JP6194226B2 - Three-dimensional measuring apparatus and three-dimensional measuring method - Google Patents

Description

  The present invention relates to a three-dimensional measuring apparatus and a three-dimensional measuring method.

  Conventionally, in various manufacturing industries, contact-type three-dimensional measuring apparatuses capable of measuring dimensions and three-dimensional shapes of machine parts and the like have been put into practical use (for example, see Patent Document 1). Such a three-dimensional measuring apparatus not only inspects the final product, but also enables feedback of inspection results during production to the design process and manufacturing process, and plays an important role in improving the efficiency of the product development cycle. It is also widely used in production lines in the machine industry field.

JP 2013-15464 A

  By the way, the conventional contact-type three-dimensional measuring apparatus detects a three-dimensional coordinate value of each contact point by bringing a measuring probe into contact with a plurality of positions of the measuring object. At this time, the apparatus itself gives an overview of the measuring object. Since the shape cannot be recognized, an advance setting by the operator is required. That is, first, as illustrated in FIG. 6, in order to grasp the general shape of the measurement object O, that is, the measurement range, the operator operates the controller or the like while viewing the actual measurement object O and the probe P, A plurality of temporary measurement points M are set by moving the probe P to the vicinity of the measurement object O. At this time, since the probe P may collide with the measuring object O when the probe P is moved from a temporary measurement point M to the next temporary measurement point M on the shortest distance, that is, in a straight line, the temporary measurement point M The escape route F is set every time. Information on the temporary measurement point M and the escape path F is sequentially input to a control computer or the like, and a measurement program is created. Thereafter, the three-dimensional measuring apparatus automatically moves the probe P according to the measurement program to perform the main measurement.

  However, in order to perform such a temporary setting operation without damaging the measurement object O and the probe P, and further to set the escape path F to a wasteful one, an operator skilled in the operation is required. Of course, there is a problem that the working efficiency decreases as the number of measurement points increases.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a three-dimensional measuring apparatus and the like that can significantly improve the working efficiency when measuring the three-dimensional shape of a measurement object. .

  In order to achieve the above object, a three-dimensional measurement apparatus according to the present invention includes an image acquisition unit that acquires an X-ray CT image of a measurement target on a three-dimensional coordinate axis, and an X-ray of the measurement target acquired by the image acquisition unit. Image display means for displaying the CT image together with the virtual probe, operation means for operating the virtual probe, actual measurement means for actually measuring the three-dimensional shape of the measurement object on the three-dimensional coordinate axis with the probe linked to the movement of the virtual probe, The three-dimensional coordinate axis used in the image acquisition means and the three-dimensional coordinate axis used in the actual measurement means are common.

  In the three-dimensional measurement apparatus according to the present invention, the operation means can include a measurement point setting means for setting a measurement point of the measurement object. As the measurement point setting means, one that sets a measurement point based on an operation of an input unit by an operator or one that calculates a measurement point based on an X-ray CT image can be adopted.

  In the three-dimensional measurement apparatus according to the present invention, the operation means detects interference between the virtual probe and the X-ray CT image when moving the virtual probe from one measurement point set by the measurement point setting means to another measurement point. It is possible to have escape route setting means for setting an escape route to avoid. As the escape route setting means, one that sets the escape route based on the operation of the input unit by the operator or one that calculates the escape route based on the X-ray CT image can be adopted.

  In the three-dimensional measuring apparatus according to the present invention, the operation means can include manual operation means for moving the virtual probe based on the operation of the input unit by the operator.

  In the three-dimensional measuring apparatus according to the present invention, the operation means may include automatic operation means for automatically moving the virtual probe so as to assist the operation of the operator. Automatic operation means include those that automatically bring the virtual probe closer to the edge of the X-ray CT image, those that automatically move the virtual probe along the edge of the X-ray CT image, and virtual that are set at the set measurement points. A probe that automatically moves the probe can be employed.

  The present invention also provides an image acquisition process for acquiring an X-ray CT image of a measurement object on a three-dimensional coordinate axis, and an image display process for displaying the X-ray CT image of the measurement object acquired in the image acquisition process together with a virtual probe. And an operation step of operating the virtual probe, and an actual measurement step of actually measuring the three-dimensional shape of the measurement object on the three-dimensional coordinate axis by the probe interlocking with the movement of the virtual probe, and the tertiary used in the image acquisition step Provided is a three-dimensional measurement method in which an original coordinate axis and a three-dimensional coordinate axis used in an actual measurement process are common.

