JP2016109580A - Measuring device and measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measuring device and a method for measurement that are favorable for suppressing decrease in measurement accuracy in measuring the shape of an object using a phase shift method as a pattern projection method.SOLUTION: The measuring device includes a projection system projecting a stripe pattern with a brightness varied like a sine wave onto an object, an imaging system imaging the object on which the stripe pattern has been projected, and a control unit calculating the shape of the object using the taken image. In S101, the projection system shifts the phases of the stripe pattern and conducts projection on an object and the imaging system takes an image of the object on which the stripe pattern has been projected. In S102 and 103, the control unit calculates the outline of the shape of the object or a reflectance distribution, using images of the object on which the stripe pattern has been projected and a preset phase shift amount. In S104, the control unit calculates the phase shift amount of each image, using the images and the calculated outline of the shape or the reflectance distribution. In S105, the control unit calculates the shape of the object, using the images and the calculated phase shift amounts.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a measuring device and a measuring method.

  Conventionally, a pattern projection method using a phase shift method is used as a method for measuring the three-dimensional shape of an object. In this pattern projection method, a fringe pattern whose brightness has changed sinusoidally by a projection system is projected onto an object three or more times with different phases, and a projection image scattered on the surface of the object by an imaging system is projected onto the projection optical axis of the projection system. Images are taken from different directions. Then, the phase of the fringe pattern changed according to the surface shape of the object is calculated from the luminance difference between the phase-shifted images, and the surface shape of the object is obtained based on the phase. In the phase shift method, three-dimensional coordinates corresponding to each point of the obtained image can be obtained by simple calculation processing, and measurement data of a high-density three-dimensional shape can be obtained by imaging at least three times. Measurement at a speed several to several tens of thousands times faster than other measurement methods becomes possible.

  Here, in order to guarantee the measurement accuracy by the phase shift method, it is necessary to project and acquire a plurality of sine wave patterns that are phase-shifted by a predetermined phase amount with high accuracy. However, in a liquid crystal projector generally used as a pattern projection system, a sine wave pattern may vibrate in time due to vibrations of an internal cooling fan. In this case, the phase shift amount given to each phase shift image may deviate from a desired value, and the phase detection accuracy may decrease. Therefore, Patent Document 1 calculates the phase of each phase-shifted image using the Fourier transform fringe analysis method, and calculates the phase shift amount from the difference phase between them, thereby causing a phase caused by PZT (piezo element). A method for reducing the effect of shift errors is disclosed.

JP 2002-162205 A

  Here, some objects to be measured by the pattern projection method include those having a complicated shape having large steps and inclinations, and those having a large reflectance distribution on the measurement surface. When the method assuming the phase shift interferometer disclosed in Patent Document 1 is applied to the measurement of the three-dimensional shape of such an object, the detection accuracy of the phase shift amount by the Fourier transform fringe analysis method is lowered, and finally There is also a possibility that the measurement accuracy of the three-dimensional shape obtained will be reduced.

  The present invention has been made in view of such a situation. For example, when measuring the shape of an object using a phase shift method as a pattern projection method, the measurement device is advantageous for suppressing a decrease in measurement accuracy. The purpose is to provide.

  In order to solve the above problems, the present invention is a measuring apparatus for measuring the shape of an object, the projection system for projecting a fringe pattern whose brightness changes in a sinusoidal shape onto the object, and the object on which the fringe pattern is projected. An imaging system for imaging, and a control unit that calculates the shape of the object using an image obtained by imaging with the imaging system, and the phase of the fringe pattern is shifted by the projection system, respectively. Are projected at least three times to capture an object on which the fringe pattern is projected each time with an imaging system, and the control unit captures each object on which the fringe pattern is projected with each imaging system. And the phase shift amount set in advance, the approximate shape or reflectance distribution of the object is calculated, and the phase shift of each image is calculated using each image and the calculated approximate shape or reflectance distribution. Calculate the amount, calculated with each image And calculating the shape of an object by using the phase shift amount.

  ADVANTAGE OF THE INVENTION According to this invention, when measuring the shape of an object using the phase shift method as a pattern projection method, for example, the measurement apparatus advantageous in suppressing the fall of a measurement precision can be provided.

