JP3454088B2 - Three-dimensional shape measuring method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring method and apparatus capable of highly accurately measuring a three-dimensional shape of an object, particularly a semitransparent object such as a human body.

[0002]

2. Description of the Related Art In the field of beauty instruments, in order to quantitatively evaluate the effect, it is desirable to be able to perform non-invasive measurement because the object to be measured is a living body. For example, in the case of evaluating a human body surface shape change such as a skin beautifier, in order to measure the shape,
Since the living body is a flexible object, the measurement method involving physical contact causes deformation of the object due to contact pressure, and accurate measurement cannot be performed. Therefore, it is necessary to measure the human body without contact.

The so-called optical cutting method is most often used in a measuring device for measuring a three-dimensional shape of a general industrial part in a non-contact manner because it is inexpensive and can obtain high accuracy. However, the above-mentioned light cutting method uses a laser beam that is harmful to the human body, especially to the eyes, and therefore cannot be used when the object is the human body. Therefore, as a method for measuring the three-dimensional shape of the human body, a phase shift method (fringe scanning method) has been used, which is capable of highly accurate measurement using a white light source that is substantially harmless to the human body.

In the phase shift method, a pattern having a sinusoidal light-dark distribution is projected onto an object a plurality of times while phase-shifting, and the object is imaged in a direction different from the projection direction of the pattern in synchronization with the phase shift. While obtaining a plurality of pattern images, the phase for one cycle for each position of the pattern image is obtained based on the change in brightness caused by the phase shift at the same position of each pattern image, and the position which becomes the boundary of the phase for one cycle is determined. The phase at each position of the pattern image is restored by detecting and connecting the phases at the phase boundary positions, and the three-dimensional shape of the object is measured from the restored phase by the principle of triangulation. .

As a conventional example of measuring the three-dimensional shape of a human body using the phase shift method, a TV camera is used to
How to measure the relatively large Kinashiwa occurring outside corner portion of the human body by coarse resolution of about 100μm per pixel,
Cosmetic Journal Vol. 28, No. 2, pp. 153 to 162 (1994)
It is described in. Further, as a technique for the above-mentioned phase restoration, as disclosed in Japanese Patent Publication (Kokoku) No. 3-38524, a wide reference plane that allows the entire pattern to be captured is arranged near the measurement object. There is a method in which a pattern having no distortion projected on a reference plane is measured as a reference phase and the distortion of the pattern projected on the object is obtained based on the measurement.

Further, as a conventional example of a three-dimensional shape measuring apparatus using the phase shift method, as disclosed in Japanese Patent Application Laid-Open No. 4-98111, in order to project light and dark patterns on an object. In some cases, the illumination device is used to illuminate from behind the lattice and a lattice-shaped pattern is projected onto an object by a condenser lens arranged in front of the lattice.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the conventional example described in Vol. 8, No. 2, pp. 153 to 162 (1994)], a relatively large wrinkle is targeted for measurement, but the width of a fine wrinkle called a so-called fine wrinkle is 1
It is often less than 00 μm, and the above-described fine wrinkles cannot be measured with the resolution of the conventional example. Therefore, measurement with higher resolution is required for measuring fine wrinkles.

However, when measurement is performed with high resolution, the effect of locally obscuring the brightness change of the pattern image due to black objects such as hair and moles scattered on the skin surface of the human body becomes great. Also, since the skin of the human body is translucent, it is easy for light to pass through, and the projected light (pattern)
Permeates and diffuses inside the skin, resulting in a difference between the change in the brightness of the pattern and the change in the brightness of the surface of the imaged object. In this way, the change in brightness of the pattern image becomes unclear, or the difference in the change in brightness has the effect of making the image acquisition means a high resolution in order to measure an extremely fine uneven shape,
Appears more prominently.

For the above reasons, in the high-resolution three-dimensional shape measurement by the phase shift method, there is a problem that noise and distortion are likely to occur in the pattern image obtained by capturing the object on which the pattern is projected. . The influence of this noise or distortion is caused when the phase boundary position is detected in the process of connecting the phases of the pattern images obtained for each cycle (0 to 2π) from the change in brightness at the same position among a plurality of pattern images. The biggest problem is that this causes an error, and that error causes a large measurement error as a result.

On the other hand, in the conventional example disclosed in Japanese Patent Publication No. 3-38524, it is necessary to capture the entire reference plane within the field of view of the TV camera, but the target object is captured only in a part of the screen. There is a problem that the resolution of the TV camera is not fully utilized because it does not exist. Further, there is a problem that it is difficult to apply it to an object such as a human body that cannot be processed, because it is necessary to set a reference surface in the structure of the measuring device.

Further, in the conventional example disclosed in Japanese Patent Laid-Open No. 4-98111, it is not necessary to install the above-mentioned reference plane, but the light from the light source with low directivity is projected onto the object. It is necessary to use a condenser lens for
In addition, there is a problem in that a mechanism for moving the grating by a physical means is required to shift the phase of the pattern, which makes the projection device of the pattern large.

