JP3408237B2 - Shape measuring 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 shape measuring apparatus for measuring a three-dimensional shape, and more particularly to a shape measuring apparatus suitable for measuring a foot shape.

[0002]

2. Description of the Related Art Generally, the size of a shoe is usually expressed by the length from the heel to the fingertip, but the shape of a person's foot varies not only with the length but also with the height of the instep, the width of the foot, etc. Is. In order to make shoes that match the shape of each person's foot, it is necessary to measure the three-dimensional shape of the foot, but at present, measure length, foot width, foot position (foot circumference) using a measure.
It is limited to measuring the size of a limited area such as.

On the other hand, there is known an active stereo shape measuring apparatus which irradiates an object to be measured with spot light or slit light to restore a three-dimensional shape from the position of an optical image observed on the surface of the object to be measured. . This shape measuring device scans spot light or slit light with a rotating mirror in order to measure the surface shape of an object to be measured, and is used in a magazine “Measurement and Control” (1999 Vol.38 No.4 P285-P288). ) Describes a system for measuring the shape of a foot by using such a shape measuring device.

In this system, one shape measuring device can measure only the shape of the part observed from the device, and cannot measure the shape of the hidden part such as the opposite side. Individual shape measuring devices are arranged around the foot, and the shape of the entire foot is measured by synthesizing the measurement results obtained by these twelve shape measuring devices on a computer.

However, in this system, since a plurality of shape measuring devices are arranged around the foot, not only the system becomes large and expensive, but also the measurement results of the plurality of shape measuring devices are accurately combined. There is a problem that it becomes difficult.

On the other hand, the applicant of the present application has already developed a shape measuring device for carrying out a measurement by gripping a compact measuring head in the hand and moving the measuring head around the object to be measured (Japanese Patent Application Laid-Open No. 2000-242242). 2000-39310). In this shape measuring apparatus, the position and the direction of the measuring head are measured by imaging a plurality of markers attached to the measuring head from above with two cameras.

In this proposal, since it is necessary to capture the entire moving range of the measuring head from two upper cameras, the two cameras are installed at positions apart from the object to be measured in order to widen the common field of view of the cameras. As a result, a large installation space is required. In addition, if some of the markers on the measurement head deviate from the common field of view of the two cameras, or if they are hidden by the hand of the person holding the measurement head or the measurement head, the shape of the measurement object can be measured. Since it disappears, the measurer must always pay attention so that the markers of the measuring head are imaged by the two cameras.

By the way, in order to measure the shapes of the upper surface and the lower surface of the foot using one measuring head, it is necessary to measure the shape in two steps. In order to simultaneously measure the shapes of the instep surface and the back surface of the foot, two measuring heads for measuring the instep surface of the foot and for measuring the back surface of the foot are required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shape measuring apparatus capable of measuring an appropriate three-dimensional shape with a small number of measuring procedures.

[0009]

A shape measuring apparatus according to the present invention comprises a mirror placed on a measuring table, a transparent glass plate arranged parallel to the mirror and above the mirror, a slit light irradiating means and an image pickup device. And a measuring head for measuring the shape of the object to be measured by the optical cutting method, a position detecting means for detecting the position of the measuring head, and an image picked up by the image sensor of the measuring head, and detected by the position detecting means. The calculating means is provided with a calculating means for obtaining the three-dimensional shape of the object to be measured based on the position of the measuring head. First, the three-dimensional shape of the normal image of the DUT in the world coordinate system is obtained by extraction.
Means, second means for obtaining the projection coordinates of the virtual image position by the mirror with respect to the lowest point of the normal image on the image pickup surface of the image pickup element, with the obtained projection coordinates as a start point, in the upward direction on the image surface of the image pickup element Third means for obtaining the three-dimensional shape of the virtual image of the measured object in the world coordinate system by tracing the slit light corresponding to the virtual image of the measured object, and the mirror surface of the three-dimensional mirror for the virtual image of the measured object. It is characterized by comprising a fourth means for obtaining a three-dimensional shape of the object to be measured by synthesizing a three-dimensional shape symmetrical with respect to and a three-dimensional shape with respect to the normal image of the object to be measured.

As a third means, when the slit light corresponding to the virtual image of the object to be measured is being tracked, if another slit light intersects with the slit light being tracked, the upper left direction and the upper right direction are detected. Among them, one provided with a means for tracking the slit light extending in a predetermined direction is used.

Further, as a third means, when the slit light corresponding to the virtual image of the object to be measured is being traced, in a region where another slit light intersects with the slit light being traced, a predetermined value before the intersection is obtained. Based on the position of the slit light corresponding to the virtual image of the DUT extracted on the horizontal line of, and the position of the slit light extracted a predetermined horizontal line ahead of it, the virtual image position between them is linearly interpolated. Obtained, based on the position of the slit light corresponding to the virtual image of the measured object extracted on the predetermined horizontal line after the intersection, and the position of the slit light extracted before the predetermined horizontal line from it,
What is provided with a means for obtaining the virtual image position between them by linear interpolation is used.

