CN117893670B - Real-time global illumination rendering method, device and electronic device - Google Patents

Abstract

The application provides a real-time global illumination rendering method, a device and electronic equipment, wherein the real-time global illumination rendering comprises the following steps: voxelization is carried out on the scene geometry of the current frame to obtain distance field voxels, wherein the attributes of the distance field voxels comprise: vector distance field, normal vector, albedo, and emission value; calculating direct illumination of a main light source with preset intensity to each distance field voxel and taking the direct illumination as emergent radiance; the outgoing radiance of the distance field voxels is anisotropically filtered to form a hierarchy to generate directional voxels; the outgoing emittance of the directional voxels is collected by the cone of ray bundles and the indirect illumination is calculated. The method and the device improve the running efficiency of real-time illumination, ensure the accuracy of illumination and improve the 3D rendering effect.

Description

Real-time global illumination rendering method, device and electronic device

Technical Field

The present application relates to the technical field of computer graphics, and in particular to a real-time global illumination rendering method, device and electronic device.

Background Art

In computer graphics, accurately computing the distribution of light in a scene is an important aspect of achieving realism, and such computations are usually expensive because light does not travel along straight paths, but bounces, scatters, and is absorbed by different objects in the scene.

The standard rendering pipeline uses triangles to represent the geometry of the scene, which are then rasterized, shaded, and ultimately displayed on the screen. This representation is efficient for local fragment operations such as direct lighting, but has many limitations for more complex operations such as global illumination.

Currently, global illumination methods in 3D graphics generally have problems such as excessive consumption, light leakage and low efficiency.

Summary of the invention

In view of this, the present application provides a real-time global illumination rendering method, device and electronic device. The method establishes an effective voxel-based lighting process for storing outgoing radiation, including solutions to voxel occlusion and voxel normal attenuation errors and an efficient voxel global illumination process, and uses cone tracing to solve the problems of excessive consumption, light leakage and low efficiency that are common in global illumination methods in 3D graphics.

In a first aspect, an embodiment of the present application provides a real-time global illumination rendering method, comprising:

voxelize the scene geometry of the current frame to obtain distance field voxels, wherein the attributes of the distance field voxels include: vector distance field, normal vector, albedo and emission value;

Calculate the direct light from the main light source of preset intensity to each distance field voxel as the outgoing radiance;

Anisotropically filtering the outgoing radiance of the distance field voxels to form a hierarchy to generate directional voxels;

Ray bundles through the cone collect outgoing radiance from directional voxels and compute indirect lighting.

In a possible implementation, voxelization is performed on the scene geometry of the current frame to obtain distance field voxels; including:

For each projected triangle of the scene geometry of the current frame, generate a bounding polygon larger than the projected triangle to generate at least one fragment, each fragment having different attributes including: an inverse normal vector, an albedo, and an emission value;

Averaging the properties of all fragments within a voxel to obtain the properties of the voxel;

Use the layered distance field representation stored in a 3D texture to represent the scene geometry, resulting in a vector distance field for the scene geometry.

In one possible implementation, the method further includes:

When the distance field voxel of the previous frame is a dynamic voxel, the attribute body and radiation body of the current frame are updated;

When the distance field voxel of the previous frame is a static voxel, the distance field voxel of the current frame uses the value of the previous frame;

Marks whether the distance field voxel of the current frame is a dynamic voxel or a static voxel.

In a possible implementation, the direct illumination of a main light source with a preset intensity on each distance field voxel is calculated as the outgoing radiance, including:

Calculate the normal falloff vector D _x,y,z for each face of the distance field voxel:

Among them, Ψ is the light direction; is the voxel normal vector for each face;

The three principal faces D _ω are selected according to the axis signs of the average normal N _ω of each face of the voxel:

Then the outgoing radiance _Vr of the main light source with preset intensity irradiating the distance field voxel is:

W＝ ^N2

Among them, _Li is the preset intensity of the main light source, ρ is the albedo of the voxel, N is the voxel normal vector, W is the voxel average normal weight vector: W = ( _Wx , _Wy , _Wz ), ( _Dx , _Dy , _Dz ) is the vector of the product of the normal attenuation vectors of the three main surfaces.