Further, in the three-dimensional shape measuring method for the human body, the object (human body or a part thereof) may be completely fixed during measurement because the object is a living body unlike industrial parts. Difficulties and an object arises in applying the above-mentioned phase shift method in which the object needs to be stationary. Further, the three-dimensional shape measuring apparatus for the human body as described above needs to measure widely for a large number of subjects, so it is essential that it is small and lightweight and easy to carry.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a three-dimensional shape measuring method capable of suppressing the occurrence of erroneous measurement due to noise or the like.

[0014]

In order to achieve the above-mentioned object, the invention of claim 1 projects a pattern having a sinusoidal light-dark distribution onto a target object a plurality of times while phase-shifting the pattern, and the phase shift A plurality of pattern images are obtained by synchronously capturing the object from a direction different from the projection direction of the pattern, and for each position of the pattern image based on the change in brightness caused by the phase shift at the same position of each pattern image. Obtain the phase for one cycle and
The phase at each position of the pattern image is restored by detecting the position that becomes the boundary of the phase of the cycle and connecting the phases at the phase boundary positions, and from the restored phase, the object is detected by the principle of triangulation. In the three-dimensional shape measuring method for measuring the three-dimensional shape of an object, the phase boundary position is detected by using a filter that detects the switching of the phase of the phase image obtained by calculating the phase of each position in the pattern image for each cycle. Is detected, the correct phase boundary position can be detected without being affected by the local disturbance of lightness such as noise or hair, and highly reliable phase restoration can be performed.

According to a second aspect of the present invention, in the first aspect of the invention, the amount of movement of the object between the plurality of pattern images is calculated based on the moving direction and speed of the object, and the positional information of the pattern image is obtained. Of the three-dimensional phase shift method by a simple correction process when the movement of the object can be regarded as a uniform linear motion even when the object is not completely stationary at the time of imaging. Shape measurement can be performed.

According to a third aspect of the present invention, in the first aspect of the present invention, the movement amount of the object between the pattern images is obtained by collating the pattern images with each other, and the positional information of the pattern images is corrected. Even if the object is not completely stationary at the time of image capturing and the movement is irregular, the three-dimensional shape measurement by the phase shift method is performed by correcting the position information. You can

According to a fourth aspect of the invention, in the first aspect of the invention, the pattern projected onto the object is corrected in consideration of the deformation of the pattern caused by the scattering of light on the semitransparent object. When distortion occurs in the projected pattern due to the object being semi-transparent, the distortion is predicted in advance, and correct measurement can be performed by correcting the pattern displayed on the pattern display means.

According to a fifth aspect of the invention, in the first aspect of the invention, the distortion of the three-dimensional height information caused by the scattering of light with respect to the semitransparent object is corrected based on the periodicity of the distortion. In the case where distortion is generated in the projected pattern due to the object being translucent, correct processing can be performed by correcting the processing result based on the distortion having periodicity.

According to a sixth aspect of the invention, in the first aspect of the invention, frequency separation processing is performed on the measured three-dimensional height information of the object, which is a global characteristic from the object. It is possible to separate local features and remove distortion that occurs periodically. According to a seventh aspect of the invention, in the first aspect of the invention, the geometric distortion of the pattern image generated by the configuration of the optical system is corrected by image processing, and the geometrical distortion is constantly generated according to the configuration of the optical system. It is possible to cancel the measurement error that occurs in the.

According to the invention of claim 8, a light irradiating means for irradiating an object with light having a linear or point light source, and a light transmissivity which is arranged in front of the light irradiating means and has a partial light transmittance. A variable pattern display means, an imaging means for capturing an image of an object on which a pattern is projected by the pattern display means over the entire field of view, a quantizing means for quantizing the pattern image captured by the imaging means, and a quantum Storage means for storing the converted pattern image and image processing means for performing image processing on the pattern image stored in the storage means, and the pattern display means phase-shifts a pattern having a sinusoidal light-dark distribution. While projecting onto the object a plurality of times, the object is imaged from a direction different from the projection direction of the pattern by the imaging means in synchronization with the phase shift, and a plurality of patterns are projected. The image processing means obtains a phase image for one cycle with respect to each position of the pattern image based on a change in brightness caused by the phase shift at the same position of each pattern image, The phase at each position of the pattern image is restored by detecting the position that becomes the phase boundary and connecting the phases at the phase boundary positions, and from the restored phase, the object 3 Measuring 3D shape 3
A three-dimensional shape measuring device, comprising :
A phase image obtained by determining the phase of each position for each cycle is provided with a filter for detecting switching of the cycle , and the phase boundary position is detected by using the filter. Noise, hair, etc. It is possible to detect the correct phase boundary position without being affected by the local disturbance of the brightness.
Reliable phase restoration is possible. Moreover, the resolution of the imaging means can be fully utilized by capturing the object in the entire field of view of the imaging means. Further, since the light irradiation means having a linear or point light source is provided, the light itself emitted from the light irradiation means has directivity, and a pattern of light and dark is formed on the object without using a projection lens. Can be projected, and the entire apparatus can be downsized.