It is a figure which shows the structure of the measuring device which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the measurement process in 1st Embodiment. It is a flowchart which shows the flow of the measurement process in 2nd Embodiment. It is a flowchart which shows the flow of the measurement process in 3rd Embodiment. It is a figure explaining the principle of triangulation.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(First embodiment)
First, the measurement apparatus and measurement method according to the first embodiment of the present invention will be described. The measurement apparatus (measurement method) according to the present embodiment employs a pattern projection method using a phase shift method to measure the three-dimensional shape of an object (measurement object). FIG. 1 is a schematic diagram illustrating a configuration of a measurement apparatus 10 according to the present embodiment. In FIG. 1, the X axis and the Y axis orthogonal to each other are taken in the plane in which the object 4 is placed, and the Z axis is taken perpendicular to the XY plane (in the vertical direction in the present embodiment). The measurement apparatus 10 includes a projection system 1, an imaging system 2, and a control unit 3.

  The pattern projection method uses the projection system 1 to project a fringe pattern whose brightness has changed in a sine wave shape onto the object 4 three or more times with different phases, and is scattered on the surface of the object 4 using the imaging system 2. This is a three-dimensional measurement method for capturing a projected image from a direction different from the projection optical axis of the projection system 1. Hereinafter, the sine wave pattern is referred to as a “sine wave pattern”. According to this measurement method, by calculating the phase of the sine wave pattern that changes according to the surface shape of the object 4 from the luminance difference between the phase-shifted images, the surface shape (three-dimensional) of the object 4 is calculated based on the phase. Shape) can be measured. Hereinafter, the phase of the sine wave pattern is shifted by the projection system 1 to project the sine wave pattern onto the object 4 at least three times, and the object 4 on which each sine wave pattern is projected is imaged by the imaging system 1. Each obtained image is referred to as a “phase shift image”.

  The projection system 1 projects a sine wave pattern onto the object 4 while sequentially shifting the phase by a predetermined angle. The projection system 1 includes, for example, a white light source, three liquid crystal panels that divide the light of the white light source into R, G, and B monochromatic light, and an optical path of R, G, and B monochromatic light that is dispersed by each liquid crystal panel. A liquid crystal projector including an optical system for matching the two.

  The imaging system 2 captures an image of the object 4 on which the sine wave pattern is projected. The imaging system 2 includes, for example, a CCD (imaging device) that employs a primary color filter, an optical system that forms an image of a subject on the imaging surface of the CCD, and R, G, This is a single-plate CCD camera including a signal processing circuit for obtaining image data for each B monochromatic light.

  The control unit 3 controls the operations of the projection system 1 and the imaging system 2 and executes image processing on the image captured by the imaging system 2. The control unit 3 is a computer including, for example, a CPU, a memory, a display, a storage device such as a hard disk, various input / output interfaces, and the like. In addition, the control unit 3 can execute the measurement method according to the present embodiment as a program (a three-dimensional shape measurement program). The control unit 3 and the projection system 1 are connected via a display interface such as DVI, for example, and the control unit 3 can control the operation of the projection system 1 (lighting on / off of the light source, light amount adjustment, etc.). . The imaging system 2 has a function of quantizing the pixel value (brightness) of each pixel and outputting it for each color of R, G, and B. The control unit 3 outputs R from the imaging system 2. , G, B digital signals can be taken in via the digital signal input interface. Furthermore, the control unit 3 can control the operation of the imaging system 2 (imaging timing, etc.) via a communication interface such as RS232C or IEEE488.

  Next, the measurement process (measurement method) in the measurement apparatus 10 will be described. FIG. 2 is a flowchart showing the flow of the measurement process in the present embodiment. When starting the measurement process, the controller 3 first acquires a phase shift image having a sine wave pattern (step S101). In the phase shift method in the present embodiment, the phase is calculated from four images (phase shift images) in which the phase is shifted by π / 2 (the phase shift amount is preset as π / 2). Shall be adopted. However, the phase shift method is not limited to the 4-bucket method because phase calculation is possible if at least three or more images are acquired at different phases. Here, the CPU in the control unit 3 reads the first sine wave pattern image (phase shift amount: 0 degree) stored in the storage device into the work area of the memory. The read image is transmitted to the projection system 1 via the display interface, and the projection system 1 projects the image onto the object 4. Next, the CPU transmits a command for capturing an image of the object 4 to the imaging system 2 via the communication interface. Upon receiving the command, the imaging system 2 captures an image of the object 4 and transmits it to the control unit 3. The CPU stores the transmitted image (phase shift image) in the work area of the memory. Thereby, the control part 3 acquired the phase shift image (A1) of the 1st sine wave pattern. Similarly to this procedure, the control unit 3 projects a sine wave pattern with phases shifted by π / 2, π, and 3π / 2, and outputs phase shift images (A2 to A4) of the second to fourth sine wave patterns. get.