  Still further, the present invention provides an image display step for displaying an X-ray CT image of a measurement object acquired on a three-dimensional coordinate axis together with a virtual probe on a computer, an operation step for operating the virtual probe, and a movement of the virtual probe. An actual measurement step of actually measuring the three-dimensional shape of the measurement object on the three-dimensional coordinate axis by an associated probe, and executing the three-dimensional coordinate axis used in the image acquisition step and the three-dimensional coordinate axis used in the measurement step. A common 3D measurement program is also provided.

It is a block diagram for demonstrating the functional structure of the three-dimensional measuring apparatus which concerns on this embodiment. It is a side view of the three-dimensional measuring apparatus which concerns on this embodiment. It is a top view of the three-dimensional measuring apparatus which concerns on this embodiment. It is a figure which shows the X-ray CT image and virtual probe of a measuring object as an example displayed on the display screen of the three-dimensional measuring apparatus which concerns on this embodiment. It is a flowchart for demonstrating the three-dimensional measuring method which concerns on this embodiment. It is explanatory drawing for demonstrating the procedure of the measurement using the conventional contact-type three-dimensional measuring apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, the configuration of the three-dimensional measuring apparatus 1 according to the present embodiment will be described with reference to FIGS. The three-dimensional measuring apparatus 1 measures a three-dimensional shape of the measurement object O, and acquires an X-ray CT image of the measurement object O on a predetermined three-dimensional coordinate axis as shown in FIGS. an image acquisition unit 10 to an image display unit 20 for displaying the X-ray CT image of the measuring object O obtained by the image obtaining unit 10 with the virtual probe P _V, and operating means 30 for operating the virtual probe P _V, tertiary And an actual measurement means 40 for actually measuring the three-dimensional shape of the measuring object O on the original coordinate axis.

  The image acquisition means 10 irradiates the measurement object O with X-rays and detects projection data for each rotation angle of the measurement object O, whereby the X-ray CT of the measurement object O on a predetermined three-dimensional coordinate axis. Get an image. For this purpose, the image acquisition means 10 includes, for example, an X-ray source 2 that emits X-rays, a detector 3 that detects characteristic X-rays transmitted through the measurement object O, an X-ray source 2, and a detector 3. Measured by the detector 3, the common stage 5 for installing the X-ray source 2, the detector 3 and the installation table 4, and the detector 3. It has signal processing means 11 for digitizing the characteristic X-ray dose (characteristic X-ray peak), and image reconstruction means 12 for reconstructing an image based on numerical data obtained by the signal processing means.

  As the detector 3, a flat panel detector, a CdTe detector, or the like can be employed. The installation base 4 is configured to perform a rotational motion around a predetermined rotational axis by a moving mechanism (not shown) and to perform a linear motion along an axis perpendicular to the rotational axis. The installation base 4 is preferably made of granite or ductile cast iron having high rigidity. As shown in FIGS. 2 and 3, the center of the three-dimensional coordinate axes (XYZ axes) used in the image acquisition unit 10 is a center position of the common stage 5 in a plan view and is a predetermined position from the upper surface of the common stage 5. It is arranged at a position above the height.

  The signal processing means 11 and the image reconstruction means 12 are configured by hardware such as a computer C and software such as programs installed therein. Specifically, when a program for the signal processing unit 11 and the image reconstruction unit 12 is read into the computer C via a communication medium such as the Internet or a recording medium such as a USB, an arithmetic processing unit such as a CPU or a memory Various processes are executed by a storage unit or the like. Various data and result data necessary for such execution are appropriately input via an input unit or a communication unit, and output via an output unit or a display unit (for example, display screen D). Here, the image reconstruction means 12 is a filtered back projection method, a successive approximation method, a brute force method (brute force search), a greedy method, a hill climbing method, an annealing method, an error back propagation method, a genetic algorithm, genetic programming. The CT image of the measurement object O can be reconstructed based on the numerical data of the detected X-ray dose using various algorithms such as evolution strategy and evolutionary programming.

  A linear scale may be disposed between the X-ray source 2 and the detector 3. If it does in this way, the position of the installation base 4 can be grasped | ascertained correctly and the X-ray CT image of the measuring object O can be acquired correctly.

