inverse function F ⁻¹ (J), the height h can be obtained from the luminance ratio J as follows.
By obtaining the relationship between the luminance ratio J and the height h in advance and making a table, it is easy to obtain the height from the luminance ratio J.

  However, in the measurement method using the above principle, when the general light having a spectral composition is used as the projection light from the projectors 31 and 32 or an error occurs in the projection angle, the luminance ratio J is the measurement object 33. Therefore, the height cannot be accurately measured from the luminance ratio J.

  In this way, all of the conventional measurement methods include continuous objects such as road surfaces, continuously moving objects such as products on the production line, measuring objects such as large and long objects such as pipes and steel plates, etc. It is difficult to perform shape measurement simply at high speed and with high accuracy using a general light source having a spectral composition that can be easily obtained.

  Accordingly, an object of the present invention is a shape using a line sensor that can easily measure the shape and deformation of the object at high speed, high accuracy, and without being affected by the measurement environment such as the reflectance fluctuation of the measurement object and background light. A measurement device and a measurement control method thereof are provided.

  In order to solve the above problems, the present invention employs the following configuration.

In other words, a constant brightness light and a density gradient pattern light are projected onto a measurement object that moves relatively continuously from a direction inclined by a predetermined angle with respect to the vertical direction by different projectors and arranged in series in the moving direction. By using at least three line sensors, the images of the measurement object in the respective states of projecting the constant luminance light, projecting the density gradient pattern light, and projecting no light are photographed and identical. A shape measuring device using a line sensor that measures the luminance of a position and can measure the shape from the calculated luminance ratio of the same position, and reflects the projection path of the constant luminance light and the density gradient pattern light or the reflection of the measuring object. The path is provided with wavelength limiting means for allowing only light in a certain wavelength range to enter each line sensor, and the optical axes of the projectors are equal to the same direction with respect to the vertical direction. Is inclined in degrees equal to the angle between a sight line of the corresponding line sensors, and linearizes the output of the relationship with respect to the input light intensity between each line sensor, it was equal to the linear gain factor.

  In general, when using general light having a spectral composition instead of monochromatic light for each light source that projects the constant luminance light and the density gradient pattern light, the luminance ratio is affected by the reflectance variation of the measurement object. receive. When a light source other than monochromatic light is used, as described above, a wavelength limiting unit is provided to limit the wavelength range, and the optical axis of the projector that projects constant luminance light and density gradient pattern light, and the line sensor line-of-sight The luminance ratio is not affected by the change in the reflectance of the measurement object. Thereby, not only the light source of monochromatic light but the general light which has a spectral composition which can obtain the brightness | luminance higher than sunlight easily can be used as a light source. That is, a general-purpose light source can be used, the apparatus configuration can be made flexible, and the apparatus cost can be reduced.

In order to specifically show the above action, first, the measurement principle of the shape measuring apparatus using the line sensor will be described. As shown in FIG. 1, the measurement object is constant in the direction of the arrow A1 with respect to the projectors 1 and 2 and the line sensors 3, 4, and 5 arranged so that the line of sight is in the vertical direction (Z direction). Assume moving at speed. A state in which the density gradient pattern light is projected from the direction inclined by the angle θ _{1 with} respect to the line of sight of the line sensor 3 by the projector 1 with respect to the measurement object, and the angle θ _{2 with} respect to the line of sight of the line sensor 4 by the projector _2. The line sensors 3, 4, and 5 capture images of a state in which light having a constant luminance is projected from a tilted direction and a state in which nothing is projected from the projector. The light emission timing of the projectors 1 and 2 and the image capturing timing of the line sensors 3, 4, and 5 with respect to the moving speed of the measurement object, that is, the relative speed between the projectors 1 and 2 and the line sensors 3, 4, and 5 By controlling, it is possible to take an image of the same position on the measurement object under the three types of states.

