A face image acquisition system, correction method and acquisition method based on spherical linear polarization technology

Abstract

The application provides a face image acquisition system, a correction method and an acquisition method based on spherical linear polarization technology, and belongs to the technical field of face three-dimensional reconstruction. The system comprises a spherical architecture, fixed light sources, a camera group and a control device. Each fixed light source is composed of a plurality of light source groups, each light source group comprising at least two light sources provided with polarizing plates. The camera group comprises a plurality of cameras provided with polarizing plates, and the plurality of cameras correspond one-to-one to the plurality of light source groups in the fixed light sources. When acquiring images, any camera in the camera group time-divisionally lights up the light sources with two polarization directions in the light source group corresponding to the camera, the polarization states of the light sources lighted up each time are completely consistent, and face images under two polarization states are acquired. By increasing the number of light bead groups on each light source, the plurality of cameras can simultaneously acquire face light field data, and the data acquisition of the whole face range of the face can be realized without moving the subject to different positions.

Description

Technical Field

[0001] This invention belongs to the technical field of three-dimensional face reconstruction, specifically relating to a face image acquisition system, correction method, and acquisition method based on spherical linear polarization technology. Background Technology

[0002] As an anisotropic material, the human face possesses a multi-layered structure, pigments, and blemishes. When light strikes the surface of the face, it undergoes complex reflections, such as subsurface scattering. In the facial reflection model used in this technology, the reflection from the facial skin surface is divided into two parts: specular reflection (solid line portion) and diffuse reflection (dashed line portion), as shown below. Figure 1 As shown, both reflection components of the human face surface reflect high-frequency geometric information, such as pores, beard, and lip lines. This is crucial for achieving high realism in 3D facial reconstruction. These two reflection components allow for the calculation of corresponding specular and diffuse normal maps, enabling the display of high-frequency details such as pores, wrinkles, and lip lines in later reconstruction. Therefore, the acquisition and separation of these two reflection components are extremely important.

[0003] Polarized spherical gradient illumination is a technique used to acquire and separate the highlight and diffuse components of a human face surface. This technique is typically used in spherical facial light field acquisition systems. Since the reflection of light on the skin surface of a face can be considered a combination of highlight and diffuse components, and specular reflection is a relatively simple surface interaction that occurs at the interface of two media with different refractive indices, assuming n1 = 1 is the refractive index of air and n2 = n is the refractive index of the face material, specular reflection satisfies the Fresnel equation:

[0004]

[0005]

[0006] Where, r s r is the ratio of the reflected electric field component perpendicular to the incident surface to the incident electric field component. p θ is the ratio of the reflected electric field component parallel to the incident plane to the incident electric field component. i Let θ be the angle of incidence. t Let θ be the angle of refraction. From Snell's law, we can obtain θ. t for:

[0007]

[0008] From the above three equations, it can be seen that the polarization state of the mirror-reflected light is determined by the polarization state of the incident light, while... Figure 1It is known that diffuse reflection light is caused by subsurface scattering and can be considered as completely unpolarized light, independent of the polarization characteristics of the incident light. Therefore, this can be used to control the polarization state of the incident light and simultaneously measure the polarization state of the reflected light, thereby achieving the purpose of separating the specular and diffuse reflection components.

[0009] For a single camera, assuming the light source, camera, and subject are all on the same horizontal plane, such as... Figure 2 As shown, linear polarizers can be placed in front of the light source and camera to separate the specular and diffuse components. When light polarized by a vertical polarizer in front of the light source is reflected off the face, ensuring that the outgoing specular reflection is also vertically polarized, a horizontal polarizer placed in front of the camera will filter out all specular reflection, allowing only half of the diffuse reflection to pass through, thus obtaining the image.

[0010]

[0011] When a vertical polarizer is placed in front of the camera, the specular reflected light passes through the polarizer completely, while half of the diffuse reflected light is still filtered out.

[0012] That is, obtain the image:

[0013]

[0014] Combining equations (4) and (5), we can obtain the diffuse reflectance map I. D and specular map I s :

[0015] I D =2I1 (6)

[0016] I s =I2-I1 (7)

[0017] Among them, I D For diffuse albedo mapping, I s For specular mapping, I1 is the image captured by the camera under horizontal polarization, and I2 is the image captured under vertical polarization.