In a possible implementation, determining whether a voxel is occluded includes:

The position of the voxel is projected in light space and the depth of the projected point is compared to the stored depth from the shadow map to determine whether the voxel is occluded.

In one possible implementation, the outgoing radiance of the distance field voxel is anisotropically filtered to form a hierarchy to generate directional voxels; comprising:

Divide the distance field voxels, then sum and average the distance field voxels in each axis, and interpolate the radiation value according to the angle of the light during sampling;

Anisotropic filtering is used, storing six direction values for each distance field voxel;

The oriented voxels are obtained by linear interpolation of the three samples obtained from the selected oriented volume.

In one possible implementation, a cone of rays collects outgoing radiance from directional voxels and computes indirect lighting, including:

Get the occlusion value _da and the outgoing radiance _dc from the directional voxel;

After the light steps through the cone for the mth time, the indirect illumination value _cm and the tracking occlusion value _αm are:

c _m =c _m-1 α _m-1 + (1-α _m-1 )d _a d _c

α _m =α _m-1 +(1-α _m-1 )d _a

Among them, C _m-1 and α _m-1 are the indirect lighting value and tracking occlusion value of the light after the m-1th step of the cone.

In a second aspect, an embodiment of the present application provides a real-time global illumination rendering device, comprising:

A voxelization unit, used for voxelizing the scene geometry of the current frame to obtain distance field voxels, wherein the attributes of the distance field voxels include: vector distance field, normal vector, albedo and emission value;

A direct lighting calculation unit, used to calculate the direct lighting of the main light source with a preset intensity irradiated on each distance field voxel as the outgoing radiance;

A processing unit for anisotropically filtering outgoing radiances of distance field voxels to generate directional voxels;

The indirect lighting calculation unit is used to collect the outgoing radiance of directional voxels through a cone of light beams and calculate the indirect lighting.

In a third aspect, an embodiment of the present application provides an electronic device, comprising: a memory and a processor, wherein an executable program is stored in the memory, and the processor executes the executable program to implement the steps of the method of the embodiment of the present application.

In a fourth aspect, an embodiment of the present application provides a storage medium, wherein the storage medium carries one or more computer programs, and when the one or more computer programs are executed by a processor, the steps of the method of the embodiment of the present application are implemented.

This application improves the operating efficiency of real-time lighting, ensures the correctness of lighting, and improves 3D rendering effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a flow chart of a real-time global illumination rendering method provided by an embodiment of the present application;

FIG2( a ) is a schematic diagram of determining whether there is a voxel at the position of a ray provided in an embodiment of the present application;

FIG2( b ) is a schematic diagram of a ray passing through a boundary of a voxelized geometric body provided in an embodiment of the present application;

FIG3 is a functional structure diagram of a real-time global illumination rendering device provided in an embodiment of the present application;

FIG. 4 is a functional structure diagram of an electronic device provided in an embodiment of the present application.

DETAILED DESCRIPTION

Various aspects and features of the present application are described herein with reference to the accompanying drawings.

It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but only as an example of an embodiment. Other modifications within the scope and spirit of the present application will occur to those skilled in the art.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the general description of the present application given above and the detailed description of the embodiments given below, serve to explain the principles of the present application.

These and other characteristics of the present application will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

It should also be understood that although the present application has been described with reference to some specific examples, those skilled in the art will be able to readily implement many other equivalent forms of the present application.

The above and other aspects, features and advantages of the present application will become more apparent in view of the following detailed description when taken in conjunction with the accompanying drawings.

Specific embodiments of the present application are described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments applied for are merely examples of the present application, which may be implemented in a variety of ways. Well-known and/or repeated functions and structures are not described in detail to avoid unnecessary or redundant details that obscure the present application. Therefore, the specific structural and functional details applied for herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present application in a variety of ways with substantially any suitable detailed structure.

This specification may use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present application.

First, the design concept of the embodiments of the present application is briefly introduced.

Calculating global illumination is a challenging and complex problem for real-time rendering in 3D applications. Currently, global illumination methods in 3D graphics generally suffer from problems such as excessive consumption, light leakage, and efficiency.

