Virtual garment rendering method and fabric apparent texture material information acquisition device

Abstract

The invention discloses a virtual garment rendering method and a fabric apparent texture material information acquisition device, and relates to the technical field of virtual garment reality rendering, and the method comprises the steps: obtaining images of a real fabric at different light source positions; calculating the BRDF parameters of the real fabric based on the images of different light source positions; and performing virtual garment rendering based on the BRDF parameters of the real fabric to obtain virtual garments. According to the invention, the realistic rendering effect of the fabric and the virtual clothing can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of realistic rendering of virtual clothing, and in particular to a method for rendering virtual clothing and a device for collecting fabric apparent texture material information. Background Art

[0002] Virtual reality technology has been widely applied in the clothing industry, and applications such as digital clothing modeling, online virtual fitting, and virtual fashion shows have gradually achieved technological industrialization. Especially against the background of the rapid development of Internet technology and the impact of the epidemic, the demand for virtual clothing applications is increasing day by day. The core difficulties in the realism of digital clothing and virtual clothing lie in two aspects. One is the material mechanics physical properties of fabric modeling, and the other is the visual properties of fabric apparent materials. To achieve high-fidelity virtual clothing modeling and simulation, not only a reasonable dynamic physical model needs to be established, but also a high-fidelity fabric rendering model is required, which is an important factor affecting the realism of virtual simulation.

[0003] In the field of computer graphics, shading refers to the process of calculating the color of a surface or polygon based on its angle and distance relative to the light source and the camera, and it is an important basis for the realistic rendering of scenes and objects. Different shading algorithms can be used for different purposes, and it is necessary to balance the realism effect and response speed of the shading algorithm. Therefore, the shading algorithm based on physical modeling mainly simulates the physical process of real light irradiating from the light source to the object surface and then being reflected from the object surface to the observer's perspective from the perspective of the light reflection attribute parameters of the object surface itself. The key lies in determining the bidirectional reflectance distribution function (BRDF) of the object. The parameters of the bidirectional reflectance distribution function include the diffuse reflection coefficient, specular reflection coefficient, and roughness of the object surface. In general rendering processes, various parameters need to be interactively adjusted according to experience to achieve a better realistic rendering effect. It requires the operator to have rich experience in adjusting rendering parameters. Nevertheless, it is still difficult to accurately determine the parameters of the bidirectional reflectance distribution function for the surface of new material objects, especially for clothing fabrics. Different material compositions, different textile processes, and different knitting structures will have an obvious impact on the visual perception. Therefore, it is of great practical significance to establish a method and a dedicated device for accurately measuring the physical properties of fabrics. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for rendering virtual clothing and a device for collecting fabric apparent texture material information, which can improve the realistic rendering effect of fabrics and virtual clothing.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A virtual clothing rendering method includes:

[0007] Obtain images of the real fabric at different light source positions;

[0008] Calculate the BRDF parameters of the real fabric based on the images at different light source positions;

[0009] Perform virtual clothing rendering based on the BRDF parameters of the real fabric to obtain a virtual clothing.

[0010] Optionally, the method for determining different light source positions is:

[0011] Construct a plurality of uniformly distributed coordinate points on a sphere; the sphere is constructed with the real fabric as the center of the sphere;

[0012] Take each uniformly distributed coordinate point on the sphere as a light source position to obtain different light source positions.

[0013] Optionally, calculating the BRDF parameters of the real fabric based on the images at different light source positions specifically includes:

[0014] Calculate the light data of each point on the real fabric in the images at different light source positions based on different light source positions; the light data includes the spherical coordinates of the incident light direction, the spherical coordinates of the outgoing light direction, and the angle between the half vector of the sphere center and the normal vector of the sphere center; the half vector of the sphere center is calculated from the spherical coordinates of the incident light direction and the spherical coordinates of the outgoing light direction;

[0015] Obtain the pixel value of each point on the real fabric in the images at different light source positions;

[0016] Calculate the BRDF parameters of the real fabric based on the light data and pixel values of each point on the real fabric in the images at different light source positions using the radiosity formula and the BRDF formula.

[0017] Optionally, calculating the BRDF parameters of the real fabric based on the light data and pixel values of each point on the real fabric in the images at different light source positions using the radiosity formula and the BRDF formula specifically includes:

[0018] Calculate the BRDF value of each point on the real fabric in the images at different light source positions based on the light data and pixel values of each point on the real fabric in the images at different light source positions using the radiosity formula;

[0019] Calculate the BRDF parameters of each point on the real fabric based on the BRDF and light data of each point on the real fabric in the images at each light source position using the BRDF formula;

[0020] Obtain the BRDF parameters of the real fabric based on the BRDF parameters of each point of the real fabric.

