CN211932790U - Human hand three-dimensional information acquisition device - Google Patents

Abstract

The utility model provides a human hand three-dimensional information acquisition device, which comprises an image acquisition device and a bearing plate, wherein the image acquisition device is positioned above the bearing plate; the image acquisition device is arranged on the rotating device, and an included angle gamma is formed between the optical axis of the image acquisition device and the rotating plane, wherein the included angle gamma is 0 degrees and less than gamma <180 degrees. The method for forming the included angle between the optical axis of the camera and the installation structure of the rotating plane is put forward for the first time to simultaneously improve the synthesis speed and the synthesis precision of the foot 3D model. The position of a camera for collecting pictures is optimized, so that the 3D synthesis speed and the synthesis precision of the feet can be improved; and when the position is optimized, the angle and the target size do not need to be measured, and the applicability is stronger.

Description

Human hand three-dimensional information acquisition device

Technical Field

The utility model relates to a technical field is measured to hand appearance, in particular to 3D appearance measurement technical field.

Background

When 3D measurement of the hand is performed, one-dimensional and two-dimensional measurement methods are generally adopted, for example, the length, width and height of the hand are measured by using a measuring tool, and the obtained data can be used for selecting a glove with a proper size for a user. However, such gloves are factory-streamlined and designed according to size specifications, and the industry is not currently making any further size subdivisions. Gloves of different sizes and shapes should be custom designed for each user in order to give the user a better wearing experience. To achieve this, 3D acquisition and measurement of the human hand is necessary. But the acquisition speed and accuracy requirements are very high for customization to thousands of different customers, which would otherwise result in a dramatic reduction in the customer experience.

In addition, the hand contains fingerprint and palm print information, and can be used for identity identification. For example, the transaction identity is confirmed by hand information during the transaction. However, the conventional fingerprint and palm print information are acquired in a 2D mode, and although some 3D fingerprint or palm print acquisition schemes are available at present, acquisition time and accuracy are difficult to be compatible, which is unacceptable for transactions.

For the acquisition of 3D information of feet, a common method at present includes acquiring pictures of an object from different angles by using a machine vision mode, and matching and splicing the pictures to form a 3D model. When pictures at different angles are collected, a plurality of cameras can be arranged at different angles of the object to be detected, and the pictures can be collected from different angles through rotation of a single camera or a plurality of cameras. However, both of these methods involve problems of synthesis speed and synthesis accuracy. The synthesis speed and the synthesis precision are a pair of contradictions to some extent, and the improvement of the synthesis speed can cause the final reduction of the 3D synthesis precision; to improve the 3D synthesis accuracy, the synthesis speed needs to be reduced, and more pictures need to be synthesized. In the prior art, in order to simultaneously improve the synthesis speed and the synthesis precision, the synthesis is generally realized by a method of optimizing an algorithm. And the art has always considered that the approach to solve the above problems lies in the selection and updating of algorithms, and no method for simultaneously improving the synthesis speed and the synthesis precision from other angles has been proposed so far. However, the optimization of the algorithm has reached a bottleneck at present, and before no more optimal theory appears, the improvement of the synthesis speed and the synthesis precision cannot be considered.

In the prior art, it has also been proposed to use empirical formulas including rotation angle, object size, object distance to define camera position, thereby taking into account the speed and effect of the synthesis. However, in practical applications it is found that: unless a precise angle measuring device is provided, the user is insensitive to the angle and is difficult to accurately determine the angle; the size of the target is difficult to accurately determine, and particularly, the target needs to be frequently replaced in certain application occasions, each measurement brings a large amount of extra workload, and professional equipment is needed to accurately measure irregular targets. The measured error causes the camera position setting error, thereby influencing the acquisition and synthesis speed and effect; accuracy and speed need to be further improved.

Therefore, the following technical problems are urgently needed to be solved: firstly, the synthesis speed and the synthesis precision of the hand 3D model can be improved simultaneously; and secondly, the hand 3D acquisition modeling cost is reduced, and the complexity and the volume of excessive equipment are not increased. The operation is convenient, professional equipment is not needed, and excessive measurement is not needed.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention has been made to provide a collecting device that overcomes or at least partially solves the above problems.

The utility model provides a human hand three-dimensional information acquisition device, including image acquisition device and loading board, wherein

The image acquisition device is positioned above the bearing plate;

the image acquisition device is arranged on the rotating device, and an included angle gamma is formed between the optical axis of the image acquisition device and the rotating plane, wherein the included angle gamma is 0 degrees and less than gamma <180 degrees.