The image display means 20 is a virtual probe as a three-dimensional image constructed in advance so as to reproduce the actual probe P from the X-ray CT image of the measurement object O on the predetermined three-dimensional coordinate axis acquired by the image acquisition means 10. It is displayed on the display screen D along with the P _V. FIG. 4 illustrates a three-dimensional X-ray CT image of the measurement object O displayed on the display screen D by the image display means 20 and a three-dimensional virtual probe image P _V. The image display means 20 is also composed of hardware such as the computer C and software such as a program mounted on the computer C. When the program for the image display means 20 is read into the computer C, the CPU or the like. Various processes are executed by the arithmetic processing unit and a storage unit such as a memory.

Operating means 30, as shown in FIG. 1, the operator input unit 6 which is operable, the manual operating unit 31 for moving the display screen D virtual probe P _V on the basis of the operation of the input unit 6 by the operator, the operator It has an automatic operating unit 32, the moving operation of the virtual probe P _V automatically on the display screen D to assist. As the input unit 6, various pointing devices or user interface devices including a mouse and a keyboard that can be used when an operator inputs various information can be adopted.

As the manual operation means 31, one that calculates the movement of the virtual probe Pv based on operation information input via the input unit 6 and moves the image of the virtual probe Pv on the display screen D can be adopted. . As the automatic operation means 32, the virtual probe P _V automatically approaches the edge of the X-ray CT image on the display screen D, or the virtual probe P _V along the edge of the X-ray CT image on the display screen D. It is possible to adopt one that automatically moves. The means operating means 31 and the automatic operating means 32 are also configured by hardware such as the computer C and software such as programs installed therein. For these manual operating means 31 and automatic operating means 32, When the program is read into the computer C, various processes are executed by an arithmetic processing unit such as a CPU and a storage unit such as a memory.

Further, the operation means 30 has a measurement point setting means 33 for setting a measurement point of the measurement object O. Measurement points are set at the measurement point setting unit 33 is used for the induction of a virtual probe P _V along the edges of the X-ray CT image on the display screen D. As the measurement point setting means 33, a measurement point is set based on an operation of the input unit 6 by an operator, or a measurement point is automatically calculated based on an X-ray CT image displayed on the display screen D. Can be adopted.

In addition, the operation unit 30 avoids interference between the virtual probe P _V and the X-ray CT image when moving the virtual probe P _V from one measurement point set by the measurement point setting unit 33 to another measurement point. There is escape route setting means 34 for setting the escape route. As the escape route setting means 34, one that sets the escape route based on the operation of the input unit 6 by the operator, or one that automatically calculates the escape route based on the X-ray CT image displayed on the display screen D is used. Can be adopted.

  The measurement point setting means 33 and the escape path setting means 34 are also configured by hardware such as the computer C and software such as programs installed therein. The measurement point setting means 33 and the escape path setting means. When the computer program 34 is read into the computer C, various processes are executed by an arithmetic processing unit such as a CPU and a storage unit such as a memory.

Found means 40, as shown in FIGS. 2 and 3, the display screen is a bridge-type device having a probe P that with the movement of the virtual probe P _V on D, the measuring object in a predetermined three-dimensional coordinate axis Measure the three-dimensional shape of O. The three-dimensional coordinate axes used in the actual measurement means 40 are the same as the three-dimensional coordinate axes used in the image acquisition means 10.

Here, the positional relationship between the positional relationship between the virtual probe image P _V and X-ray CT image of the measuring object O obtained by the image obtaining unit 10, and the actual measurement object O and the probe P of the actual measurement means 40, So as to coincide with each other, the three-dimensional coordinate axis used in the actual measurement means 40, more specifically, for example, the origin of the probe P is set automatically or by an operator's operation. As such a setting method, for example, the probe P of the actual measurement means 40 is moved to a certain characteristic point on the actual measurement object O, that is, a specific point, and the X-ray CT of the measurement object O corresponding to the specific point. on an image, moving the virtual probe P _V point, and a method of matching the both coordinates, using the gauge described in JP 2012-137301, the sphere on the X-ray CT images of the gauge A method of matching the center coordinates with the center coordinates of the sphere of the gauge measured by the probe P of the actual measurement means 40 can be mentioned, but is not limited thereto.