Next, the control unit 3 calculates a schematic shape of the object 4 (step S102). Here, regarding the brightnesses I _{0 to} I ₃ at the same position P (x, y) on the four images A1 to A4 acquired in step S101, the absolute brightness is the surface shape or color at that position. It changes by etc. On the other hand, the relative brightness difference always shows a change by only the phase difference of the projected sine wave pattern. Therefore, the relative phase value φ _i (x, y) of the sine wave pattern at the position P (x, y) can be obtained from the equation (1).

Here, the relative phase value φ _i (x, y) is a value for each phase of the sine wave pattern, that is, between −π to π, as is apparent from the fact that Equation (1) is composed of an arctangent function. since that is the value, by performing phase unwrapping process (unwrapping), absolute phase value phi _a is calculated. Line obtained by connecting the points this absolute phase value phi _a are equal, since represents a cross-sectional shape taken along a plane which is the object 4 as with cut line in the light section method, based on the absolute phase value phi _a Thus, the three-dimensional shape of the object 4 can be calculated by the principle of triangulation.

FIG. 5 is a diagram for explaining the principle of triangulation. The absolute phase value φ _a of the sine wave pattern, that is, the position δ on the actual lattice A of the projection system 1 used for the projection of the fringe pattern, and the imaging point position P (x, y) on the imaging device B of the imaging system 2 Is in a relationship as shown in FIG. Therefore, on the object 4 corresponding to the point P (x, y) on the image, using the formula (2) representing the principle of triangulation based on the optical arrangement of the projection system 1 and the imaging system 2. If the three-dimensional coordinate value (X, Y, Z) of the projection point is obtained, the three-dimensional shape of the object 4 can be obtained.

  Note that the phase shift amounts of the images A2, A3, and A4 with respect to the image A1 may deviate from the desired values π / 2, π, and 3π / 2 due to the vibration of the projector. The resulting three-dimensional shape is undesirable in terms of accuracy.

Next, the control unit 3 calculates the reflectance distribution of the object 4 (step S103). The reflectance distribution of the object 4 corresponds to the distribution of the average intensity I _ave (x, y) of the sine wave pattern included in the equation (3).

However, γ (x, y) represents modulation of a sine wave pattern. From equation (3), I _ave (x, y) is expressed by equation (4) using the intensities I ₀ (x, y) to I ₃ (x, y) of each image.

  Next, the control unit 3 calculates the phase shift amount of each of the phase shift images A1 to A4 acquired in step S101 (step S104). In this step, the CPU in the control unit 3 firstly, the flatness of the schematic shape does not exceed a predetermined threshold for the schematic shape calculated in step S102 and the reflectance distribution calculated in step S103, and The measurement region (analysis region) in which the reflectance distribution does not exceed a predetermined threshold is determined. These threshold values are determined in advance according to the finally required three-dimensional measurement accuracy. Next, the CPU cuts out images of the determined measurement areas from the four phase shift images A1 to A4 acquired in step S101, and acquires four partial images A1 ′ to A4 ′. Next, the CPU calculates a phase for each of the cut out four partial images using a Fourier transform fringe analysis method.

  Here, the Fourier transform fringe analysis method will be outlined. The Fourier transform fringe analysis method is a method of introducing the carrier frequency (by the relative inclination between the surface of the object to be observed (corresponding to the object 4) and the reference plane) from one fringe image to the phase of the object to be observed. This is a method for obtaining. First, the interference fringe intensity when the carrier frequency is introduced is expressed by Expression (5) unless the initial phase of the object to be observed is considered.

However, a (x, y) is the background of the interference fringes, b (x, y) is stripes visibility, phi (x, y) is the phase of the object to be observed, _and, f x, _{f y} is , X and y direction carrier frequencies. Furthermore, equation (5) can be transformed as equation (6).