Optionally, the rotating device is a rotating arm or a rotating disk.

Optionally, the image capturing device is two cameras respectively located at two opposite ends of the rotating device.

Optionally, the at least two image capturing devices are respectively located above and below the bearing plate.

Optionally, the image acquisition device is connected with the rotating device through a connecting piece in an angle-adjustable manner.

Optionally, the image capturing device can slide relative to the rotating device to change its attachment position on the rotating device.

Optionally, the inner wall of the housing is provided with an illumination light source.

Optionally, the bearing plate has an indication mark thereon.

Optionally, when the image acquisition device rotates around the bearing plate, the following conditions are satisfied at two adjacent acquisition positions:

wherein L is the linear distance between the optical centers of the two adjacent image acquisition positions; f is the focal length of the image acquisition device; d is the rectangular length of the photosensitive element of the image acquisition device; m is the distance from the photosensitive element of the image acquisition device to the surface of the target object along the optical axis; μ is an empirical coefficient.

Alternatively, μ < 0.357.

Invention and technical effects

1. The method for forming the included angle between the optical axis of the camera and the installation structure of the rotating plane is put forward for the first time to simultaneously improve the synthesis speed and the synthesis precision of the foot 3D model.

2. The position of a camera for collecting pictures is optimized, so that the 3D synthesis speed and the synthesis precision of the feet can be improved; and when the position is optimized, the angle and the target size do not need to be measured, and the applicability is stronger.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic structural diagram of a hand 3D information acquisition device according to an embodiment of the present invention;

FIG. 2 is a schematic view of the position of the image capturing device and the connecting member according to the present invention;

FIG. 3 is a schematic view of the connecting post of the image capturing device sliding in the sliding slot to another position according to the present invention;

FIG. 4 is a schematic diagram of an image capturing device according to the present invention with a camera position adjusted on a slide rail;

FIG. 5 is a schematic structural diagram of a hand 3D information acquisition device according to another embodiment of the present invention;

the correspondence of the components to the reference numerals is as follows:

the device comprises an image acquisition device 1, a bearing plate 2, a rotating arm 3, a rotation driving device 4, a connecting piece 5 and a sliding rail 6.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

Hand 3D information acquisition device structure

In order to solve the technical problem, the utility model provides a foot 3D information acquisition device, including image acquisition device 1, loading board 2, swinging boom 3, rotation driving device 4, as shown in fig. 1.

The image acquisition device 1 is connected with the rotating arm 3 through a connecting piece 5 and is arranged at one end of the rotating arm 3. The image acquisition device 1 can adjust the pitch angle through the connecting piece 5, thereby changing the included angle between the optical axis and the rotating arm 3. One conventional way to change pitch is: the connecting piece 5 is provided with a circular arc-shaped sliding groove, a connecting column of the image acquisition device slides in the sliding groove, and the connecting column is fastened in the sliding groove after the preset pitch angle is changed, as shown in fig. 2 and 3. The change of the pitch angle can adapt to different sizes of human hands.

The connecting member 5 is connected to the rotary arm 3 by means of a sliding rail 6, so that the connecting member 5 can move on the rotary arm 3, thereby changing the position of the image capturing device 1 on the rotary arm 3, as shown in fig. 4. Instead of the slide rails 6, a screw connection can also be used, by rotating the screw, the position of the connecting piece 5 on the swivel arm 3 being changed. After the position of the image acquisition device 1 is determined, it is fixed by a fastening device.

Preferably, the image capturing devices 1 have two, one at each end of the rotating arm 3. In this case, the relative distance of the two image capturing devices 1 can be changed by moving.

Meanwhile, a rotating disk may be used as the rotating means in addition to the rotating arm 3. The image acquisition device 1 is located at the outer edge of the rotating disk. The other structures are the same as described above.

The middle of the rotating arm 3 is provided with a rotating shaft which is connected with a rotating driving device 4. The rotary drive 4 may be an electric motor or a combination of an electric motor and a transmission. Which drives the rotating arm to rotate through the rotating shaft. Typically, the transmission is a gear or set of gears.