To this end, the present application proposes a global illumination rendering method, which uses a vector distance field for step tracing to calculate the outgoing radiation stored in the voxel and a simplified version of the scene to calculate indirect lighting in real time. This method includes diffuse reflection, specular reflection and double-reflection indirect lighting of emissive materials. The relevant structure in the distance field is based on a directional hierarchical structure stored in a 3D texture through mipmapping, which is updated in real time using the GPU and can approximate the indirect lighting of dynamic scenes. A vector distance field-based light path is used to directly calculate the effective voxels in the distance field. And global illumination, ambient occlusion, soft shadows and indirect lighting for simplified outgoing radiation.

The method of the embodiment of the present application uses discretization of the scene with voxel and cone tracking to achieve:

A real-time distance field calculation process that stores only the information needed to capture direct and indirect lighting for each voxel.

An efficient voxel-based lighting process that stores outgoing radiance, including solutions for voxel occlusion and voxel normal falloff errors.

An efficient voxel global illumination pass that uses cone tracing to expand the filtered outgoing radiance with an indirect diffuse term.

This application improves the operating efficiency of real-time lighting, ensures the correctness of lighting, and improves 3D rendering effects.

After introducing the application scenarios and design concepts of the embodiments of the present application, the technical solutions provided by the embodiments of the present application are described below.

As shown in FIG1 , an embodiment of the present application provides a real-time global illumination rendering method, comprising:

Step 101: voxelizing the scene geometry of the current frame to obtain distance field voxels, the attributes of which include: vector distance field, normal vector, albedo and emission value;

Among them, the embodiment of the present application uses a layered distance field stored in a 3D texture to represent discrete scene geometry, for which a step-wise vector distance field construction process is used. Only the lighting data required for diffuse lighting, such as normals and albedo, is stored in the voxel using the average operation of all fragments in the distance field voxel space. In addition, emission is also stored to approximate the luminous surface.

Step 102: Calculate the direct illumination of the main light source of preset intensity onto each distance field voxel and use it as the outgoing radiance;

Outgoing radiance is computed for each distance field voxel, and for direct diffuse lighting, standard lighting techniques are used. An averaging operation is used during voxelization, which can lead to undesired normal directions for the resulting average normal. This can create loading issues for the normal attenuation term. To reduce this problem, a normal-weighted directional shading model for normal attenuation is proposed. To compute occlusion, ray casting is used in addition to standard shadow mapping techniques: a ray is traced from the voxel position in the light direction, and the voxel volume is sampled to test for ray-voxel collisions.

Step 103: The outgoing radiance of the distance field voxel is subjected to anisotropic filtering to form a hierarchy to generate a directional voxel;

The embodiment of the present application uses anisotropic filtering to fill the levels of the voxel representation hierarchy to generate directional voxels. To this end, directional integrals and averaging operations are used to filter the values from higher to lower detail levels in the hierarchy in the axial direction; the detail levels are stored in mipmap levels for 3D textures. The MIPMAP method is equivalent to texture LOD. When an object is close to the observer, a high-resolution MIPMAP image is used: when the object gradually moves away from the observer, a low-resolution image is used.

Texture is not just a piece of image data, it may be a series of image data, because when the image is enlarged or reduced, the texture needs to be interpolated, which is a time-consuming process. In order to avoid this time-consuming calculation and improve performance, the graphics card uses a multi-level texture method for one image. Different levels of texture are used according to the distance between the camera and the texture. For example, if the camera is close to the texture, a larger texture is selected, and if the camera is far from the texture, a smaller texture is selected. This is a multi-level texture.

Step 104: Collect the outgoing radiance of the directional voxels through the cone of rays and calculate the indirect lighting.

To approximate the second bounce of indirect light, another step can be added after filtering the values from the outgoing radiance calculation. At this point, the necessary information to calculate the indirect diffuse component using cone tracing is available in the voxel structure. For each voxel, cone tracing is performed to approximate the indirect diffuse component, and then the filtering step is repeated, so that the outgoing radiance in the voxel representation now contains both direct lighting and the first bounce of the indirect diffuse.

Diffuse and specular reflections, as well as ambient occlusion. For each visible fragment, direct and indirect lighting are calculated. For the indirect component, a final acquisition scheme is used, tracing a cone over a hemisphere in the normal direction to collect the outgoing radiance stored in the voxel representation.