Assuming that the light intensity with respect to a certain wavelength λ is the height h on the line of sight of each of the line sensors 3, 4, 5, fg (h, λ), fn (h, λ), fb (h, λ) When general light having a spectral composition is used for the light sources 1 and 2, the brightness imaged and measured by the corresponding line sensors 3 and 4 is Ig, In, nothing is projected, that is, by the line sensor 5 in the background light. The luminance to be photographed and measured is Ib, and expressed in a generalized form.
It becomes. Here, λ is the wavelength, λ ₁ and λ ₂ , λ ₃ and λ ₄ are the lower and upper limit wavelengths that pass through the bandpass filter, R (θ ₁ , λ), R (θ ₂ , λ) , R (θ ₃ , λ) is the reflectance of the measurement object under the above three types of conditions, C1 to C3 are line sensor gain coefficients, and γ1 to γ3 are output dependences on the input light quantity of the line sensor. Represents an index representing gender. The luminance ratio J is defined as follows by removing the reflection component Ib of the background light.

A linear gain coefficient (C1) ^{1 / is obtained} by linearizing the relationship between the input light amount and the output of each of the line sensors 3, 4, and 5, and making the exponents γ1, γ2, and γ3 all equal to ^1. If γ ¹ , (C2) ^{1 /} γ ² , and (C3) ^{1 /} γ ³ are set to be equal to each other, the above equation (9) becomes as follows.
Thus, it is not affected by background light.

The linearization (γ1 = γ2 = γ3 = 1) will be described. As shown in FIG. 2A, the output L ₀ for the input light amount I of the line sensor generally has a gain coefficient C ₀ and an output for the input light amount. If the dependence index is γ, L ₀ = C ₀ * Iγ. As shown in FIG. 2B, when both sides of this equation are raised to the 1 / γ power and smoothed as shown in FIG. 2C, the relationship between the input light quantity I and the output L becomes a straight line. That is, it is linearized and the index γ can be 1. By performing such smoothing processing in the image capturing process of the line sensors 3, 4, and 5, linearization is realized. Note that, as shown in FIG. 2C, the linear gain coefficient is the slope C of a straight line when the relationship of the output L (L = L ₀ ^{1 /} γ) to the input light quantity I to the line sensor is linearized. (C = C ₀ ^{1 /} γ).

Since the wavelength range of the reflected light incident on the line sensors 3 and 4 is limited by the wavelength range limiting means, the influence of the wavelength λ on the reflectance R can be ignored. If the angle θ ₁ with respect to the line of sight 3 is equal to the angle θ ₂ with respect to the line of sight of the line sensor 4 of the projector 2 (θ ₁ = θ ₂ ), then R (θ ₁ , λ) = R (θ ₂ , λ). Therefore, the above equation (10) is
Thus, the luminance ratio J is not affected by the reflectance of the measurement object together with the background light.

From the above equation (11), when F (h) has a monovalent inverse function, the height h of the measurement object is not affected by the measurement environment such as the reflectance and the fluctuation of the background light. As can be seen from the luminance ratio J.

  Since it is complicated to analytically determine the height h of the measurement object from the luminance ratio J by the above formulas (11) and (12), a standard test piece made of flat plates having different heights is practically used. The brightness ratio J with respect to each height is obtained for each pixel of the CCD element by changing the height of the reference plane, and the luminance ratio is obtained by linearly interpolating the measurement points for the height of each reference plane at that time. J and the height h of the measurement object are tabulated in advance. In this way, it is possible to reduce the time required to calculate the height h of the measurement object from the luminance ratio J, and to perform high-speed measurement.

  In addition to the direction of the height h (Z direction), the measurement data in the movement direction of the above-described shape measuring apparatus and the direction perpendicular to the movement direction (XY direction) are moved without using the luminance ratio J. It can be easily obtained from the velocity field and each pixel of the line sensor. That is, when the traveling direction of the vehicle is the X direction, the X coordinate can be calculated by taking the number of times of sampling of the image of the line sensor. Since the width direction of the track surface is the Y direction, the Y coordinate can be calculated by comparing the pixel position of the line sensor with the width data.

  It is desirable that both the light sources for projecting the constant luminance light and the density gradient pattern light are strobe light sources.

  A strobe light source is a light source that emits light for a short time by utilizing the good discharge characteristics of xenon gas, and its emission spectrum is close to that of sunlight, so that a higher luminance than that of sunlight is obtained and luminous efficiency is also good. By using a general-purpose strobe light source in this way, the light emission timing, that is, the on / off of the discharge can be controlled in a very short time, and the shape can be measured at a high speed. Moreover, since a large amount of light can be obtained with a smaller wattage than a light source for continuous lighting, the light source device can be reduced in size.

  With the shape measuring device using the above line sensor, the shape measuring device can be mounted on a vehicle and continuously moved to measure the shape of the road surface.