  The actual measurement means 40 has a moving mechanism 7 that moves the probe P relative to the measurement object O installed on the installation table 4. The moving mechanism 7 is supported by a support member so that it can be moved up and down in the vertical direction, a cylindrical spindle having a probe P at the tip, a Z-direction drive mechanism for moving the spindle up and down, and the installation table 4 and the spindle in the vertical direction. And an X-direction drive mechanism and a Y-direction drive mechanism that move relative to each other in directions orthogonal to each other. In addition, an air balance mechanism that generates a push-up force corresponding to the weight of the spindle including the probe P on the spindle can be adopted as a part of the moving mechanism 7 or the actual measurement means 40. The probe P and the moving mechanism 7 are installed on a common stage 5 on which the above-described X-ray source 2 and detector 3 and the installation base 4 for the measurement object O are arranged. That is, elements for X-ray CT image capturing and elements for three-dimensional shape measurement are combined on one stage to constitute one measuring apparatus. The setting of the three-dimensional coordinate axis in this apparatus configuration is as described above.

Further, the measured unit 40 has a probe moving means 41 for moving the probe P to work in the movement of the virtual probe P _V, the tip of the probe P is pressure-sensitive sensor S is provided on the display screen D It has been. When the probe P moved by the probe moving means S comes into contact with the measurement object O, the pressure-sensitive sensor S detects the contact, and the three-dimensional information of the contacted position is detected. The detected three-dimensional position information of the measuring object O is sent to the computer C or the like for processing. The probe moving means 41 is also composed of hardware such as the computer C and software such as a program mounted on the computer C. When the program for the probe moving means 41 is read into the computer C, the CPU or the like Various processes are executed by the arithmetic processing unit and a storage unit such as a memory.

  Note that the three-dimensional measuring apparatus 1 preferably has a vibration isolation function as a countermeasure against external vibration. Further, the three-dimensional measuring apparatus 1 is preferably shielded by a shield made of lead, tungsten, or the like, and the temperature and humidity inside thereof are preferably maintained constant by the air conditioning means. In this way, the influence of the external environment can be suppressed when acquiring image information or measuring the three-dimensional shape, and more accurate three-dimensional information can be obtained.

  Next, a method (three-dimensional measurement method) for measuring the three-dimensional shape of the measurement object O using the three-dimensional measurement apparatus 1 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, the X-ray source 2 of the image acquisition unit 10 irradiates the measurement object O with X-rays, and the projection data for each rotation angle of the measurement object O is detected by the detector 3 to obtain a predetermined three-dimensional An X-ray CT image of the measurement object O on the coordinate axis is acquired (image acquisition step: S1).

Then, the X-ray CT image of the measuring object O obtained in the image acquisition step S1, the display screen D on the image display unit together with the virtual probe P _V (image display step: S2).

Next, prior to the operation of the virtual probe P _V , the measurement point of the measurement object O is set (measurement point setting step: S3), and the virtual probe P _V is moved from one measurement point to another measurement point. A relief path for avoiding interference between the virtual probe P _V and the X-ray CT image is set (escape path setting step: S4). In the measurement point setting step S3, for example, as shown in FIG. 4, a perfect circular trajectory T is automatically calculated based on the position of the edge E of the measurement object O, and equidistant on the perfect circular trajectory T. A plurality of measurement points M can be automatically calculated. In the escape route setting step S4, for example, as shown in FIG. 4, on the basis of the position of the edge E of the X-ray CT images, one measurement point while avoiding interference with the virtual probe P _V and the measurement object O It is possible to automatically calculate an optimum escape path F that reaches from M to another measurement point M.

Then, based on the displayed X-ray CT image on the display screen D, operating the virtual probe P _V on the display screen D in the operating means 30 so as to measure the three-dimensional shape of the measuring object O (Operation Step: S5). In operation step S5, the move the X-ray CT images while visually confirming the operator, the virtual probe P _V by operating their own input section 6 on the display screen D along the edge of the X-ray CT images, the computer C There may be or automatically move on the display screen D along the edge of the X-ray CT images a virtual probe P _V by the automatic operation means 32. When carrying out such operation step S5, in conjunction probe P of the measured unit 40 to the movement of the virtual probe P _V is on the display screen D, the automatic is measured three-dimensional shape of the measurement object O in the three-dimensional coordinate axes (Actual measurement step: S6).

