WO2023066121A1

WO2023066121A1 - Rendering of three-dimensional model

Info

Publication number: WO2023066121A1
Application number: PCT/CN2022/125043
Authority: WO
Inventors: 陶然; 杨瑞健; 赵代平
Original assignee: 上海商汤智能科技有限公司
Priority date: 2021-10-18
Filing date: 2022-10-13
Publication date: 2023-04-27
Also published as: CN114494570A; CN113658316B; CN113658316A

Abstract

Embodiments of the present disclosure provide a three-dimensional model rendering method and apparatus, a storage medium, and a computer device. The method comprises: determining light-dark distribution of a three-dimensional model from the perspective of a rendering camera, wherein the light-dark distribution is used for representing a brightness value of each fragment on the three-dimensional model; dividing, on the basis of the light-dark distribution, the three-dimensional model into a bright area and a shadow area; and rendering the bright area on the basis of the color of the three-dimensional model, and rendering the shadow area on the basis of a predetermined shadow color.

Description

Rendering of 3D models

Related Application Cross Reference

This application claims the priority of the Chinese patent application with the application number 202111211776.4 and the filing date of October 18, 2021. The entire content of the Chinese patent application is hereby incorporated by reference into this application.

technical field

The present disclosure relates to the technical field of image processing, and in particular to a three-dimensional model rendering method and device, a storage medium, and computer equipment.

Background technique

The rendering of three-dimensional (3D) models can generally be divided into photorealistic rendering (PR) and non-photorealistic rendering (NPR). The main purpose of rendering is to simulate a specific art style. The purpose of realistic rendering is to obtain a realistic rendering effect, while the purpose of non-realistic rendering is more diverse, mainly to simulate an artistic drawing style and present a hand-painted effect. However, the rendering method in the related art needs to first completely draw the entire 3D model on the 2D image, and then perform post-processing on the drawn image, and the rendering efficiency of this method is low.

Contents of the invention

In the first aspect, an embodiment of the present disclosure provides a method for rendering a 3D model, the method including: determining the light and dark distribution of the 3D model under the viewing angle of the rendering camera, and the light and dark distribution is used to characterize each slice on the 3D model The luminance value of the element; divide the 3D model into a bright area and a shadow area based on the light and dark distribution; render the bright area based on the color of the 3D model, and render the shadow based on a predetermined shadow color area to render.

In a second aspect, an embodiment of the present disclosure provides a method for rendering a 3D model, the method comprising: in a first rendering pass, rendering a bright area of the 3D model based on the color of the 3D model, and based on a predetermined The shadow color renders the shadow area of the three-dimensional model; in the second rendering pass, the three-dimensional model is enlarged to obtain an enlarged model, and the enlarged model is rendered based on a predetermined stroke color, and the enlarged The middle area of the model is occluded by the three-dimensional model.

In a third aspect, an embodiment of the present disclosure provides a method for rendering a 3D model. The method includes: zooming in on the 3D model to obtain an enlarged model, the middle area of the zoomed-in model is blocked by the 3D model; The stroke color renders the enlarged model. The embodiments of the present disclosure directly use the stroke color to render the enlarged model, which can effectively improve the rendering efficiency compared with the traditional rendering method in which the entire 3D model is first rendered and then edge segmentation is performed through post-processing.

In a fourth aspect, an embodiment of the present disclosure provides a rendering device for a 3D model, the device comprising: a determination module configured to determine the light and dark distribution of the 3D model under the viewing angle of the rendering camera, and the light and dark distribution is used to characterize the 3D model Brightness values of each fragment; a division module, configured to divide the three-dimensional model into a bright area and a shadow area based on the light and dark distribution; a rendering module, configured to render the bright area based on the color of the three-dimensional model, The shaded area is rendered based on a predetermined shade color.

In a fifth aspect, an embodiment of the present disclosure provides an apparatus for rendering a 3D model, the apparatus comprising: a first rendering module, configured to, in a first rendering pass, perform color rendering on a bright area of the 3D model based on the color of the 3D model Rendering, and rendering the shadow area of the 3D model based on a predetermined shadow color; a second rendering module, configured to amplify the 3D model in a second rendering pass to obtain an enlarged model, based on a predetermined The stroke color renders the enlarged model, and the middle area of the enlarged model is blocked by the three-dimensional model.

