Surface light field compression device, surface light field decoder, surface light field compression program, and surface light field decoding program

Abstract

To implement interpolation of discretely represented light rays through mathematically grounded procedures and systematically compress data.SOLUTION: A surface light field compression device includes: spherical harmonic function expansion means which determines the n-th (n is a natural number) coefficient to be obtained when expanding surface light field described with a set of one or more light rays, using a spherical harmonic function; coefficient multiplexing means which generates light ray data of which the first to the T-th (T is a natural number) coefficients are associated with start point coordinates of the one or more light rays, out of the coefficients determined by the spherical harmonic function expansion means; and light ray multiplexing means which multiplexes one or more pieces of light ray data generated by the coefficient multiplexing means to represent a set of light rays emitted from at least one of an object surface and the space. The set of light rays emitted from at least one of the object surface and the space is modeled.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a surface light field compression device, a surface light field decoding device, a surface light field compression program, and a surface light field decoding program. [Background technology]

[0002] Light fields are a well-known method for representing a collection of light traveling through space. Light fields represent light ray information, which consists of information about the direction of light travel, the position of the light's origin, and information about the light's intensity or color, as one or more collections or fields.

[0003] In computer graphics (CG), modeling light field information makes it possible to reproduce the parallax that occurs when an object is viewed from various angles, differences in appearance due to the optical texture of the object, and the depth of focus that occurs when an object passes through a lens or the eye.

[0004] Among light fields, a light field in which information about the light's starting point position is expressed as the coordinates of a point on the surface of an object in three-dimensional space is called a surface light field. A surface light field can be expressed as a light with color information added to each point in a five-dimensional space consisting of the light's starting point coordinates (X, Y, Z) and the light's traveling direction (θ, φ). The light's starting point coordinates (X, Y, Z) are, for example, in a Cartesian coordinate system. In addition, in the light's traveling direction (θ, φ), θ is the angle with the Z axis, and φ is the azimuth angle. The color information may be the intensity values ​​of the three colors red, green, and blue, or it may be only brightness values, or it may be a spectrum.

[0005] By applying a surface light field to a three-dimensional shape model, it becomes possible to reproduce viewpoint-dependent changes in appearance, such as diffuse reflection, specular reflection, anisotropic reflection, transmission, refraction, and scattering (see, for example, Patent Document 1). Patent Document 1 discloses a technique for discretely expressing a light field by linking one or more vectors consisting of the azimuth and elevation angles of a directional vector, which is the direction of travel of light, and pixel values, which are color information, to the coordinates (X, Y, Z) of the light's starting point. Meanwhile, Non-Patent Document 1 discloses research using spherical harmonics to describe directional colors in a radiance field. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-8697 [Non-patent literature]

[0007] [Non-Patent Document 1] B.Kerbl, G.Kopanas, T.Leimkuhler, G.Drettakis, "3D Gaussian Splatting for Real-Time Radiance Field Rendering", ACM Trans. Graph., Vol.42, No.4, August 2023. Summary of the Invention [Problem to be solved by the invention]

[0008] The surface light field adds color information to points in five-dimensional space, resulting in a huge amount of data.

[0009] The technology described in Patent Document 1 can reduce the amount of data by representing a light field using one or more discretized light rays. However, this representation does not include information about light observed from directions that do not match the directions of any of the one or more discretized light rays, so interpolation is required to represent that light. Furthermore, although the technology described in Patent Document 1 can reduce the amount of data by thinning out the number of light rays, it cannot systematically derive which light rays should be thinned out.

[0010] The technology described in Non-Patent Document 1 makes it possible to represent differences in the appearance of colors depending on the viewpoint. However, the technology described in Non-Patent Document 1 is formulated with the aim of approximating a radiance field, and does not perform interpolation for discretely expressed light rays.