  In this way, if the shape measuring device is moved so as to move continuously relative to the fixed measurement target object, the shape of the road surface such as a railroad ballast or road surface of the railway can be measured at high speed. it can.

  A measurement control method of a shape measuring apparatus using a line sensor for projecting the above-mentioned constant luminance light and density gradient pattern light by a strobe light source, and a required light emission delay from the time when a light emission trigger signal of the strobe light source is issued It is desirable to start taking an image of the measurement target object by the line sensor after a certain time.

  In general, the light emission time of the strobe light source is defined by the half-value width of the light amount of one flash, that is, between 50% light emission luminance in the light emission waveform. When the strobe light source is used, the light emission timing and the image capturing timing by the line sensor are controlled in consideration of the light emission delay time as described above, so that the line sensor can emit light at the maximum light emission between the 50% light emission luminances. An image can be taken by exposing a photosensitive element, that is, a CCD element. For this reason, with a small amount of light source power, luminance several times or more that of sunlight can be obtained, and a luminance ratio with sunlight can be increased. Thereby, the shape measurement accuracy obtained from the luminance ratio of the general luminance light and the density gradient pattern light by the projection light is improved. The required light emission delay time is preferably set to a time required to reach at least 25% light emission luminance from the time when the light emission trigger signal of the strobe light source is issued.

  According to the present invention, a shape measuring apparatus using a line sensor that projects a constant luminance light and a density gradient pattern light from different light sources and obtains a measurement result from a luminance ratio at the same position of a measurement object. The constant brightness light and the density gradient pattern light are inclined at the same angle in the same direction with respect to the vertical direction, and the angle formed with the optical axis of the line sensor is made equal to keep the projection light scattering angle the same. Since the band pass filter is provided in the projection path or the reflection path of, the wavelength range is limited, and the relationship between the input light quantity and the output in each line sensor is linearized, and the linear gain coefficient is set to be the same. Even when a light source other than monochromatic light is used, the luminance ratio is not affected by the fluctuation of the reflectance of the measurement object, and no extra device or algorithm is required for the reflectance correction. The most difficult measurement among the three-dimensional shape measuring the height direction of the measurement accuracy of the measuring object can be improved. For this reason, a general-purpose light source having a spectral composition can be used, and the apparatus configuration can be made flexible.

  Further, when a strobe light source is used as the general-purpose light source, it is possible to control the on / off of the discharge in a very short time and to measure the shape at a high speed. Moreover, since a large amount of light can be obtained with a smaller wattage than a light source for continuous lighting, the light source device can be reduced in size.

  In addition, since the light emission timing and image shooting timing are controlled so that the image is captured by the line sensor when the strobe light source emits the maximum light, a brightness that is several times higher than that of sunlight can be obtained with a small amount of light source power. The luminance ratio with sunlight can be increased, and the shape measurement accuracy is improved.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 3 to 6.

FIG. 3 shows the configuration of the shape measuring apparatus using the line sensor of the embodiment, and FIG. 4 shows the arrangement of the line sensor and the projector. The shape measuring device is provided with a projector 1 for projecting density gradient pattern light and a projector 2 for projecting constant luminance light, which are inclined from the vertical direction, and the lines of sight in the vertical direction and parallel to each other at equal intervals L. Based on line sensors 3, 4, and 5 having CCD elements arranged linearly on the light receiving surface, vehicle speed receiving device 7 having a pulse counter, a high speed CPU personal computer with a CPU system and an image input board A line sensor image processing device 8 and a three-dimensional shape analysis device 9 based on a high-speed personal computer are also included. The projectors 1 and 2 and the line sensors 3, 4, and 5 are housed in a device housing case 10, respectively. ing. As shown in FIG. 4, the projectors 1 and 2 are provided in the same plane so that their optical axes are inclined with respect to the vertical direction by an equal angle in the same direction. Scattering angles θ ₁ and θ ₂ (θ ₁ = θ ₂ ) equal to the respective lines of sight provided in the direction are formed. The tilt angles of the projectors 1 and 2, that is, the scattering angles θ ₁ and θ ₂ (θ ₁ = θ ₂ ) are preferably smaller than 45 °, and preferably about 30 °. In the figure, h indicates the range of the height of the measurement object, and the arrow indicates the projection range in the height direction of the density gradient pattern light.