The periphery of the upper part of the bearing plate 2 is provided with a circular ring-shaped illumination light source which is arranged below the image acquisition device 1 and arranged on the inner wall of the shell. The radius of the annular light source is larger than the rotation radius of the image acquisition device 1, so that the interference caused by the direct incidence of the light source into the image acquisition device 1 is prevented on the premise of illuminating the hand. Meanwhile, a shielding device can be arranged at the upper part of the light source to prevent light from directly entering the image acquisition device 1. The light source can be an LED light source or an intelligent light source, namely, the light source parameters are automatically adjusted according to the conditions of the target object and the ambient light. Usually, the light sources are distributed around the lens of the image capturing device 1, for example, the light sources are ring-shaped LED lamps around the lens. In particular, a light softening means, for example a light softening envelope, may be arranged in the light path of the light source. Or the LED surface light source is directly adopted, so that the light is soft, and the light is more uniform. Preferably, an OLED light source can be adopted, the size is smaller, the light is softer, and the flexible OLED light source has the flexible characteristic and can be attached to a curved surface.

The bearing plate 2 has an indication mark thereon for indicating the position of palm placement to help the user place the palm within the field of view of the image capturing device 1. The indication mark can be a line on the bearing plate 2, and can also be a convex or concave structure. More preferably, it may be a projected laser line. In the laser line projection scheme, the size of the indicating pattern formed by the laser line can be changed according to the size of the hand of the customer, so that the marks with the closest size are projected to help different customers to determine the hand placement position to the greatest extent. Therefore, the side collection obstacle caused by insufficient finger opening amplitude can be prevented; and the difference between the palm and the indication line can be prevented from causing different ranges of the fingers opened by the user each time, so that the acquisition precision is reduced. The mode of indicating by an external light source can also be adopted: in the user preparation stage, the hand region is projected on the light-transmitting material through the external light source, and the palm of the user is helped to be placed at the right position. But at the beginning of the acquisition the light source is switched off. This prevents the marking of the hand region from affecting the subsequent 3D synthesis modeling. In another method, the device further comprises a display connected to the camera and capable of displaying an image of the hand captured by the camera. Meanwhile, marks of the hand area are displayed on the display, the image of the hand collected by the camera is overlapped with the marks on the display, and the position of the hand can be adjusted by observing the display, so that the hand is aligned with the marks.

The device also comprises a processing unit which can be directly arranged in the shell of the image acquisition device 1 and also can be connected with the image acquisition device 1 through a data line or in a wireless mode. For example, an independent computer, a server, a cluster server, or the like may be used as a processing unit, and the image data acquired by the image acquisition apparatus 1 may be transmitted thereto to perform 3D synthesis. Meanwhile, the data of the image acquisition device 1 can be transmitted to the cloud platform, and 3D synthesis is performed by using the powerful computing capability of the cloud platform.

In a further development, as shown in fig. 5, the carrier (carrier plate) is made of a light-transmitting material. Another set of image capturing device 1 and a rotating arm 3 are also arranged below the bearing device, namely the upper part and the lower part of the hand are respectively provided with the image capturing device 1 for capturing the images of the palm and the back of the hand. The upper and lower sets of image acquisition devices 1 can rotate synchronously or respectively. However, the refractive index of the light-transmitting material is different from that of air, and some light rays are reflected or scattered by the light-transmitting material, and these reflected or scattered light rays are also collected by the image collecting device 1, and an object is formed on the collected image as a noise image. To solve this problem, an antireflection film may be provided on the transparent material so that the light of the hand is totally transmitted to the lower side without being reflected, preventing a noisy image from appearing. However, both the antireflection film and the antireflection film have an operating wavelength, and therefore, when the above film system is used, a light source having a corresponding wavelength should be selected. Of course, these noise images can also be removed by preprocessing the subsequent images.

In order to facilitate the measurement of the actual size of the hand of the user, a mark point with known coordinates may be set at a position where the image capturing device 1 can capture the hand. For example, a hand indicator on the carrier plate can be selected. By collecting the marker points and combining the known coordinates thereof, the absolute dimensions of the 3D synthetic model are obtained.

In this hand 3D information acquisition equipment use, the user stretches into the shell with the hand, and the centre of palm is upwards to place on loading board 2, align the index mark on loading board 2. The rotation driving device 4 drives the rotation arm to rotate, so as to drive the image acquisition device 1 to rotate around the hand. Every time the image acquisition device 1 rotates a certain distance, two groups of cameras of the image acquisition device 1 acquire an image of a target object, and when the rotating arm 3 rotates for a half circle, each camera also rotates for a half circle around the hand of a user. If only one camera is provided, a complete rotation of the rotary arm 3 is required. At this time, the image acquisition device can acquire a group of images of 360 degrees of the hand. Since the image capturing device 1 may comprise a plurality of sets of cameras, each set of cameras will obtain a corresponding set of images. The image acquisition process can be completed synchronously with the rotation, and at the moment, a shutter of the camera needs to be set, and a higher shutter is needed. Or the camera can rotate for a certain distance and then stop, and then continue to rotate after shooting, and so on. And transmitting the plurality of groups of images to a processing unit, and constructing a 3D model of the hand of the user in the processing unit by using a 3D synthesis modeling algorithm.