The invention of claim 9 is characterized in that, in the invention of claim 8, a liquid crystal panel is used as the pattern display means, and a mechanical mechanism for shifting the phase of the pattern is unnecessary, and the device The whole can be miniaturized. The invention of claim 10 is the same as the invention of claim 8,
A feature is that a cylindrical lens is arranged on the optical axis of the light irradiating means, and the light irradiating the pattern displaying means can be made into parallel rays, so that the pattern is not distorted, and even a deep object in the depth direction can be obtained. It becomes possible to measure.

An eleventh aspect of the present invention is characterized in that, in the eighth aspect, a mirror is provided in at least one of an optical path from the light irradiation means to the object or an optical path from the object to the imaging means. By folding the optical path with a mirror, the light irradiation means and the imaging means can be installed side by side, and the overall size of the device can be reduced. According to a twelfth aspect of the present invention, in the eighth aspect, an optical filter having a narrow color pass band is arranged in the optical path, and a measurement error caused by chromatic aberration of a lens of a light irradiation system and an imaging system. Can be suppressed.

A thirteenth aspect of the present invention is characterized in that, in the eighth aspect of the invention, a polarizing filter is arranged in front of a portion of the image pickup means for taking in light, and is used for measuring an object having a glossy surface. At this time, the influence of ambient light can be reduced .

[0024]

DETAILED DESCRIPTION OF THE INVENTION

(Embodiment 1) Hereinafter, an embodiment in which the method and apparatus for measuring a three-dimensional shape of the present invention are applied to a method for measuring a three-dimensional shape of a human face, in particular, a wrinkle at the outer corner of the eye and a measuring apparatus will be described with reference to the drawings. The details will be described.

First, the structure of the three-dimensional shape measuring apparatus of the present invention will be described. FIG. 1 is a block diagram showing the device of the present invention. An image pickup section 1 such as a CCD camera, and a light irradiation section 2 for irradiating light such as white light which is safe even when irradiated on a human body as extremely thin linear light. A liquid crystal display unit 3 arranged in front of the light irradiation unit 2 in the irradiation direction to form a sinusoidal pattern,
The liquid crystal driving unit 4 for driving the liquid crystal display unit 3, the quantizing unit (frame grabber) 5 for quantizing the analog image captured by the image capturing unit 1, and the pixel data of the digital image quantized by the quantizing unit 5 A memory unit 6 to be stored, an image processing unit 7 for performing various processes described below on a digital image (pixel data) stored in the memory unit 6, and a pattern control command from the image processing unit 7 to a liquid crystal driving unit. 4 and an interface section 8 for transmission to the image pickup section 4, the image pickup section 1, the light irradiation section 2, the liquid crystal display section 3 and the liquid crystal drive section 4 are housed in a housing 9 to form a measuring head A. The quantization unit 5, the memory unit 6, the image processing unit 7, and the interface unit 8 are
For example, it is configured by a personal computer equipped with a display device.

The housing 9 of the measuring head A has an opening 9
a is provided, the optical axis of the imaging unit 1 is substantially aligned with the normal direction of the plane (opening surface) including the opening 9a, and light is emitted in a direction inclined by a predetermined angle from the normal direction of the opening surface. The optical axes of the parts 2 are aligned. Then, by fixing the head H of the human body, which is the object of measurement, in the vicinity of the opening 9a of the housing 9 by the fixing base 10, the optical axis of the imaging unit 1 is substantially aligned with the outer corner of the head H. It is designed to be orthogonal.

As shown in FIG. 2, the light irradiation section 2 has an extremely thin linear light emitting section 2a. The light emitting unit 2a is composed of, for example, an optical fiber array, and has a measuring head A
The light introduced into the housing 9 from a light source (not shown) provided outside the housing is emitted toward the liquid crystal display unit 3. On the other hand, the liquid crystal display unit 3 is composed of a liquid crystal panel capable of multi-gradation display, can display an arbitrary pattern according to the display density, and is irradiated with light from the light irradiation unit 2 from the rear. As a result, a pattern corresponding to the display density can be projected on the object (the outer corner of the head H) through the opening 9a of the housing 9. Here, the pattern is a striped pattern in which the display density changes sinusoidally in a direction substantially orthogonal to the longitudinal direction of the light emitting section 2a of the light irradiation section 2 (see FIG. 3). The phase of this pattern can be instantaneously switched by the liquid crystal drive unit 4 based on the pattern control command transmitted from the image processing unit 7 via the interface unit 8.