[0018] Spherical linear polarization illumination technology for acquiring facial light fields has become a commonly used method in recent years. Currently, the acquisition of facial reflection fields based on spherical linear polarization illumination can be mainly divided into the following types:

[0019] (1) Researchers have proposed a method for rapidly acquiring specular reflection normal maps and diffuse reflection normal maps based on polarized spherical gradient illumination. This method uses a face light field acquisition system as its hardware foundation. Each light source has a white LED, totaling 156 light sources. A linear polarizer is installed in front of each light source to form a spherical polarization direction field. At the same time, a custom hardware is installed in front of the camera to quickly flip the polarizer in front of the camera to change its linear polarization direction, forming two modes together with the light source: vertical polarization and parallel polarization. Then, eight photos are taken under the two polarization states of parallel polarization and vertical polarization, with three gradient illuminations decreasing along the X / Y / Z axes and one uniform full-brightness illumination, for a total of eight photos.

[0020] This method separates and obtains the specular and diffuse components by utilizing the difference in their polarization characteristics. Specifically, the specular component in the reflected light remains linearly polarized, while the diffuse component can be considered completely unpolarized light. Therefore, adding a polarizer with a perpendicular polarization direction (vertical polarization) in front of the light source and camera can filter out the specular component, while adding a polarizer with a parallel polarization direction (parallel polarization) in front of the light source and camera can simultaneously retain the specular component and half of the diffuse component. This method can obtain the specular and diffuse components under four spherical gradient lighting modes. Using the method of calculating normals for gradient lighting, the corresponding specular reflection normal maps and diffuse reflection normal maps can be calculated.

[0021] This method of separating specular and diffuse components is viewpoint-dependent, which means the required polarization direction field is highly dependent on the observation direction. It also prevents multiple cameras from acquiring images simultaneously. To collect data covering the entire face, the subject needs to be moved to different positions to capture more of the face, introducing computational errors and making the shooting process cumbersome. Furthermore, this method requires custom hardware to quickly flip the polarizer in front of the camera, increasing system complexity.

[0022] (2) Based on Technique 1, some researchers have proposed a viewpoint-independent method for acquiring specular and diffuse reflection components. This method establishes a new spherical polarization direction field, which can acquire the specular and diffuse reflection components of the subject's face from multiple perspectives, thereby calculating the corresponding normal map. This method designs a new polarization direction field, dividing the entire spherical system into multiple regions by meridians and parallels. The LED beads of each light source are divided into two groups, with horizontal and vertical polarizers installed respectively. On each parallel, the polarization direction of all polarizers with horizontal polarizers is adjusted to be along the direction of that parallel. Correspondingly, on each meridian, the polarization direction of all polarizers with vertical polarizers is adjusted to be along the direction of that meridian. The polarization direction of the polarizer in front of the camera is fixed to be along the meridian where the camera is located. The polarization direction field of the entire spherical face light field acquisition system is symmetrical along the Y-axis. This symmetry allows the camera to be placed at any perspective on the equator of the spherical XOZ plane for shooting.

[0023] Although this method can acquire highlight and diffuse reflection components from multiple perspectives, it cannot achieve complete highlight elimination in vertical polarization mode under this spherical polarization direction field. Compared with the first technique, its separation effect of highlight and diffuse reflection components is poor, which will lead to the loss of some details of the subject's face and the inability to use data of certain areas of the face.

[0024] The above analysis shows that although spherical linear polarization illumination has a good acquisition effect in face light field acquisition systems, the acquisition method of diffuse reflection and specular reflection components is viewpoint-dependent. It is impossible to separate diffuse reflection and specular reflection components from other viewpoints. If a single camera is used for image acquisition, the subject needs to be moved to different positions to capture more of the face, which introduces calculation errors. If multiple cameras are used for image acquisition, the spherical polarization field needs to be changed, but at the cost of sacrificing the separation effect of specular and diffuse reflection. Compared with images acquired by a single camera, the separation effect of specular and diffuse reflection components is worse, which will lead to the loss of some facial details and the inability to use data in certain areas of the face. Summary of the Invention

[0025] In view of this, and in response to the problems existing in the current face image acquisition system, the present invention provides a face image acquisition system, correction method and acquisition method based on spherical linear polarization technology.