As the position detecting means, for example, a means for detecting the position of the measuring head by a stereo method using two cameras is used.

It is preferable to provide guide means for regulating the attitude of the measuring head so that the light beam emitted from the slit light irradiating means of the measuring head is emitted perpendicularly to the light reflecting surface of the mirror. The guide means is preferably one that regulates the movement path of the measuring head. Further, it is preferable to include a driving unit for moving the measuring head along the guide unit.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

[1] Description of schematic configuration of shape measuring apparatus

FIG. 1 shows a schematic configuration of the shape measuring apparatus.

An arcuate guide rail 204 is fixed to the measuring table 201. A flat plate-shaped mirror 205 is arranged in a region surrounded by the guide rails 204. Mirror 205
As for the stainless steel mirror 2 having a light reflecting surface
05 is used. Further, a transparent glass plate 206 is arranged above the mirror 205 with a space. Mirror 205
A spacer (not shown) is interposed between the transparent glass plate 206 and the transparent glass plate 206 at the peripheral edge thereof. Then, a foot 100 as an object to be measured is placed on the glass plate 206. In addition, a column 202 that is detachable from the measurement table 201 is attached to the measurement table 201, and a horizontal bar 203 is attached to the upper part thereof.

The shape measuring apparatus includes a measuring head 10 manually moved by a measurer along a guide rail 204, stereo cameras 21 and 22 attached to both ends of a horizontal bar 203, their control, and various calculations. And a control device 30 including a personal computer for performing the above. A bandpass filter 23 that selectively transmits the frequency band of the light emitted by the marker 14 shown in FIG. 2 is attached to the imaging lenses of the stereo cameras 21 and 22.

[2] Description of Schematic Structure of Measuring Head 10

FIG. 2 shows a schematic structure of the measuring head 10 shown in FIG.

The measuring head 10 has a casing 11 having a rectangular parallelepiped shape and having a front opening, and a casing 1 housed in the casing 11.
A CCD camera 12 and a slit light source 13, and six LED light sources 14a to 14a provided on the upper surface of the casing 11.
And a marker 14 composed of 14f. A semiconductor laser is used as the slit light source 13. In this embodiment, from the inside of the casing 11 to the casing 1
When viewed toward the opening direction of 1, the slit light source 13 is arranged at the left position and the CCD camera 12 is arranged at the right side.

The measuring head 10 is mounted movably along the guide rails 204 by a support mechanism (not shown). The measuring head 10 is attached to the guide rail 204 by a support mechanism (not shown), so that the luminous flux emitted from the slit light source 13 is emitted along a plane perpendicular to the stainless steel mirror 205. Posture is regulated.

Six LED light sources 1 constituting the marker 14
In order to identify the direction of the measuring head 10, 4a to 14f are not arranged in point symmetry but are arranged in line symmetry with respect to the center line of the measuring head 10. Here, casing 1
LED light sources 14b, 14c, 14d, 14 on the upper surface of 1.
Five points e and 14f are arranged so as to form a rectangle, and the LED light source 14a is arranged at the center of gravity of these five points. In order to measure the position and direction of the measuring head 10 in the three-dimensional space, at least three LEs are used as markers.
It is sufficient to have the D light source, but by using four or more LED light sources, the measurement accuracy of the position and direction of the measuring head 10 is improved in the least squares manner.

Further, the shape measuring apparatus 10 is provided with an encoder 16 for detecting the position of the shape measuring apparatus 10 on the guide rail 204. The output of the encoder 16 is input to the control device 30.

[3] Description of measurement principle of the shape measuring device

FIG. 3 shows the measuring principle of the shape measuring apparatus.

The coordinates of a measurement point A are measured using the measuring head 10 which is moved on the guide rail 204 by the measurer. The measured coordinates are coordinates (X) in the coordinate system of the measuring head center (hereinafter referred to as camera coordinate system).
c, Yc, Zc). The camera coordinate system is a coordinate system that moves as the measuring head 10 moves.

On the other hand, the shape of the object 100 to be measured is represented by a fixed coordinate system, which is called world coordinate. The coordinates of the measurement points measured by the measurement head 10 in the world coordinate system are (Xw, Yw, Zw). Since the shape of the DUT 100 needs to be described in the world coordinate system, the coordinates (Xc, Yc, Zc) of the measuring point A measured by the measuring head 10 in the camera coordinate system are converted into the world coordinate system. This conversion is performed based on the following Equation 1 using the rotation matrix R that represents the movement of the measuring head 10 and the translation vector t.

[0029]

[Equation 1]

In this embodiment, as shown in FIG.
The origin of the world coordinate system (Xw, Yw, Zw) is set at the focus position of one of the stereo cameras 21, 22. The Zw axis of the world coordinate system is set in the optical axis direction of the camera 21. The Yw axis of the world coordinate system is set in the direction orthogonal to the Zw axis and extending from the origin to the rear of the shape measuring device. The Xw axis of the world coordinate system is set in a direction orthogonal to the Zw axis and extending obliquely to the upper right of the shape measuring device from the origin.