Thus, a striped pattern whose brightness in the lateral direction changes in a sinusoidal shape is projected on the outer corner of the head H facing the opening 9a, and an image is taken from a direction different from the projection direction of this pattern. Deformation (distortion) caused by the unevenness of the surface of the head H (face) is observed in the image of the imaging unit 1 (hereinafter, referred to as “pattern image”). As described above, the light emitting unit 2 and the liquid crystal display unit are arranged so that the longitudinal direction of the light emitting unit 2a of the light emitting unit 2 substantially matches the vertical direction (stripe direction) of the striped pattern displayed on the liquid crystal display unit 3. By arranging 3, the striped pattern displayed on the liquid crystal display unit 3 can be projected on the object without using a projection lens. Moreover, by adopting the above-mentioned configuration in which the light of the light source provided outside is guided to the light irradiation unit 2 using an optical fiber or the like, the light source that causes the size increase is arranged outside, and the projection lens is not required. Together with this, the measurement head A can be made smaller and lighter.

Next, a three-dimensional shape measuring method using the device of the present invention will be described with reference to the flow chart shown in FIG. First, the device of the present invention is set as shown in FIG. 1, and a striped pattern as shown in FIG. 3 is projected on an object (the outer corner of the head H), and an image of the object on which the pattern is projected is projected. The (pattern image) is captured by the image capturing unit 1. The captured pattern image is quantized by the quantizer 5 and stored in the memory 6. When the pattern image is captured, the image processing unit 7 having a CPU as a main component outputs a pattern control command to the liquid crystal drive unit 4 via the interface unit 8 to shift the phase of the striped pattern by π / 2. The pattern is displayed on the liquid crystal display unit 3, and the pattern is projected on the object. After that, by capturing the pattern image four times while shifting the phase by π / 2,
Four pattern images G _{1 to} G ₄ as shown in FIG. 5 are obtained.

Here, focusing on an arbitrary position (pixel) P of the pattern images G _{1 to} G ₄ , there is a graph between the change in the lightness (data of the density value) at the position P and the phase modulation amount of the pattern. There is a relationship as shown in 6. However, in FIG. 6, the brightness I at the position P is plotted on the vertical axis, and the phase modulation amount is plotted on the horizontal axis. By approximating this change in brightness with a sine function, the phase at the position P in the pattern image G ₁ of the original pattern (pattern with zero phase modulation amount) can be obtained.

Now, the position P is P in the two-dimensional Cartesian coordinate system.
(X, y), the phase of the position P is α (x, y), and the brightness of the position P (x, y) in each of the pattern images G _{1 to} G ₄ is I ₁ (x, y) to I ₄ (x , Y), the phase α
(X, y) is calculated by the following equation 1.

[0032]

[Formula 1]

The image processing unit 7, the above equation 1 phase alpha (x, y) for all positions of the pattern image G ₁ by determining, for each position in the pattern image G ₁ as shown in FIG. 7 An image (hereinafter referred to as a “phase image”) in which the phase is obtained for each cycle (0 to 2π) is generated. further,
The phase switching position S ₁ for each cycle is obtained, and 2π is added to the phase for each cycle, whereby the phase in the pattern image G ₁ is completely restored, and based on the phase value at each position. The three-dimensional shape of the object can be measured by the principle of triangulation. In addition, regarding the calculation for obtaining the three-dimensional shape (each coordinate value in the three-dimensional orthogonal coordinate system) from the phase value at each position, the prior art (Cosmetic Technology Journal Vol. 28, No. 2, pp. 153-
162 (1994) or Japanese Patent Application Laid-Open No. 4-98111), the detailed description is omitted.

Next, the part that is the gist of the present invention will be described. As described above, when obtaining the phase switching position S ₁ ... For each cycle, the position at which the phase changes from 2π to 0 is usually taken as the phase boundary position (phase switching position) of the cycle. A method is used. However,
The surface of the human head H as an object are scattered features black such as the hair and moles, in such part there are cases where correct phase value for Lightness is very low can not be obtained.
Further, since the human skin is translucent, the pattern light projected on the object permeates and diffuses inside, and the lightness value I ₁ (x, y) of each position of the pattern images G _{1 to} G ₄ I
₄ (x, y) may be lower than it actually is.
Therefore, at the phase boundary position, as shown in FIG. 8, it is easy to uncertain whether the phase value near the phase boundary is a value close to 0 or 2π, and the phase boundary position becomes unclear. Correct phase restoration may not be performed by the method of simply setting the position where the phase value changes from 2π to 0 as the phase boundary position.

On the other hand, the phase image obtained by obtaining the phase for every cycle for all positions is a sawtooth image in which the phase for each position in the lateral direction is discontinuous for each cycle as shown in FIG. Becomes Therefore, in the present invention, a filter for extracting such a feature is applied to the phase image so that correct phase restoration can be performed even if the phase boundary position is unclear as described above.

