JP3298992B2 - 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 device for measuring the shape of a thick object.

[0002]

2. Description of the Related Art Natural or man-made objects are generally three-dimensional.
It has a dimensional contour shape and a fine surface shape. In order to measure each of these shapes, non-contact and high-precision measuring devices have been prototyped and developed. The following devices are currently reported or put into practical use. First, as a device for measuring a fine surface shape, a device using a high-resolution camera equipped with a lens that is sufficiently stopped down so as to increase the depth of field is generally used. Further, as a device for measuring a three-dimensional contour shape, a scanning type measuring device which scans the surface of a measurement object using optical scanning means and detects reflected light is used.

[0003]

Since the conventional shape measurement is performed as described above, there are the following problems.

In the method using a high-resolution measurement camera, the selection of the lens and the measurement camera requires great care.
In other words, there is a problem that a lens capable of forming a clear image of the measurement target portion in practical use and a high-resolution measurement camera capable of capturing an image with a sufficient SN ratio even with the stop must be combined. In practice, it is extremely difficult to satisfy such a combination when using a high-power microscope lens or the like even if a normal standard lens is used. Further, this method can obtain minute surface information of the object to be measured, but has a problem that it is almost impossible to measure the position in the observation direction.

In the method using optical scanning, position measurement in the observation direction is possible in principle, but it is necessary to perform accurate scanning with a sufficiently narrowed light beam in order to improve measurement accuracy. Therefore, there has been a problem that the structure of the device must be made rigid, and the device is necessarily large and complicated. Also, when performing position measurement in one direction, it is necessary to scan the entire measurement object in three dimensions for accurate measurement, taking into account the irradiation direction of the scanning light beam and the direction of the measurement surface. Becomes
There was a problem that a huge measurement time was required.

The present invention has been made in view of the above situation, and provides a shape measuring apparatus capable of easily and accurately measuring fine surface information of a measurement object or the outer shape of the measurement object. The purpose is to do.

[0007]

According to the shape measuring apparatus of the present invention, when a surface having a weak contrast is imaged, a differential value relating to the position of the luminance of the image when the focal length coincides with the focal length set at the time of imaging is obtained. A phenomenon in which the absolute value of (hereinafter, simply referred to as a differential value of an image) becomes maximum is used. In the first shape measuring apparatus of the present invention, imaging is performed at various focal lengths while maintaining a fixed viewing direction, and differential value data in which the absolute value of the differential value is maximum for each pixel in these captured images is obtained. The surface shape information is obtained by adopting the data as the data of each pixel. Further, in the second shape measuring device of the present invention, in addition to the first shape measuring device, the focal length at which the absolute value of the differential value is maximum for each pixel is adopted as the distance from the imaging plane in the imaging means. By doing so, surface shape information and three-dimensional contour shape information are obtained.

That is, the first shape measuring apparatus according to the present invention comprises: (a) an image pickup means capable of setting a focal length at the time of image pickup;
(B) differentiating means for differentiating the video signal output from the imaging means for each pixel; (c) digitizing means for converting the differential video signal for each pixel output from the differentiating means into digital data; Image data storage means having a capacity for recording at least one frame of digital differential video signal data for each pixel output from the digitizing means;
(E) comparing the absolute value of the digital differential video signal data for each pixel output from the digitizing means with the absolute value of the corresponding pixel data recorded in the image data storage means, and determining a larger value as the absolute value; A data comparing / updating means for recording the stored data at a corresponding pixel position in the image data storing means; and (f) a display for converting the data stored in the image data storing means into a video signal as image data and displaying an image. And means.

Further, the second shape measuring device of the present invention comprises:
(A) imaging means capable of setting a focal length during imaging,
(B) a focal length data storage unit having a capacity for recording at least one frame of focal length data at the time of imaging by the imaging unit for each pixel; and (c) a differentiation for differentiating a video signal output from the imaging unit for each pixel. Means, (d) digitizing means for converting a differential video signal for each pixel output from the differentiating means into digital data, and (e) digital differential video signal data for each pixel output from the digitizing means, Image data storing means for recording one frame, (f) absolute value of digital differential video signal data for each pixel output from the digitizing means, and absolute value of corresponding pixel data recorded in the image data storing means. And update and record the data having the larger value as the absolute value in the corresponding pixel position of the image data storage means, And data comparing updating means for recording the focal distance data at the time of imaging of the frame containing the data to be newly recorded in the corresponding pixel position of the focal distance data storage means,
(G) display means for displaying an image using the data stored in the image data storage means as image data.