In this embodiment, as shown in FIG. 4, a mirror coordinate system (Xu, Yu, Zu) is further set. The origin of the mirror coordinate system is set at the intersection of the Zw axis of the world coordinate system and the mirror surface of the stainless steel mirror 205. The Xu axis of the mirror surface coordinate system is set as an axis that passes through the origin and projects the Xw axis of the world coordinate system onto the mirror surface. The Zu axis of the mirror surface coordinate system passes through the origin and is set in the direction of the normal vector of the mirror surface. The Yu axis of the mirror surface coordinate system is set to the outer product of the Xu axis and the Z axis of the mirror surface coordinate system.

In this embodiment, the coordinates (Xc, Yc, Zc) of the measuring point A measured by the measuring head 10 in the camera coordinate system are converted into the world coordinate system (Xw, Y).
w, Zw), and then the specular coordinate system (Xu,
Yu, Zu). The coordinates (Xw, Yw, Zw) in the world coordinate system are replaced by the coordinates (Xu, Y
u, Zu) will be described later.

[4] Description of the problem of sole measurement via a glass plate

In this embodiment, as shown in FIG.
Glass plate 2 placed above the stainless mirror 205
The device under test 100 is placed on 06. The distance from the upper surface of the stainless steel mirror 205 to the upper surface of the glass plate 206 is set to 30 mm in this example. In the mirror surface coordinate system, the Zu coordinate on the upper surface of the stainless steel mirror 205 is 0, and the Zu coordinate on the upper surface of the glass plate 206 is 30.

As described above, the object to be measured 100 is placed on the glass plate 206 placed above the stainless steel mirror 205, and the stainless steel mirror 2 is measured by using the measuring head 10.
When measuring the shape of the sole (sole) of the object to be measured reflected in 05, more foot shapes can be measured than when the object 100 is placed on the stainless steel mirror 205. become able to.

However, as shown in FIG. 6, there is a problem that the false reflection image reflected by the upper surface of the glass plate 206 is erroneously extracted. Further, since light passes through the glass plate 206, there is a problem that it is affected by the refraction of light by the glass plate 206. The shape measuring apparatus according to this embodiment solves the above problems.

[5] Description of measurement processing procedure by the shape measuring apparatus

The shape measurement by this shape measuring apparatus is executed by the following processing procedure.

(1) First step (preprocessing 1): Information relating to each measurement position of the measurement head 10 in the world coordinate system is associated with the output value of the encoder 16 at each measurement position of the measurement head 10 and controlled. It is stored in a memory (not shown) mounted on the device 30.

(2) Second step (preprocessing 2): A conversion formula for converting the coordinates (Xw, Yw, Zw) in the world coordinate system into the coordinates (Xu, Yu, Zu) in the mirror coordinate system is obtained. .

(3) Third step (pretreatment 3): Position of the slit light from the slit light source 13 on the mirror surface of the stainless steel mirror 205 on the image of the CCD camera 12, and
The position of the slit light on the image of the CCD camera 12 on the surface of the glass plate 206 is acquired and stored in a memory (not shown).

(4) Fourth Step: Using the measuring head 10, the coordinates of the measurement points on the object to be measured in the mirror coordinate system are obtained by the light section method. By the way, when the measurement point on the measured object is to be measured by the light section method, as described above, the CCD camera 12 of the measurement head 10 is reflected on the normal image of the measured object and the stainless steel mirror 205. A virtual image,
The false reflection image reflected on the surface of the glass plate 206 is captured. In the fourth step, the coordinates of the normal image of the object to be measured and the coordinates of the virtual image reflected on the stainless steel mirror 205 are extracted, and the coordinates of the false reflection image reflected on the surface of the glass plate 206 are not extracted. .

(5) Fifth step: Of the measurement points in the world coordinate system, the coordinates on the virtual image reflected on the stainless steel mirror 205 are converted into the coordinates on the regular image.

Each of these steps will be described below.

[6] Description of the first step

FIG. 7 is a flow chart for explaining the processing procedure of the first step.

First, the measuring head 10 is attached to the guide rail 20.
4 is set at the reference position (step 1), and the output value of the encoder 16 at that position is stored in the memory of the control device 30 (step 2).

Next, the coordinates of the marker 14 provided on the measuring head 10 in the world coordinate system are measured by the stereo cameras 21 and 22. Since this position measuring method is well known as the stereo method, its explanation is omitted (step 3).

Next, the coordinates of the LED light sources 14a to 14f constituting the marker 14 in the camera coordinate system are respectively set to (Xc
i, Yci, Zci), and the stereo camera 2
Each LED light source 14a-14 measured by 1, 22
The coordinates of f in the world coordinate system are (Xwi,
Ywi, Zwi). However, i is 1, 2, ... Each coordinate (Xci, Yci, Zci) of the camera coordinate system of each LED light source 14a to 14f is known.

A rotation matrix R1 representing the movement of the measuring head 10.
And the translation vector t1 into a matrix R1 that satisfies the following equation 2.
And a vector t1 is obtained (step 4). And
The obtained matrix R1 and vector t1 are stored in the memory in association with the output value of the encoder 16 previously stored in the memory (step 5).