[0026] The technical solution for implementing the present invention is as follows:

[0027] On one hand, this application proposes a face image acquisition system based on spherical linear polarization technology, including a spherical structure, a fixed light source, a camera group, and a control device; wherein, each fixed light source is composed of multiple light source groups, and each light source group includes at least two light sources equipped with polarizers; the camera group includes multiple cameras equipped with polarizers, and the multiple cameras correspond one-to-one with the multiple light source groups in the fixed light source;

[0028] The polarization direction of the polarizer mounted in front of the camera is parallel to the polarization direction of at least one polarizer in front of the corresponding light source group, and the polarization direction of the polarizer mounted in front of the camera is perpendicular to the polarization direction of at least one polarizer in front of the corresponding light source group.

[0029] Furthermore, in another embodiment of this application, each fixed light source includes three light source groups, and the camera group includes three cameras.

[0030] Furthermore, in another embodiment of this application, the three light source groups contained in each fixed light source are arranged in a triangle.

[0031] Furthermore, in another embodiment of this application, each light source group includes three light sources, which are white LEDs, two of which are equipped with polarizers, and the other LED is not equipped with a polarizer.

[0032] Furthermore, in yet another embodiment of this application, three cameras are mounted at the equatorial position of the architecture.

[0033] On the other hand, an embodiment of this application provides a face image correction method based on spherical linear polarization technology, the specific process of which is as follows:

[0034] Place a reference point at the center of the spherical structure;

[0035] For each camera's corresponding light source group, the polarization direction of the polarizer in front of the light source within the group is adjusted to complete the correction of the acquisition system. The specific adjustment process is as follows:

[0036] Adjust the polarizer in front of at least one of the light sources in all the light source groups corresponding to the current camera until all the highlight spots on the surface of the reference object captured by the camera are eliminated;

[0037] Rotate the polarizer in front of the current camera by 90°;

[0038] Adjust the polarizers in front of the remaining light sources in all light source groups corresponding to the current camera until all the highlight spots on the surface image of the reference object captured by the camera are eliminated.

[0039] Furthermore, the reference object in the embodiments of this application is a non-metallic reference object.

[0040] On the other hand, an embodiment of this application provides a face image acquisition method based on spherical linear polarization technology, the specific process of which is as follows:

[0041] The photographer's head is positioned at the center of the spherical structure;

[0042] When any camera in the camera group is acquiring an image, it illuminates two types of light sources with different polarization directions in the light source group corresponding to that camera in a time-division manner. The polarization state of the light source is completely consistent each time it is illuminated, so as to acquire face images under the two polarization states.

[0043] Beneficial effects:

[0044] First, without changing the original hardware system, the present invention enables multiple cameras to simultaneously collect facial light field data by increasing the number of LED groups on each light source, thereby achieving full-face data collection without requiring the subject to move to different positions.

[0045] Secondly, this invention performs polarization correction processing before facial image acquisition. By cleverly using the polarization direction of the polarizer in front of the camera as a reference, it achieves correction of the polarizer in front of the light source, thus avoiding interference from highlights on facial image acquisition.

[0046] Third, when capturing facial images under different polarization states, this invention only requires lighting the light source under the corresponding polarization state, making the operation simple and convenient. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the reflection on the surface of a human face.

[0048] Figure 2 This is a schematic diagram of the light source, camera, and subject.

[0049] Figure 3 This is a diagram showing the connection between the lighting unit camera and the main control unit.

[0050] Figure 4 An improved light source solution.

[0051] Figure 5 A top view showing the positions of the three cameras.

[0052] Figure 6 This is a flowchart of polarization correction.

[0053] Figure 7 This is a flowchart of the face image acquisition process. Detailed Implementation Plan

[0054] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0055] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0056] It should be noted that various aspects of the embodiments described below are within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0057] On one hand, this application proposes a face image acquisition system based on spherical linear polarization technology, including a spherical structure, a fixed light source, a camera group, and a control device; wherein, each fixed light source is composed of multiple light source groups, and each light source group includes at least two light sources equipped with polarizers; the camera group includes multiple cameras equipped with polarizers, and the multiple cameras correspond one-to-one with the multiple light source groups in the fixed light source;

[0058] The polarization direction of the polarizer mounted in front of the camera is parallel to the polarization direction of at least one polarizer in front of the corresponding light source group, and the polarization direction of the polarizer mounted in front of the camera is perpendicular to the polarization direction of at least one polarizer in front of the corresponding light source group.