Specifically, by applying a so-called one-dimensional edge point detection filter as shown in FIG. 9, a certain pixel of interest P (x,
At the position y), the image processing unit 7 performs a convolution operation of the edge detection filter and the image,
The detection value V (x, y) of the saw tooth is obtained. That is, when the width of the edge point detection filter is n (n = 6 in this embodiment), the detection value V (x, y) is represented by the following expression 2.

V (x, y) =-P (xn / 2, y) -P (xn / 2 + 1, y) ......- P
(x-1, y) + P (x, y) + P (x + 1, y) ...... + P (x + n / 2-1, y) + P (x + n / 2,
y) FIG. 10 shows an image obtained as a result of performing the above filter processing on the phase image shown in FIG. This detected value V
By detecting the peak value in the horizontal direction (X direction) of (x, y), the correct phase boundary position can be detected without being affected by the above-mentioned noise and local disturbance of lightness such as hair. Therefore, it is possible to perform highly reliable phase restoration.

FIG. 11 shows a flow chart in the case where the phase boundary position is obtained by the filter processing in the image processing section 7. The convolution calculation with the edge point detection filter is executed on the phase image to detect the detected value V ( x, y) is obtained, the position where the peak value of the detected value V (x, y) in the area where the obtained detected value V (x, y) is equal to or less than the threshold value is extracted, and the extracted detected value V is extracted. A process is performed in which the phase boundary position is obtained by detecting the position having the maximum value between the downward peak values of (x, y), and registered as the phase boundary position.

As described above, according to the three-dimensional shape detecting method of the present invention, the one-dimensional edge point detection filter is applied to the phase image obtained by obtaining the phase for every position at every position. Thus, the processing of detecting the phase boundary position for each cycle and restoring the phase of the pattern image is performed without installing a reference plane as in the conventional apparatus disclosed in Japanese Patent Publication No. 3-38524, and This can be performed without being affected by the local disturbance of brightness such as noise or hair, and highly reliable phase restoration is possible.

By the way, in the structure of the device of the present invention, since the directivity of the light emitting section 2a of the light irradiation section 2 is transferred to project a striped pattern, the distance between the light emitting section 2a and the liquid crystal display section 3 is reduced. The feature that the size of the pattern projected on the object increases as the distance increases. Therefore, when the vertical range of the pattern is large, this is the pattern image G.
₁ may cause distortion. Therefore,
In such a case, if a cylindrical lens is arranged in front of the light emitting section 2a of the light irradiating section 2 and the linear light from the light emitting section 2a is made into a substantially parallel light beam, a pattern without the above-mentioned distortion can be obtained. Can be projected. When using a cylindrical lens as described above, there is a drawback that chromatic aberration occurs in the peripheral portion of the pattern. To deal with this, a filter that selectively transmits light in a specific band (color) such as a metal thin film interference filter is inserted between the cylindrical lens and the light emitting section 2a in the optical path of the linear light. By doing so, the influence of such chromatic aberration can be eliminated.

Further, in the present embodiment, the image pickup unit 1 is arranged in the housing 9 of the measuring head A so that the optical axis substantially faces the object (head H), and the optical axis of the image pickup unit 1 is set. It is necessary to dispose the light irradiation section 2 and the liquid crystal display section 3 in the housing 9 so that the optical axis is tilted by a predetermined angle. For this reason, if the image pickup unit 1, the light irradiation unit 2, and the liquid crystal display unit 3 are to be housed in one housing 9, the size of the entire measurement head A becomes large. Therefore, by disposing a mirror in at least one optical path from the light irradiation section 2 to the opening surface or from the opening surface to the imaging section 1, and folding at least one optical path by this mirror, the directions of the above two optical axes can be obtained. When the difference is set to be small, the measuring head A can be downsized.

By the way, since the surface of human skin is coated with sebum and is glossy, it is possible that the light source, ambient light, and the like are reflected in the surface of the human skin, which interferes with the measurement. In such a case, by attaching a polarization filter to the front surface of the lens of the image pickup unit 1, it is possible to eliminate the above-mentioned reflection and prevent the occurrence of a measurement error. (Embodiment 2) In the underlying phase shift method of the three-dimensional shape measuring method of the present invention, each pattern image G ₁ ~G ₄
Since it is necessary to perform a process of comparing the brightness of the same position (pixel) of, the object needs to be stationary while the image pickup unit 1 captures the pattern images G _{1 to} G ₄ . However, in the present embodiment, since the target object is a person (head H), it is difficult to completely fix the target object, and there is a possibility that the target object moves while capturing the pattern images G _{1 to} G ₄ . The pattern images G _{1 to} G ₄ are moved by the movement of the object.
In some cases, the coordinate values of the same position of does not become the same position of the object. Therefore, it is necessary to obtain and correct the amount of movement of the object.

