High-performance analysis triangular surface element color computer-generated hologram generation method

Abstract

The invention relates to the technical field of information optics, in particular to a high-performance analysis triangular surface element color computer-generated hologram generation method, and aims to overcome the defects of an existing analysis surface element method for generating a computer-generated hologram. The method comprises the following steps: on the basis of primitive triangle frequency spectrum expression under three-dimensional affine transformation, generating a color computer-generated hologram with good reconstruction visual quality by adding orthogonal mapping textures and Blinn-Phong illumination model information into inclined triangle surface element amplitude; meanwhile, based on the RGB-YCbCr color space conversion relation, the texture image is converted from RGB to YCbCr color space so as to avoid repeated redundancy calculation of the triangular surface element frequency spectrum under each color, and the hologram generation efficiency is greatly improved while the quality of the reproduced image of the hologram is ensured.

Description

Technical Field

[0001] The invention relates to the field of information optics technology, and in particular to a high-performance analytical triangular facet color computer-generated hologram generation method. Background Art

[0002] The vigorous development of emerging industrial technologies in modern society, such as digital twins and metaverse, has led to more and more application scenarios that require a comprehensive understanding and presentation of the real world from different perspectives. Three-dimensional display technology is gradually becoming a key driving force in the digital economy and virtual reality fields. As an ideal naked-eye 3D display technology, computational holography, which does not require complex interference to record the optical path, especially color computational holography that can realistically present three-dimensional models with rich texture and lighting information, has attracted much attention in the market and has broad application prospects.

[0003] The rich colors of objects in nature are a mixture of red, green and blue light in different proportions. Based on this principle, color holography uses three-color laser beams of RGB to illuminate the target object to form interference fringes. When reproducing the hologram, three-color laser beams are required to illuminate the hologram and superimpose the three-color light fields. Therefore, the amount of calculation required to generate a color hologram in RGB color space will be three times that of a monochrome computer hologram. The existing three-dimensional color computer hologram generation methods can be roughly divided into three categories: point element method, layered method and surface element method. Among them: the calculation time of the point element method is proportional to the product of the number of point sources and sampling points of the three-dimensional object, which is very time-consuming and difficult to handle occlusion problems; the layered method is only applicable to objects with diffuse reflection surfaces and can only provide a very narrow observation area; the hologram reconstructed image generated by the surface element method lacks detailed information and realism. There are mainly two types of methods: numerical method and analytical method. The latter directly obtains the diffraction light field of the triangular surface element through three-dimensional affine transformation and full analytical spectrum calculation. Compared with the former, the calculation efficiency is higher, but it is difficult to add additional information to the surface element. In addition, since the analytical facet method does not include color information when generating the triangular facet spectrum, the triangular facet spectrum must be calculated one by one at three wavelengths when generating a color computer hologram in the RGB color space. If the amount of calculation required to add lighting and texture information to the triangular facets is taken into account, the generation efficiency of the color computer hologram will be further reduced. Summary of the invention

[0004] The purpose of the present invention is to provide a high-performance analytical triangular facet color computer-generated hologram generation method, aiming to solve the problems of poor quality, low efficiency and impact on observer experience of computer-generated holograms generated by the existing analytical facet method, ensure the quality of color hologram reproduction images and improve the efficiency of hologram generation.

[0005] To achieve the above object, the present invention provides a high-performance analytical triangular facet color computer-generated hologram generation method, comprising the following steps:

[0006] Step 1: Generate a hologram based on the 3D model and use external normals to remove hidden surfaces;

[0007] Step 2: Generate triangular facet spectrum;

[0008] Step 3: The texture image is converted to the YCbCr color space and orthogonal texture mapping is used to add texture information to the triangular facet spectrum;

[0009] Step 4: Add lighting information to the triangular face spectrum

[0010] Step 5: Diffract the triangular facet spectrum onto the holographic surface and convert it back to the RGB color space to generate a three-dimensional model color hologram.

[0011] Optionally, during the execution of step 1, vertex information and facet information are obtained from the three-dimensional model. When generating a hologram, it is necessary to distinguish between visible facets and hidden facets in the three-dimensional model. The basis for determining the visible facets is as follows: Assume is the normal vector to the hologram plane, is the normal vector of any triangle face, when When the condition is met, determine whether the triangle element is a visible element.