Here, the focal length data storage means is a part of the storage area of one frame memory device, and the image data storage means is a portion of the storage area of the frame memory device excluding the focal length data storage area. It may be characterized. Further, the image display means displays the luminance by reflecting the data stored in the image data storage means, and displays the color by reflecting the data stored in the focal length data storage means.
It may be characterized.

[0011]

The first shape measuring apparatus according to the present invention measures the surface shape of the measured object as follows. Prior to the start of measurement, all data for each pixel, which is the content of the image data storage means, is initialized to "0 (digital value)". After this preparation work is completed, the imaging by the imaging means is started.

First, the focal length of the imaging means is set to an initial value, and the field of view is set to the measurement direction to perform imaging. An analog video signal is output from the imaging means by the imaging action and input to the differentiating means. The differentiating means differentiates the input video signal that changes continuously with time with respect to time, and outputs a differential video signal as a result of the differentiation. This differential signal is input to the digitizing means, digitized at each time corresponding to the pixel, and sequentially output as digital differential image signal data for each pixel.

The thus obtained digital differential image signal data for each pixel is input to the data comparing and updating means. The data comparing / updating unit simultaneously receives the stored data at the position corresponding to the pixel of the digital differential image signal data input from the data storage unit, and compares the absolute values of the respective values. The data comparing / updating unit updates the data by recording the data value determined to be larger as a result of the comparison at a position corresponding to the pixel in the data storage unit.

The operations from the analog differential operation to the data update are performed for all pixels of the captured image.

Subsequently, while changing the value of the focal length of the imaging means, the contents of the data storage means are sequentially updated for all the pixels of the captured image for each focal length,
The surface shape of the measured object is measured.

The contents recorded in the data storage means, which are the measurement results of the surface shape thus obtained, are processed as image data, displayed by the display means, and directed to the user of the apparatus. This display result is not the captured image itself, but is composed of the absolute value of the position differential value when each pixel is focused on the surface of the measured object, and is an image that reflects a subtle change in the surface shape Becomes

The second shape measuring apparatus of the present invention simultaneously measures the three-dimensional contour shape of the measured object in addition to the surface shape of the measured object. Regarding the surface shape of the object to be measured,
The measurement is performed in the same manner as in the shape measuring device. This device measures the three-dimensional contour shape of the visible surface from the imaging direction of the measured object at the same time as the measurement of the surface shape as follows.

The focal length value set for imaging is always notified to the focal length data storage means as focal length value data during measurement. The comparison updating means, when updating the contents of the image data storage means in the measurement of the surface shape, simultaneously issues a content update instruction to the focal length data storage means. When this update instruction is received, the focal length data storage means updates the content of the storage position corresponding to the pixel to the notified focal length value data. By performing this update operation together with the surface shape measurement operation,
The distance of each pixel from the imaging plane in the imaging means is recorded in the focal length data storage means.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

(First Embodiment) The apparatus of this embodiment belongs to the first shape measuring apparatus of the present invention, and has a surface shape (such as fine irregularities) in a visible region in the measurement direction of the measured object. Is a device for measuring, emphasizing, and displaying.

FIG. 1 is a schematic block diagram of the apparatus of the present invention. As shown in the figure, this apparatus can set an arbitrary focal length, and inputs an image pickup unit 100 that changes the focal length to image the measurement object 900 and a video signal output from the image pickup unit 100. A data processing unit that extracts and records the differential value of the video signal when the image is focused at the time of imaging for each pixel, and outputs a basic timing signal of an imaging operation and a focal length setting information signal to the imaging unit 100 200, and a display unit 500 for displaying an image based on the data for each pixel recorded by the data processing unit 200.

FIG. 2 is a block diagram of the apparatus, including the internal configurations of the image pickup unit 100, the data processing unit, and the display unit.

As shown in FIG. 2, the imaging unit 100 includes a high-precision camera 110 that captures an image of the measurement object 900 and outputs a video signal, and an electric focus lens 120 that adjusts the focus to a designated focal length. Be composed.