Specifically, the specific implementation process of step 101 is as follows:

During voxelization, normal vectors, albedo, and emission values are stored in voxels, with each attribute having its own 3D texture. This information is necessary to calculate diffuse and normal falloff for separate light paths, where instead of calculating lighting per pixel, it is calculated per voxel. This structure can be extended to support more complex prediction models, but this may mean higher memory consumption for storing the additional data.

Additionally, the distance field step tracing process uses another structure. The lighting calculation results for each voxel are stored in another 3D texture, called the radiation volume. To approximate the increasing diameter of the cone and its sampling volume, the level of detail of the voxelized scene is used. For anisotropic voxels, six 3D textures with half the resolution of the radiation volume are needed, one texture for each axis, also in positive and negative directions. The level of detail is stored in the mipmap levels of these textures, called directional volumes.

The radiation volume represents the maximum level of detail of the voxelized scene, this texture is separate from the direction volume. To bind these two structures, linear interpolation is used between samples of the two structures when the mipmap level required by the distance field range is between the maximum level and the first filtered level of detail.

The voxelization process is performed using a conservative voxelization scheme, which means that if the geometry exists in the voxel's space, there must be a voxel in that space. A thin surface voxelization of a triangle can be calculated for each voxel B by testing whether the plane defined by the triangle's vertices intersects B, and whether the 2D projection of the triangle along its normal's principal axis intersects the 2D projection of B.

For each projected triangle, a slightly larger bounding polygon is generated to ensure that no matter how small the projected triangle is, it will generate at least one fragment. To create this polygon, each triangle edge is moved outward so that the triangle is enlarged. The bounding polygon does not overestimate the coverage of the projected triangle, so excess fragments are discarded using the expanded bounding box defined by the projected triangle vertices.

A voxel can contain many fragments, and all of these fragments can have different values for the stored attributes (i.e. albedo, normal, and emission). To get a good approximation of the discrete geometry, an average operation is applied to all values within the voxel space for each attribute. Attributes must be written and read using atomic operations at each voxel location in their respective 3D texture to ensure temporally consistent results.

For dynamic updates, the attribute calculations of the corresponding vector distance fields of static and dynamic geometry are separated. Although static voxelization occurs only once, dynamic voxelization occurs in each frame or when needed. Voxelization of the two types of geometry occurs in the same process described above, so a method is needed to indicate which voxels are static. The embodiment of the present application uses a single-valued 3D texture to identify static voxels. This texture will be referred to as a flow volume. During the static voxelization process, after the voxel is generated, a value is written to the flow volume to indicate that the position is static. In contrast, during the dynamic voxelization process, before the voxel is generated, a value is read from the flow volume at the voxel write position. If the value indicates that the position is marked as static, the write is abandoned, leaving the static voxel unchanged.

In order to continuously reshape the scene, it is necessary to clear previously stored dynamic voxels from the 3D texture. This is done before dynamic voxelization using general-purpose computation on the graphics processing unit (GPU) or computation with ComputeShading. The flow volume is read to clear voxels under two conditions: if the voxel exists and if the voxel is dynamic.

Specifically, the specific implementation process of step 102 includes:

In order to correctly approximate the indirect lighting during the vector distance field ladder calculation tracing step, it is necessary to store the incoming radiation in a radiation volume of the voxel structure. Inspired by deferred rendering, a voxel light path is implemented that calculates the direct lighting of each voxel. However, unlike deferred rendering where the light path is performed for each visible pixel, here the lighting calculation is performed for each voxel, visible or invisible. This is necessary to avoid visibility issues, as the structure is used to approximate indirect lighting. In this case, it does not matter whether the light distribution contributes to visible debris, occlusions from the camera or invisible geometry. To speed up this process, the GPU executes one thread for each voxel reserved for the radiation volume based on a GPGPU approach.

For the Lambert reflectance model, the shading of each voxel can be calculated using the information stored in the 3D texture during the voxelization process. For each light source, the following equation is calculated per voxel to describe the voxel outgoing radiance V _r :

Where _Li is the light intensity, ρ is the albedo of the voxel, N is the voxel normal vector, and Ψ is the light direction. For non-uniform light sources such as spotlights and point lights, the position of the voxel is required. This can be obtained by projecting the position of the voxel in texture space into world space.