  The shape measuring device is mounted on a shape measuring vehicle, and the vehicle moves on the rails 11 and 11 at a required speed in the moving direction of the arrow at a constant speed V while the rails 11 and 11 shown in FIG. The shape measurement of the roadbed ballast 12a, which is the object to be measured, laid between and on both sides, that is, the height distribution of the roadbed ballast 12a is measured in a direction orthogonal to the rails 11 and 11. Note that the line-of-sight of each of the line sensors 3, 4, and 5 is not necessarily provided in the vertical direction as long as they are parallel to each other. However, in order to measure the height of the measurement object, the shape analysis and the data calculation process are simply performed. In order to do so, it is desirable to provide it in the vertical direction.

  The projector 1 includes a strobe light source (xenon) in a lamp house, and a substrate made of quartz glass for projecting density gradient pattern light between a condenser lens and a projection lens arranged in front of the projector 1. A vapor deposition film of aluminum is formed on the surface, and the film thickness is inclined, and a projection pattern slide is built in that the transmittance of the projection light from the strobe light source is changed to change the inclination. A pattern image is given. In addition, the line sensors 3, 4 and 5 are provided with a bandpass filter which is the above-mentioned wavelength band limiting means on the front side of the light receiving lens, and the wavelength ranges from an ultraviolet region of about 400 nm to an infrared region of about 1 μm. The CCD element is exposed only by the reflected light of the area. The wavelength band limiting means may be attached to each of the projectors 1 and 2, or may be separately provided on the projection path or the reflection path by the measurement object. In addition, the bandpass filter limits the wavelength range received by the line sensor from 400 nm to 1 μm because the sensitivity of the line sensor becomes difficult for reflected light in the wavelength range of 400 nm or less, and it exceeds 1 μm. This is because the transmission characteristics to the line sensor become poor with respect to reflected light in the wavelength range, and in either case, the reliability of the image data is lowered and the reproducibility becomes poor.

  The line sensor image processing apparatus 8 linearizes the relationship between the input light amount to the line sensors 3, 4, and 5 and the output due to the reflection of the projection light from the measurement object 6 as described above. Linearization processing means are incorporated. The linear gain coefficients of the line sensors 3, 4, and 5 are all set to be the same.

  Next, the shape measuring method will be described. When measuring the shape of the ballast laid on both sides of the rails 11 and 11 as the measurement object, and measuring the position of the point P in the movement direction of the shape measuring device (see FIG. 3), that is, measuring the height distribution of the ballast. When the corresponding line sensor 3 comes to the position of the point P, the density gradient pattern light projected from 1 is exposed to take an image. At this time, in order to expose the CCD element of the line sensor 3 at the time of maximum light emission between 50% light emission luminances of the strobe light source of the projector 1, the light emission timing and the image shooting timing are controlled, as shown in FIG. From the time when the light emission trigger signal of the strobe light source is generated, for example, a required delay time of about 15 μs is provided, and the CCD element of the line sensor 3 is exposed for about 40 μs to take an image.

  The light emission trigger of the strobe light source that emits constant luminance light of the projector 2 includes the movement speed V of the shape measuring device, that is, the speed of the vehicle on which the shape measuring device is mounted, the line sensor 3 corresponding to the projector 1, It is emitted based on the movement time of the line sensor 4 to the measurement position P, which is calculated from the distance L from the line sensor 4 corresponding to the projector 2. At that time, as in the case of the projector 1, in order to expose the CCD element of the line sensor 4 at the maximum light emission between 50% light emission luminances of the strobe light source of the projector 2, as shown in FIG. From the time when the light emission trigger signal is issued, for example, the timing of light emission and the timing of image shooting are set such that a required delay time of about 15 μs is provided and the CCD element of the line sensor 4 is exposed for about 40 μs to perform image shooting. Is controlled. And the movement time to the measurement position P point of the line sensor 5 calculated from the distance L between the movement speed V, the line sensor 4 and the line sensor 5 for photographing the measurement object under the background light. Based on this, as shown in FIG. 5, the line sensor 5 CCD element is exposed with a delay time similar to that in the case where the strobe light source emits light, and an image is taken under background light. In this way, the line sensor 3, the line sensor 4 and the line sensor 4, and the line sensor 4 and the line so that each line sensor 3, 4, 5 shoots the ballast at the same position (point P), that is, the measurement object. The shooting interval with the sensor 5 is kept the same.