Therefore, in the present embodiment, the movement amount of the object between the pattern images G _{1 to} G ₄ is obtained by so-called template matching, and the position correction of each pattern image G _{1 to} G ₄ is performed based on the obtained movement amount. I'm trying to do. FIG. 12 is a flowchart showing the position correction process performed by the image processing unit 7. The image processing unit 7 displays the first pattern image G ₁ as a reference image on a screen such as a display device (not shown), and the measurer selects a rectangular portion to be cut out as a matching template at an arbitrary position on the screen. , It is registered as a template for matching. Then, other pattern images G ₂ ~
The registered template is applied to G ₄ , a portion similar to the template is searched for from each of the pattern images G _{2 to} G _4, and the position where the template is cut out from the reference image (pattern image G ₁ ) and other pattern images. G ₂
The amount of movement with the difference between the positions where the template is matched in ~G _4. However, since a striped pattern is projected on the object and the phase of the pattern is shifted by each of the pattern images G _{1 to} G ₄ , each pattern image G is once processed as a pre-process for performing the template matching process. It is desirable to perform a process of detecting edges _{1 to} G ₄ . By performing the pattern matching on the image in which the edge is detected as described above, it is possible to exclude the influence of the brightness change due to the projected pattern. Then, the position correction is completed by performing the process of scrolling the pattern images G _{2 to} G ₄ by the amount that the sign of the calculated movement amount is inverted.

By the way, in the case of measuring the wrinkles of the outer corners of the eyes of the person as in the present embodiment, since a plurality of pattern images G _{1 to} G ₄ can be taken in in a short time, the target object (head H) Can be regarded as a constant velocity linear motion. In this way, when the movement of the object can be regarded as a constant-velocity linear motion, the template matching processing is performed by the first pattern image G ₁ and the last pattern image G _1.
This is executed only for ₄ , and the movement amount with respect to the other pattern images G ₂ , G ₃ can be obtained by interpolation from the movement between the pattern images G ₁ , G ₄ .

(Embodiment 3) As described above, since the skin of the human body, which is the object of this embodiment, is translucent, it is observed that the projected pattern is slightly blurred. This state is shown in FIG. In the figure, a is a curve of the projected pattern, and b is a curve of the observed lightness value. For the human body,
Since the projected light penetrates into the skin and diffuses, the characteristic that the bright portion is observed narrower than the projected pattern in the curve b of the observed brightness value as shown in FIG. Therefore, the change in the phase value measured in the relevant portion becomes steeper than the true value, and as a result, the measured three-dimensional shape has periodic distortion (see FIG. 14).

Therefore, in the present embodiment, in consideration of the above characteristics, the pattern to be projected on the object is transformed in advance from the sine wave (curve a'of the pattern), as shown in FIG. The observed brightness curve b ′ is close to a sine wave, and a three-dimensional shape without distortion can be obtained. Alternatively, by utilizing the fact that the above-described distortion appears in a cycle that matches the cycle of the projected pattern, a coefficient for correcting the distortion of the phase value that occurs in each cycle of the pattern is set in advance as a function of the phase value, A method of correcting the phase value by using the information of the phase boundary value detected by the edge point detection filter described above is effective.

Alternatively, a method of obtaining the same effect by performing frequency separation can be considered. As described above, the distortion occurs with a certain periodicity, and thus can be removed by spatial frequency filtering such as Fourier transform. With respect to the distortion of the pattern image G _1, ... In addition to the above factors, the distortion of the image pickup unit 1 due to the aberration of the lens also occurs. Since such distortion always appears as the same amount of distortion in the entire pattern screen G _1, ..., First, the reference plane is measured, and the difference between the measurement result for the reference plane and each measurement result is effective. Can be corrected dynamically.

[0048]

According to the first aspect of the invention, a pattern having a sinusoidal light-dark distribution is projected onto an object a plurality of times while phase-shifting, and is synchronized with the phase-shifting from a direction different from the projection direction of the pattern. The object is imaged to obtain a plurality of pattern images, and a phase for one cycle with respect to each position of the pattern image is obtained based on a change in brightness caused by the phase shift at the same position of each pattern image. The phase at each position of the pattern image is restored by detecting the position that becomes the boundary of the phase and connecting the phases at the phase boundary positions, and from the restored phase, the principle of triangulation is applied to the object. Three
In a three-dimensional shape measuring method for measuring a three-dimensional shape, the phase at each position in the pattern image was obtained for each cycle.
Since the phase boundary position is detected by using a filter that detects the switching of the period for the phase image , the correct phase boundary position can be detected without being affected by the local disturbance of brightness such as noise or hair. Therefore, there is an effect that the phase can be restored with high reliability.

According to the second aspect of the present invention, the amount of movement of the target object between the plurality of pattern images is obtained based on the moving direction and speed of the target object, and the positional information of the pattern image is corrected. At this time, even when the object is not completely stationary, the effect that the three-dimensional shape measurement by the phase shift method can be performed by the simple correction process when the movement of the object can be regarded as the uniform linear motion. is there.