When the voxel's normal vector is used for the normal attenuation term (NΨ), it may give undesirable results. Since an average operation is used to store the normal vector, the resulting average normal may end up pointing in an inconvenient direction. This problem is noticeable when the normal vectors within the voxel space are not uniform. To reduce this problem, the present embodiment uses normal weighted attenuation, where the normal attenuation is first calculated per face of the voxel as follows:

Calculate the normal falloff vector D _x,y,z for each face of the distance field voxel:

Among them, Ψ is the light direction; is the voxel normal vector for each face;

The three principal faces D _ω are selected according to the axis signs of the average normal N _ω of each face of the voxel:

Then the outgoing radiance _Vr of the main light source with preset intensity irradiating the distance field voxel is:

W＝ ^N2

Among them, _Li is the preset intensity of the main light source, ρ is the albedo of the voxel, N is the voxel normal vector, W is the voxel average normal weight vector: W = ( _Wx , _Wy , _Wz ), ( _Dx , _Dy , _Dz ) is the vector of the product of the normal attenuation vectors of the three main surfaces.

In order to produce accurate results in the Vector Distance Field tracing step, voxels need to be occluded, otherwise voxelized geometry that would have little outgoing radiance would contribute to the indirect lighting calculations.

The position of the voxel is projected in light space, and the depth of the projected point is compared with the stored depth from the shadow map to determine whether the voxel is occluded. A simple improvement to this technique is as follows: instead of using the voxel center position Vp, the position is translated along the voxel's normal vector by half a voxel size Vsize, that is, Vp = Vp + N × Vsize × 0.5, which further exposes the voxel position in case the center position may be occluded by geometry near the voxel.

The present application embodiment uses ray casting within the volume to calculate occlusion. Any resulting volume from the voxelization process can be used, because the algorithm only needs to determine whether a voxel exists at a specific position. In order to determine the occlusion of a voxel, a ray is traced from the position of the voxel along the direction of the light, and the volume is sampled to determine whether there is a voxel at the position of the ray (as shown in Figure 2(a)). If this condition is met, the voxel is occluded.

Instead of stopping the ray immediately after finding a voxel, the soft shadow can be approximated with a single ray, accumulating a value κ for each collision and dividing it by the tracing distance t, that is, the current soft shadow |Α ₁ is:

|Α ₁ ＝|Α ₀ +(1-|Α ₀ )κ÷t

Among them, the soft shadow of the previous frame is |Α ₀ ; from the perspective of light, the number of collisions is usually higher for light that passes through the boundary of voxelized geometry (as shown in Figure 2(b)).

After obtaining the direct lighting value, the emission term from the voxelization process is added to this value for each voxel. In the cone tracing step, these voxels will appear bright even on occluded areas, so the indirect light from these areas of the voxelized scene is accumulated on each cone.

Specifically, the specific implementation process of step 103 includes:

To get more accurate results in the vector distance field tracing step, anisotropic voxels are used. The mipmapping level will store six orientation values for each voxel, one for each orientation axis. Each cone has an origin, aperture angle, and orientation, the last factor determining which three volumes are sampled. Orientation samples are obtained by linearly interpolating the three samples obtained from the selected orientation volume.

To generate anisotropic voxels, to calculate the direction value, volume integration is performed over the depth, and the direction values are averaged to obtain the result value for a specific direction. This embodiment uses the GPU to execute one thread for each voxel at the mipmap level, which will filter using the value of the previous level, and this process is performed at each mipmap level.

Vector distance field tracing is similar to ray marching, advancing a certain distance with each step, except that the sampling volume increases along the diameter of the distance field. Mipmap levels in the direction volume are used to approximate the expansion of the sampling volume during conical tracing to ensure smooth changes between samples, using quartic linear interpolation.

In the conical step process, the diameter of the cone is defined by d, which can be extracted using the tracking distance t, as follows:

d＝2t×tan(θ/2)

Where θ is the aperture angle.