[0012] Optionally, in step 2, the triangular face element is regarded as a triangular light-transmitting aperture, and the diffraction light field generated on the holographic surface after the incident plane wave passes through the aperture is solved. By specifically combining the three-dimensional affine transformation with the given primitive triangular face element spectrum, an analytical expression of the spectrum of any triangular face element can be obtained.

[0013] Optionally, the execution process of step 3 includes the following steps:

[0014] Step 3.1: RGB-YCbCr color space conversion of texture image;

[0015] Step 3.2: Texture information extraction based on orthogonal mapping;

[0016] Step 3.3: Add texture information to the triangle surface spectrum.

[0017] Optionally, in step 4, a Blinn-Phong reflection model is used to generate simulated illumination information in the tilted triangular facet light field and add the information to the triangular facet spectrum.

[0018] Optionally, in step 5, the triangular facet spectrum is diffracted onto the holographic surface and converted back to the RGB color space to generate a three-dimensional model color hologram.

[0019] The present invention provides a high-performance analytical triangular facet color computer-generated hologram generation method. Aiming at the shortcomings of the existing analytical facet method for generating computer-generated holograms, after acquiring vertex information and facet information of a three-dimensional model, based on the spectrum expression of primitive triangles under three-dimensional affine transformation, orthogonal mapping texture and Blinn-Phong illumination model information are added to the amplitude of tilted triangular facets, so as to generate a color computer-generated hologram with good reconstructed visual quality; at the same time, based on the RGB-YCbCr color space conversion relationship, the texture image is converted from RGB to YCbCr color space to avoid repeated redundant calculation of the triangular facet spectrum under each color, so as to greatly improve the hologram generation efficiency while ensuring the quality of the hologram reproduction image. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic flow chart of the steps of a high-performance analytical triangular facet color computer-generated hologram generation method of the present invention.

[0022] Figure 2 It is a schematic diagram of the three-dimensional affine transformation relationship between the primitive triangle and the tilted triangle in the global coordinate system and the local coordinate system.

[0023] Figure 3 It is a schematic diagram of the accelerated generation process of a color hologram in the YCbCr color space of the present invention.

[0024] Figure 4 It is a schematic diagram of the alignment coordinates of the three-dimensional model of the present invention using orthogonal mapping texture.

[0025] Figure 5 It is a schematic diagram of the process of transforming primitive triangles in the orthogonal mapping texture processing process of the present invention.

[0026] Figure 6 It is a schematic diagram of a three-dimensional model of three groups of triangular face elements according to a specific embodiment of the present invention.

[0027] Figure 7 It is a schematic diagram of a texture image selected in a specific embodiment of the present invention.

[0028] Figure 8 It is a schematic diagram of the hologram reproduction result after adding texture images to the three-dimensional model of a specific embodiment of the present invention in different mapping methods.

[0029] Fig. 9 It is a schematic diagram of a three-channel computer-generated hologram generated in the RGB color space of a specific embodiment of the present invention.

[0030] Fig.10 It is a schematic diagram of a three-channel computer-generated hologram generated in the YCbCr color space of a specific embodiment of the present invention.

[0031] Fig.11 It is a schematic diagram of the color reproduction image of the three-channel hologram of each model according to the specific embodiment of the present invention. DETAILED DESCRIPTION

[0032] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0033] See also Figure 1 The present invention provides a high-performance method for generating a color computer-generated hologram by analyzing a triangular facet, comprising the following steps:

[0034] S1: Generate a hologram based on a 3D model and use external normals to remove hidden surfaces;

[0035] S2: Generate triangular facet spectrum;

[0036] S3: The texture image is converted to the YCbCr color space and the texture information is added to the triangular facet spectrum using orthogonal texture mapping;

[0037] S4: Adding illumination information to the triangular facet spectrum.

[0038] S5: diffract the triangular facet spectrum onto the holographic surface and convert it back to the RGB color space to generate a three-dimensional model color hologram.

[0039] The following is a further explanation based on the specific steps:

[0040] The process of step S1 is 3D model data processing: vertex information and facet information are obtained from the 3D model. To ensure the accuracy of the amplitude intensity in the reconstructed image, it is necessary to distinguish between visible facets and hidden facets in the 3D model when generating a hologram, and use external normals to remove hidden facets: Assume is the normal vector to the hologram plane, is the normal vector of any triangle face, when When the condition is met, determine whether the triangle element is a visible element.