Particularly, after the image acquisition in the palm direction of the user is finished, the user can turn over the palm to acquire the image on the back of the hand. And (4) sending the two groups of images acquired twice into a processing unit for 3D synthesis, so that a 3D model of the whole palm can be synthesized.

Acquisition position optimization of image acquisition device

When 3D acquisition is performed, the direction of the optical axis of the image acquisition device at different acquisition positions does not change relative to the target object, and is generally approximately perpendicular to the surface of the target object, and at this time, the positions of two adjacent image acquisition devices 1, or two adjacent acquisition positions of the image acquisition devices 1, satisfy the following conditions:

wherein L is the linear distance between the optical centers of the two adjacent acquisition position image acquisition devices 1; f is the focal length of the image acquisition device 1; d is the rectangular length of a photosensitive element (CCD) of the image acquisition device; m is the distance from the photosensitive element of the image acquisition device 1 to the surface of the target along the optical axis; μ is an empirical coefficient.

When the two positions are along the length direction of the photosensitive element of the image acquisition device 1, d is a rectangular length; when the two positions are along the width direction of the photosensitive element of the image pickup device 1, d takes a rectangular width.

In the image capturing device 1, the distance from the photosensitive element to the surface of the target object along the optical axis is M in any one of the two positions.

As mentioned above, L should be a straight-line distance between the optical centers of the two image capturing devices 1, but since the optical center position of the image capturing device 1 is not easily determined in some cases, the center of the photosensitive element of the image capturing device 1, the geometric center of the image capturing device 1, the center of the shaft connecting the image capturing device and the pan/tilt head (or platform, support), the center of the proximal or distal surface of the lens may be used instead in some cases, and the error caused by the above is found to be within an acceptable range through experiments, so that the above range is also within the protection scope of the present invention.

Utilize the utility model discloses the device is tested, has obtained following experimental result.

From the above experimental results and a lot of experimental experience, it can be concluded that the value of μ should satisfy μ <0.482, and at this time, it is already possible to synthesize a part of the 3D model, and although some parts cannot be automatically synthesized, it is acceptable in the case of low requirements, and the part that cannot be synthesized can be compensated manually or by replacing the algorithm. Particularly, when the value of μ satisfies μ <0.357, the balance between the synthesis effect and the synthesis time can be optimally taken into consideration; mu <0.198 can be chosen for better synthesis, where the synthesis time increases but the synthesis quality is better. When μ is 0.5078, it cannot be synthesized. It should be noted that the above ranges are only preferred embodiments and should not be construed as limiting the scope of protection.

The above data are obtained only by experiments for verifying the conditions of the formula, and are not limited to the structure of the utility model. Without these data, the objectivity of the formula is not affected. Those skilled in the art can adjust the equipment parameters and the step details as required to perform experiments, and obtain other data which also meet the formula conditions.

The adjacent collection positions refer to two adjacent positions of collection action on the moving track when the image collection device moves relative to the target object. This is generally easily understood for the image acquisition device movements. However, when the target object moves to cause relative movement between the two, the movement of the target object should be converted into the movement of the target object, which is still, and the image capturing device moves according to the relativity of the movement. And then measuring two adjacent positions of the image acquisition device in the converted movement track.

Hand attachment production

In order to make a suitable glove for a user, a 3D model can be synthesized by collecting 3D information of the hand of the user, so that the suitable glove can be designed or selected according to the size of the 3D model of the hand.

In addition to the production of gloves, a prosthetic can also be produced based on the above data. For example, a patient's hand requires amputation, and the acquisition and construction of a 3D model of the hand is performed prior to amputation, so that a suitably sized prosthesis can be provided for the hand after amputation.

In addition, any processing and manufacturing that can be performed using hand data can be performed, and the present invention is not limited thereto.