Depending on the diameter of the cone, which mipmap level Vlevel should be sampled, the following equation can be used:

Vlevel＝log2(d÷Vsize)

Where Vsize is the size of the voxel at the maximum level of detail.

Specifically, the specific implementation process of step 104 includes:

Get the occlusion value _da and the outgoing radiance _dc from the directional voxel;

After the light steps through the cone for the mth time, the indirect illumination value _cm and the tracking occlusion value _αm are:

c _m =c _m-1 α _m-1 + (1-α _m-1 )d _a d _c

α _m =α _m-1 +(1-α _m-1 )d _a

Among them, cm _-1 and αm _-1 are the indirect lighting value and tracking occlusion value of the light after the m-1th step of the cone.

To ensure good integration quality between samples, the distance d0 between steps is modified by a factor β. When β = 1, the value of d0 is equal to the diameter d of the cone, and values less than 1 produce higher quality results but require more samples, which degrades performance.

For efficiency, this process is implemented in screen space, using deferred rendering. For each visible fragment, a set of cones are tracked to achieve a different effect.

A coarse Monte Carlo approximation is used for indirect lighting. The hemispherical region that is integrated in the rendering equation can be divided into a sum of integrals. For regular partitions, each partitioned region resembles a cone. For each cone, their results are approximated using traced valid voxels in the distance field, and then the resulting values are weighted to obtain the accumulated result at the cone origin.

For Blinn Phong materials, several large cones distributed over the hemisphere in the normal direction estimate the diffuse reflection, while a single distance field in the reflection direction (whose aperture depends on the specular exponent) approximates the specular reflection.

For efficiency, ambient occlusion can be approximated using the same cone used for diffuse reflection. For the ambient occlusion term δ, only the occlusion value _da is accumulated, and at each step, the accumulated value is multiplied by a weighting function f(r):

f(r)＝1/(1+λr)

Where r is the current radius of the cone and λ is a user-defined value.

Controls the speed at which f(r) decays along the tracing distance. After the light steps through the cone for the mth time, the ambient occlusion term _δm is updated to:

δ _m =δ _m-1 +(1-δ _m-1 )d _a f(r)

Among them, δ _m-1 is the ambient occlusion term after the light steps through the cone for the m-1th time.

Cone tracing can also be used to implement soft shadows by tracing a cone from a surface point towards the light. The cone aperture controls the softness and diffuseness of the resulting shadows. For soft shadows with cones, only occlusion values are accumulated at each step.

In order to compute the diffuse reflection at a surface point using Vector Distance Field Step Tracing, its normal vector, albedo, and the incoming radiance at that point are required. Since the geometry normal vector and albedo are voxelized as a 3D texture, all the information required for the indirect diffuse term is available after computing the voxel direct illumination. A corresponding distance field step trace is performed for each valid voxel using GPGPU to compute the first bounce of the indirect diffuse at each voxel. This step is done after anisotropic filtering of the outgoing radiance value of the voxel direct illumination pass.

For each voxel, a set of cones are generated around a hemisphere in the normal direction using its average normal vector to compute the indirect diffuse for the voxel's position. The effective weighted result from all distance fields is then multiplied by the voxel's albedo and added to the direct lighting value.

The final outgoing radiance of the radiation volume now stores the first bounce of direct illumination and indirect diffuse. The anisotropic filtering process needs to be repeated for the new values. The second bounce of indirect illumination can be approximated in the staircase calculation step of the final distance field for each pixel.

Based on the same inventive concept, an embodiment of the present application provides a real-time global illumination rendering device. Referring to FIG. 3 , the real-time global illumination rendering device 200 provided in the embodiment of the present application at least includes:

A voxelization unit 201 is used to voxelize the scene geometry of the current frame to obtain distance field voxels, and the properties of the distance field voxels include: vector distance field, normal vector, albedo and emission value;

A direct illumination calculation unit 202, used to calculate the direct illumination of the main light source of preset intensity irradiated on each distance field voxel and use it as the outgoing radiance;

A processing unit 203 is used to form a hierarchy by anisotropic filtering the outgoing radiance of the distance field voxels to generate directional voxels;

The indirect lighting calculation unit 204 is used to collect the outgoing radiance of the directional voxels through the cone-shaped light beam and calculate the indirect lighting.