[0041] The process of step S2 is the calculation of triangular facet spectrum: since it is difficult to directly calculate the diffracted light field of a plane light source, the light field distribution of a three-dimensional object when the facet method generates a computer-generated hologram is usually equivalent to a triangular light-transmitting aperture described by a constant surface function, that is, the triangular facet is regarded as a triangular light-transmitting aperture, and then the diffracted light field generated on the holographic surface after the incident plane wave passes through the aperture is solved. By combining the three-dimensional affine transformation with the given primitive triangular facet spectrum, the analytical expression of the spectrum of any triangular facet can be obtained.

[0042] like Figure 2 As shown, let O-XYZ represent the global coordinate system, o-xyz represent the local coordinate system, and the hologram plane O-XY is located at Z=0; P1(X1, Y1, Z1), P2(X2, Y2, Z2) and P3(X3, Y3, Z3) are the three vertices of any (inclined) triangle ΔABC in the global coordinate system; p1(x1, y1, z1) = (0, 0, 0), p2(x2, y2, z2) = (1, 0, 0) and p3(x3, y3, z3) = (0, 1, 0) are the three vertices of the primitive triangle ΔA'B'C' in the local coordinate system, then the three-dimensional affine transformation relationship between the primitive triangle and the inclined triangle can be expressed as:

[0043]

[0044] Among them, a ij (i=1,2,3;j=1,2,3,4) are the elements of the three-dimensional affine transformation matrix. Further, assuming that the intensity inside the primitive triangle is 1 and the intensity outside the triangle is 0, that is, the surface function f of the primitive triangle Δb (x,y,z) is:

[0045]

[0046] make represents Fourier transform, f x ,f y is the frequency coordinate of the primitive triangle in the local coordinate system, then the frequency spectrum F of the primitive triangle Δb (f x ,f y ) can be calculated based on its surface function, that is:

[0047]

[0048] Similarly, let the inclined triangle surface function be f Δo (X, Y, Z), since the slanted triangle can be obtained by performing a three-dimensional affine transformation on the primitive triangle, that is, f Δo (X,Y,Z) can be obtained by f Δb (x, y, z) represents the frequency spectrum F of the tilted triangle on the hologram plane.Δo (f X ,f Y )for:

[0049]

[0050] Where F1 = exp[-i2π(f X a 14 +f Y a 24 +f Z a 34 )],f X With f Y They are the frequency variables of the X-axis and Y-axis, and the frequency coordinates of the axial transmission: λ is the wavelength. Further, let f′ X =a 11 f X +a 21 f Y +a 31 f Z , f Y ′=a 12 f X +a 22 f Y +a 32 f Z , then (f′ X ,f′ Y ) can be regarded as the new frequency coordinates under the three-dimensional affine transformation, and is composed of the fundamental frequency (f X ,f Y ). The three-dimensional affine transformation will cause the overall frequency coordinate to shift, and the frequency shift factor a can be set 13 / λ and a 23 / λ for the new frequency coordinate (f′ X ,f′ Y ) to compensate, that is:

[0051]

[0052] Using the Jacobian determinant J = a 11 a 22 -a 12 a 21 The integral variable is transformed from (X, Y) to (x, y). Taking into account that when the triangular face element diffracts at a certain angle to the z-axis, black lines will appear between adjacent face elements. Here, the spectrum of any triangular face element can be rewritten as:

[0053]

[0054] The process of step S3 is the process of converting the texture image into the YCbCr color space and using orthogonal texture mapping to add texture information to the triangular facet spectrum: the triangular facet spectrum obtained in step S2 lacks details and realism after diffraction reconstruction, and it is difficult to meet the actual three-dimensional display requirements. It is possible to consider adding texture information to further increase the visual effect of the holographic reproduction image. Since the triangular facet spectrum does not contain color information, when generating a color computational hologram, the texture image containing the color image needs to be divided into three channels according to the RGB color space for calculation, which causes redundant calculations. Therefore, this step does not directly use the RGB color space to calculate and generate a color hologram, but converts it to the YCbCr color space. It is only necessary to generate a computational hologram under red light, and use the conversion relationship between the RGB and YCbCr color spaces to directly obtain the computational holograms under the other two color lights (green and blue), thereby avoiding repeated redundant calculations in the RGB color space. Figure 3 As shown, the color hologram acceleration generation in the YCbCr color space of the present invention is divided into the following steps:

[0055] Step 3.1: RGB-YCbCr color space conversion of texture image. That is, establish a color space conversion relationship, convert the RGB component of the texture image to the brightness component (Y), blue difference chromaticity component (Cb) and red difference chromaticity component (Cr) in the YCbCr color space. The conversion relationship between the two is as follows:

[0056]

[0057]

[0058] Among them, T R , T G With T B are the three-channel components of the texture image in the RGB color space; T Y , T Cb With T Cr They are respectively the three-channel components of the texture image in the YCbCr color space.