The data processing section 200 receives a signal output from the imaging section 100, performs a differential operation to output a differential video signal, and inputs the differential video signal, and performs analog-to-digital conversion (hereinafter referred to as analog-to-digital conversion). , AD conversion)
A / D conversion circuit 220 that outputs digital differentiated video signal data by applying digital differential video signal data, and has a capacity to store digital differentiated video signal data for one frame. After comparing the absolute value of the digital differential video signal data for the pixel immediately after the imaging with the absolute value of the digital differential video signal data already recorded for the pixel read out from the frame memory 230, If the absolute value of the digital differential video signal data relating to the immediately succeeding pixel is larger, the comparison update instructing the frame memory 230 to write the digital differential video signal data relating to the pixel immediately after imaging at the recording position for the pixel. The circuit 240 generates a focal length at the time of imaging and notifies the imaging unit 100 of the focal length. A focal plane position setting circuit 250, an address generating circuit 260 specifies an address corresponding to the pixel position relative to the frame memory 230, a timing generating circuit 270 for generating an operation timing of the apparatus,
And a control circuit 280 for controlling the entire apparatus and processing collected data.

Here, the differentiating circuit 210 converts the impedance of the signal output from the imaging unit 100 and outputs the impedance, the differentiator 212 that differentiates the signal output from the impedance converter 211,
And an impedance converter 212 that converts the impedance of the signal output from the differentiator 212 and outputs the converted signal.

The AD conversion circuit 220 includes a differentiating circuit 2
A sample-and-hold unit 2 that receives the differential video signal output from the input device 10 and holds the amplitude of the differential video signal in synchronization with the pixel timing output from the timing generation circuit 270
21 and an AD converter 222 for AD-converting the output signal of the sample-and-hold unit 221 in synchronization with the pixel timing output from the timing generation circuit 270. In this apparatus, an AD converter having a digitization bit number of 8 bits and an output digital data code of a COB (Complementary Offset Binary) code is used.

In the frame memory 230, one pixel corresponds to one address, and stores eight bits of data per address. Note that the frame memory 230 of the present apparatus
Can initialize all areas (set all data to "0 (7F ₍₁₆₎ )" ₎ by an initialization instruction from the outside, and output a display video signal for output to the display unit 500. Has a port.

The comparing / updating circuit 240 receives the data output from the AD converter 222 and converts it into an absolute value, and the data read out from the frame memory and converts the data into an absolute value. If the absolute value of the data output from the AD converter 222 is larger than the absolute value of the absolute value
And a comparator 245 that outputs a write instruction signal to 0. Note that the absolute value converters 241 and 242 of the present apparatus
Outputs the absolute value data by performing a logical operation on the other bits after judging positive or negative according to the value of the upper-order bit in accordance with the COB code data output from the AD converter 222.

The display section 500 includes an image display device 510 for inputting a display video signal output from the frame memory 230 and displaying an image, and an image printing device 520 for printing the image.

Hereinafter, the measurement of the surface shape of the object to be measured by the present apparatus will be described with reference to the timing chart of the measurement operation shown in FIG. In FIG. 3, pixels are 3 × 3 for simplicity.
The case of an array is shown. Further, the timing chart for each signal name in FIG. 3 shows a temporal change of the signal given the same signal name in FIG.

First, at the start of measurement, the control circuit 28
0 issues an initialization signal (IR signal). The IR signal is
Frame memory 230 and focal plane position setting circuit 260
Will be notified. Upon receiving the IR signal, the frame memory 230 sets the memory contents to "0" over the entire area. When the focusing plane position setting circuit 260 receives the IR signal,
The focal length of imaging is set to an initial value, and this value is notified to the electric focus lens 120. The motorized lens focus 120 adjusts the lens position so as to have a designated focal length. In this manner, the initial setting of the measurement is completed, and in this initial setting state, the high-resolution camera 110 performs imaging, and sequentially outputs a video signal (OVS signal) as an output signal of the imaging unit 100 for each imaging pixel.

The OVS signal output from the imaging unit 100 is input to a differentiating circuit 210 of the data processing unit 200.
In the differentiating circuit 210, the video signal is differentiated by the differentiator 212 after passing through the impedance converter 211, and the differentiated video signal (DV) is further passed through the impedance converter 211.
S signal) is output to the AD conversion circuit 220. In the AD conversion circuit 220, the sample hold unit 221 samples the input DVS signal in accordance with the pixel timing 1 (OS1 signal) generated by the timing generation circuit 270, and holds the signal amplitude value (DVS * signal) at that time. The held output value of the sample hold unit 221 is input to the AD converter 222, AD-converted in synchronization with the pixel timing 2 (OS2 signal) generated by the timing generation circuit 270, and converted into 8-bit digital data (DDC signal). It is output to the frame memory 230 and the comparison / update circuit 240.