[0011] An embodiment according to the present disclosure aims to realize interpolation of discretely expressed rays using a mathematically proven procedure, and to systematically realize data compression. [Means for solving the problem]

[0012] A surface light field compression device according to an embodiment of the present disclosure includes: spherical harmonic function expansion means for calculating the n-th coefficient when a surface light field described by a set of one or more rays is expanded using spherical harmonic functions, where n is a natural number; coefficient multiplication means for generating light ray data in which the 1st to T-th coefficients among the coefficients calculated by the spherical harmonic function expansion means are linked to the coordinates of the starting points of the one or more rays; and ray multiplexing means for expressing a set of rays emitted from at least one of an object surface and space by multiplexing one or more of the light ray data generated by the coefficient multiplication means, thereby modeling the set of rays emitted from at least one of the object surface and space. [Effects of the Invention]

[0013] According to the embodiments of the present disclosure, interpolation of discretely expressed rays can be realized using a mathematically proven procedure, and data compression can be systematically achieved. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram illustrating an example of the configuration of a surface light field compression device according to a first embodiment. [Figure 2] 1 is a flowchart showing processing by a surface light field compression device according to the first embodiment. [Figure 3A] FIG. 2 is a schematic diagram showing a surface light field discrete model in the surface light field compression device according to the first embodiment. [Figure 3B] FIG. 2 is a schematic diagram showing a continuous model obtained by interpolating a surface light field discrete model in the surface light field compression device according to the first embodiment. [Figure 4] FIG. 10 is a block diagram showing an example of the configuration of a surface light field decoding device according to a second embodiment. [Figure 5] 10 is a flowchart showing processing by the surface light field decoding device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments will be described with reference to the drawings. To facilitate understanding of the description, the same components in each drawing will be assigned the same reference numerals whenever possible, and duplicate descriptions will be omitted as appropriate. Note that the embodiments described below exemplify a surface light field compression device, a surface light field decoding device, a surface light field compression program, and a surface light field decoding program for embodying the technical ideas of the present disclosure, and the present disclosure is not limited to the embodiments described below.

[0016] [First embodiment] <Configuration of the surface light field compression device according to the first embodiment> The configuration of a surface light field compression device according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an example of the configuration of a surface light field compression device 1 according to the first embodiment.

[0017] The surface light field compression device 1 is a device that models a set of light rays emitted from at least one of an object surface and a space. For example, the surface light field compression device 1 models a set of light rays emitted from at least one of an object surface and a space, and compresses data related to the set of modeled light rays.

[0018] As shown in FIG. 1, the surface light field compression device 1 includes a spherical harmonic function expansion means 12 that calculates the n-th coefficient when a surface light field described by a set of one or more light rays is expanded using a spherical harmonic function, where n is a natural number. The surface light field compression device 1 also includes a coefficient multiplexing means 13 that generates light ray data in which the first to T-th coefficients among the coefficients calculated by the spherical harmonic function expansion means 12 are linked to the coordinates of the starting points of one or more light rays. The surface light field compression device 1 also includes a ray multiplexing means 14 that multiplexes one or more pieces of light ray data generated by the coefficient multiplexing means 13 to represent a set of light rays emitted from at least one of the object surface and space. The surface light field compression device 1 shown in FIG. 1 also includes a first vertex selection means 11 that outputs the three-dimensional position vector of the m-th vertex selected from M vertices that make up the point cloud, where M and m are natural numbers, and all light rays multiplexed at that vertex.

[0019] The surface light field compression device 1 receives a discrete surface light field model H0 in which the surface light field is discretely modeled. The discrete surface light field model H0 is represented by a plurality of rays associated with a plurality of parts in a three-dimensional shape.

[0020] A three-dimensional shape model can be expressed in any format, such as a mesh, voxel, or point model. In the following description, a three-dimensional shape modeled using a point cloud is exemplified. However, even when a three-dimensional shape is modeled using a mesh, the following description using a point cloud as an example of modeling can also be applied to mesh modeling, provided that the vertices constituting the mesh are regarded as the vertices of a point cloud. Furthermore, even when a three-dimensional shape is modeled using voxels, the following description using a point cloud as an example of modeling can also be applied to voxel modeling, provided that the centers of each voxel are regarded as the vertices of the point cloud.

[0021] If a 3D shape is modeled by a point cloud consisting of M vertices, then the mth vertex V (m) Three-dimensional position vector S (m) is expressed by equation (1). Note that T in equation (1) represents transposition.

[0022]

number

[0023] As shown in equation (2), the vertex V (m) N (m) Contains N rays. (m) In this example, the nth ray is expressed as a vector L n (m) It is expressed as follows. (m) is a natural number greater than or equal to 2. n is a number greater than or equal to 1. (m) The following natural numbers:

[0024]

number

[0025] Vector L n (m)is composed of information about the direction in which a ray of light travels and information about the color of the ray of light. For example, the information about the direction in which a ray of light travels can be expressed by the unit vector shown in equation (3) in a world coordinate system, such as an orthogonal coordinate system consisting of the X, Y, and Z axes. The right-hand side of equation (3) represents the unit sphere, i.e., equation (4).