  FIG. 6 shows an image processing flow of the shape measuring apparatus. As described above, projection of density gradient pattern light and pattern projection 14 of constant luminance light are performed on the measurement object 6 from the projectors 1 and 2 using a strobe light source, for example, via the projector control device 13. Under the condition of light and background light, the brightness of the measurement object is measured by the line sensors 3, 4, and 5 that have undergone the shooting condition setting process 15 from the line sensor image processing device 8. At that time, the vehicle speed is input to the CPU processing system of the image processing device 8 by the vehicle speed input processing 16 from the vehicle speed receiving device 7, and an image at the same position of the measurement object can be taken at the maximum light emission of the strobe light source. Thus, the light emission timing of the strobe light source and the image capturing timing of the line sensors 3, 4, and 5 are controlled by the synchronization circuit 17. By this timing control, the interval between the external synchronization triggers for starting image capturing issued to the line sensors 3, 4 and 5 is performed every 10 ms at the fastest. From the distance between the fastest external synchronization trigger and the vehicle speed, that is, the moving speed V of the shape measuring device, the shortest distance between the measuring objects capable of measuring the shape is calculated. Image capturing data from the line sensors 3, 4, and 5 is received by an image capture control 21 in the CPU system of the image processing apparatus 8 via an image input board 20 having a video capture board 18 and a DMA transfer frame memory 19. Then, the image photographing data storage process 22 (image data buffering) is performed in the buffer of the storage device of the image processing apparatus 8. In the three-dimensional shape analysis apparatus 9, sampling processing 23 of the image shooting data is performed, and the shape analysis processing 24 is performed based on the luminance ratio obtained from the image shooting data and a table indicating the relationship between the luminance ratio and the height of the measurement object. , And the shape data calculation process 25 of the height (Z direction) distribution is performed. The shape calculation processing in the X direction and the Y direction can be performed directly from the pixel data of the line sensors 3 and 4 without going through the luminance ratio. Then, a three-dimensional shape display process 26 is finally performed from the calculated shape data, and the shape data is stored in a data file of a storage device of the three-dimensional shape analyzer 9 by a three-dimensional shape data management process 27. Is done. In addition, the height of the reference plane is changed using standard test pieces made of flat plates having different heights, and the image data taken for the reference plane of each height is sampled to obtain the luminance ratio J for each pixel of the CCD element. In this case, measurement is performed from the luminance ratio J by performing a calibration process in which the luminance ratio J and the height h of the measurement object are tabulated in advance by linearly interpolating the measurement points for each reference plane. The time required for calculating the height h of the object can be shortened and high-speed measurement can be performed.

  The embodiment of the present invention is configured as described above, and the features thereof will be described below.

A band pass filter is attached to each of the line sensors 3, 4, and 5, and as shown in FIG. 4, the optical axis of the projector 1 that projects the density gradient pattern light on the measurement object and the reflected light thereof. The angle θ ₁ formed with the line of sight of the line sensor 3 that receives light, and the angle θ ₂ formed by the line of sight of the line sensor 4 that receives the reflected light with the optical axis of the projector 2 that projects light of constant luminance are made equal. That is, a conversion formula for equalizing the scattering angles of the two projection lights and linearizing the relationship between the input light amount and the output is incorporated in each of the line sensors 3, 4, 5. Since the linear gain coefficients are set to be equal to each other, the luminance ratio J is influenced by the reflectance of the measurement object and the change in the background light even when the projecting light source having the spectral composition of the projectors 1 and 2 is used. Receive Live in. As a result, even if general light is used as a light source, it is not affected by the measurement environment, and an extra device or algorithm is not required for reflectance correction, and shape measurement can be performed with high accuracy.

  Further, since a general strobe light source is used as the light source of the projectors 1 and 2, the light emission timing can be controlled in a very short time, and the shape can be measured at high speed. Further, since the CCD element, which is the photosensitive element of the line sensor, is exposed at the time of maximum light emission between 50% emission luminance of the strobe light source, and the light emission timing and imaging timing are controlled so as to take an image, a small amount of light is emitted. With the light source power, a luminance several times higher than that of sunlight can be obtained, the luminance ratio with sunlight can be increased, and the shape measurement accuracy is improved.