[0021] Optionally, the radiance formula is:

[0022]

[0023] where, L o,p (r) represents the radiance in the outgoing direction r of the p-th point of the real fabric in the image; Ω p represents the sky hemisphere at the light source position p; f r,p (θ i,p , φ i,p , θ r,p , φ r,p ) represents the BRDF of the p-th point of the real fabric in the image; L k,p (i) represents the light intensity in the incident light direction i of the p-th point of the real fabric in the image; n p represents the normal vector of the p-th point of the real fabric in the image; ω k,p represents the solid angle of the p-th point of the real fabric in the image; d p represents the tangential normal vector of the p-th point of the real fabric in the image.

[0024] Optionally, the BRDF formula is:

[0025]

[0026] where, f r,p (θ i,p , φ i,p , θ r,p , φ r,p ) represents the BRDF of the p-th point of the real fabric in the image; ρd p represents the diffuse reflection coefficient of the p-th point of the real fabric; ρs p represents the specular reflection coefficient of the p-th point of the real fabric; (θ i,p , φ i,p ) represents the spherical coordinates of the incident light direction i of the p-th point of the real fabric in the image; θ i,p represents the angle between the incident light direction i and the normal vector of the p-th point of the real fabric in the image; (θ r,p , φ r,p ) represents the spherical coordinates of the outgoing direction p of the x-th point of the real fabric in the image; θ r,p represents the angle between the outgoing direction r and the normal vector of the p-th point of the real fabric in the image; δ p represents the angle between the half vector and the normal vector of the p-th point of the real fabric in the image; α p represents the roughness of the p-th point of the real fabric; φ r,pDenote the angle between the outgoing direction r of the p-th point of the real fabric in the image and the tangent vector; φ i,p Denote the angle between the incident light direction i of the p-th point of the real fabric in the image and the tangent vector.

[0027] A device for collecting fabric apparent texture material information includes: a rotating cantilever guide rail, a cantilever guide rail ground track, a light source device, a camera device, and a processor;

[0028] The rotating cantilever guide rail is a semi-circular guide rail; the cantilever guide rail ground track is a circular guide rail; the rotating cantilever guide rail and the cantilever guide rail ground track have the same radius; the light source device is movably arranged on the rotating cantilever guide rail; the real fabric is placed at the center position of the cantilever guide rail ground track; both ends of the rotating cantilever guide rail are connected to the cantilever guide rail ground track; both the rotating cantilever guide rail and the light source device are connected to the processor; the processor is used to control the rotation angles of the rotating cantilever guide rail and the light source device, so that the light source device irradiates the real fabric at different light source positions;

[0029] The camera device is connected to the processor; the camera device is used to acquire images of the real fabric at different light source positions and transmit the images of the real fabric at different light source positions to the processor;

[0030] The processor is further used to calculate a virtual garment based on the images of the real fabric at different light source positions by using the virtual garment rendering method as described above.

[0031] Optionally, the device for collecting fabric apparent texture material information further includes a guide rail suspension bearing and a rotating motor of the cantilever guide rail;

[0032] The rotating motor of the cantilever guide rail is arranged on the rotating cantilever guide rail through the guide rail suspension bearing; the rotating motor of the cantilever guide rail is connected to the processor; the processor is used to control the rotation angle of the rotating motor of the cantilever guide rail so that the rotating cantilever guide rail rotates.

[0033] Optionally, the light source device includes a light source driving motor, a white light source, and a light source driving motor control line;

[0034] The control end of the light source driving motor is connected to the processor through the light source driving motor control line; the output end of the light source driving motor is connected to the white light source; the light source driving motor and the white light source are movably arranged on the rotating cantilever guide rail; the processor is used to control the rotation angle of the light source driving motor so that the white light source rotates.

[0035] Optionally, the device for collecting fabric apparent texture material information further includes a white board;

[0036] The white board is placed at the center position of the cantilever guide rail ground track; the real fabric is placed on the white board.