[0059] Step 3.2: Adding texture information. In computer graphics, there are three main ways to map a 2D texture image to the surface of a 3D object: spherical mapping, planar mapping, and orthogonal mapping. Since the mapping of a two-dimensional plane to the surface of a three-dimensional sphere will produce geometric deformation, the 2D texture image mapping under spherical mapping is prone to deformation and stretching, especially near the poles; the planar mapping based on perspective transformation requires that the physical sizes of the texture plane and the hologram plane maintain a suitable proportional relationship. Therefore, when the three-dimensional model is smaller than the hologram plane, only a small amount of texture information can be mapped to the three-dimensional model surface. The present invention adopts an orthogonal mapping method to accurately establish the correspondence between the texture coordinate system (u, v) and the three-dimensional object space coordinate system (X, Y, Z), thereby avoiding information loss and distortion caused by inaccurate size association in other texture mapping processes. Figure 4 As shown, when the three-dimensional model uses orthogonal mapping texture, any inclined triangle has a corresponding normalized texture triangle in the texture image and the coordinate correspondence is calculated as follows:

[0060]

[0061] This coordinate correspondence is used to ensure that the texture image is correctly mapped to the entire 3D model surface. Further, let T(u,v) represent the texture information at the coordinate (u,v) on the texture triangle. According to equation (6), the frequency spectrum of the tilted triangle carrying the corresponding texture information can be expressed as:

[0062]

[0063] Since it is assumed that the primitive triangle has a uniform and fixed amplitude function, when the number of facets in the 3D model is insufficient to express the details of the texture image, the texture of the hologram reconstruction will be blurred. This problem can be solved by self-similar segmentation of the triangle and synchronous fine sampling of the texture image based on the coordinates of the sub-triangle barycenter, thereby ensuring that the sub-triangle obtains rich texture information. Figure 5 As shown, the present invention divides each side of the primitive triangle into M equal parts, and the primitive triangle is divided into M 2 self-similar small triangles, including M*(M+1) / 2 positive sub-triangles Δ represented by blue in the figure f(m,n) , the M*(M-1) / 2 reverse sub-triangle Δ represented by green r(m,n) , where m and n represent the index values ​​of the rows and columns. Accordingly, any inclined triangle obtained by the three-dimensional affine transformation can also be divided into a set of positive triangles and reverse triangles. Theoretically, the present invention only needs to solve Δ f(0,0) With Δ r(0,0) The spectrum of the other self-similar sub-triangles can be obtained by simple translation. According to the row and column index values ​​(m, n), the spectrum F of the forward sub-triangle can be obtained. f The spectrum F of the inverse sub-triangler :

[0064]

[0065]

[0066] The centroid P of the positive subtriangle in the primitive triangle f for The centroid P of the reverse subtriangle r for According to the three-dimensional affine transformation, the centers of the positive sub-triangle and the negative sub-triangle of the inclined triangle are:

[0067]

[0068]

[0069] The spectrum of an arbitrarily tilted triangle surface carrying a texture is calculated as follows:

[0070]

[0071] Among them, F Tf With F Tr These are the spectra that carry texture information for the forward sub-triangle and the reverse sub-triangle respectively.

[0072] The process of step S4 is the process of adding illumination information to the triangular facet spectrum. Although the triangular facet spectrum carrying texture information has been obtained in the previous step, not considering the illumination information will cause the hologram reconstruction result to lack three-dimensionality. The simulated illumination information in the tilted triangular facet light field is generated by the Blinn-Phong reflection model widely used in computer graphics. This model uses a combination of ambient, diffuse and specular components to characterize the surface illumination effect of an object. Let L represent the direction of the incident light, N be the normal vector of the observation point, L be the reflection vector of the incident light, and V be the viewing angle vector pointing to the viewer or camera direction. The light intensity Ip at any point in the scene is calculated as follows:

[0073]

[0074] The process of step S5 is to diffract the triangular facet spectrum onto the holographic surface and convert it back to the RGB color space to generate a three-dimensional model color hologram. The triangular facet spectrum obtained above can be diffracted onto the holographic surface to obtain three light field complex amplitudes (H Y ,H Cb ,H Cr The light field of the triangular surface element in the YCbCr color space is converted to obtain the complex amplitude of the light field of the triangular surface element in the RGB color space (H R ,H G ,H B), that is:

[0075]

[0076] The obtained complex amplitude of the triangular surface element light field (H R ,H G ,H B ) is encoded to generate the final color CGH. It should be pointed out that the three color CGHs of RGB given by this method will have an erroneous focusing effect when reconstructing the phenomenon at the same depth distance z. This can be solved by placing the green and blue CGHs respectively at and to compensate for the distance loss.