Rotational motion, for gathering in-process preceding position collection plane and back position collection plane and taking place alternately but not parallel, or preceding position image acquisition device optical axis and back position image acquisition position optical axis take place alternately but not parallel. That is, the capture area of the image capture device moves around or partially around the target, both of which can be considered as relative rotation. Although the embodiment of the present invention lists more orbital rotation motions, it can be understood that the limitation condition of the present invention can be applied only if the non-parallel motion occurs between the collection area of the image collection device and the target object, which is the rotation category. The protection scope of the present invention is not limited to the rail rotation in the embodiments.

The adjacent collection positions refer to two adjacent positions of collection action on the moving track when the image collection device moves relative to the target object. This is generally easily understood for the image acquisition device movements. However, when the target object moves to cause relative movement between the two, the movement of the target object should be converted into the movement of the target object, which is still, and the image capturing device moves according to the relativity of the movement. And then measuring two adjacent positions of the image acquisition device in the converted movement track.

The target object, and the object all represent objects for which three-dimensional information is to be acquired. The object may be a solid object or a plurality of object components. For example, the head, hands, etc. The three-dimensional information of the target object comprises a three-dimensional image, a three-dimensional point cloud, a three-dimensional grid, a local three-dimensional feature, a three-dimensional size and all parameters with the three-dimensional feature of the target object. The utility model discloses the three-dimensional is that to have XYZ three direction information, especially has degree of depth information, and only two-dimensional plane information has essential difference. It is also fundamentally different from some definitions, which are called three-dimensional, panoramic, holographic, three-dimensional, but actually comprise only two-dimensional information, in particular not depth information.

The collection area of the present invention is the range that the image collection device (e.g., camera) can take. The utility model provides an image acquisition device can be CCD, CMOS, camera, industry camera, monitor, camera, cell-phone, flat board, notebook, mobile terminal, wearable equipment, intelligent glasses, intelligent wrist-watch, intelligent bracelet and have all equipment of image acquisition function.

The 3D information of multiple regions of the target obtained in the above embodiments can be used for comparison, for example, for identification of identity. Utilize at first the utility model discloses a scheme acquires the 3D information of human face and iris to with its storage in the server, as standard data. When the system is used, for example, when the system needs to perform identity authentication to perform operations such as payment and door opening, the 3D acquisition device can be used for acquiring and acquiring the 3D information of the face and the iris of the human body again, the acquired information is compared with standard data, and if the comparison is successful, the next action is allowed. It can be understood that the comparison can also be used for identifying fixed assets such as antiques and artworks, namely, the 3D information of a plurality of areas of the antiques and the artworks is firstly acquired as standard data, when the identification is needed, the 3D information of the plurality of areas is acquired again and compared with the standard data, and the authenticity is identified.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

The various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It will be appreciated by those skilled in the art that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functionality of some or all of the components in an apparatus in accordance with embodiments of the present invention. The present invention may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present invention may be stored on computer-readable media or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims (10)

1. The utility model provides a three-dimensional information acquisition device of human hand which characterized in that: comprises an image acquisition device and a bearing plate, wherein

The image acquisition device is positioned above the bearing plate;

the image acquisition device is arranged on the rotating device, and an included angle gamma is formed between the optical axis of the image acquisition device and the rotating plane, wherein the included angle gamma is 0 degrees and less than gamma <180 degrees.

2. The apparatus of claim 1, wherein: the rotating device is a rotating arm or a rotating disk.

3. The apparatus of claim 1, wherein: the image acquisition devices are two cameras which are respectively positioned at two opposite ends of the rotating device.

4. The apparatus of claim 1, wherein: at least two image acquisition devices are respectively positioned above and below the bearing plate.

5. The apparatus of claim 1, wherein: the image acquisition device is connected with the rotating device in an angle-adjustable manner through a connecting piece.

6. The apparatus of claim 1, wherein: the image acquisition device can slide relative to the rotating device to change the connection position of the image acquisition device on the rotating device.

7. The apparatus of claim 1, wherein: the inner wall of the shell is provided with an illumination light source.

8. The apparatus of claim 1, wherein: the bearing plate is provided with an indicating mark.

9. The apparatus of claim 1, wherein: when the image acquisition device rotates around the bearing plate, the following conditions are met at two adjacent acquisition positions:

μ＜0.482

wherein L is the linear distance between the optical centers of the two adjacent image acquisition positions; f is the focal length of the image acquisition device; d is the rectangular length of the photosensitive element of the image acquisition device; m is the distance from the photosensitive element of the image acquisition device to the surface of the target object along the optical axis; μ is an empirical coefficient.

10. The apparatus of claim 9, wherein: μ < 0.357.

Images