[0026]

number

[0027]

number

[0028] The information on the direction of travel of the light ray is given by the azimuth angle α n (m) and the angle δ with the Z axis n (m) It may be expressed as:

[0029]

number

[0030] "atan2(Y,X)" in equation (5) is the vector [X,Y] in the XY plane, as shown in equation (6). T This is a function to calculate the argument of .

[0031]

number

[0032] According to the following equation (7), the azimuth angle α n (m) and the angle δ with the Z axis n (m) can also be converted to the unit vector in equation (3).

[0033]

number

[0034] The color information of the light beam may be the brightness value of a monochrome image, and may be expressed as a vector C consisting of the brightness of a predetermined number of primary colors, for example, red (r), green (g), and blue (b). n (m) may be.

[0035] The color information of the light beam is expressed as the luminance values ​​r for each of the red, green, and blue primary colors. n (m) , g n (m) and b n (m) When expressed as above, it can be expressed as in equation (8).

[0036]

number

[0037] Ray L n (m) is expressed as in equation (9).

[0038]

number

[0039] In the example shown in FIG. 1, the first vertex selection means 11 selects the m-th vertex from M vertices that make up the point cloud and calculates the three-dimensional position vector S (m) (hereinafter referred to as the starting point coordinates) and all rays expressed by the following equation (10) that are multiplexed on the vertex (hereinafter referred to as the ray group) are output.

[0040]

number

[0041] The spherical harmonic function expansion means 12 expands the group of rays (L1, L2, . . . , L N )(L n =[α n ,δ n ,r n,g n ,b n ] T ) is approximated for each color component by expansion coefficients using spherical harmonic functions, and the expansion coefficient sequence for each color component expressed by equation (11) is output.

[0042]

number

[0043] R k,l is the expansion coefficient for the red component. G k,l is the expansion coefficient for the green component. B k,l is the expansion coefficient for the blue component. However, when K is an integer greater than or equal to 0, k is an integer greater than or equal to 0 and less than or equal to K, and l is an integer greater than or equal to -k and less than or equal to k.

[0044] Gathering W R is the set of indices of the expansion coefficient sequence for the red component. G is the set of indices of the expansion coefficient sequence for the green component. B is the set of subscripts of the expansion coefficient sequence for the blue component. Note that these sets are the same, i.e., W R =W G =W B =W can also be used.

[0045] The set W can be expressed by equation (12).

[0046]

number

[0047] In equation (12), the number of elements T in the set W is T=(K+1) 2 This becomes:

[0048] Spherical harmonic function Y k,l (θ,φ) is defined by equation (13).

[0049]

number

[0050] The spherical harmonic function expansion means 12 derives the expansion coefficient sequences for each color component represented by Equation (11) through the following procedure using Equations (14) to (18).

[0051] [Number] Note that the superscript * represents the complex conjugate.

[0052] [α n , δ n T It is desirable that the direction vector represented by [α n , δ n T has a direction obtained by sampling the unit sphere with n ∈ {1, 2, ···, N}. On the other hand, when the direction vector represented by [α n , δ n T can only be obtained in the upper hemisphere direction, etc., it may be A steradians (A is a real number with 0 < A ≤ 4π) out of the total solid angle of 4π steradians. In that case, the approximation accuracy can be improved by using the following Equation (15) instead of Equation (14).

[0053] [Number]

[0054] Here, the expansion coefficient sequences for each color component obtained by inputting the ray group (L1 (m) , L2 (m) , ···, L N (m) )(L n (m) = [α n (m) , δ n (m) , r n (m) , g n <00​​​​​​

[0055]

number

[0056] The coefficient multiplication means 13 multiplies the starting point coordinate S output from the first vertex selection means 11 by (m) The ordered set (quad) Q expressed by equation (17) is obtained by multiplying the expansion coefficient sequence expressed by equation (16). (m) Output.