[0051]

[Equation 2]

Then, the measuring head 10 is attached to the guide rail 2
04, and repeat the processes of steps 2 to 5 for all the measurement positions (step 6,
7). As a result, table data in which the output value of the encoder 16 is associated with the rotation matrix R1 and the translation vector t1 at that position is generated and stored in the memory of the control device 30.

[7] Description of the second step

In the second step, first, the glass plate 206 provided on the measuring table 201 is removed. Then, the stainless steel mirror 205 provided on the measuring table 201 is covered with an opaque thin plate (white plate), and the coordinates of the points on the thin plate in the world coordinate system are measured by the stereo method.

Next, based on the coordinates of the obtained points on the thin plate in the world coordinate system, the equation A _M Xw + B _M Yw + C _M Zw + D _M representing the plane of the stainless steel mirror 205 is obtained.
= 0 is calculated. In calculating the equation of the plane, at least three points should be set on the flat plate.

Instead of covering the stainless steel mirror 205 with an opaque thin plate and measuring it, at least three markers are provided on the stainless steel mirror 205 and the positions of the markers are measured to calculate the equation of the plane of the stainless steel mirror 205. You may do it.

Further, using the measuring head 10, the equation A _M Xw + B _M Yw representing the plane of the stainless steel mirror 205 is obtained.
+ C _M Zw + D _M = 0 may be obtained. That is, the stainless steel mirror 205 provided on the measuring table 201 is covered with an opaque thin plate, the thin plate is imaged by the measuring head 10, and the coordinates of three points (coordinates in the camera seat system) for obtaining the plane of the thin plate are obtained. Extract. The coordinates of the three points in the extracted camera coordinate system are set to the rotation matrix R1 and the translation vector t1 corresponding to the position of the measurement head 10 obtained in the first step.
Based on and, convert to coordinates in the world coordinate system. An equation of the plane of the thin plate in the world coordinate system is obtained based on the obtained coordinates of the three points in the world coordinate system.

The conversion formula for converting the coordinates (Xu, Yu, Zu) in the mirror surface coordinate system into the coordinates (Xw, Yw, Zw) in the world coordinate system is the stainless steel mirror 20.
The equation expressing the plane of 5 is A _M Xw + B _M Yw + C _M Zw
When + D _M = 0, it is represented by the following mathematical formula 3.

[0059]

[Equation 3]

Therefore, the coordinates of the world coordinate system (X
w, Yw, Zw) are the coordinates (Xu, Yu,
The conversion formula for converting into Zu) is obtained by the following formula 4.

[0061]

[Equation 4]

[8] Description of the third step

In the third step, first, the glass plate 206
Place a thin white plate on top. Then, slit light is output from the slit light source 13 of the measuring head 10 and the CCD
By capturing an image of the slit light illuminated on the white plate on the glass plate 206 by the camera 12, the position of the slit light intersecting the surface of the glass plate 206 on the image of the CCD camera 12 is acquired and stored in the memory.

Next, the glass plate 206 is removed, and a thin white plate is placed on the stainless steel mirror 205. Then, slit light is output from the slit light source 13 of the measuring head 10 and the stainless steel mirror 205 is used by the CCD camera 12.
By imaging the slit light illuminated on the upper white plate, the position on the image of the CCD camera 12 of the slit light intersecting the mirror surface of the stainless steel mirror 205 is acquired and stored in the memory.

A straight line Lg in FIG. 8 shows an image of slit light intersecting with the surface of the glass plate 206 on the image of the CCD camera 12, and a straight line Lm in FIG. An image of slit light intersecting the mirror surface of the stainless steel mirror 205 is shown. Since a normal image and a virtual image of the object to be measured cannot exist between the glass plate 206 and the mirror surface of the stainless steel mirror 205, the slit light appearing in the region sandwiched between these straight lines Lg and Lm at the time of shape measurement does not appear. The slit light corresponding to the normal image and the virtual image of the object to be measured is determined to be false slit light.

[8] Description of Fourth Step

In the fourth step, the object to be measured is placed on the glass plate 206 for measurement. In this case, since the stereo cameras 21 and 22 are not used, as shown by the arrow in FIG. 1, the support 202 is detached from the measurement table 201 and the measurement is performed.

First, a method of measuring the position of the measuring point by the measuring head 10 will be described.

As shown in FIG. 9, the camera coordinate system is C
The optical center of the CD camera 12 is the origin, and the optical axis direction is Zc.
An axis is a coordinate system in which the horizontal direction of the CCD camera 12 is the Xc axis and the vertical direction of the CCD camera 12 is the Yc axis. CCD
The image plane S of the camera 12 exists at the position of the focal length f from the origin. That is, the image surface S is a plane parallel to the Xc-Yc plane and Zc = f.

The position measuring method itself by the measuring head 10 is a known measuring method called a light cutting method. A predetermined point on the line on the surface of the DUT 100 on which the slit light from the slit light source 13 is irradiated is referred to as a measurement point A.