[0059] In this embodiment, by setting multiple light source groups on each fixed light source, with each light source group corresponding to one camera, multiple cameras can simultaneously acquire facial light field data without changing the original hardware system. This allows for full-face data acquisition without requiring the subject to move to different positions. It solves the problem that the spherical linear polarization direction field required for separating specular and diffuse reflection components using traditional linear polarization methods is highly dependent on the observation direction. When the observation direction changes, the polarization state of the specularly reflected light entering the camera changes compared to the original observation direction, making it impossible to separate specular and diffuse reflection components.

[0060] Furthermore, in another embodiment of this application, each fixed light source includes three light source groups, and the camera group includes three cameras.

[0061] In this embodiment, the light source group is set to 3, and the camera group also includes 3 cameras. The 3 cameras correspond to different field of view angles, so the full face image of the human face can be captured better.

[0062] Furthermore, in another embodiment of this application, the three light source groups contained in each fixed light source are arranged in a triangle.

[0063] In this embodiment, the three light source groups are arranged in a triangle, which avoids gaps between the three light source groups, prevents mutual interference between the three light sources, and facilitates installation.

[0064] Furthermore, in another embodiment of this application, each light source group includes three light sources, which are white LEDs, two of which are equipped with polarizers, and the other LED is not equipped with a polarizer.

[0065] In this embodiment, each light source group contains three light sources, one of which is not equipped with a polarizer and can be used to capture unpolarized facial images.

[0066] Furthermore, in yet another embodiment of this application, three cameras are mounted at the equatorial position of the architecture.

[0067] In this embodiment, three cameras are arranged at the equator so that the distance between adjacent cameras is the same. When shooting a face, they correspond to viewpoints view1, view2, and view3 respectively. The installation position of the cameras can facilitate the acquisition of full-face images of the face.

[0068] On the other hand, an embodiment of this application provides a face image correction method based on spherical linear polarization technology, the specific process of which is as follows:

[0069] Place a reference point at the center of the spherical structure;

[0070] For each camera's corresponding light source group, the polarization direction of the polarizer in front of the light source within the group is adjusted to complete the correction of the acquisition system. The specific adjustment process is as follows:

[0071] Adjust the polarizer in front of at least one of the light sources in all the light source groups corresponding to the current camera until all the highlight spots on the surface of the reference object captured by the camera are eliminated;

[0072] Rotate the polarizer in front of the current camera by 90°;

[0073] Adjust the polarizers in front of the remaining light sources in all light source groups corresponding to the current camera until all the highlight spots on the surface image of the reference object captured by the camera are eliminated.

[0074] In this embodiment, the polarization direction of the polarizer in front of the camera is cleverly used as a reference. By adjusting the polarization direction of the polarizer in front of the light source, it can be ensured that the polarization direction of the polarizer in front of the light source is parallel or perpendicular to the polarization direction of the camera.

[0075] Furthermore, the reference object in the embodiments of this application is a non-metallic reference object.

[0076] In this embodiment, a non-metallic material is used as a reference to ensure the accuracy of the correction.

[0077] On the other hand, an embodiment of this application provides a face image acquisition method based on spherical linear polarization technology, the specific process of which is as follows:

[0078] The photographer's head is positioned at the center of the spherical structure;

[0079] When any camera in the camera group is acquiring an image, it illuminates two types of light sources with different polarization directions in the light source group corresponding to that camera in a time-division manner. The polarization state of the light source is completely consistent each time it is illuminated, so as to acquire face images under the two polarization states.

[0080] Example:

[0081] This application discloses a face reflection field acquisition system. This system primarily focuses on high-fidelity 3D face reconstruction. Its overall structure is spherical, derived from a regular icosahedron with 42 vertices, 80 faces, and 120 edges. Light sources are fixed at the midpoint of each vertex and edge, totaling 162. To facilitate the entry and exit of the experimental subject, five bottom edges and one vertex were removed, resulting in an actual total of 156 light sources. Each light source consists of three white LED beads. The entire device has a diameter of two meters. Each light source is equipped with an optical lens to focus the light onto the subject. A high-speed digital camera is mounted on the equator of this spherical system, enabling high-resolution and high-frame-rate photography under different lighting conditions. A DMX controller controls the lighting and simultaneously triggers the camera shutter for shooting. During shooting, the subject's head is positioned at the origin of the entire system. The connection method between the LED beads, camera, and main controller is as follows: Figure 3 As shown, the LED beads are connected to the central control computer via a DMX controller. The computer controls the brightness, whether the LED beads are lit, and their polarization state via USB signals. The camera is connected to the computer via a USB signal cable. The computer uses a PCI card for USB expansion and changes camera parameters, obtains camera status, and downloads photos taken by the camera via the USB signal cable.