[0057]

number

[0058] The beam multiplexing means 14 multiplexes the quadruple Q generated by the coefficient multiplexing means 13. (m) is multiplexed for all m∈{1, 2, , M} selected by the first vertex selection means 11. As a result, the ray multiplexing means 14 generates a surface light field spherical harmonic function expansion model H. The ray multiplexing means 14 outputs the generated surface light field spherical harmonic function expansion model H. The ray multiplexing means 14 multiplexes, for example, a quadruple Q for all m∈{1, 2, , M}. (m) The ordered set is output as a surface light field spherical harmonic function expansion model H shown in the following equation (18).

[0059]

number

[0060] <Processing by the surface light field compression device 1 according to the first embodiment> Fig. 2 is a flowchart showing an example of processing by the surface light field compression device 1. The surface light field compression device 1 starts the processing shown in Fig. 2 when, for example, a surface light field discrete model H0 is input.

[0061] First, in step S11, the surface light field compression device 1 selects a three-dimensional position vector S as a starting point coordinate by the first vertex selection means 11. (m) and a group of rays multiplexed at the starting point coordinates.

[0062] Subsequently, in step S12, the surface light field compression device 1 converts the surface light field described by a set of one or more rays into a spherical harmonic function Y k,l The n-th coefficient when expanded by (θ, φ) is obtained by the spherical harmonic expansion means 12.

[0063] Next, in step S13, the surface light field compression device 1 generates an ordered set (quad) Q(m) by the coefficient multiplexing means 13 as ray data in which the first to Tth coefficients among the coefficients acquired by the spherical harmonic expansion means 12 are linked to the starting point coordinates of one or more rays.

[0064] Next, in step S14, the surface light field compression device 1 multiplexes one or more pieces of light ray data generated by the coefficient multiplexing means 13, thereby representing a set of light rays emitted from at least one of the object surface and space using the light ray multiplexing means 14. The light ray multiplexing means 14 generates a surface light field spherical harmonic function expansion model H.

[0065] Subsequently, in step S15, the surface light field compression device 1 outputs the surface light field spherical harmonic expansion model H by the ray multiplexing means 14.

[0066] As described above, the surface light field compression device 1 can model a set of light rays emitted from at least one of an object surface and space. For example, the surface light field compression device 1 can model a set of light rays emitted from at least one of an object surface and space, and compress data related to the set of modeled light rays. Furthermore, in this embodiment, it is possible to provide a surface light field compression program that causes the surface light field compression device 1 to execute the processing shown in FIG. 2 .

[0067] <Operational Effects of the Surface Light Field Compression Device 1 According to the First Embodiment> In this way, the surface light field compression device 1 can realize the interpolation of discretely expressed light rays using a mathematically supported procedure and can systematically realize data compression. Note that "interpolation of discretely expressed light rays" means obtaining a surface light field that includes light observed from directions that do not match any of the directions of one or more discretized light rays.

[0068] In the surface light field compression device 1, for example, if 25 light rays are assigned to the surface light field discrete model, the number of samples can be reduced by 16 / 25 = 0.64 times by approximating with 16 expansion coefficients. Also, if 25 light rays are assigned to the surface light field discrete model, the number of samples can be reduced by 9 / 25 = 0.36 times by approximating with 9 expansion coefficients.

[0069] In the surface light field compression device 1, the spherical harmonic function expansion means 12 expands a set of one or more light rays into a spherical harmonic function Y for each color component. k,lThe surface light field is approximated using expansion coefficients based on (θ,φ) and a sequence of expansion coefficients for each color component is output. The surface light field is a collection of light rays emitted from each point on the object surface. From the perspective of representation symmetry, the approximation process is most simplified by considering a unit sphere centered on the point of interest and recording the light intensity in each direction on that unit sphere. Furthermore, when performing compression and / or data volume control on uniformly sampled data in a Cartesian coordinate system, it is common to perform expansion using sinusoidal basis functions, such as Fourier transforms and cosine transforms. On the other hand, when performing compression and / or data volume control on uniformly sampled data in a spherical coordinate system, it is appropriate to use spherical harmonics, which enable uniform representation, rather than sine waves. As described above, the surface light field compression device 1 can simplify and homogenize the approximation process by approximating the surface light field described in a spherical coordinate system as a collection of one or more light rays using spherical harmonic function expansion.

[0070] The surface light field compression device 1 can control the approximation accuracy and data volume of the surface light field according to the number of associated spherical harmonic function expansion coefficients. Furthermore, since spherical harmonic functions are continuous functions, it is possible to calculate the amplitude of light rays in any direction, and it is possible to naturally realize the interpolation processing required for a light field with a collection of discrete light rays.