[0037] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention:

[0038] The present invention discloses a virtual clothing rendering method and a fabric apparent texture material information acquisition device. The method includes obtaining images of a real fabric at different light source positions; calculating BRDF parameters of the real fabric based on the images at different light source positions; and performing virtual clothing rendering based on the BRDF parameters of the real fabric to obtain a virtual clothing. The present invention can improve the realistic rendering effect of the fabric and the virtual clothing. Description of the Drawings

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0040] Figure 1 It is a flowchart of the virtual clothing rendering method provided by the present invention;

[0041] Figure 2 It is a schematic diagram of the virtual clothing rendering method provided by the present invention;

[0042] Figure 3 It is a structural diagram of the fabric apparent texture material information acquisition device provided by the present invention;

[0043] Figure 4 It is a schematic diagram of different light source positions provided by the present invention;

[0044] Figure 5 It is a schematic diagram of the principle of BRDF parameter calculation provided by the present invention;

[0045] Figure 6 It is an internal structure diagram of the computer device provided by the present invention.

[0046] Symbol Explanation:

[0047] Rotating cantilever guide rail - 1, guide rail suspension bearing - 2, cantilever guide rail rotating motor - 3, cantilever guide rail support wheel - 4, cantilever guide rail ground track - 5, light source drive motor - 6, white light source - 7, cantilever guide rail motor control line - 8, light source drive motor control line - 9, motor programmable controller - 10, server - 11, camera control line - 12, digital camera - 13, whiteboard - 14, fabric sample - 15, light-shielding darkroom - 16. Detailed Embodiments

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] The purpose of the present invention is to solve the problem of determining the physical parameters of fabrics in the realistic rendering of virtual clothing, and provides a virtual clothing rendering method and a device for collecting fabric apparent texture material information, which can improve the realistic rendering effect of fabrics and virtual clothing.

[0050] Facing the realistic rendering requirements of virtual clothing and dynamic digital fashion shows, in order to achieve the effect of high-fidelity rendering, it is necessary to accurately measure and calculate the light reflection parameters of different fabrics. The present invention calculates the bidirectional reflectance distribution function of fabrics through images with multi-angle changes of light sources, realizes the goal of accurate parameter determination during the realistic rendering of fabrics, and has important practical significance for improving the realistic rendering effect of fabrics and virtual clothing, thereby providing technical and data support for online applications based on virtual clothing.

[0051] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Embodiment 1

[0053] As Figure 1 shown, a virtual clothing rendering method in this embodiment includes:

[0054] Step 101: Obtain images of the real fabric at different light source positions.

[0055] When establishing a virtual clothing model using virtual clothing modeling software, it is necessary to specify the type of fabric selected. According to the selected fabric, select a real clothing fabric, cut a fabric specimen according to appropriate dimensions, which can be square to ensure the specimen is flat.

[0056] During the process of image capture at different light source positions, the position of the imaging device remains fixed, and the position of the light source moves in a specified step size to cover the sky hemisphere Ω, that is, the hemisphere formed by the movement trajectory during the rotation of the cantilever guide rail, simulating the incident light sources from various angles; it is necessary to first set the movement strategy of the light source, with step size changes in the altitude angle in the vertical plane and step size changes in the azimuth angle in the horizontal direction respectively. Calculate the rotation angle according to the movement strategy, and calculate the rotation angle of the cantilever guide rail rotation motor (controlling the azimuth angle φ) and the rotation angle of the light source drive motor (controlling the altitude angle θ) according to the actual running track radius of the fabric apparent texture material information acquisition device. The processor controls the operation of each drive motor, thereby accurately realizing the position change of the light source.

[0057] The method for determining different light source positions is as follows:

[0058] As Figure 4 shown, construct a plurality of uniformly distributed coordinate points on the spherical surface. The spherical surface is constructed with the real fabric as the center.

[0059] Take each uniformly distributed coordinate point on the spherical surface as a light source position to obtain different light source positions.

[0060] Construct N points uniformly distributed on the spherical surface by the minimum potential energy method, defined as: Imagine the scattered points on the spherical surface as identical particles of the same kind of charge, distributed on the spherical surface to minimize the total potential energy, that is, find a set of N points:

[0061] x i' ∈X = {||x||2 = R}, i' = 1, 2, …, N'

[0062] Satisfy the conditions:

[0063]

[0064] Among them, x i' represents the position coordinate of the i'-th particle (point) on the spherical surface; X represents the set of all particles (points) on the spherical surface; x represents a particle (point) on the spherical surface in a general sense; R represents the radius of the spherical surface; E(x) represents the total potential energy of all particles (points); x j' represents the position coordinate of the j'-th particle (point) on the spherical surface.