Coordinates (X
A method of obtaining u, Yu, Zu) will be described.

The pixel coordinates (PIX unit) of the point A'corresponding to the measurement point A observed on the image surface S with respect to the measurement point A are set to (X
p, Yp). The image coordinates (Xp, Yp) are converted into the sensor coordinates (Xs,
Ys, f). Note that f at the sensor coordinates (Xs, Ys, f) of the observation point A ′ is the CCD camera 12
Is known as the focal length of. Cx is the Xp coordinate of the image center, and Cy is the Yp coordinate of the image center.

[0073]

[Equation 5]

The sensor coordinates (X
s, Ys, f) is the equation of the plane representing the slit light in the camera coordinate system and is A _L Xc + B _L Yc + C _L Zc + D _L =
0 is used to convert to coordinates (Xc, Yc, Zc) in the camera coordinate system based on the following Equation 6. The equation of the plane representing the slit light is obtained by calibrating the measuring head 10.

[0075]

[Equation 6]

The coordinates of the obtained camera coordinate system (Xc, Y
c, Zc) is converted into coordinates (Xw, Yw, Zw) in the world coordinate system based on the following Equation 7.

[0077]

[Equation 7]

The obtained coordinates of the world coordinate system (Xw, Y
w, Zw) is converted into coordinates (Xu, Yu, Zu) in the mirror coordinate system based on the following formula 8.

[0079]

[Equation 8]

FIG. 11 shows the processing procedure executed in the fourth step.

FIG. 10 shows an example of the slit light imaged by the CCD camera 12. In FIG. 10, L1 indicates the slit light (normal image) directly irradiated to the object to be measured, L2 indicates the slit light corresponding to the virtual image reflected on the mirror surface of the stainless steel mirror 205, and L3 and L4 indicate
The slit light corresponding to the false reflection image reflected on the surface of the glass plate 206 is shown.

First, as shown in FIG. 10, the slit light L is extracted line by line from the top to the bottom of the screen (step 11). Every time the slit light is extracted, the pixel coordinates (Xp, Y) of the width center (center of gravity) position of the slit light are extracted.
p) by the method described above, the coordinates (Xu, Y
u, Zu) to obtain the position data of the measurement point. Then, the coordinates (Xu,
It is determined whether Zu of (Yu, Zu) is less than 30 mm (step 12). That is, the position of the measurement point is
It is determined whether the position is the lower side of the glass plate 206.

When it is not determined in step 12 that the position of the measurement point is below the glass plate 206, the position data obtained in step 11 is stored in the memory as position data for the normal image (step 13). Then, the process returns to step 11.

In step 12, the position of the measuring point is the glass plate 2
Until it is determined that the lower side is 06, steps 11, 1
The processes 2 and 13 are repeated.

When it is determined in step 12 that the position of the measurement point is below the glass plate 206, the coordinates of the measurement point measured one line before the measurement point are set to the lowest point of the normal image. (Step 14). The lowest point position of the normal image is represented by P1 in FIG.

Next, the virtual image position by the stainless steel mirror 205 with respect to the lowest point of the normal image is obtained in the mirror coordinate system (step 15). That is, if the coordinates of the lowest point of the normal image in the mirror coordinate system are (Xu1, Yu1, Zu1), the coordinates of the virtual image position of the lowest point of the normal image in the mirror coordinate system are (Xu1, Yu
1, -Zu1).

Next, the coordinates in the mirror coordinate system of the virtual image position of the lowest point of the normal image are converted into the coordinates (Xp, Yp) in the pixel coordinate system (step 16).

For convenience of explanation, the coordinates of the virtual image position of the lowest point of the normal image in the mirror coordinate system will be represented by (Xu, Yu, Zu). First, the virtual image position of the lowest point of the normal image will be described. The coordinates (Xu, Yu, Zu) in the mirror surface coordinate system are converted into the coordinates (Xw, Yw, Zw) in the world coordinate system based on the following Expression 9.

[0089]

[Equation 9]

The obtained coordinates in the world coordinate system (Xw,
Yw, Zw) is converted into coordinates (Xc, Yc, Zc) in the camera coordinate system based on the following formula 10.

[0091]

[Equation 10]

The obtained coordinates of the camera coordinate system (Xc, Y
c, Zc) is converted into coordinates (Xs, Ys, f) in the sensor coordinate system based on the following formula 11.

[0093]

[Equation 11]

The coordinates of the obtained sensor coordinate system (Xs, Y
s, f) is converted into coordinates (Xp, Yp) in the pixel coordinate system based on the following Expression 12.

[0095]

[Equation 12]

Then, the coordinates (X
(p, Yp) is subjected to glass refraction inverse correction based on a glass refraction inverse correction formula obtained in advance (step 17). Since the slit light is refracted when the slit light passes through the glass plate 206, the coordinates (Xp, Y) of the obtained pixel coordinate system.
p) is corrected to the pixel coordinates when there is refraction. The position represented by the coordinates (Xp ′, Yp ′) after the glass refraction correction is represented by P2 in FIG.