In a sixth aspect, an embodiment of the present disclosure provides a three-dimensional model rendering device, the device comprising: an enlargement module configured to enlarge the three-dimensional model to obtain an enlarged model, and the middle area of the enlarged model is blocked by the three-dimensional model ; a rendering module, configured to render the enlarged model based on a predetermined stroke color. The embodiments of the present disclosure directly use the stroke color to render the enlarged model. Compared with the traditional rendering method in which the entire 3D model is rendered first, and then edge segmentation is performed through post-processing, the embodiments of the present disclosure can effectively improve rendering efficiency.

In a seventh aspect, an embodiment of the present disclosure provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the method described in any one of the first aspect to the third aspect is implemented.

In an eighth aspect, an embodiment of the present disclosure provides a computer device, including a memory, a processor, and a computer program stored on the memory and operable on the processor. When the processor executes the program, the first aspect to the second aspect are implemented. The method described in any one of the three aspects.

In a ninth aspect, an embodiment of the present disclosure provides a computer program product, the product includes a computer program, and when the computer program is executed by a processor, the method described in any one of the first aspect to the third aspect is implemented.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Description of drawings

The accompanying drawings here are incorporated into the description and constitute a part of the present description. These drawings show embodiments consistent with the present disclosure, and are used together with the description to explain the technical solution of the present disclosure.

FIG. 1A and FIG. 1B are schematic diagrams of different rendering styles of some embodiments, respectively.

Figure 2 is a schematic diagram of the rendering method.

Fig. 3 is a flow chart of a rendering method of a 3D model according to an embodiment of the present disclosure.

FIG. 4A and FIG. 4B are schematic diagrams of different rendering camera perspectives, respectively.

FIG. 5 is a schematic diagram of an original three-dimensional model and an enlarged model of an embodiment of the present disclosure.

FIG. 6 is a schematic diagram of a stroke effect according to an embodiment of the present disclosure.

FIG. 7 is a schematic diagram of rendering methods of culling front and culling back surfaces according to an embodiment of the present disclosure.

Fig. 8 is a schematic diagram of a moving manner of an enlarged model.

FIG. 9A is a flowchart of a three-dimensional model rendering method according to another embodiment of the present disclosure.

FIG. 9B is an overall flowchart of an embodiment of the present disclosure.

Fig. 10 is a flowchart of a rendering method of a 3D model according to yet another embodiment of the present disclosure.

Fig. 11 is a block diagram of a three-dimensional model rendering device according to an embodiment of the present disclosure.

Fig. 12 is a block diagram of a three-dimensional model rendering device according to another embodiment of the present disclosure.

Fig. 13 is a block diagram of an apparatus for rendering a 3D model according to yet another embodiment of the present disclosure.

FIG. 14 is a schematic structural diagram of a computer device according to an embodiment of the present disclosure.

Detailed ways

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatuses and methods consistent with aspects of the present disclosure as recited in the appended claims.

The terminology used in the present disclosure is for the purpose of describing particular embodiments only, and is not intended to limit the present disclosure. As used in this disclosure and the appended claims, the singular forms "a", "the", and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the term "and/or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality.

It should be understood that although the terms "first", "second", "third", etc. may be used in the present disclosure to describe various information, the information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of the present disclosure, first information may also be called second information, and similarly, second information may also be called first information. Depending on the context, the word "if" as used herein may be interpreted as "at" or "when" or "in response to a determination."

In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present disclosure, and to make the above-mentioned purposes, features and advantages of the embodiments of the present disclosure more obvious and understandable, the technical solutions in the embodiments of the present disclosure are described below in conjunction with the accompanying drawings The program is described in further detail.

The rendering of 3D models can generally be divided into realistic rendering and non-realistic rendering. The purpose of the realistic rendering is to obtain a realistic rendering effect. As shown in FIG. 1A , the rendering effect of continuously changing colors can be obtained through the realistic rendering. Non-realistic rendering can simulate an artistic drawing style, and the two-dimensional rendering style is one of the effects that has been widely used in recent years. As shown in Figure 1B, the two-dimensional rendering can simulate the effect of color and brightness block in animation.

Generally, the rendering of the 3D model is performed by post-processing. Figure 2 shows a rendering process. First, in step 201, model information of a 3D model illuminated by a light source may be acquired, and the model information may include position information, color information, etc. of each vertex in the 3D model. In step 202, the three-dimensional model can be completely drawn on the two-dimensional image based on the model information acquired in step 201. In step 203, color correction is performed on the drawn two-dimensional image. In some embodiments, the color of each pixel in the two-dimensional image can be obtained, and multiple different colors whose color difference values are within a preset range are corrected to the same color, thereby realizing color partitioning of the two-dimensional image, Achieve the effect of color mutation in the second dimension. It can be seen that the above rendering process needs to draw the 3D model completely first, and then read the color of each pixel in the 2D image one by one. The rendering takes a long time and the rendering efficiency is low.