[0065] Using a typical smooth optimization problem on the manifold, it is necessary to solve it numerically through optimization to make the traversal positions of the light source relatively uniform. As Figure 4 shown, 2500 points uniformly distributed on the spherical surface are constructed by the minimum potential energy method as the traversal positions of the light source.

[0066] After the position change is completed, control the camera to capture an image, transmit the image to the server, and name the index with the corresponding position coordinates.

[0067] The BRDF parameters ρd, ρs, and α of the fabric are the diffuse reflection coefficient of the fabric (RGB three channels, i.e., ρdR, ρdG, ρdB), the specular reflection coefficient (RGB three channels, i.e., ρdR, ρdG, ρdB), and the roughness (single channel, α); for each image, the color of any point p in the specimen area of the image is, from a physical perspective, the radiance of that point in the outgoing direction. The image pixel color value of the whiteboard is taken to calculate the environmental incident light radiance. Combining the position and angle of the light source, a BRDF equation can be constructed for each image. Each image is a sampling sample, and the number of sampling samples is much larger than the number of unknowns (BRDF parameters). The optimal solution of the unknowns is solved as the calculation result of the BRDF parameters of the fabric specimen to be determined.

[0068] As Figure 1 shown, step 102: Calculate the BRDF parameters of the real fabric based on the images with different light source positions.

[0069] Calculate the light data of each point of the real fabric in the images with different light source positions; the light data includes the spherical coordinates of the incident light direction, the spherical coordinates of the outgoing light direction, and the angle between the half vector of the spherical center and the normal vector of the spherical center; the half vector of the spherical center is calculated from the spherical coordinates of the incident light direction and the spherical coordinates of the outgoing light direction.

[0070] Obtain the pixel values of each point of the real fabric in the images with different light source positions.

[0071] Calculate the BRDF parameters of the real fabric based on the light data and pixel values of each point of the real fabric in the images with different light source positions using the radiance formula and the BRDF formula.

[0072] Calculate the BRDF value of each point of the real fabric in the images with different light source positions based on the light data and pixel values of each point of the real fabric in the images with different light source positions using the radiance formula.

[0073] As Figure 5 shown, the radiance formula is:

[0074]

[0075] where, L o,p (r) represents the radiance in the outgoing direction r of the p-th point of the real fabric in the image; Ω p represents the sky hemisphere at the light source position p; f r,p (θ i,p , φ i,p , θ r,p , φ r,p) represents the BRDF of the p-th point of the real fabric in the image; L k,p (i) represents the light intensity of the incident light direction i at the p-th point of the real fabric in the image; n p represents the normal vector at the p-th point of the real fabric in the image; ω k,p represents the solid angle at the p-th point of the real fabric in the image; d p represents the tangential normal vector at the p-th point of the real fabric in the image.

[0076] The BRDF parameters of each point of the real fabric are calculated based on the BRDF and light data of each point of the real fabric in the image at each light source position using the BRDF formula.

[0077] The BRDF formula is:

[0078]

[0079] where, f r,p (θ i,p , φ i,p , θ r,p , φ r,p ) represents the BRDF of the p-th point of the real fabric in the image; ρd p represents the diffuse reflection coefficient of the p-th point of the real fabric; ρs p represents the specular reflection coefficient of the p-th point of the real fabric; (θ i,p , φ i,p ) represents the spherical coordinates of the incident light direction i at the p-th point of the real fabric in the image; θ i,p represents the angle between the incident light direction i and the normal vector at the p-th point of the real fabric in the image; (θ r,p , φ r,p ) represents the spherical coordinates of the outgoing direction p at the x-th point of the real fabric in the image; θ r,p represents the angle between the outgoing direction r and the normal vector at the p-th point of the real fabric in the image; δ p represents the angle between the half vector and the normal vector at the p-th point of the real fabric in the image; α p represents the roughness of the p-th point of the real fabric; φ r,p represents the angle between the outgoing direction r and the tangent vector at the p-th point of the real fabric in the image; φ i,p represents the angle between the incident light direction i and the tangent vector at the p-th point of the real fabric in the image.