Converting the coordinates of the pixel coordinate system when there is glass refraction into the coordinates of the pixel coordinate system when there is no glass refraction is called glass refraction correction, and the coordinates of the pixel coordinate system when there is no glass refraction are the glass. Converting to the coordinates of the pixel coordinate system when there is refraction is called glass refraction inverse correction.

A method of obtaining the glass refraction correction formula and the glass refraction inverse correction formula will be described. Stainless steel mirror 205
Place a color plate with a specific pattern (eg, grid) printed on it's mirror surface. When the glass plate 206 is present,
The CCD camera 12 captures an image of a specific pattern, depending on whether the glass plate 206 does not exist. A glass refraction correction formula and a glass refraction inverse correction formula are experimentally obtained based on the obtained two types of images.

Next, the coordinates (Xp ',
The position represented by Yp ') is set as the initial position of the tracking process,
Virtual image tracking processing is performed (step 18).

FIG. 12 shows a virtual image tracking processing procedure.

First, as shown in FIG. 10, from the initial position P2 (Xp ', Yp') of the tracking process, slit light existing in a search window 50 of a predetermined width is extracted line by line upward ( Step 21). When the slit light is extracted, it is determined whether or not there is only one slit light in the search window (step 22).

If there is only one slit light beam existing in the search window, glass refraction correction is performed on the pixel coordinates (Xp, Yp) of the barycentric position of the slit light beam (step 23). That is, the pixel coordinates (Xp, Yp) of the barycentric position of the slit light are converted into the pixel coordinates when there is no glass refraction.

Then, the pixel coordinates (X
By converting (p, Yp) into coordinates (Xu, Yu, Zu) in the mirror coordinate system, the position data of the measurement point is obtained and stored in the memory (step 24). Then, it is determined whether or not the tracking position has reached the normal image area (step 25). In this determination, the stainless steel mirror 2 whose pixel coordinates (Xp, Yp) of the measurement point are obtained in the third step (pretreatment 3)
Position Lm on the image of the CCD camera 12 of the slit light from the slit light source 13 on the mirror surface of 05, and the glass plate 20.
It is performed by determining whether or not the slit light on the surface of No. 6 exists in a region between the slit light and the position Lg on the image of the CCD camera 12. Pixel coordinates of measurement point (Xp, Y
If p) is in the region between the straight lines Lm and Lg, the tracking position
It is determined that the position has reached the normal image area . When the position data of the measurement point extracted on the line of interest obtained in step 24 has reached the normal image area at the tracking position, the process ends. If the tracking position has not reached the normal image area, step 2
Return to 1.

In step 22, if there are two or more slit lights in the search window, the outermost width W1 of the slit light in the search window on the target line is extracted (step 26). In addition, returning by one line, the width of the search window 50 is widened to extract the outermost width W2 of the slit light within the search window width (step 2).
7). Then, it is determined whether the outermost width W2 is larger than the outermost width W1 (step 28).

By the way, when there are two or more slit lights existing in the search window on the line of interest n, when the slit light L2 is traced upward as shown in FIG. 13 (a). And the other slit light L4 is L
As you approach the point where you are about to cross 2,
As shown in FIG. 3 (b), when the slit light L2 is being traced in the upward direction, the slit light L2 and L4 approach the point where these slit light L2 and L4 are branched in two from the intersection of the slit light L2 and L4. There are some cases.

In the case of FIG. 13A, in the line (n-1) which is one line before the target line n, the width of the search window is widened to extract the outermost width W2 of the slit light within the search window width. In that case, W2 becomes larger than the outermost width W1 of the slit light on the line of interest.

On the other hand, in the case of FIG. 13B, in the line (n-1) one line before the target line n, the width of the search window is widened and the outermost width W2 of the slit light within the search window width W2. Is extracted, W2 is smaller than the outermost width W1 of the slit light on the line of interest.

When it is determined in step 28 that the outermost width W2 is larger than the outermost width W1, when the slit light L2 is being traced upward as shown in FIG. It is determined that the other slit light L4 has approached the vicinity of the point where it is about to intersect L2. In this case, the pixel coordinates (Xp, Yp) of the barycentric position Qa of the left slit light of the two slit lights extracted on the line of interest are obtained (step 29).

The reason for selecting the left slit light is as follows.
The CCD camera 12 and the slit light source 13 are arranged as shown in FIG.
13 is a curved surface that spreads downward, the slit light L2 for the virtual image and the slit light L4 for the false reflection image are directed from the lower right to the upper left as shown in FIG. This is because it is thought that they will cross toward each other.

Next, as shown in FIG. 13A, the slit light is extracted by advancing five lines from the target line, and the pixel coordinates (Xp, Yp) of the barycentric position Qb are acquired (step 30). Then, based on the pixel coordinates (Xp, Yp) of Qa obtained in step 29 and the pixel coordinates (Xp, Yp) of Qb obtained in step 30, the barycentric position of the slit light for four lines therebetween is located. The image coordinates of are obtained by primary interpolation (step 31).