[0071] The relationship between the surface light field discrete model and the continuous model obtained by interpolating the surface light field discrete model will be described in detail with reference to Figures 3A and 3B. Figure 3A is a schematic diagram showing the surface light field discrete model. Figure 3B is a schematic diagram showing the continuous model obtained by interpolating the surface light field discrete model.

[0072] FIG. 3A shows a first discrete model 201a, a second discrete model 202a, a third discrete model 203a, and a fourth discrete model 204a as models of discretely expressed light rays. FIG. 3B shows a first continuous model 201b, a second continuous model 202b, a third continuous model 203b, and a fourth continuous model 204b as continuous models obtained by interpolating the models of discretely expressed light rays. The first continuous model 201b is obtained by interpolating the first discrete model 201a. The second continuous model 202b is obtained by interpolating the second discrete model 202a. The third continuous model 203b is obtained by interpolating the third discrete model 203a. The fourth continuous model 204b is obtained by interpolating the fourth discrete model 204a.

[0073] As shown in FIGS. 3A and 3B, the surface light field compression device 1 uses a spherical harmonic function Y k,l Interpolation is performed using (θ, φ). As a result, the surface light field compression device 1 can express discretely expressed light rays as a set of multiple light rays whose traveling direction changes continuously between adjacent light rays.

[0074] [Second embodiment] Next, a surface light field decoding device according to a second embodiment will be described with reference to Fig. 4. Note that the same names and symbols as those in the already described embodiments indicate the same or similar members or configurations, and detailed descriptions thereof will be omitted as appropriate.

[0075] <Configuration of a surface light field compression device according to the second embodiment> 4 is a block diagram showing an example of the configuration of a surface light field decoding device 2 according to the second embodiment. Based on the coefficients output from the surface light field compression device 1 according to the first embodiment, the surface light field decoding device 2 derives light rays observed from any specified direction as the sum of spherical harmonic functions multiplied by the coefficients. For example, the surface light field decoding device 2 can decode a set of light rays modeled by the surface light field compression device 1.

[0076] 4, the surface light field decoding device 2 includes a second vertex selection means 21, a coefficient demultiplexing means 22, a line of sight vector calculation means 23, and a spherical harmonic function substitution means 24. The surface light field decoding device 2 shown in FIG. 4 selects a vertex V of a specified vertex number m in an input surface light field spherical harmonic function expansion model H. (m) The color when observed from the viewpoint coordinate p is calculated and output as color information expressed by the following equation (19).

[0077]

number

[0078] The second vertex selection means 21 selects a quadruple Q, which is the m-th term of the surface light field spherical harmonic function expansion model H, based on the input surface light field spherical harmonic function expansion model H and the input vertex number m. (m) Extract and output.

[0079] The coefficient demultiplexing means 22 demultiplexes the input quadruple Q (m) From the starting coordinate S (m) and the expansion coefficient sequence for each color component expressed by equation (11). (m) is input to line-of-sight vector calculation means 23. Furthermore, coefficient demultiplexing means 22 inputs the expansion coefficient sequence for each color component to spherical harmonic function substitution means 24.

[0080]

number

[0081] The line-of-sight vector calculation means 23 calculates the line-of-sight vector by calculating the line-of-sight vector p and the start point coordinate S (m) Based on this, the starting point S (m) Vector q=[qx,qy,qz] from to viewpoint coordinate p T Calculate.

[0082]

number

[0083] Furthermore, the line-of-sight vector calculation means 23 converts the vector q into the azimuth angle and the angle with the axis shown in equation (22), and inputs the conversion result to the spherical harmonic function substitution means 24.

[0084]

number

[0085] The spherical harmonic function substitution means 24 substitutes the azimuth angle and the angle with the Z axis shown in equation (22) into the spherical harmonic function, and then calculates the expansion coefficient R k,l , G k,l and B k,l The color vector calculated by equation (23) is output as color information by weighting and summing the weights.

[0086]

number

[0087] <Processing by the surface light field decoding device 2 according to the second embodiment> 5 is a flowchart showing an example of processing by the surface light field decoding device 2. The surface light field decoding device 2, for example, converts a surface light field described by a set of one or more rays into a spherical harmonic function Yk,l When the coefficients expanded by (θ, φ) are input from the surface light field compression device 1, the process shown in FIG. 5 is started.