[0080] The light source traverses 1250 points evenly distributed over the hemisphere. The Voronoi diagram is segmented according to the spherical scatter distribution. The solid angle differential of the scatter point is calculated using the area S of the Voronoi diagram cell of the k-th light source traversal point k,p Calculate the solid angle differential of this scatter point:

[0081] dω k，p = S k,p / 4πR 2

[0082] The 1250 acquired images contain the object radiance at 1250 different light source positions on the spherical surface. The unknowns in the whole calculation are (θ r,p , φ r,p ), (θ i,p , φ i,p ), δ p , ρd p , ρs p , α p , L k,p (i). Since when acquiring the image data, the camera position and the specimen being photographed remain stationary, only the light source moves. However, since the spherical coordinates corresponding to the light source position have been recorded by the system during image capture, the (θ r,p , φ r,p ), (θ i,p , φ i,p ) and δ p in each image can be calculated. At the same time, L k,p (i) is the pixel value of the image, and L k,p (i) can be obtained by calculating the color value of the whiteboard in the image. In this way, the unknowns in the BRDF formula are reduced to ρd p , ρs p and α p . For any point on the specimen, 1250 different (θ r,p , φ r,p ), (θ i,p , φ i,p ) and δ p of the light intensity and radiance can be obtained from the 1250 acquired images. In fact, 1250 equations with three unknowns of ρd p , ρs p and α p can be constructed. By solving the overdetermined system of equations, the above parameters can be obtained, that is, the material of the specimen fabric sample can be fitted.

[0083] Obtain the BRDF parameters of the real fabric based on the BRDF parameters of each point of the real fabric.

[0084] Using the BRDF parameters of each point of the real fabric for rendering, the rendered image can be output using a programming language according to the constructed rendering equation, or the values of each parameter can be input through the corresponding parameter items of a third-party rendering tool that supports interaction.

[0085] Such as Figure 1As shown, step 103: Perform virtual clothing rendering based on the BRDF parameters of the real fabric to obtain the virtual clothing.

[0086] The method further includes: adding rendering physical properties to the fabric database; adding the corresponding values of the rendering physical properties of the completed fabric to the fabric database. The conventional fabric database includes information such as the material properties, fabric process parameters, and physical properties of each fabric. The fabric database associated with the added rendering physical properties supports program calls for virtual clothing rendering, and the corresponding fabric rendering physical property parameters can be directly selected for specific program applications.

[0087] Embodiment 2

[0088] As Figure 3 shown, a device for collecting fabric apparent texture material information includes: a rotating cantilever guide rail 1, a cantilever guide rail ground track 5, a light source device, a camera device, and a processor.

[0089] The rotating cantilever guide rail 1 is a semi-circular guide rail; the cantilever guide rail ground track 5 is a circular guide rail; the rotating cantilever guide rail 1 and the cantilever guide rail ground track 5 have the same radius; the light source device is movably arranged on the rotating cantilever guide rail 1; the real fabric is placed at the center position of the cantilever guide rail ground track 5; both ends of the rotating cantilever guide rail 1 are connected to the cantilever guide rail ground track 5; both the rotating cantilever guide rail 1 and the light source device are connected to the motor programmable controller 10 in the processor; the processor is used to control the rotation angle of the rotating cantilever guide rail 1 and the rotation angle of the light source device, so that the light source device irradiates the real fabric at different light source positions.

[0090] The light source device includes a light source drive motor 6, a white light source 7, and a light source drive motor control line 9.

[0091] The control end of the light source drive motor 6 is connected to the motor programmable controller 10 in the processor through the light source drive motor control line 9; the output end of the light source drive motor 6 is connected to the white light source 7; the light source drive motor 6 and the white light source 7 are movably arranged on the rotating cantilever guide rail 1; the processor is used to control the rotation angle of the light source drive motor 6, so that the white light source 7 rotates. The device realizes the movement traversal of the white light source 7 at any position on the hemisphere, and always faces the center point of the hemisphere during the movement.

[0092] The rotating cantilever guide rail 1 is installed with a rack-type guide rail, and the light source drive motor 6 includes a gear mechanism, so that the white light source 7 can rotate 180 degrees along the rotating cantilever guide rail 1, and the light source faces the center point of the bottom cantilever guide rail ground track 5.

[0093] The imaging device is connected to the processor; the imaging device is used to acquire images of the real fabric at different light source positions and transmit the images of the real fabric at different light source positions to the processor.

[0094] The processor is further used to calculate a virtual garment based on the images of the real fabric at different light source positions by using the virtual garment rendering method described in Embodiment 1.