Based on this, the present disclosure provides a three-dimensional model rendering method, referring to FIG. 3 , the method includes steps 301 to 303 .

Step 301: Determine the light and dark distribution of the 3D model under the viewing angle of the rendering camera, and the light and dark distribution is used to characterize the brightness value of each fragment on the 3D model.

Step 302: Divide the three-dimensional model into a bright area and a shadow area based on the light and dark distribution.

Step 303: Render the bright area based on the color of the 3D model, and render the shadow area based on a predetermined shadow color.

The three-dimensional model can be rendered in a two-dimensional rendering style through the methods of the embodiments of the present disclosure. When rendering in the embodiment of the present disclosure, it is not necessary to first draw the entire 3D model on a 2D image, but first divide the 3D model into a bright area and a shadow area, and then directly render the bright area based on the color of the 3D model , and render the shadow area based on a predetermined shadow color, so that the final rendering effect can be obtained directly. Compared with the rendering method in which the 3D model to be rendered is first drawn on a 2D image and then post-processed, the rendering method of the embodiment of the present disclosure has higher rendering efficiency and is more suitable for real-time rendering scenarios.

In step 301, the three-dimensional model may be a model corresponding to a target object in the scene to be rendered, and the scene to be rendered may include one or more target objects, and the target object may include but not limited to people, animals, tables, Bags, houses, etc., can also include local areas on objects, eg, faces, roofs of houses. In some embodiments, the rendering manner of the embodiment of the present disclosure may be used to render the three-dimensional models corresponding to all target objects in the scene to be rendered. In other embodiments, it is also possible to render only the 3D model corresponding to a part of the target objects in the scene to be rendered by using the rendering method of the embodiment of the present disclosure, and use other rendering methods to render the 3D model corresponding to another part of the target object in the scene to be rendered. The model is rendered, or the 3D models corresponding to different target objects are rendered in different styles. For example, if the scene to be rendered includes target object A and target object B, the 3D model corresponding to target object A can be rendered in a two-dimensional rendering style, and the 3D model corresponding to target object B can be rendered in a realistic rendering style, so as to realize the A mix and match of the two-dimensional rendering style and other rendering styles in the scene.

The rendering camera may be a virtual camera. When rendering, a rendering camera may be created at a preset position of the 3D model, and the 3D model is under the perspective of the rendering camera. When the rendering camera is at different positions, the parts of the 3D model that can be photographed under the perspective of the rendering camera are often different, and thus the final rendering effects are also different. Taking the 3D model of a person as an example, as shown in Figure 4A, when the perspective of the rendering camera is facing the face, the part of the 3D model under the perspective of the rendering camera is the front of the person (including the side of the face), and the final rendering results in The 2D image of also includes the front of the person. When the perspective of the rendering camera is facing the back of the character, as shown in Figure 4B, the part of the 3D model under the perspective of the rendering camera is the back of the character (including the back of the head), and the final rendered 2D image also includes the back of the character.

The light and dark distribution of the 3D model is used to represent the brightness value of each fragment on the 3D model. Wherein, a fragment refers to a surface formed by connecting vertices. In some embodiments, a real number between 0 and 1 may be used to represent the brightness value of the fragment. The closer the brightness value of the fragment is to 1, the brighter the fragment is; the closer the brightness value is to 0, the darker the fragment is. Those skilled in the art can understand that the way of expressing the brightness is not limited thereto, and other numerical ranges (for example, 0 to 100) can also be used to represent the brightness value. Letters and symbols can also be used to indicate the brightness level, for example, the letters "A", "B" and "C" are used to indicate the brightness level from low to high in turn, and the higher the brightness level of the slice, the brighter the slice ; The lower the brightness level of the fragment, the darker the fragment.

Since the final rendering result only includes the model area of the 3D model under the rendering camera perspective, this step can only obtain the light and dark distribution of the model area of the 3D model under the rendering camera perspective, that is, each slice in the model area The brightness value of the element. Still taking the 3D model of a person as an example, when the perspective of the rendering camera is facing the face, only the brightness value of each fragment in front of the person can be obtained.

In some embodiments, the first light and dark distribution of the 3D model under the viewing angle of the rendering camera may be determined based on the illumination direction, the normal map of the 3D model, and the position of the rendering camera, and based on the A shadow map, determining a second light and dark distribution of the 3D model under the rendering camera viewing angle; determining the light and dark distribution of the 3D model under the rendering camera viewing angle based on the first light and dark distribution and the second light and dark distribution . Wherein, the normal map is used to represent the normal of each vertex on the three-dimensional model, and can determine the unevenness of each vertex. The shadow map is used to characterize the distance between each vertex of the 3D model and the light source, so as to determine whether each vertex is occluded. Using the normal map and the shadow map to determine the light and dark distribution together can obtain higher accuracy.