[0077] Furthermore, the present invention also proposes a specific embodiment for auxiliary explanation:

[0078] The four sets of triangular facet 3D models used to generate color CGI holograms in this specific embodiment are generated by 3Dsmax, namely: "ball", "teapot", "Venus", Figure 6 The three-dimensional model is placed at the center origin of the hologram plane z = 150 mm, the hologram resolution is Nx×Ny=1024×1024, the sampling interval is 8μm, and the wavelengths of the incident light used to generate the hologram are λ r =632.8nm,λ g =532nm,λ b = 457.9nm. Under this condition, when the hologram is illuminated by incident light of a given wavelength, a clear reconstructed image will be formed near z = 150mm. The texture image selected is as follows: Figure 7 As shown, the "Earth" texture image is mapped to the surface of the 3D model of the ball, the "24-color map" texture image is mapped to the surface of the 3D model of the teapot ball, and the "flower" texture image is mapped to the surface of the 3D model of Venus.

[0079] In order to compare different texture mapping methods, this specific embodiment only changes the texture mapping method based on the proposed method and conducts a comparative experiment. Figure 8 The hologram reconstruction results of the three-dimensional model after adding texture images in different mapping methods are given, among which: the first column is the hologram reconstruction result under spherical mapping, the second column is the hologram reconstruction result under plane mapping, and the third column is the hologram reconstruction result under orthogonal mapping. Figure 8It can be seen that the visual effects under different texture mapping methods are also significantly different. The spherical mapping texture performs well in the holographic reconstruction image of the sphere model, but shows serious texture distortion in the Venus model. Therefore, the spherical mapping texture is more suitable for the surface of three-dimensional models with special shapes such as spheres; although the plane mapping texture does not show distortion in the holographic reconstruction result, there is obvious loss of texture information; the orthogonal mapping texture method in the present invention better avoids the shortcomings of the first two texture mapping methods, and its holographic reconstruction retains complete texture information without distortion. The reason is that this mapping method uses the vertex coordinate correspondence between the inclined triangle and the texture triangle to enable the texture information to be more accurately mapped to the three-dimensional model surface, and because the size of the three-dimensional model is taken into account, the loss of texture information caused by inaccurate association during the mapping process is avoided.

[0080] To compare the generation efficiency and quality of the 3D model color computer hologram in RGB and YCbCr color spaces, Table 1 lists the calculation time of the color hologram in the two color spaces. Figure 9-10 The three-channel computer-generated holograms generated in two color spaces are given, where the wavelength of the incident light when generating the color hologram in the YCbCr space is λ r ,The quality of the reconstructed image is evaluated by the structural similarity (SSIM) between two images x,y, which is calculated as follows:

[0081]

[0082] In the formula, u x ,u y are the means of x and y respectively, are the variances of x and y, σ xy is the covariance of x and y, C1=(0.01·L) 2 , C2=(0.03·L) 2 , L = 2 B -1, B is the number of bits of image pixels.

[0083] Table 1 Statistics of calculation time of three groups of 3D model color holograms

[0084]

[0085]

[0086] Table 2 SSIM statistics of color CGH reconstruction images in YcbCr space (λ=632nm) and RGB space

[0087]

[0088] Table 3 SSIM statistics of color CGH reconstruction images in YcbCr space (λ=532nm) and RGB space

[0089]

[0090] Table 4 SSIM statistics of color CGH reconstruction images in YcbCr space (λ=457nm) and RGB space

[0091]