[0095] As an embodiment, the fabric apparent texture material information acquisition device further includes a guide rail suspension bearing 2 and a cantilever guide rail rotation motor 3.

[0096] The cantilever guide rail rotation motor 3 is arranged on the rotating cantilever guide rail 1 through the guide rail suspension bearing 2; the cantilever guide rail rotation motor 3 is connected to the motor programmable controller 10 in the processor; the processor is used to control the rotation angle of the cantilever guide rail rotation motor 3 to make the rotating cantilever guide rail 1 rotate.

[0097] As an embodiment, the fabric apparent texture material information acquisition device further includes a whiteboard 14.

[0098] The whiteboard 14 is placed at the center position of the ground track 5 of the cantilever guide rail; the real fabric is placed on the whiteboard 14. The whiteboard 14 is a standard reference whiteboard.

[0099] At the center of the ground track 5 of the cantilever guide rail is the sample area where the whiteboard 14 is placed horizontally, and above the whiteboard 14 is the fabric sample 15 placed horizontally. The whiteboard 14 and the fabric sample 15 can be square. The size of the fabric sample 15 is smaller than that of the whiteboard 14, and it is ensured that the whiteboard 14 and the fabric sample 15 are within the light source irradiation range and the camera shooting range.

[0100] The whiteboard 14 can use white paper considered to be uniform diffuse reflection, with a cut size of 1m * 1m, and the cut size of the fabric sample 15 can be set to 0.5m * 0.5m.

[0101] As an embodiment, the processor includes a motor programmable controller 10 and a server 11.

[0102] The motor programmable controller 10 is connected to the cantilever guide rail rotating motor 3 through the cantilever guide rail motor control line 8, and the motor programmable controller 10 is connected to the light source driving motor 6 through the light source driving motor control line 9. The motor programmable controller 10 is connected to the server 11. The motor programmable controller 10 drives the rotating cantilever guide rail 1 to rotate 180 degrees in the horizontal plane, and at the same time drives the light source driving motor 6 to control the light source to rotate 180 degrees in the vertical plane of the rotating cantilever guide rail 1, so as to realize the movement of the light source at various angular positions in the sky hemisphere region with the midpoint of the bottom surface as the center and the radius of R, and always face the bottom center; the position of the light source is determined by the elevation angle (the angle with the specified vertically upward Z-axis direction) and the azimuth angle (the angle with the specified X-axis direction in the horizontal plane), and the sky hemisphere region is defined as Ω.

[0103] The motor programmable controller 10 is connected to the server 11 for communication, receives the instructions of the server 11, and controls the angle and position change of the light source.

[0104] Taking the spatial distance dDis = 0.5m as the spatial average interval distance of the light source position points, first determine the angular step interval (radian value) in the vertical direction, dθ = dDis / R; then for each fixed elevation angle θ, the circumferential trajectory radius in the horizontal direction is R(θ) = R * sin(θ), and calculate the dφ step interval (radian value) of the azimuth angle in the horizontal direction in turn, dφ = dDis / (R * sin(θ)), so as to determine the position of the light source, and then convert it into the rotation angle of the driving motor through the server 11 and the programmable processor.

[0105] As an embodiment, the fabric apparent texture material information acquisition device further includes a cantilever guide rail support wheel 4, a cantilever guide rail motor control line 8, and a light-shielding darkroom 16.

[0106] The cantilever guide rail support wheel 4 is arranged at the connection of the cantilever guide rail ground track 5 and the rotating cantilever guide rail 1, and the cantilever guide rail support wheel 4 is used to stabilize the rotating cantilever guide rail 1.

[0107] The cantilever guide rail rotating motor 3 is connected to the motor programmable controller 10 through the cantilever guide rail motor control line 8.

[0108] The light-shielding darkroom 16 is used to provide a dark environment for the fabric apparent texture material information acquisition device, so that the light source in the fabric apparent texture material information acquisition device only comes from the white light source 7, and the accuracy of the data is provided.

[0109] The height of the light-shielding darkroom 16 is more than 2.5 m. Therefore, the radius of the sky hemisphere can be set to 2.5 m, that is, the radii of the rotating cantilever guide rail 1 and the cantilever guide rail ground track 5 are both set to 2.5 m. Taking the center of the cantilever guide rail ground track 5 as the origin, the vertically upward direction as the positive direction of the Z axis, designating any horizontal direction as the positive direction of the X axis, and calculating the positive direction of the Y axis according to the right-hand rule, the positive direction along the X axis is defined as the direction angle of 0 degrees.