In some embodiments, for each fragment of the 3D model under the viewing angle of the rendering camera, the first brightness value of the fragment may be determined based on the first light and dark distribution, and the first brightness value of the fragment may be determined based on the second light and dark distribution Determine a second brightness value of the slice; determine the brightness value of the slice according to the first brightness value and the second brightness value. For example, the product of the first brightness value and the second brightness value may be determined as the brightness value of the fragment. Alternatively, the smaller one of the first brightness value and the second brightness value may also be determined as the brightness value of the fragment. Alternatively, the first luminance value of the fragment may be determined first, and if the first luminance value of the fragment is less than or equal to a preset luminance threshold, the first luminance value of the fragment may be directly determined as the If the first brightness value is greater than the brightness threshold, determine the second brightness value of the fragment, and if the second brightness value of the fragment is less than or equal to the brightness threshold, determine the The second brightness value of the fragment is determined as the brightness value of the fragment, and if the second brightness value of the fragment is greater than the brightness threshold, the first brightness value of the fragment is determined as the brightness value of the fragment.

In some other embodiments, the first light-dark distribution or the second light-dark distribution may also be directly determined as the light-dark distribution of the three-dimensional model under the viewing angle of the rendering camera. Or combine at least one of the first light-dark distribution and the second light-dark distribution and the third light-dark distribution determined by other means to determine the light-dark distribution of the three-dimensional model under the viewing angle of the rendering camera.

In step 302 , the three-dimensional model may be divided into bright areas and shadow areas based on the light and dark distribution determined in step 301 . For example, the model area of the 3D model under the perspective of the rendering camera can be divided into a bright area and a shadow area. Wherein, the shadow area refers to the area on the 3D model that is not irradiated by the light source or can only be irradiated by a small amount of light, so that it is in the shadow, and the brightness value of the fragments in the shadow area is relatively small. The bright area refers to the area outside the shadow area on the 3D model. These areas can be illuminated by a large amount of light, and the brightness value of the fragments in the bright area is relatively large. By dividing bright areas and shadow areas, it is possible to simulate the effect of sudden changes in brightness in the second dimension.

In some embodiments, an area whose brightness value satisfies a first preset brightness condition on the three-dimensional model may be determined as the bright area; an area whose brightness value satisfies a second preset brightness condition on the three-dimensional model may be determined as the shaded area.

In some embodiments, the first preset brightness condition may be that the brightness value is greater than or equal to the lower brightness threshold, and the second preset brightness condition may be that the brightness value is smaller than the upper brightness threshold. Wherein, the brightness lower threshold and the brightness upper threshold may be equal. Alternatively, the brightness lower threshold may be greater than the brightness upper threshold. The area whose luminance value is between the upper luminance threshold and the lower luminance threshold may be randomly determined as a bright area or a shadow area, or may be further determined as a bright area or a shadow area based on other conditions.

In some embodiments, the first preset brightness condition may be that the brightness value is within a preset range of brightness values [L1, L2], and the second preset brightness condition may be that the brightness value is within the brightness value Out of the interval [L1, L2]. Alternatively, the first preset brightness condition may be that the brightness value is equal to any one of a preset group of brightness values, and the second preset brightness condition may be that the brightness value is not equal to the preset group of brightness values. any of the values. The first preset brightness condition and the second preset brightness condition can also be set as other conditions according to actual needs, so as to obtain different rendering effects.

The solutions of the embodiments of the present disclosure will be described below by taking the first preset brightness condition that the brightness value is greater than or equal to the brightness threshold and the second preset brightness condition that the brightness value is less than the brightness threshold as an example.

The larger the brightness threshold is set, the smaller the area of the bright area and the larger the area of the shadow area. Therefore, the brightness threshold can be set as desired. If you want to divide more model areas on the 3D model into shadow areas, you can set a larger brightness threshold; conversely, if you want to divide more model areas on the 3D model into bright areas, you can set a smaller brightness threshold.