In parallel with the above-described differential operation, the address generation circuit 260 is operated by the A / D converter 22 for each pixel.
The address value for reading and writing of the frame memory 230 is updated in synchronization with the pulse end of the conversion completion signal (EOC signal) of No. 2. This address generating circuit 260
The data (MDC signal) read from the frame memory 230 is output to the comparison / update circuit 240 in accordance with the address specified by (1). That is, the AD converter 22
2 completes the AD conversion, the comparison / update circuit 2
40, two types of data (DDC signal and MDC signal)
Signal), the respective pixels match.

In the comparing / updating circuit 240, the DDC signal is converted into an absolute value through the absolute value converter 241 and output to the comparator 245. The MDC signal is output to the absolute value converter 24.
2 and is output to the comparator 245 as an absolute value. The comparator 245 compares the absolute value of the input DDC signal with the absolute value of the MDC signal. If the absolute value of the DDC signal is larger, the comparator 245 writes the absolute value of the DDC signal to the frame memory 230 in synchronization with the EOC signal. Instruction signal (WRITE
Signal). When a write instruction is received by this WRITE signal, the data content of the position indicating the storage position of the data relating to the comparison pixel in the frame memory 230 is changed to DDC.
Updated to signal value.

The operation for each pixel from the above differential operation to comparison / update is continued for one frame by following the input speed of the OVS signal from the imaging unit.

The vertical synchronization signal (V) generated by the timing generation circuit 270 when the imaging time for one frame has elapsed.
D signal) in synchronization with the front end of the pulse.
The focal length data of 0 is updated and the electric focus lens 12 is updated.
At the same time, the address generation circuit 260 is initialized. Next, the contents of the frame memory 230 are updated from the imaging with the updated focal length. The updating of the focal length and the updating of the contents of the frame memory 230 from the imaging are repeated, and finally the differential video signal value at the time of focus for each pixel reflecting the surface shape of the measured object is stored in the frame memory. Record at 230.

The image reflecting the surface shape of the measured object visible in the measurement direction recorded in this way is output from the image signal output terminal of the frame memory 230 to the display section 500 as a video signal reflecting the data value to the luminance value. You. The display unit 500 receives a video signal and receives the image signal.
0 or output to the image printing device 520.

(Second Embodiment) The apparatus of the present embodiment belongs to the second shape measuring apparatus of the present invention, and has a surface shape (fine irregularities, etc.) in a visible region in the measurement direction of the measured object. And a device for measuring and displaying the contour shape of a visible region in the measurement direction of the measured object.

FIG. 3 is a schematic block diagram of the apparatus of the present invention. This device is different from the first embodiment in that the data processing unit 30
0 has a different internal configuration. That is, the present apparatus can set an arbitrary focal length, and changes the focal length to capture an image of the measurement object 900, and inputs a video signal output from the Extracts and records the differential value of the video signal when the image is focused at the time of imaging, records focal length data when the image is focused at the time of imaging for each pixel, and transmits the basic data of the imaging operation to the imaging unit 100. A data processing unit 300 that outputs a timing signal and a focal length setting information signal; a display unit 500 that displays an image based on data for each pixel recorded by the data processing unit 300;
Consists of

FIG. 5 is a block diagram of this apparatus. The image pickup unit 100, the data processing unit 300, and the display unit 50
FIG. 2 is a diagram including the internal configuration of the imaging unit 100 and the imaging unit 100 and the display unit 500 are configured in the same manner as in the first embodiment.

The data processing unit 300 is different from the data processing unit of the first embodiment except that the number of data bits per address of the frame memory, the data input signal to the frame memory, and the output video signal from the frame memory are different. 2
It has the same configuration as 00. That is, the data area of the frame memory 330 of the present embodiment is the image data area 331.
And a focal length data area 332. The use of the data area divided into two parts covers all addresses, and the writing of the input DDS signal value is performed in the image data area 33.
1, writing of the focal length data (FSC signal) value output from the focal plane position setting circuit 250 is performed in the focal length data area 332. Writing to both of these areas is performed simultaneously with the address notified by the address generation circuit 260 according to the write instruction notified from the comparison / update circuit 240. Also, the frame memory 33
A value of 0 reflects the image data value of each pixel as a luminance value and the focal length data value as a color when outputting a video signal to the display unit 500.

520.