[0110] As an embodiment, the imaging device includes a camera control line 12 and a digital camera 13.

[0111] The digital camera 13 is connected to the server 11 in the processor through the camera control line 12.

[0112] The digital camera 13 is fixed in position. The digital camera 13 is fixed at a position 3.0 m away from the center in the positive direction of the X axis defined in the horizontal plane and with a height of 2 m. The digital camera 13 is located outside the sky hemisphere and does not affect the operation of the light source and the guide rail.

[0113] The server 11 is connected to the digital camera 13 through the camera control line 12. The camera control line 12 realizes the acquisition and transmission of the camera shooting instruction and the image, transmits the image sequence captured by the digital camera 13 to the server 11, and associates it with the position of the light source, that is, the altitude angle θ and the azimuth angle φ of the light source.

[0114] As an embodiment, Embodiment 1 and Embodiment 2 are combined for discussion, as Figure 2 shown:

[0115] S1: Build an image sequence acquisition device, that is, a fabric apparent texture material information acquisition device. The image sequence is images of different light source positions.

[0116] S2: The virtual clothing simulates real fabric sampling.

[0117] S3: Shoot an image sequence of the changing light source position.

[0118] S4: Calculate the BRDF parameters of the fabric specimen.

[0119] S5: Use the fabric BRDF parameters for virtual clothing rendering.

[0120] S6: Add rendering physical properties to the fabric database.

[0121] Embodiment 3

[0122] A computer-readable storage medium stores a computer program thereon. When the computer program is executed by a processor, the steps of the virtual clothing rendering method in Embodiment 1 are implemented.

[0123] Embodiment 4

[0124] A computer program product includes a computer program which, when executed by a processor, implements the steps of the virtual clothing rendering method in Embodiment 1.

[0125] Embodiment 5

[0126] A computer device, which can be a database, and its internal structure diagram can be as Figure 6 shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store transactions to be processed. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with an external terminal through a network connection. The computer program, when executed by the processor, implements the virtual clothing rendering method in Embodiment 1.

[0127] It should be noted that the object information (including but not limited to object device information, object personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present invention are all information and data authorized by the object or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with the relevant laws, regulations, and standards of relevant countries and regions.

[0128] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tapes, floppy disks, flash memories, optical memories, high-density embedded non-volatile memories, resistive random access memories (ReRAM), magnetoresistive random access memories (MRAM), ferroelectric random access memories (FRAM), phase change memories (PCM), graphene memories, etc. Volatile memories can include random access memory (RAM) or external cache memories, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided by the present invention can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided by the present invention can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0129] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0130] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A virtual clothing rendering method, characterized in that, The method includes: Obtaining images of the real fabric at different light source positions; Calculating the BRDF parameters of the real fabric based on the images at different light source positions; Performing virtual clothing rendering based on the BRDF parameters of the real fabric to obtain a virtual clothing.

2. The virtual clothing rendering method according to claim 1, wherein The method for determining different light source positions is: Constructing a plurality of uniformly distributed coordinate points on a spherical surface; the spherical surface is constructed with the real fabric as the center of the sphere; Regarding each uniformly distributed coordinate point on the spherical surface as a light source position to obtain different light source positions.

3. The virtual clothing rendering method according to claim 2, wherein Calculating the BRDF parameters of the real fabric based on the images at different light source positions specifically includes: Calculating the light data of each point on the real fabric in the images at different light source positions based on different light source positions; the light data includes the spherical coordinates of the incident light direction, the spherical coordinates of the outgoing light direction, and the angle between the half vector of the center of the sphere and the normal vector of the center of the sphere; the half vector of the center of the sphere is calculated through the spherical coordinates of the incident light direction and the spherical coordinates of the outgoing light direction; Obtaining the pixel value of each point on the real fabric in the images at different light source positions; Calculating the BRDF parameters of the real fabric by using the radiosity formula and the BRDF formula based on the light data and pixel values of each point on the real fabric in the images at different light source positions.