It should be noted that the principle of solving the technical problem by the real-time global illumination rendering device 200 provided in the embodiment of the present application is similar to the method provided in the embodiment of the present application. Therefore, the implementation of the real-time global illumination rendering device 200 provided in the embodiment of the present application can refer to the implementation of the method provided in the embodiment of the present application, and the repeated parts will not be repeated.

As shown in Figure 4, the electronic device 300 provided in the embodiment of the present application includes at least: a processor 301, a memory 302, and a computer program stored in the memory 302 and executable on the processor 301. When the processor 301 executes the computer program, the real-time global illumination rendering method provided in the embodiment of the present application is implemented.

The electronic device 300 provided in the embodiment of the present application may further include a bus 303 connecting different components (including the processor 301 and the memory 302). The bus 303 represents one or more of several types of bus structures, including a memory bus, a peripheral bus, a local bus, and the like.

The memory 302 may include a readable medium in the form of a volatile memory, such as a random access memory (RAM) 3021 and/or a cache memory 3022 , and may further include a read-only memory (ROM) 3023 .

The memory 302 may also include a program tool 3024 having a set (at least one) of program modules 3025, the program modules 3025 including but not limited to: an operating subsystem, one or more applications, other program modules and program data, each of which or some combination may include the implementation of a network environment.

The electronic device 300 may also communicate with one or more external devices 304 (e.g., keyboards, remote controllers, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device 300 (e.g., mobile phones, computers, etc.), and/or, may communicate with any device that enables the electronic device 300 to communicate with one or more other electronic devices 300 (e.g., routers, modems, etc.). Such communication may be performed via an input/output (I/O) interface 305. Furthermore, the electronic device 300 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and/or a public network, such as the Internet) via a network adapter 306. As shown in FIG. 4 , the network adapter 306 communicates with other modules of the electronic device 300 via a bus 303. It should be understood that although not shown in Figure 4, other hardware and/or software modules can be used in conjunction with the electronic device 300, including but not limited to: microcode, device drivers, redundant processors, external disk drive arrays, disk arrays (Redundant Arrays of Independent Disks, RAID) subsystems, tape drives, and data backup storage subsystems.

It should be noted that the electronic device 300 shown in FIG. 4 is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

The embodiment of the present application also provides a computer-readable storage medium, which stores computer instructions. When the computer instructions are executed by a processor, the real-time global illumination rendering method provided by the embodiment of the present application is implemented.

In addition, although the operations of the method of the present application are described in a specific order in the drawings, this does not require or imply that the operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and/or one step may be decomposed into multiple steps.

Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims (6)

1. A real-time global illumination rendering method, comprising:

voxelization is carried out on the scene geometry of the current frame to obtain distance field voxels, wherein the attributes of the distance field voxels comprise: vector distance field, normal vector, albedo, and emission value;

calculating direct illumination of a main light source with preset intensity to each distance field voxel and taking the direct illumination as emergent radiance, wherein the method specifically comprises the following steps of:

A normal attenuation vector D _x,y,z for each face of the distance field voxel is calculated:

wherein ψ is the light direction; a voxel normal vector for each face;

Three main faces D _ω are selected according to the axis sign of the average normal N _ω to each face of the voxel:

the emergent radiance V _r of the main light source with preset intensity irradiated to the distance field voxel is:

W＝N²

Wherein L _i is the preset intensity of the main light source, ρ is the albedo of the voxels, N is the voxel normal vector, and W is the voxel average normal weight vector: w= (W _x,W_y,W_z),(D_x,D_y,D_z) is the vector of the normal decay vector product of the three main faces;

judging whether the voxel is blocked or not, specifically comprising: projecting the position of the voxel in a light space and comparing the depth of the projected point with the stored depth from the shadow map to determine if the voxel is occluded;

The outgoing radiance of the distance field voxels is anisotropically filtered to form a hierarchy to generate directional voxels, comprising:

Dividing the distance field voxels, summing the distance field voxels in each axial direction, taking a mean value, and interpolating according to the angle of the light during sampling to obtain a radiation value;

storing six direction values for each distance field voxel using anisotropic filtering;

obtaining directional voxels by linear interpolation of three samples obtained from the selected directional volume;