From the line of interest thus obtained, 5
Glass refraction correction is performed on the pixel coordinates (Xp, Yp) of the slit light for 6 lines up to the line ahead (step 23). Then, the pixel coordinates (Xp, Yp) after the glass refraction correction are converted into the coordinates (Xu, Yu,
Zu) to obtain the position data of each measurement point and store it in the memory (step 24). Then, it is determined whether or not the tracking position has reached the normal image area (step 2
5). If the tracking position has reached the normal image area, the processing ends. If the tracking position has not reached the normal image area, the process returns to step 21.

In step 28, when the outermost width W2 is smaller than the outermost width W1, as shown in FIG. 13B, when the slit light L2 is traced upward,
From the intersection of the slit lights L2 and L4, it is determined that the slit lights L2 and L4 have approached the point where they are branched into two. In this case, the pixel coordinates (Xp, Yp) of the barycentric position Qc of the slit light on the right side of the two slit lights extracted on the line of interest are obtained (step 32).

Next, five lines are returned from the line of interest, the slit light is extracted, and the pixel coordinates (X
p, Yp) is obtained (step 33). Then, the pixel coordinates of Qc obtained in step 32 (Xp, Yp)
And the pixel coordinates of Qd (Xp,
Yp), the image coordinates of the barycentric position of the slit light for four lines between them are obtained by linear interpolation (step 34).

From the line of interest thus obtained, 5
Glass refraction correction is performed on the pixel coordinates (Xp, Yp) of the slit light for 6 lines up to the line before the line (step 23). Then, the pixel coordinates (Xp, Yp) after the glass refraction correction are converted into the coordinates (Xu, Yu,
Zu) to obtain the position data of each measurement point and store it in the memory (step 24). At this time, the coordinates of the mirror surface coordinate system for the slit light for 5 lines other than the line of interest are already stored in the memory, so these data already stored are rewritten.

Then, it is determined whether or not the tracking position has reached the normal image area (step 25). If the tracking position has reached the normal image area, the processing ends. If the tracking position has not reached the normal image area, the process returns to step 21.

The above-described processing of the fourth step is performed for every observation position on the guide rail 204 while moving the measuring head 10 along the guide rail 204.

[8] Description of the fifth step

When the process of the fourth step is performed at all the observation positions on the guide rail 204, as shown in FIG. 14, a set of coordinates (Xu, Yu, Zu) in the mirror coordinate system of the measurement point is displayed. 100 images are generated. In FIG. 14, the broken line is the normal image I ₁ of the foot 100, and the solid line is the virtual image I of the foot 100 reflected on the stainless steel mirror 205.
_{Is 2} .

In the fifth step, a symmetric image I ₂ ′ of the virtual image I ₂ with respect to the plane (Zu = 0) of the stainless steel mirror 205 is obtained, and the obtained symmetric image I ₂ ′ is combined with the normal image I _1. By doing so, an image of the foot 100 as shown in FIG. 15 is obtained.

Thus obtained, as shown in FIG.
The foot of the arch of the foot 100 is stainless steel.
Virtual image I reflected in Ra 205₂Generated based on
Image I ₂’The shape of the foot 100 is more faithfully supplemented by
The shape is reproduced.

As described above, according to the above embodiment, the stainless steel mirror 20 is formed on the normal image of the foot 100 as the object to be measured.
Since the images generated based on the virtual image reflected in FIG. 5 are combined, it is possible to supplement the image of the recessed portion such as the arch of the foot 100, and to generate an appropriate three-dimensional shape of the foot 100. It will be possible.

At this time, since the image (virtual image) of the recessed portion such as the arch of the foot 100 and the side surface (normal image) are simultaneously measured, an appropriate three-dimensional shape can be measured with a small number of measuring procedures. .

Further, according to the above-described embodiment, the luminous flux emitted from the slit light source 13 is transmitted to the stainless steel mirror 205.
Since the posture of the measurement head 10 is regulated so that the measurement head 10 is emitted along a surface perpendicular to, at the time of measurement,
The luminous flux emitted directly from the slit light source 13 to the foot 100 and the foot 1 after being reflected by the stainless steel mirror 205 once
00 and the luminous flux irradiated to 00 will overlap. As a result, the light flux reflected by the stainless steel mirror 205 does not generate an erroneous image, and it is possible to perform accurate measurement.

Further, according to the above embodiment, after the initialization in the first and second steps is completed, the stereo cameras 21 and 22 are detached from the measuring table 201 to measure the object to be measured. Therefore, the measuring device can be downsized.

Even if the trajectory of the guide rail 204 changes due to movement of the measuring device or the like, accuracy can be maintained by installing the stereo cameras 21 and 22 and updating the table data.

Although the measuring head 10 is manually moved by the measurer in the above-described embodiment, the measuring head 10 is automatically moved by using the motor.
You may make it move along 04. This makes it possible for the measurer to automatically measure the object to be measured without touching the measuring head 10.