However, c (x, y) is the complex amplitude of the interference fringes and is expressed by Expression (7). C ^* (x, y) is a conjugate of c (x, y).

  Further, when Expression (6) is Fourier transformed, Expression (8) is obtained.

However, A (η, ξ) is the Fourier transform of a (x, y), C (η-f x, ξ-f y) and _{^{C * (η-f x,}} ξ-f y) and the , Respectively, are Fourier transforms of c (x, y) and c ^* (x, y).

Then, C by filtering from the equation _{(8) (η-f x} , ξ-f y) was removed, transferred to the spectral peaks located at the coordinate _(f x, _{f y)} the origin of the frequency coordinate system, the carrier Remove frequency. Next, c (x, y) is obtained by inverse Fourier transform, and the wrapped phase φ (x, y) is obtained by Equation (9). Finally, a phase connection process (unwrapping process) is performed to obtain the phase φ (x, y) of the object to be observed.

Based on the above description, the Fourier transform fringe analysis method is applied to the present embodiment. First, since the four partial images A1 ′ to A4 ′ are in a state where a spatial carrier is added, the intensities I ₀ (x, y) to I ₃ (x, y) of the partial images are expressed by the equation (6). ), It is represented by equation (10).

However, c _k (x, y) is expressed by Expression (11).

However, (delta) _k is the phase shift amount (k = 0-3) given to each image.

  Next, when Fourier transform is performed on the four partial images A1 ′ to A4 ′, a Fourier transform image represented by Expression (12) is obtained in the same manner as Expression (8).

Next, from the equation (12), as described above, finally, similarly to the equation (9), the relative phase value θ _k ⁱ (x) wrapped by −π to π represented by the equation (13) is expressed. , Y).

Next, an absolute phase value θ _k ^a (x, y) is obtained by performing phase connection processing on the relative phase value θ _k ⁱ (x, y) represented by Expression (13). Then, as shown in Expression (14), each of the second to fourth absolute phase values θ _k ^a (x, y) (where k = 1 to 3) and the first absolute phase value θ ₀ ^a From the difference from (x, y), the phase shift amount δ _k ^′ (where k = 1 to 3) for the first image is obtained.

  The phase shift amount of each image in each partial image, that is, the partial measurement region is calculated by the steps so far in step S104. Subsequently, the CPU calculates the phase shift amount of each image in the entire measurement region. Here, the phase shift amount error that may occur due to the vibration of the projector is caused by the piston component that is uniformly offset in the screen and the tilt component that has a primary tilt in the screen. Can be expressed. Therefore, the CPU calculates the piston component and the tilt component by performing plane fitting on the two-dimensional map of the phase shift amount obtained in the partial measurement region. Then, the CPU can calculate the phase shift amount of the entire measurement region by extending the piston component and the tilt component in the partial measurement region to the entire measurement region.

  Here, the Fourier transform fringe analysis method is used as a method for calculating the phase from one image. However, instead of the Fourier transform fringe analysis method, for example, a plurality of reference gratings having different phases are multiplied. Thus, an electronic moire method for calculating the phase may be used.

  Next, the control unit 3 calculates the three-dimensional shape of the object 4 using the phase shift amount calculated in step S104 (step S105). Here, the control unit 3 calculates the phase of the object 4 before calculating the three-dimensional shape of the object 4. If the phase of the object 4 is from four phase-shifted images that are phase-shifted by π / 2, it can be easily calculated by using Expression (1). However, the phase shift amount to be calculated in step S104 may actually not be accurately shifted by π / 2 due to the vibration of the projector. Therefore, in order to obtain the phase of the object 4 from the phase shift image to which an arbitrary phase shift amount is given, the control unit 3 executes phase calculation using the least square method as follows.

First, an image when an arbitrary phase shift amount δ _k (where k = 0 to 3) is given is expressed by Expression (15).

Here, c ₀ (x, y), c ₁ (x, y), and c ₂ (x, y) are respectively defined as in Expression (16).

  In this case, equation (15) can be transformed as equation (17).