The method for collecting the emergent radiance of the directional voxels through the cone ray bundles and calculating indirect illumination specifically comprises the following steps:

Obtaining a shielding value d _a and an emergent radiance d _c from the directional voxels;

After the mth step of the cone, the indirect illumination value c _m and the tracking occlusion value alpha _m are:

c_m＝c_m-1α_m-1+(1-α_m-1)d_ad_c

α_m＝α_m-1+(1-α_m-1)d_a

Wherein c _m-1 and alpha _m-1 are indirect illumination values and tracking occlusion values of the light after the m-1 th step of the cone.

2. The real-time global illumination rendering method according to claim 1, wherein the scene geometry of the current frame is subjected to voxelization to obtain distance field voxels; comprising the following steps:

Generating a larger boundary polygon than the projected triangle for each scene geometry of the current frame to generate at least one segment, each segment having a different attribute, comprising: inverse normal vector, albedo, and emission value;

averaging the attributes of all fragments in a voxel to obtain the attribute of the voxel;

The layered distance field representation stored in the 3D texture is used to derive the vector distance field for the scene geometry.

3. The real-time global illumination rendering method of claim 1, further comprising:

When the distance field voxel of the previous frame is a dynamic voxel, updating the attribute body and the radiator of the current frame;

when the distance field voxel of the previous frame is a static voxel, the distance field voxel of the current frame uses the value of the previous frame;

The distance field voxels of the current frame are marked as dynamic voxels or static voxels.

4.A real-time global illumination rendering apparatus, comprising:

The voxelization unit is used for voxelization processing of the scene geometry of the current frame to obtain distance field voxels, and the attributes of the distance field voxels comprise: vector distance field, normal vector, albedo, and emission value;

the direct illumination calculation unit is used for calculating the direct illumination of the main light source with preset intensity irradiated to each distance field voxel and used as emergent radiance, and specifically comprises the following steps:

A normal attenuation vector D _x,y,z for each face of the distance field voxel is calculated:

wherein ψ is the light direction; a voxel normal vector for each face;

Three main faces D _ω are selected according to the axis sign of the average normal N _ω to each face of the voxel:

the emergent radiance V _r of the main light source with preset intensity irradiated to the distance field voxel is:

W＝N²

Wherein L _i is the preset intensity of the main light source, ρ is the albedo of the voxels, N is the voxel normal vector, and W is the voxel average normal weight vector: w= (W _x,W_y,W_z),(D_x,D_y,D_z) is the vector of the normal decay vector product of the three main faces;

judging whether the voxel is blocked or not, specifically comprising: projecting the position of the voxel in a light space and comparing the depth of the projected point with the stored depth from the shadow map to determine if the voxel is occluded;

the processing unit is used for forming a hierarchy by anisotropically filtering the emergent radiance of the distance field voxels to generate directional voxels, and specifically comprises the following steps:

Dividing the distance field voxels, summing the distance field voxels in each axial direction, taking a mean value, and interpolating according to the angle of the light during sampling to obtain a radiation value;

storing six direction values for each distance field voxel using anisotropic filtering;

obtaining directional voxels by linear interpolation of three samples obtained from the selected directional volume;

An indirect illumination calculation unit for collecting outgoing radiance of the directional voxels through the ray bundles of the cone and calculating indirect illumination, specifically comprising:

Obtaining a shielding value d _a and an emergent radiance d _c from the directional voxels;

After the mth step of the cone, the indirect illumination value c _m and the tracking occlusion value alpha _m are:

c_m＝c_m-1α_m-1+(1-α_m-1)d_ad_c

α_m＝α_m-1+(1-α_m-1)d_a

Wherein c _m-1 and alpha _m-1 are indirect illumination values and tracking occlusion values of the light after the m-1 th step of the cone.

5. An electronic device, comprising: a memory and a processor, the memory having stored therein an executable program, the processor executing the executable program to implement the steps of the method of any one of claims 1 to 3.

6. A storage medium carrying one or more computer programs which, when executed by a processor, implement the steps of the method of any one of claims 1 to 3.