[0127]

According to the present invention, by arranging the mirror on the measuring table, not only the real image of the object to be measured but also the virtual image reflected on the mirror can be used for the measurement, so that a small number of measurements can be performed. It becomes possible to generate a three-dimensional shape of the object to be measured by the procedure.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first configuration of a shape measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a schematic configuration of a measuring head in the shape measuring apparatus of FIG.

FIG. 3 is an explanatory diagram illustrating a measurement principle in the shape measuring apparatus of FIG.

FIG. 4 is a schematic diagram showing a world coordinate system and a mirror surface coordinate system.

FIG. 5 is a schematic diagram showing that the sole of a foot can be measured.

FIG. 6 is a schematic diagram showing that reflected light from a glass plate is extracted by a CCD camera.

FIG. 7 is a flowchart illustrating a processing procedure in a first step.

FIG. 8: CCD camera 12 acquired in the third step
The image of the slit light that intersects the surface of the glass plate 206 on the image of, and the image of the slit light that intersects the mirror surface of the stainless steel mirror 205 on the image of the CCD camera 12 acquired in the third step. It is a schematic diagram.

9 is an explanatory diagram illustrating a measurement method for measuring the position of a measurement point using the measurement head of FIG.

FIG. 10 is a schematic diagram for explaining a process of a fourth step.

FIG. 11 is a flowchart illustrating a processing procedure of a fourth step.

FIG. 12 is a flowchart illustrating a processing procedure of step 18 in FIG. 11.

FIG. 13 is a schematic diagram for explaining the process of step 18 of FIG.

FIG. 14 is an explanatory diagram showing an image of a foot obtained in a fourth step.

FIG. 15 is an explanatory diagram showing an image of a foot obtained in a fifth step.

[Explanation of symbols]

10 Measuring head 12 CCD camera 13 slit light source 14 markers 16 encoder 21 stereo camera 22 stereo camera 201 measuring table 204 Guide rail 205 stainless steel mirror 206 glass plate

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinpei Fukumoto 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) Reference JP 2001-338278 (JP, A) JP 2001 -204512 (JP, A) JP-A-11-101623 (JP, A) JP-A-10-38524 (JP, A) JP-A-9-14930 (JP, A) JP-A-8-189818 (JP, A) ) JP-A-5-60538 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11 /-11/30 102 A43D 1/02 A61B 5/103-5/117

Claims (7)

(57) [Claims] 1. An object to be measured, which comprises a mirror mounted on a measuring table, a transparent glass plate arranged in parallel with the mirror and above the mirror, a slit light irradiating means and an image sensor, and by a light cutting method. An object to be measured based on a measuring head for measuring a shape, a position detecting means for detecting the position of the measuring head, and an image picked up by an image sensor of the measuring head, and the position of the measuring head detected by the position detecting means. Of the normal image of the object to be measured by extracting slit light that appears above the surface of the plate glass on the image surface of the image sensor of the measuring head. The first means for obtaining the three-dimensional shape in the world coordinate system, the second means for obtaining the projected coordinates of the virtual image position by the mirror with respect to the lowest point of the normal image on the image pickup surface of the image pickup element, and the obtained projected coordinates are opened. As a point, the slit light corresponding to the virtual image of the object to be measured is traced upward in the image plane of the image sensor to obtain the three-dimensional shape of the virtual image of the object to be measured in the world coordinate system. The three-dimensional shape of the object to be measured is synthesized by combining the means and the three-dimensional shape symmetrical to the mirror surface of the mirror having the three-dimensional shape with respect to the virtual image of the object to be measured and the three-dimensional shape with respect to the normal image of the object to be measured. Fourth to seek
A shape measuring device comprising: 2. The third means is, when the slit light corresponding to the virtual image of the object to be measured is being tracked, and when another slit light intersects with the slit light being tracked, the upper left direction and the upper right direction. The shape measuring apparatus according to claim 1, further comprising: a unit that traces slit light that extends in a predetermined direction. 3. A third means is, when tracking slit light corresponding to a virtual image of an object to be measured, in a region where another slit light intersects with the slit light being traced, a predetermined distance before the intersection. Based on the position of the slit light corresponding to the virtual image of the DUT extracted on the horizontal line and the position of the slit light extracted a predetermined horizontal line ahead of it, the virtual image position between them is obtained by linear interpolation. , The position of the slit light corresponding to the virtual image of the object to be measured extracted on the predetermined horizontal line after the intersection, and the position of the slit light extracted a predetermined horizontal line before it, the virtual image between them The shape measuring apparatus according to claim 2, further comprising means for determining a position by linear interpolation. 4. The shape measuring device according to claim 1, wherein the position detecting means detects the position of the measuring head by a stereo method using two cameras. 5. A guide means for regulating the attitude of the measuring head is provided so that the luminous flux emitted from the slit light irradiating means of the measuring head is emitted perpendicularly to the light reflecting surface of the mirror. The shape measuring apparatus according to claim 1, 2, 3, or 4. 6. The shape measuring apparatus according to claim 5, wherein the guide means regulates a moving path of the measuring head. 7. The shape measuring apparatus according to claim 6, further comprising driving means for moving the measuring head along the guide means.