[0092] As can be seen from Table 2, compared with the RGB color space, the computational efficiency of the three-dimensional model color hologram generation in the YcbCr color space is nearly 3 times higher, indicating that the repeated interference calculation of the three RGB color lights can be effectively avoided by using the conversion relationship between the RGB and YcbCr color spaces. Fig.11 A closer look Fig.10 The color reproduction images of the three-channel holograms of each model in the figure, where: the first column is the color reproduction result of the hologram in the RGB color space; the second to fourth columns are the color reproduction results of the hologram obtained with red light, green light, and blue light as the incident light in the YCbCr color space. Theoretically, when generating a color hologram of a three-dimensional model in the YCbCr color space, any one of the red, green, and blue lights can be used as the incident light for calculation, and the holograms of the other two colors can be obtained by using the conversion relationship between the YCbCr and RGB color spaces. Fig.11 At the same time, the same model is given to generate the reconstructed image of the RGB three-channel hologram in the YCbCr color space using green and blue light as the incident light (see Fig.11 The third and fourth columns in the table), the structural similarity between the reconstructed image and the reconstructed image of the three-channel hologram in the RGB color space is listed in Tables 2-4. It can be seen from the data in the table that when generating an RGB three-channel hologram in the CbCr color space, the structural similarity between the reconstructed image of a certain channel hologram directly obtained by calculating a certain color light as the incident light and the corresponding channel hologram in the RGB color space is highly consistent (both greater than 0.99), and the structural similarity of the hologram reconstructed image of the other two color lights indirectly obtained by the conversion relationship between the YCbCr and RGB color spaces is different to varying degrees. In general, when the RGB three-channel hologram is generated in the YCbCr space with red light as the incident light, the average structural similarity of the reconstructed image between it and the three-channel hologram in the RGB space is the best (all models are greater than 0.90). Although it has not yet reached the ideal value of 1.0, in terms of the visual quality of the reconstructed image, the two are very close and no geometric changes can be detected. Therefore, when generating an RGB three-channel hologram in the YCbCr space of the present invention, red light is used as the incident light, thereby greatly improving the efficiency of hologram generation while ensuring the quality of the reproduced image.

[0093] In summary, the present invention has the following beneficial effects:

[0094] 1. Generate color computer-generated holograms that have both illumination information and texture information, which improves the visual effect of color computer-generated holograms.

[0095] 2. Based on the YCbCr color space, repeated calculations of the three RGB color components are avoided, which improves the calculation efficiency of color computer-generated holograms.

[0096] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A high-performance analytical triangular facet color computer-generated hologram generation method, characterized in that: The following steps are involved: Step 1: Generate a hologram based on the 3D model and use external normals to remove hidden surfaces; Step 2: Generate triangular facet spectrum; Step 3: Convert the texture image to YCbCr color space and use orthogonal texture mapping to add texture information to the triangular facet spectrum; Step 4: Adding illumination information to the triangular facet spectrum; Step 5: Diffract the triangular facet spectrum onto the holographic surface and convert it back to the RGB color space to generate a three-dimensional model color hologram.

2. The high-performance analytical triangular facet color CGI hologram generation method according to claim 1, characterized in that: During the execution of step 1, vertex information and facet information are obtained from the three-dimensional model. When generating a hologram, it is necessary to distinguish between visible facets and hidden facets in the three-dimensional model. The basis for determining visible facets is as follows: Assume is the normal vector to the hologram plane, is the normal vector of any triangle face, when When the condition is met, determine whether the triangle element is a visible element.

3. The high-performance analytical triangular facet color CGI hologram generation method according to claim 2, characterized in that: In step 2, the triangular face element is regarded as a triangular light-transmitting aperture, and then the diffraction light field generated on the holographic surface after the incident plane wave passes through the aperture is solved. By combining the three-dimensional affine transformation with the given primitive triangular face element spectrum, the analytical expression of the spectrum of any triangular face element can be obtained.

4. The high-performance analytical triangular facet color CGI hologram generation method according to claim 3, characterized in that: The execution process of step 3 includes the following steps: Step 3.1: RGB-YCbCr color space conversion of texture image; Step 3.2: Map the 2D texture image to the 3D object surface using orthogonal mapping; Step 3.3: Calculate the spectrum of the triangular surface in the YCbCr color space.

5. The high-performance analytical triangular facet color CGI hologram generation method according to claim 4, characterized in that: In step 4, the Blinn-Phong reflection model is used to generate simulated illumination information in the tilted triangular facet light field and add it to the triangular facet spectrum.

6. The high-performance analytical triangular facet color CGI hologram generation method according to claim 5, characterized in that: In step 5, the triangular facet spectrum is diffracted onto the holographic surface and converted back to the RGB color space to generate a three-dimensional model color hologram.

Images