[0082] Based on the above embodiments, the inventive points of this application will be described in detail below:

[0083] The improved fixed light source assembly in the embodiments of this application is as follows: Figure 4As shown, the total number of light sources remains unchanged at 156, but the number of individual light sources has been expanded from one group to three groups, with three LEDs in each group. One LED is not equipped with a polarizer, while the other two are equipped with polarizers. The three groups of LEDs are named as follows: Where s = 1, 2, ... 156 represents the number of light sources. The three LEDs in each group with different polarization states are denoted by their subscripts: n (without polarizer), p (with polarizer), and c (with polarizer), for example: These represent three LEDs in the first light source group A: one without a polarizer, one with a polarizer, and one with a polarizer.

[0084] Because each light source has two additional sets of white LED beads, two more cameras can be added to the existing one, enabling three cameras to simultaneously collect data on the entire face. The three high-speed digital cameras, Camera1, Camera2, and Camera3, are mounted on the equator of a spherical grid structure frame. When capturing the face, they correspond to viewpoints view1, view2, and view3, respectively. All three cameras are located at the equator of the spherical system, and their distribution is shown in the top view below. Figure 5 As shown.

[0085] Based on the above improvement ideas, the improved acquisition system according to the embodiments of this application includes a spherical structure, a fixed light source, a camera, and a control device. Each fixed light source consists of three light source groups, and each light source group includes three light sources equipped with polarizers. The three light source groups are respectively denoted as... (s=1,2,…156); there are 3 cameras, mounted on the equator of the spherical grid structure frame, each corresponding to one light source group in each fixed light source, i.e., Camera1 corresponds to… Camera2 corresponds to Camera3 corresponds to A polarizer is loaded in front of each camera.

[0086] When the polarization direction of the polarizer in front of the light source is vertical, the light polarized by the vertical polarizer in front of the light source is reflected off the face surface, ensuring that the outgoing specular reflection light is also vertically polarized. In this case, if a horizontal polarizer is placed in front of the camera, it will filter out all specular reflection light, allowing the image to be obtained through half of the diffuse reflection. When the polarization direction of the polarizer in front of the light source is horizontal, the light polarized by the horizontal polarizer in front of the light source is reflected off the face surface, ensuring that the outgoing specular reflection light is also horizontal. In this case, if a horizontal polarizer is placed in front of the camera, the specular reflection light can pass completely through the polarizer, while half of the diffuse reflection light is still filtered out to obtain the image, thus achieving face image acquisition. Therefore, ensuring that the polarization directions of the polarizer in front of the camera and the polarizer in front of the light source are strictly horizontal or vertical is crucial for achieving high-precision face image acquisition. To this end, polarization correction is required for the acquisition system. In this embodiment, the polarization direction of the polarizer in front of the light source is corrected to ensure that its polarization direction is horizontal or vertical with that of the polarizer in front of the camera. The specific process is as follows:

[0087] (1) Place a snooker ball at the origin (center) of the acquisition system.

[0088] (2) For Camera1 under view1, the polarization direction of the polarizer installed in front of Camera1 needs to be parallel to the polarization direction of the positive polarizer in front of one of the light sources in the corresponding light source group, and perpendicular to the polarization direction of the other polarizer, so as to perform the following operation.

[0089] Adjust the corresponding Camera1 (s=1,2,…156) A polarizer is installed in front of the light source (subscript c) until all the highlights on the surface of the snooker ball captured from Camera1 are eliminated. The polarization direction of the polarizer at this time is defined as the vertical direction.

[0090] Rotate the polarizer in front of Camera1 by 90°;

[0091] Adjust the corresponding Camera1 (s=1,2,…156) A polarizer is installed in front of the light source (subscript p) until all the highlights on the surface of the snooker ball captured from Camera1 are eliminated. The polarization direction of the polarizer at this time is defined as the horizontal direction.

[0092] Similarly, the LEDs corresponding to Camera2 and Camera3 from the other two perspectives... The same applies to polarization correction. The polarization correction process described above can be used... Figure 6 The flowchart shown is an example.

[0093] The above correction method can ensure that the polarizer in front of the camera and the polarizer in front of the light source are strictly perpendicular or parallel.