  This invention is not affected by the environment such as the reflectance of the measurement object and the background light, and under the measurement conditions in which the shape measurement device and the measurement object move relatively continuously using general light such as a strobe light source. It can be used for high-speed shape measurement of railroad floor ballasts, road surfaces, products transported at a constant speed on production lines, and long object surface shapes such as continuously moving pipes and steel plates.

Explanatory drawing which shows the measurement principle of embodiment of this invention (A)-(c) Explanatory drawing which shows linearization of the input-output characteristic of a line sensor same as the above. Explanatory drawing which shows the structure of the measuring device using a line sensor same as the above Explanatory drawing showing the layout of the line sensor and projector Explanatory drawing which shows the relationship between the light emission timing of a projector same as the above, and the shooting timing of a line sensor. Explanatory drawing showing the flow of shape measurement Explanatory drawing which shows an example of the measurement principle of the shape measuring device using a line sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2: Projector 3, 4, 5: Line sensor 6: Measurement object 7: Vehicle speed receiving apparatus 8: Line sensor image processing apparatus 9: Three-dimensional shape analyzer 10: Apparatus storage case 11: Rail 12: Sleeper 12a: Roadbed ballast 13: Projector control device 14: Pattern projection 15: Line sensor condition setting process 16: Vehicle speed input process 17: Synchronous circuit 18: Video cap charter board 19: Frame memory 20: Image input board 21: Image capture control 22 : Storage processing 23: Sampling processing 24: Shape analysis processing 25: Shape data calculation processing 26: Three-dimensional shape display processing 27: Three-dimensional shape data management processing 28: Calibration processing

Claims (5)

A constant brightness light and density gradient pattern light are projected onto a measurement object that moves relatively continuously from a direction inclined by a predetermined angle with respect to the vertical direction by different projectors, and arranged in series in the moving direction. At least three line sensors take images of the measurement object in the respective states of projecting the constant luminance light, projecting the density gradient pattern light, and projecting no light. A shape measurement apparatus using a line sensor that measures luminance and enables shape measurement from the calculated luminance ratio at the same position, wherein the constant luminance light and the density gradient pattern light are projected by the reflection path or the measurement object The path is provided with wavelength limiting means for allowing only light in a certain wavelength range to enter each line sensor, and the optical axes of the projectors are equal to the same direction with respect to the vertical direction. Use a line sensor that is tilted at a degree to equalize the angle formed with the line of sight of the corresponding line sensor, linearize the relationship of the output to the input light quantity between each line sensor, and set the linear gain coefficient equal. A shape measuring device. 2. The shape measuring apparatus using a line sensor according to claim 1, wherein both light sources for projecting the constant luminance light and the density gradient pattern light are strobe light sources. A shape measuring device using the line sensor according to claim 1 or 2, wherein the shape measuring device is mounted on a vehicle and continuously moves to measure the shape of a road surface. Shape measuring device. A constant brightness light and density gradient pattern light are projected onto a measurement object that moves relatively continuously from a direction inclined by a predetermined angle with respect to the vertical direction by different projectors, and arranged in series in the moving direction. At least three line sensors take images of the measurement object in the respective states of projecting the constant luminance light, projecting the density gradient pattern light, and projecting no light. A shape measurement method using a line sensor capable of measuring the luminance and measuring the shape from the calculated luminance ratio at the same position, wherein the constant luminance light and the concentration gradient pattern light are projected by the reflection path or the measurement object The path is provided with wavelength limiting means for allowing only a part of the wavelength of light to enter each line sensor, and the optical axes of the projectors are equal to the same direction with respect to the vertical direction. Inclined at a degree, the angle formed by the line of sight of the corresponding line sensor is made equal, and the wavelength of a part of the width of each line sensor in the projection path of the constant luminance light and the density gradient pattern light or the reflection path by the measurement object A shape measuring method using a line sensor, characterized in that wavelength limiting means for allowing only light to enter is provided, the relationship of the output with respect to the input light quantity is linearized between the line sensors, and the linear gain coefficient is set equal. The light sources that project the constant luminance light and the density gradient pattern light are both strobe light sources, and the required light emission delay from the time when the light emission trigger signal of the strobe light source that projects the constant luminance light and the density gradient pattern light is emitted. 5. The shape measuring method using a line sensor according to claim 4, wherein image capturing of the measurement target object by the line sensor is started after a certain period of time.