4. The virtual clothing rendering method according to claim 3, wherein Calculating the BRDF parameters of the real fabric by using the radiosity formula and the BRDF formula based on the light data and pixel values of each point on the real fabric in the images at different light source positions specifically includes: Calculating the BRDF value of each point on the real fabric in the images at different light source positions by using the radiosity formula based on the light data and pixel values of each point on the real fabric in the images at different light source positions; Calculating the BRDF parameters of each point on the real fabric by using the BRDF formula based on the BRDF and light data of each point on the real fabric in the images at each light source position; Obtaining the BRDF parameters of the real fabric based on the BRDF parameters of each point on the real fabric.

5. The virtual clothing rendering method according to claim 4, wherein The radiosity formula is: where L o,p (r) represents the radiance of the outgoing direction r of the p-th point of the real fabric in the image; Ω p represents the sky hemisphere at the light source position p; f r,p (θ i,p , φ i,p , θ r,p , φ r,p ) represents the BRDF of the p-th point of the real fabric in the image; L k,p (i) represents the light intensity of the incident light direction i of the p-th point of the real fabric in the image; n p represents the normal vector of the p-th point of the real fabric in the image; ωk ,p represents the solid angle of the p-th point of the real fabric in the image; d p represents the tangential normal vector of the p-th point of the real fabric in the image.

6. The virtual clothing rendering method according to claim 4, wherein The BRDF formula is: where f r,p (θ i,p , φ i,p , θ r,p , φ r,p ) represents the BRDF of the p-th point of the real fabric in the image; ρd p represents the diffuse reflection coefficient of the p-th point of the real fabric; ρs p represents the specular reflection coefficient of the p-th point of the real fabric; (θ i,p , φ i,p ) represents the spherical coordinates of the incident light direction i of the p-th point of the real fabric in the image; θ i,p represents the angle between the incident light direction i and the normal vector of the p-th point of the real fabric in the image; (θ r,p , φ r,p ) represents the spherical coordinates of the outgoing direction p of the p-th point of the real fabric in the image; θ r,p represents the angle between the outgoing direction r and the normal vector of the p-th point of the real fabric in the image; δ p represents the angle between the half vector and the normal vector of the p-th point of the real fabric in the image; α p represents the roughness of the p-th point of the real fabric; φ r,p represents the angle between the outgoing direction r and the tangent vector of the p-th point of the real fabric in the image; φ i,p represents the angle between the incident light direction i and the tangent vector of the p-th point of the real fabric in the image.

7. A device for collecting fabric apparent texture material information, characterized in that, The device includes: a rotating cantilever guide rail, a cantilever guide rail ground track, a light source device, a camera device, and a processor; The rotating cantilever guide rail is a semi-circular guide rail; the cantilever guide rail ground track is a circular guide rail; the radii of the rotating cantilever guide rail and the cantilever guide rail ground track are the same; the light source device is movably arranged on the rotating cantilever guide rail; the real fabric is placed at the center position of the cantilever guide rail ground track; both ends of the rotating cantilever guide rail are connected to the cantilever guide rail ground track; both the rotating cantilever guide rail and the light source device are connected to the processor; the processor is used to control the rotation angle of the rotating cantilever guide rail and the rotation angle of the light source device so that the light source device irradiates the real fabric at different light source positions; The camera device is connected to the processor; the camera device is used to obtain images of the real fabric at different light source positions and transmit the images of the real fabric at different light source positions to the processor; The processor is further used to calculate a virtual clothing based on the images of the real fabric at different light source positions by using the virtual clothing rendering method as described in claims 1 - 6.

8. The fabric apparent texture material information acquisition device according to claim 7, characterized in that The fabric apparent texture material information acquisition device further includes a guide rail suspension bearing and a cantilever guide rail rotation motor; The cantilever guide rail rotation motor is arranged on the rotating cantilever guide rail through the guide rail suspension bearing; the cantilever guide rail rotation motor is connected to the processor; the processor is used to control the rotation angle of the cantilever guide rail rotation motor to make the rotating cantilever guide rail rotate.

9. The fabric apparent texture material information acquisition device according to claim 7, wherein The light source device includes a light source drive motor, a white light source, and a light source drive motor control line; The control end of the light source drive motor is connected to the processor through the light source drive motor control line; the output end of the light source drive motor is connected to the white light source; the light source drive motor and the white light source are movably arranged on the rotating cantilever guide rail; the processor is used to control the rotation angle of the light source drive motor to make the white light source rotate.

10. The fabric apparent texture material information acquisition device according to claim 7, wherein, The fabric apparent texture material information acquisition device further includes a white board; The white board is placed at the center position of the ground track of the cantilever guide rail; the real fabric is placed on the white board.

Images