[0094] After the data acquisition system is calibrated, data acquisition can proceed. The specific steps are as follows:

[0095] (1) Have the subject sit in the center of the system with their head at the origin. Once ready, the light-controlled camera shooting program can be started.

[0096] (2) Turn on the LED beads Camera1 takes a picture and acquires an image. Turn off the LEDs after taking the picture.

[0097] (3) Turn on the LED beads Camera1 takes a picture and acquires an image. Turn off the LEDs after taking the picture.

[0098] (4) Turn on the LED beads Camera2 takes a picture and acquires an image. Turn off the LEDs after taking the picture.

[0099] (5) Turn on the LED beads Camera2 takes a picture and acquires an image. Turn off the LEDs after taking the picture.

[0100] (6) Turn on the LED beads Camera3 takes pictures and acquires images. Turn off the LEDs after taking the picture.

[0101] (7) Turn on the LED beads Camera3 takes pictures and acquires images. Turn off the LEDs after taking the picture.

[0102] Each shot takes about six seconds with a DSLR camera, but real-time acquisition is possible with a high-speed camera. The entire acquisition and data processing flow is as follows: Figure 7 As shown.

[0103] Through the above process, diffuse albedo maps and specular maps of Camera1, Camera2, and Camera3 at their respective viewpoints can be obtained simultaneously. This overcomes the problem that the spherical linear polarization direction field required for separating specular and diffuse components using the linear polarization method is highly dependent on the observation direction, which prevents multiple cameras from acquiring images simultaneously.

[0104] This invention can collect multi-view facial data without moving the face, achieving full automation of the process. Compared with previous technical solutions, it can improve the efficiency of the data collection process and reduce data errors introduced by manual intervention.

[0105] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A face image acquisition system based on spherical linear polarization technology, characterized in that, The system comprises a spherical framework, fixed light sources, a camera group and a control device. Each fixed light source is composed of multiple light source groups, each of which comprises at least two light sources with polarizers. The camera group comprises multiple cameras with polarizers, each of which corresponds to a light source group in the fixed light sources. The multiple cameras correspond to different field angles, which facilitates the collection of full-face images. The polarization direction of the polarizer in front of the camera is parallel to that of the polarizer in front of at least one light source in the corresponding light source group. The polarization direction of the polarizer in front of the camera is perpendicular to that of the polarizer in front of at least one light source in the corresponding light source group. 2.The face image acquisition system based on spherical linear polarization technology according to claim 1, wherein, Each fixed light source comprises three light source groups, and the camera group comprises three cameras. 3.The face image acquisition system based on spherical linear polarization technology according to claim 1, wherein, The three light source groups in each fixed light source are arranged in a triangular shape.

4. The face image acquisition system based on spherical linear polarization technology according to any one of claims 1 to 3, characterized in that, Each light source group comprises three light sources, which are white LED lights. Two of the light sources are equipped with polarizers, and the other is not equipped with a polarizer.

5. The face image acquisition system based on spherical linear polarization technology according to claim 1, characterized in that, The three cameras are installed at the equatorial position of the framework.

6. The correction method for the face image acquisition system based on the spherical linear polarization technology according to any one of claims 1-5, characterized in that, The specific process of the correction method is as follows: a reference object is placed at the center of the spherical framework. For each camera corresponding light source group, the polarization direction of the polarizer in front of the light source is adjusted, and the correction of the collection system is completed. The specific adjustment process is as follows: Adjust the polarization direction of the polarizer in front of at least one light source in the light source group corresponding to the current camera until all the highlights on the surface image of the reference object collected by the camera are eliminated. Rotate the polarizer in front of the current camera by 90°. Adjust the polarization direction of the polarizer in front of the remaining light sources in the light source group corresponding to the current camera until all the highlights on the surface image of the reference object collected by the camera are eliminated.

7. The face image acquisition system based on spherical linear polarization technology according to claim 6, characterized in that, The reference object is a non-metallic reference object.

8. A face image acquisition method based on the spherical line polarization technology, which is implemented by using the face image acquisition system based on the spherical line polarization technology according to claim 1. The specific process of the collection method is as follows: The photographer's head is at the center of the spherical framework. When collecting images, any camera in the camera group alternately lights up the light sources with two polarization directions in the light source group corresponding to the camera. The polarization state of the light sources is completely consistent each time, and the face images under the two polarization states are obtained.

Images