Then, in order to obtain the phase φ (x, y), the CPU in the control unit 3 a ₀ (x, y), which minimizes the merit function M (x, y) shown in Expression (18). It is only necessary to calculate a ₁ (x, y) and a ₂ (x, y) and calculate φ (x, y) from a ₁ (x, y) and a ₂ (x, y).

Specifically, a ₀ (x, y), a ₁ (x, y), a ₂ (x, y) are calculated by solving the simultaneous equations shown in Expression (19).

Next, from the equation (20), φ (x, y) is calculated using a ₁ (x, y) and a ₂ (x, y).

  Finally, since the phase calculated above is a relative phase value wrapped by −π to π, the CPU performs a phase connection process in the same manner as the procedure described in step S102 to perform absolute phase. A value is calculated, and a three-dimensional shape is calculated using equation (2).

  As described above, in the pattern projection method using the phase shift method, the measurement apparatus 10 uses the schematic shape and reflectance distribution of the object 4 to extract a region where the schematic shape and the like are specifically uniform. The phase shift amount of each image is detected by performing a Fourier transform fringe analysis method or the like. As a result, even when the object 4 has a complicated shape having a large step or inclination, or the measurement surface has a large reflectance distribution, the influence of the phase shift error caused by the vibration of the projector or the like is reduced. Can be reduced. Therefore, the measuring device 10 can measure the three-dimensional shape of the object 4 with high accuracy.

  As described above, according to the present embodiment, it is possible to provide a measurement device and a measurement method that are advantageous in suppressing a decrease in measurement accuracy when measuring the shape of an object using the phase shift method as a pattern projection method. Can do.

(Second Embodiment)
Next, a measuring apparatus and a measuring method according to the second embodiment of the present invention will be described. A feature of the measurement device or the like according to the present embodiment is that the average intensity of the sine wave pattern, specifically, the average intensity of each pixel of the four phase shift images A1 to A4 acquired in step S101 in FIG. And a step of correcting the intensity so as to be uniform. FIG. 3 is a flowchart showing the flow of the measurement process in the present embodiment. The measurement process in the present embodiment is different from the measurement process in the first embodiment in that the following process is included between steps S103 and S104.

After step S203 (corresponding to step S103 in FIG. 2), the control unit 3 uses the reflectance distribution I _ave (x, y) of the object 4 calculated in step S203 to provide four phase shift images A1 to A4. Intensities I ₀ (x, y) to I ₃ (x, y) are corrected (step S204). Here, the corrected intensity I _k ^′ (x, y) is expressed by Expression (21).

Then, the control unit 3 uses the four phase shift images A1 ′ to A4 ′ obtained using the corrected intensities I ₀ ^′ (x, y) to I ₃ ^′ (x, y) calculated in step S204. Thus, the phase shift amount is calculated in the same manner as in step S104 in FIG. 2 (step S205). Henceforth, step S206 is the same as that of step S105.

  According to the present embodiment, by calculating and correcting the intensity unevenness of the image, it is possible to reduce the calculation error of the phase shift amount that may occur due to the reflectance distribution of the object 4. Compared with the embodiment, a decrease in measurement accuracy can be further suppressed.

(Third embodiment)
Next, a measuring apparatus and a measuring method according to the third embodiment of the present invention will be described. The feature of the measurement device and the like according to the present embodiment is that it includes a step of reacquiring four phase shift images after step S103 of the measurement step in the first embodiment shown in FIG. FIG. 4 is a flowchart showing the flow of the measurement process in the present embodiment. The measurement process in the present embodiment is different from the measurement process in the first embodiment in that the following process is included between steps S103 and S104.

After step S303 (corresponding to step S103 in FIG. 2), the control unit 3 acquires four phase shift images A1 ″ to A4 ″ (step S304). Here, the phase of the sine wave pattern adjusted so that the average intensity of each pixel of the four phase shift images A1 to A4 acquired in step S301 is uniform within the measurement region is shifted by π / 2. Then, it is projected onto the object 4 to obtain four phase shift images. Specifically, the CPU in the controller 3 reflects the reflectance distribution I of the object 4 calculated in step S303 for four sine wave patterns obtained by shifting the phase stored in the storage device by π / 2. Each of _ave (x, y) is divided to generate four new sine wave patterns. Then, similarly to the method described in step S101 in FIG. 2, the four newly generated sine wave patterns are projected onto the object 4, and the four phase shift images A1 ″ to A4 ″ are reacquired.