According to the third aspect of the present invention, the movement amount of the object between the pattern images is obtained by collating the pattern images with each other, and the positional information of the pattern images is corrected. Even if the object is not completely stationary and its movement is irregular, there is an effect that the three-dimensional shape measurement by the phase shift method can be performed by correcting the position information.

According to the invention of claim 4, the pattern projected onto the object is corrected in consideration of the deformation of the pattern caused by the scattering of light on the object which is semi-transparent. When a distortion occurs in the projected pattern, there is an effect that the distortion is predicted in advance and the pattern displayed on the pattern display unit is corrected, so that the correct measurement can be performed.

According to the fifth aspect of the present invention, the distortion of the three-dimensional height information caused by the scattering of light with respect to the semitransparent object is corrected based on the periodicity of the distortion, so that the object is semitransparent. Due to this, when distortion occurs in the projected pattern, correct processing can be performed by correcting the processing result based on the fact that the distortion has periodicity.

According to a sixth aspect of the invention, the measured object 3
Since frequency separation processing is performed on dimensional height information, it is possible to separate global features and local features from the object, and to eliminate cyclically generated distortion. . According to the invention of claim 7, the geometrical distortion of the pattern image generated by the configuration of the optical system is corrected by the image processing. Therefore, it is possible to cancel the measurement error that is constantly generated due to the configuration of the optical system. The effect is that According to an eighth aspect of the present invention, a light irradiating means having a linear or point light source for irradiating an object with light, and a pattern arranged in front of the light irradiating means and having a partially variable light transmittance. Display means, imaging means for capturing an image of the object onto which the pattern is projected by the pattern display means in the entire field of view, quantizing means for quantizing the pattern image captured by the imaging means, and quantized A plurality of storage units are provided for storing the pattern image and an image processing unit for performing image processing on the pattern image stored in the storage unit, and a plurality of times are performed while phase shifting the pattern having the sinusoidal light-dark distribution by the pattern display unit. Over the object, and in synchronization with the phase shift, the object is imaged by the imaging means from a direction different from the projection direction of the pattern to obtain a plurality of pattern images. At the same time, the image processing means obtains a phase for one cycle with respect to each position of the pattern image based on a change in brightness caused by the phase shift at the same position of each pattern image, and determines a phase boundary for the one cycle. Is detected and the phases at the phase boundary positions are connected to restore the phase at each position of the pattern image, and the three-dimensional shape of the object is measured from the restored phase by the principle of triangulation. a three-dimensional shape measurement device, each position in the pattern image
Since the phase boundary position is detected by using a filter that detects the switching of the cycle for the phase image obtained by calculating the phase of each cycle for each cycle , the local brightness of noise, hair, etc. is detected. There is an effect that the correct phase boundary position can be detected without being affected by the disturbance of the, and the phase can be restored with high reliability. Further, there is an effect that the resolution of the image pickup means can be fully utilized by capturing the object in the entire visual field of the image pickup means. Further, since the light irradiation means having a linear or point light source is provided,
The light itself emitted from the light emitting means has directivity, and a bright and dark pattern can be projected on an object without using a projection lens, and the size of the entire apparatus can be reduced.

According to the ninth aspect of the invention, since a liquid crystal panel is used as the pattern display means, a mechanical mechanism for shifting the phase of the pattern is not required, and the size of the entire apparatus can be reduced. There is. According to the tenth aspect of the invention, since the cylindrical lens is arranged on the optical axis of the light irradiating means, the light irradiating the pattern displaying means can be made into parallel rays, so that the pattern is not distorted, and the pattern in the depth direction is This has the effect that even deep objects can be measured.

According to the eleventh aspect of the present invention, since the mirror is disposed in at least one of the optical path from the light irradiating means to the object or the optical path from the object to the image pickup means, the optical path is folded back by the mirror. The irradiation means and the imaging means can be installed in parallel, and the size of the entire apparatus can be reduced. The invention of claim 12 is
Since the optical filter having a narrow color pass band is arranged in the optical path, it is possible to suppress the occurrence of a measurement error due to the chromatic aberration of the lenses of the light irradiation system and the imaging system.

According to the thirteenth aspect of the present invention, since a polarizing filter is arranged in front of the light taking-in portion of the image pickup means, the influence of ambient light can be reduced when measuring an object having a glossy surface. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an embodiment of a three-dimensional shape measuring apparatus according to the present invention.

FIG. 2 is a perspective view showing a light irradiation unit and a liquid crystal display unit in the above.

FIG. 3 is a diagram showing a striped pattern displayed on the liquid crystal display unit of the above.

FIG. 4 is a flowchart showing a process for measuring a three-dimensional shape in the above.

FIG. 5 is an explanatory diagram for explaining the same as above.

FIG. 6 is an explanatory diagram for explaining the same as above.

FIG. 7 is an explanatory diagram for explaining the same as above.

FIG. 8 is an explanatory diagram for explaining the same as above.