  Thereafter, the operator or the computer C determines whether or not a predetermined measurement end condition is satisfied (end determination step: S7). When the measurement end condition is satisfied, the measurement is ended. On the other hand, when the measurement end condition is not satisfied, the operation step S5 and the measurement step S6 are performed again until the measurement end condition is satisfied.

Or in the three-dimensional measuring device 1 according to the embodiment described, it can be displayed on the display screen D of the X-ray CT images of the measurement object O in the acquired predetermined three-dimensional coordinate axis with the virtual probe P _V. Then, by operating the virtual probe P _V with the operation means 30 so as to measure the three-dimensional shape of the measurement object O on the display screen D, the probe P of the actual measurement means 40 is interlocked with the virtual probe P _V. Thus, actual measurement of the three-dimensional shape of the measuring object O can be realized on the same coordinate axis. That is, an outline shape (X-ray CT image) of the measurement object O is acquired in advance and displayed on the display screen D, and the measurement object O and the virtual probe P _V are operated based on the X-ray CT image. The three-dimensional shape of the measuring object O can be measured very easily without damaging the probe P of the three-dimensional measuring apparatus. As a result, the working efficiency when measuring the three-dimensional shape of the measuring object O can be significantly improved.

In particular, according to the three-dimensional measuring apparatus 1, it is possible to perform three-dimensional measurement of complex shapes having many deep holes and irregularities that have been difficult to measure until now. In the case of measuring the hole diameter, it is necessary to determine the measurement coordinates by inserting a minute probe (stylus) into the hole. Since this operation is usually performed manually, a skilled operator has been required. According to the three-dimensional measuring apparatus 1 according to the present embodiment, the general shape of the measurement object O can be visualized, and the virtual probe P _V is manipulated on the obtained image to obtain a complicated shape. The probe P can be accurately moved to the measurement position. In addition, by digitizing the measurement object O in advance, digital engineering processing such as dimensional evaluation with CAD drawings becomes smoother, which improves measurement technology, advances digital engineering technology, and applies in the field of high-precision simulation. Be expected.

Further, in the above three-dimensional measuring device 1 according to the embodiment described, the interference between the virtual probe P _V and X-ray CT image at the time of moving the virtual probe P _V from one measurement point to another measurement point The escape route to avoid can be set by the escape route setting means 34. At this time, when the escape route setting means 34 for setting the escape route based on manual operation (operation of the input unit 6 by the operator) is adopted, the escape route is searched by trial and error on the display screen D by the operator. Therefore, there is an advantage that an optimum escape route can be set even by an operator having a relatively low skill level. On the other hand, when the escape route setting means 34 that automatically sets the escape route is adopted, it is possible to save time and labor for the operator to set the escape route, so that work efficiency can be remarkably improved.

Further, in the above three-dimensional measuring device 1 according to the embodiment described, with automatic operating means 32 automatically moves the virtual probe P _V on the display screen D can assist the operation of the operator. Specifically, the virtual probe P _V is automatically brought close to the edge of the X-ray CT image on the display screen D, or the virtual probe P _V is automatically moved along the edge of the X-ray CT image on the display screen D. Can be moved to. Therefore, the three-dimensional shape of the measurement object O can be measured more easily, and the working efficiency can be further improved.

Incidentally, in the above embodiment, the measurement of the three-dimensional shape of the measurement object O by operating the virtual probe P _V along the edge of the X-ray CT image of the measuring object O obtained in the image acquisition process S1 However, the edge of the X-ray CT image of the measurement object O acquired in the image acquisition step S1 (herein referred to as an image edge) can also be corrected.

That is, before the measurement of the three-dimensional shape of the measurement object O by the operation of the virtual probe P _V , the operator moves the probe P of the actual measuring means 40 to acquire the three-dimensional shape position information of the measurement object O. When the difference between an edge formed by connecting these point groups (referred to herein as an actual measurement edge) and the image edge exceeds a predetermined threshold, the image edge is brought close to the actual measurement edge. Thus, the X-ray CT image can be updated. In this way, it is possible to compensate for the resolution limit of the X-ray CT images effectively, it is possible to more efficiently perform measurements of the three-dimensional shape of the measuring object O by the operation of the virtual probe P _V.