  Next, the control unit 3 calculates the phase shift amount of each of the phase shift images A1 ″ to A4 ″ reacquired in step S304 (step S305). A specific calculation method is the same as the method described in step S104 in FIG. Then, the control unit 3 calculates a three-dimensional shape using the phase shift amount calculated in step S305 (step S306). A specific calculation method is the same as the method described in step S105 in FIG.

  According to the present embodiment, by re-acquiring the phase shift image in which the intensity unevenness of the image is corrected, the calculation error of the phase shift amount that may occur due to the reflectance distribution of the object 4 is reduced. Therefore, a decrease in measurement accuracy can be further suppressed as compared with the first embodiment.

  In each of the above embodiments, it is assumed that the phase shift amount is detected by extracting a region where both the flatness of the rough shape and the reflectance distribution do not exceed a predetermined threshold. On the other hand, the present invention may extract a region where one of the flatness or reflectance distribution of the approximate shape does not exceed a predetermined threshold. Specifically, for example, either step S102 or S103 of the measurement process shown in FIG. 2 is omitted, and in step S104, one of the flatness or reflectance distribution of the approximate shape has a predetermined threshold value. It is good also as what calculates the phase shift amount by extracting the area | region which does not exceed. Even in this case, the calculation error of the phase shift amount that may be caused by one of the schematic shape of the object 4 or the reflectance distribution is reduced, and the phase shift amount can be detected with high accuracy.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 1 Projection system 2 Imaging system 3 Control part 10 Measuring apparatus

Claims (6)

A measuring device for measuring the shape of an object,
A projection system that projects a fringe pattern whose brightness changes in a sinusoidal shape onto the object;
An imaging system for imaging the object on which the fringe pattern is projected;
A control unit that calculates the shape of the object using an image obtained by imaging with the imaging system;
Have
The phase of the fringe pattern is shifted by the projection system to project the fringe pattern onto the object at least three times, and the object on which the fringe pattern is projected each time is imaged by the imaging system.
The controller is
The approximate shape or reflectance distribution of the object is calculated using each image obtained by imaging the object on which the fringe pattern is projected each time by the imaging system and a preset phase shift amount. And
Calculate the phase shift amount of each image using each image and the calculated schematic shape or reflectance distribution,
A measuring apparatus that calculates the shape of the object using each of the images and the calculated phase shift amount. The control unit calculates the schematic shape,
From each image obtained by imaging with the imaging system, extract a region where the flatness of the approximate shape does not exceed a threshold,
Calculate the phase of each image using a Fourier transform fringe analysis method or an electronic moire method in the extracted region,
Calculating the phase shift amount based on the calculated phase;
The measuring apparatus according to claim 1. The control unit calculates the reflectance distribution,
From each image obtained by imaging with the imaging system, extract a region where the reflectance distribution does not exceed a threshold,
Calculate the phase of each image using a Fourier transform fringe analysis method or an electronic moire method in the extracted region,
Calculating the phase shift amount based on the calculated phase;
The measuring apparatus according to claim 1. The control unit calculates the reflectance distribution,
Using the calculated reflectance distribution, correct the intensity of each image so that the average intensity of the fringe pattern is uniform within the measurement region,
Extracting the region from each of the corrected images;
The measuring apparatus according to claim 2 or 3, wherein The control unit calculates the reflectance distribution,
The projection system is configured to project the fringe pattern adjusted so that the average intensity of the fringe pattern is uniform in the measurement region using the reflectance distribution onto the object at three or more different phases. And re-acquiring each image in the imaging system,
Extracting the region from each re-acquired image;
The measuring apparatus according to claim 2 or 3, wherein A measurement method for measuring the shape of an object,
By projecting the fringe pattern whose brightness changes in a sine wave shape onto the object at least three times by shifting the phase of the fringe pattern, and imaging each object on which the fringe pattern is projected each time. Acquiring an image;
Calculating the approximate shape or reflectance distribution of the object using each acquired image and a preset phase shift amount; and
Calculating the phase shift amount of each image using each acquired image and the calculated schematic shape or reflectance distribution;
Calculating the shape of the object using each acquired image and the calculated phase shift amount; and
A measurement method comprising:

Images