Hereinafter, the measurement of the surface shape and the contour shape of the object to be measured by the present apparatus will be described with reference to the timing chart of the measuring operation shown in FIG. FIG. 6 shows a case where pixels are arranged in a 3 × 3 array for simplicity. Further, the timing chart for each signal name in FIG. 6 shows a temporal change of the signal given the same signal name in FIG.

First, at the start of measurement, the control circuit 28
0 issues an initialization signal (IR signal). The IR signal is
Frame memory 330 and focal plane position setting circuit 260
Will be notified. Upon receiving the IR signal, the frame memory 330 sets the memory contents to "0" over the entire area. When the focusing plane position setting circuit 260 receives the IR signal,
The focal length of imaging is set to an initial value, and this value is notified to the electric focus lens 120 and the frame memory 330. The motorized lens focus 120 adjusts the lens position so as to have a designated focal length. In this manner, the initial setting of the measurement is completed, and in this initial setting state, the high-resolution camera 110 performs imaging, and sequentially outputs a video signal (OVS signal) as an output signal of the imaging unit 100 for each imaging pixel.

The OVS signal output from the imaging unit 100 is input to a differentiating circuit 210 of the data processing unit 200.
In the differentiating circuit 210, the video signal is differentiated by the differentiator 212 after passing through the impedance converter 211, and the differentiated video signal (DV) is further passed through the impedance converter 211.
S signal) is output to the AD conversion circuit 220. In the AD conversion circuit 220, the sample hold unit 221 samples the input DVS signal in accordance with the pixel timing 1 (OS1 signal) generated by the timing generation circuit 270, and holds the signal amplitude value (DVS * signal) at that time. The held output value of the sample hold unit 221 is input to the AD converter 222, AD-converted in synchronization with the pixel timing 2 (OS2 signal) generated by the timing generation circuit 270, and converted into 8-bit digital data (DDC signal). The data is output to the frame memory 330 and the comparison / update circuit 240.

In parallel with the above-described differential operation, the address generation circuit 260 is operated by the A / D converter 22 for each pixel.
The address value for reading and writing of the frame memory 330 is updated in synchronization with the end of the pulse of the conversion completion signal (EOC signal) of No. 2. This address generating circuit 260
The data (MDC signal) read from the frame memory 330 is output to the comparison / update circuit 240 in accordance with the address specified by. That is, the AD converter 22
2 completes the AD conversion, the comparison / update circuit 2
40, two types of data (DDC signal and MDC signal)
Signal), the respective pixels match.

In the comparing / updating circuit 240, the DDC signal is converted into an absolute value through the absolute value converter 241 and output to the comparator 245, and the MDC signal is output to the absolute value converter 24.
2 and is output to the comparator 245 as an absolute value. The comparator 245 compares the absolute value of the input DDC signal with the absolute value of the MDC signal. If the absolute value of the DDC signal is larger, the comparator 245 writes the absolute value of the DDC signal to the frame memory 330 in synchronization with the EOC signal. Instruction signal (WRITE
Signal). When the write instruction is received by the WRITE signal, the data content of the position indicating the storage position of the data relating to the comparison pixel in the image data area 331 is DD.
The value is updated to the value of the C signal, and in the focal length data area 332, the data content at the position indicating the storage position of the data regarding the comparison pixel is updated to the value of the FSC signal.

The operation for each pixel from the above differential operation to comparison / update is continued for one frame by following the input speed of the OVS signal from the imaging unit.

The vertical synchronizing signal (V) generated by the timing generation circuit 270 when the imaging time for one frame has elapsed.
D signal) in synchronization with the front end of the pulse.
The focal length data of 0 is updated and the electric focus lens 12 is updated.
At the same time, the address generation circuit 260 is initialized. Next, the contents of the frame memory 330 are updated from the imaging with the updated focal length. This updating of the focal length and the updating of the contents of the frame memory 330 from the imaging are repeated, and finally the differential video signal value and the focal length when each pixel is focused, reflecting the surface shape of the measured object, are reflected. The data is recorded in the frame memory 330.

The recorded image reflecting the surface shape and contour shape of the measured object visible in the measurement direction reflects the image data value from the image signal output terminal of the frame memory 330 to the luminance value and the focal length data. The value is output to the image display unit 500 as a video signal reflecting the color. The image display unit 500 receives a video signal and receives an image signal.
Output to

The present invention is not limited to the above embodiment, and various modifications are possible.