  The present invention is not limited to the above-described embodiment, and those in which those skilled in the art appropriately modify the design are included in the scope of the present invention as long as they have the features of the present invention. . In other words, each element included in the embodiment and its arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be appropriately changed. Moreover, each element with which the said embodiment is provided can be combined as much as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Three-dimensional measuring apparatus 6 ... Input part 10 ... Image acquisition means 20 ... Image display means 30 ... Operation means 31 ... Manual operation means 32 ... Automatic operation means 33 ... Measurement point setting means 34 ... Escape route setting means D ... Display screen O ... the measurement object P ... probe P _V ... virtual probe S1 ... image acquisition step S2 ... image display step S3 ... measuring point setting step S4 ... escape route setting step S5 ... operation step S6 ... measured step

Claims (12)

Image acquisition means for acquiring an X-ray CT image of a measurement object on a three-dimensional coordinate axis, image display means for displaying an X-ray CT image of the measurement object acquired by the image acquisition means together with a virtual probe, and the virtual A tertiary unit used in the image acquisition unit, comprising: an operation unit that operates a probe; and an actual measurement unit that actually measures a three-dimensional shape of the measurement object on a three-dimensional coordinate axis using a probe that is linked to the movement of the virtual probe. The original coordinate axis and the three-dimensional coordinate axis used in the actual measurement means are a three-dimensional measuring device that is common ,
The operation means includes a measurement point setting means for setting a measurement point of the measurement object, and the virtual probe when moving the virtual probe from one measurement point set by the measurement point setting means to another measurement point. A three-dimensional measuring apparatus comprising escape path setting means for setting an escape path for avoiding interference between a probe and the X-ray CT image . The three-dimensional measurement apparatus according to claim 1 , wherein the measurement point setting unit sets the measurement point based on an operation of an input unit by an operator. The three-dimensional measurement apparatus according to claim 1 , wherein the measurement point setting unit calculates the measurement point based on the X-ray CT image. The three-dimensional measuring apparatus according to any one of claims 1 to 3, wherein the escape path setting means sets the escape path based on an operation of an input unit by an operator. The three-dimensional measuring apparatus according to any one of claims 1 to 3, wherein the escape path setting means calculates the escape path based on the X-ray CT image. The three-dimensional measuring apparatus according to any one of claims 1 to 5 , wherein the operation unit includes a manual operation unit that moves the virtual probe based on an operation of an input unit by an operator. It said operating means comprises automatically operated means for automatically moving said virtual probe so as to assist the operation of the operator, the three-dimensional measuring apparatus according to any one of claims 1 to 6. The three-dimensional measuring apparatus according to claim 7 , wherein the automatic operation means automatically brings the virtual probe close to an edge of the X-ray CT image. The three-dimensional measurement apparatus according to claim 7 , wherein the automatic operation unit automatically moves the virtual probe along an edge of the X-ray CT image. An image acquisition step of acquiring an X-ray CT image of a measurement object on a three-dimensional coordinate axis, an image display step of displaying the X-ray CT image of the measurement object acquired in the image acquisition step together with a virtual probe, and the virtual An operation step of operating a probe, and an actual measurement step of actually measuring the three-dimensional shape of the measurement object on a three-dimensional coordinate axis with a probe that is linked to the movement of the virtual probe, and is used in the image acquisition step The original coordinate axis and the three-dimensional coordinate axis used in the actual measurement step are the same three-dimensional measurement method,
The operation step includes a measurement point setting step for setting a measurement point of the measurement object, and the virtual probe when moving the virtual probe from one measurement point set in the measurement point setting step to another measurement point. And a relief path setting step for setting a relief path for avoiding interference between the probe and the X-ray CT image . The three-dimensional measurement method according to claim 10 , wherein in the operation step, the virtual probe is moved based on an operation of an input unit by an operator, or the virtual probe is automatically moved so as to assist an operator's operation. An image display step for displaying an X-ray CT image of a measurement object acquired on a three-dimensional coordinate axis on a computer together with a virtual probe, an operation step for operating the virtual probe, and a probe linked to the movement of the virtual probe. An actual measurement step of actually measuring the three-dimensional shape of the measurement object on the original coordinate axis, and the three-dimensional coordinate axis used in the image acquisition step and the three-dimensional coordinate axis used in the actual measurement step are common. A three-dimensional measurement program,
The operation step includes a measurement point setting step for setting a measurement point of the measurement object, and the virtual probe when moving the virtual probe from one measurement point set in the measurement point setting step to another measurement point. A three-dimensional measurement program comprising: an escape path setting step for setting an escape path for avoiding interference between a probe and the X-ray CT image .

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