FIG. 9 is an explanatory diagram for explaining a one-dimensional edge point detection filter used in the above.

FIG. 10 is an explanatory diagram for explaining a process of obtaining a phase boundary position using an edge point detection filter in the above.

FIG. 11 is a flowchart for explaining a process for obtaining a phase boundary position using the edge point detection filter in the above.

FIG. 12 is a flowchart showing a position correction process in the second embodiment.

FIG. 13 is an explanatory diagram illustrating a third embodiment.

FIG. 14 is an explanatory diagram for explaining the same as above.

FIG. 15 is an explanatory diagram for explaining the above.

[Explanation of symbols]

1 Imaging unit 2 Light irradiation part 3 Liquid crystal display 4 LCD drive 5 Quantizer 6 memory section 7 Image processing unit 8 Interface section 9 housing 9a opening 10 fixed base A measuring head

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-138056 (JP, A) JP-A-7-198319 (JP, A) JP-A-4-98111 (JP, A) JP-A-61- 76906 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 A61B 5/10-5/117 G06T 1/00 G06T 7/00 G06T 7/60

Claims (13)

(57) [Claims] 1. A pattern having a sinusoidal light and dark distribution is projected onto an object a plurality of times while phase-shifting, and the object is imaged from a direction different from the projection direction of the pattern in synchronization with the phase shift. Of the pattern image, the phase of one cycle for each position of the pattern image is obtained based on the change in brightness caused by the phase shift at the same position of each pattern image, and the position becomes the boundary of the phase of the one cycle. Is detected and the phases at the phase boundary positions are concatenated to restore the phase at each position of the pattern image, and the three-dimensional shape of the object is measured from the restored phase by the principle of triangulation 3 in dimension shape measurement method, you said pattern image
A three-dimensional shape measuring method, characterized in that the phase boundary position is detected for a phase image in which the phase at each position is calculated for each cycle by using a filter that detects switching of the cycle . 2. The amount of movement of the object between the plurality of pattern images is calculated based on the moving direction and speed of the object,
The three-dimensional shape measuring method according to claim 1, wherein position information of the pattern image is corrected. 3. The three-dimensional structure according to claim 1, wherein the positional information of the pattern images is corrected by obtaining the amount of movement of the object between the pattern images by collating the pattern images with each other. Shape measurement method. 4. The three-dimensional shape measuring method according to claim 1, wherein the pattern projected on the object is corrected in consideration of deformation of the pattern caused by light scattering on the semi-transparent object. 5. The three-dimensional shape according to claim 1, wherein distortion of three-dimensional height information caused by light scattering on a semitransparent object is corrected based on the periodicity of the distortion. Measuring method. 6. The frequency separation processing is performed on the measured three-dimensional height information of the object.
The described three-dimensional shape measuring method. 7. The three-dimensional shape measuring method according to claim 1, wherein geometric distortion of the pattern image generated by the configuration of the optical system is corrected by image processing. 8. A light irradiating means having a linear or point light source for irradiating an object with light, and a pattern display means arranged in front of the light irradiating means and capable of partially varying light transmittance. An image pickup means for picking up and picking up an image of an object on which the pattern is projected by the pattern display means, a quantizing means for quantizing the pattern image picked up by the image pickup means, and a quantized pattern image For storing a pattern image stored in the storage means, and image processing means for performing image processing on the pattern image stored in the storage means. When a plurality of pattern images are obtained by projecting onto an object and synchronizing the phase shift with the imaging means to image the object from a direction different from the projection direction of the pattern. At the same time, the image processing means sets 1 for each position of the pattern image based on the change in brightness caused by the phase shift at the same position of each pattern image.
The phase at each position of the pattern image is restored by finding the phase for the cycle, detecting the position that becomes the boundary of the phase for the one cycle, and connecting the phases at the phase boundary positions. A three-dimensional shape measuring device for measuring the three-dimensional shape of the object from the phase according to the principle of triangulation, wherein the phase at each position in the pattern image is set to 1
A three-dimensional shape measuring apparatus comprising a filter for detecting switching of the cycle for a phase image obtained for each cycle, and detecting the phase boundary position using the filter. 9. The three-dimensional shape measuring apparatus according to claim 8, wherein a liquid crystal panel is used as the pattern display means. 10. The three-dimensional shape measuring apparatus according to claim 8, wherein a cylindrical lens is arranged on the optical axis of the light irradiation means. 11. The three-dimensional shape measuring apparatus according to claim 8, further comprising a mirror arranged on at least one of an optical path from the light irradiation means to the object and an optical path from the object to the imaging means. . 12. The three-dimensional shape measuring apparatus according to claim 8, wherein an optical filter having a narrow color pass band is arranged in the optical path. 13. The three-dimensional shape measuring apparatus according to claim 8, wherein a polarization filter is arranged on the front surface of a portion of the image pickup means for taking in light.