[0088] First, in step S21, the surface light field decoding device 2 decodes a light ray observed from an arbitrary specified direction using a spherical harmonic function Y k,l It is derived as the sum of (θ, φ) multiplied by the above coefficients.

[0089] Subsequently, in step S22, the surface light field decoding device 2 converts the azimuth angle φ and the angle θ with the Z axis into a spherical harmonic function Y k,l The color vector calculated by weighting the expansion coefficients and taking the sum of what is substituted into (θ, φ) is output as color information.

[0090] In this way, the surface light field decoding device 2 decodes the light ray observed from any specified direction based on the coefficients output from the surface light field compression device 1 using the spherical harmonic function Y k,l For example, the surface light field decoding device 2 can decode a set of rays modeled by the surface light field compression device 1.

[0091] The surface light field decoding device 2 can reconstruct color information observed when viewed from a specified viewpoint position from the surface light field approximately expressed by spherical harmonic functions. Furthermore, this embodiment can provide a surface light field decoding program that causes the surface light field decoding device 2 to execute the processing shown in Fig. 5.

[0092] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0093] The ordinal numbers, quantities, and other numbers used in the above-described embodiments are all provided as examples to specifically explain the technology of the present disclosure, and the present disclosure is not limited to the illustrated numbers. Furthermore, the connection relationships between the components are provided as examples to specifically explain the technology of the present disclosure, and the connection relationships that realize the functions of the present disclosure are not limited to these. [Explanation of symbols]

[0094] 1. Surface Light Field Compressor 11 First vertex selection means 12 Spherical harmonic function expansion method 13 Coefficient multiplexing means 14 Ray multiplexing means 2. Surface Light Field Decoder 21 Second vertex selection means 22 Coefficient demultiplexing means 23. Gaze vector calculation means 24 Spherical Harmonic Function Substitution Method 201a First Discrete Model 202a Second Discrete Model 203a Third Discrete Model 204a Fourth Discrete Model 201b 1st serial model 202b 2nd consecutive model 203b 3rd consecutive model 204b 4th consecutive model

Claims

1. a spherical harmonic function expansion means for calculating an n-th coefficient when a surface light field described by a set of one or more light rays is expanded by a spherical harmonic function, where n is a natural number; a coefficient multiplexing means for generating light ray data in which the first to T-th coefficients among the coefficients calculated by the spherical harmonic function expansion means are linked to the coordinates of the starting points of the one or more light rays, where T is a natural number; a ray multiplexing means for multiplexing one or more of the ray data generated by the coefficient multiplexing means to represent a set of rays emitted from at least one of an object surface and space, A surface light field compressor that models a set of light rays emanating from at least one of the object surface and the space.

2. 2. The surface light field compression device according to claim 1, further comprising a first vertex selection means for outputting a three-dimensional position vector of an m-th vertex selected from M vertices constituting the point cloud, where M and m are natural numbers, and all light rays multiplexed onto the vertex.

3. 2. The surface light field compression device according to claim 1, wherein the spherical harmonic function expansion means approximates the set of one or more light rays with expansion coefficients by spherical harmonic functions for each color component, and outputs a sequence of expansion coefficients for each color component.

4. 4. A surface light field decoding device that derives light rays observed from any specified direction as the sum of the spherical harmonic functions multiplied by the coefficients, based on the coefficients output from the surface light field compression device according to any one of claims 1 to 3.

5. The n-th coefficient when a surface light field described by a set of one or more light rays is expanded by a spherical harmonic function, where n is a natural number, is calculated by a spherical harmonic function expansion means; generating, by coefficient multiplexing means, light ray data in which the first to T-th coefficients among the coefficients calculated by the spherical harmonic function expansion means are linked to the coordinates of the starting points of the one or more light rays, where T is a natural number; expressing a set of light rays emitted from at least one of an object surface and a space by a light ray multiplexing means by multiplexing one or more of the light ray data generated by the coefficient multiplexing means; Modeling a set of rays emanating from at least one of the object surface and the space. A surface light field compression program that causes a surface light field compression device to perform the processing.

6. When a surface light field described by a set of one or more light rays is expanded using a spherical harmonic function, where n is a natural number, the n-th coefficient is used to derive the light rays observed from any specified direction as the sum of the spherical harmonic functions multiplied by the coefficients. A surface light field decoding program that causes a surface light field decoding device to execute the process.

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