For example, if the field of view of the imaging unit is not sufficient due to the relationship between the size of the measurement object and the distance from the imaging unit to the measurement object, the imaging unit is moved on the same plane perpendicular to the measurement direction. Imaging may be performed. Further, the display of the contour shape in the second embodiment may be a graph display other than the color display.

[0053]

As described above in detail, according to the first shape measuring apparatus of the present invention, the differential video signal at the point of time when there is a focus where the differential value of the video signal of the imaging result is maximum for each pixel Since the values are collected and displayed, the surface shape can be measured quickly and easily, and the subtle contrast derived from the minute unevenness on the surface can be emphasized and displayed.

Further, according to the second shape measuring apparatus of the present invention, the differential video signal value and the focal length value at the point of time when there is a focus where the differential value of the video signal of the imaging result becomes the maximum for each pixel are collected. The surface shape and the contour shape can be measured quickly and easily, so that the display can be displayed with emphasizing the delicate contrast derived from the minute irregularities on the surface and the three-dimensional contour shape can be displayed.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a shape measuring device according to a first embodiment of the present invention.

FIG. 3 is a timing chart of the operation of the shape measuring apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a shape measuring apparatus according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a shape measuring apparatus according to a second embodiment of the present invention.

FIG. 6 is a timing chart of the operation of the shape measuring apparatus according to the second embodiment of the present invention.

[Explanation of symbols]

100: imaging unit, 110: high-resolution camera, 120: electric focus lens, 200, 300: data processing unit
210: Differentiating circuit, 211, 213: Impedance matching device, 212: Differentiator, 220: AD conversion circuit, 221
... Sample hold device, 222 ... AD converter, 230,
330 ... frame memory, 331 ... image data area, 3
32: focal length value data area; 240: comparison / update circuit;
241, 242: absolute value converter, 245: comparator, 250
... Focusing surface position setting circuit, 260.
70: timing generation circuit, 280: control circuit, 500
... Display unit, 510 ... Image display device, 520 ... Image printing device

Continuation of the front page (56) References JP-A-2-162469 (JP, A) JP-A-62-279931 (JP, A) JP-A-62-1006 (JP, A) JP-A-61-120002 (JP) JP-A-5-175312 (JP, A) JP-A-5-60528 (JP, A) JP-A-3-63507 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) G01B 11/00-11/30 G06T 1/00

Claims (4)

(57) [Claims] 1. An image pickup device capable of setting a focal length at the time of image pickup, a differentiator for differentiating a video signal output from the imager for each pixel, and a differential video signal for each pixel output from the differentiator To digital data, image data storage means having a capacity to record at least one frame of digital differential video signal data for each pixel output from the digitizing means, and output from the digitizing means. The absolute value of the digital differential video signal data for each pixel is compared with the absolute value of the corresponding pixel data recorded in the image data storage means, and the data having a larger absolute value is compared with the image. A data comparing / updating unit that records data at a corresponding pixel position of the data storage unit; It was converted into a video signal as over data, shape measurement apparatus characterized in that it is configured to include a display means for displaying an image, a. 2. An image pickup means capable of setting a focal length at the time of image pickup, a focal distance data storage means having a capacity for recording at least one frame of focal length data at the time of image pickup by the image pickup means, and A differentiating means for differentiating a video signal output from the means for each pixel; a digitizing means for converting a differential video signal for each pixel output from the differentiating means into digital data; and a pixel output from the digitizing means. Image data storage means for recording at least one frame of digital differential video signal data for each pixel, and the absolute value of digital differential video signal data for each pixel output from the digitizing means and the image data storage means The corresponding pixel data is compared with the absolute value of the corresponding pixel data. Data comparing and updating means for updating and recording at a corresponding pixel position of the data storage means, and recording focal length data at the time of imaging of a frame including the data to be updated and recorded at a corresponding pixel position of the focal length data storing means, A display unit configured to convert the data stored in the image data storage unit and the data stored in the focal length data storage unit into a video signal as image data and display an image. A shape measuring device characterized by the above-mentioned. 3. The storage device of claim 1, wherein the focal length data storage means is a part of a storage area of one frame memory device, and the image data storage means is a portion of the storage area of the frame memory device excluding a focal length data storage area. 3. The shape measuring apparatus according to claim 2, wherein: 4. The image display means displays brightness by reflecting data stored in the image data storage means, and displays color by reflecting data stored in the focal length data storage means. The shape measuring device according to claim 2 or 3, wherein