In step 303, the colors for rendering the bright area and the shadow area may be respectively determined in different ways. Wherein, the color used to render the bright area is the color corresponding to the bright area in the 3D model. For example, if the color of the fragments in the bright area in the 3D model is red, the fragments in the bright area are rendered as red. The color used for rendering the shadow area is a shadow color, or is determined based on the shadow color and the color corresponding to the shadow area in the three-dimensional model. The shadow color can be pre-specified by the user, or a default color can be used. It is also possible to randomly select one of multiple predefined candidate colors as the shadow color, or determine the shadow color based on other methods.

When rendering, the color of the shadow area can be directly rendered as a shadow color, that is, the shadow color is used to replace the color corresponding to the shadow area in the 3D model. For example, if the color corresponding to the shaded area in the 3D model is red, and the shaded color is black, then the color of the shaded area can be directly rendered as black.

It is also possible to first determine the color corresponding to the shadow area in the 3D model (called model color) based on the diffuse reflection map corresponding to the 3D model, wherein the diffuse reflection map can be used to characterize the reflection and surface color of the 3D model surface, and The model color is corrected by the shadow color, and the shadow area is rendered with the corrected color. For example, the R channel value, G channel value, and B channel value of the model color can be summed with the corresponding channel value of the shadow color to obtain the corrected color. Assuming that the components of the model color in the R channel, G channel and B channel are (R1, G1, B1), and the components of the shadow color in the R channel, G channel and B channel are (R2, G2, B2), the corrected color is (R1+R2, G1+G2, B1+B2). Of course, the correction method is not limited to simple superposition of each channel component of the color.

It is also possible to render the shadow area with the model color and shadow color on different layers, and combine the rendered two layers to obtain the rendering result of the shadow area. For example, if the model color is red and the shadow color is black, you can render red on the first layer and black on the second layer, and superimpose the two layers together to get the rendering result of the shadow area. At the same time, the transparency of the first layer and the transparency of the second layer can also be adjusted separately, so as to present different rendering effects.

In the above embodiment, the color of the 3D model corresponding to the bright area and the color of the 3D model corresponding to the shadow area may be determined based on the diffuse reflection map corresponding to the 3D model. In the case where the brightness threshold is a single threshold, by drawing the original diffuse reflection map color of the 3D model in the bright area; in the shadow area, the original diffuse reflection map color of the 3D model is adjusted according to the predefined shadow color and then Perform rendering to achieve the rendering effect of the secondary color in the two-dimensional style.

In some embodiments, the rendering effect of multi-level shading can also be achieved by specifying multiple thresholds. For example, the second preset brightness condition includes that the brightness value is less than or equal to a first brightness threshold. The predetermined shadow color includes a plurality of shadow colors, and the plurality of shadow colors correspond to a plurality of different brightness sub-intervals; The brightness interval is obtained by dividing the brightness interval, wherein the maximum brightness value in the plurality of different brightness sub-intervals is less than or equal to the first brightness threshold. The luminance subinterval to which the luminance value of each fragment in the shadow area belongs may be determined; and each fragment in the shadow area is rendered according to the shadow colors corresponding to the luminance subintervals to which the luminance value of each fragment belongs. This way of determining the shade color is called subinterval-based. Assuming that a real number between 0 and 1 is used to represent the brightness value of the fragment, and the first brightness threshold is 0.8, the brightness interval of [0,0.8] can be divided into two brightnesses of [0,0.3] and [0.3,0.8] subinterval, and the shadow color corresponding to the brightness subinterval [0,0.3] is black, and the shadow color corresponding to the brightness subinterval [0.3,0.8] is gray. If the luminance value of fragment A in the shadow area is within the luminance subinterval [0,0.3], the shade color for rendering fragment A is black; if the luminance value of fragment A in the shadow area is within the luminance subinterval Within the interval [0.3,0.8], the shade color for rendering fragment A is gray. Those skilled in the art can understand that the above-mentioned embodiment is only for illustration, and the number and division method of brightness sub-intervals may be different from the above-mentioned embodiment.

Further, the larger the value of the brightness range of the brightness subinterval to which the brightness value of a fragment belongs, the lighter the shadow color of the fragment (that is, the larger the brightness value of the fragment); on the contrary, the brightness value of a fragment belongs to The smaller the value of the luminance range of the sub-interval, the darker the shadow color of the fragment (that is, the smaller the luminance value of the fragment). In this way, the effect that the shadow color becomes darker in layers as the brightness value of the fragment decreases can be presented. Of course, the above-mentioned change trend is not necessary, and other ways can also be used to set the shadow color corresponding to each sub-interval, so as to obtain other shadow rendering effects.

For another example, the second preset brightness condition includes that the brightness value is less than or equal to a second brightness threshold; the predetermined shadow color includes a plurality of shadow colors, and the plurality of shadow colors respectively correspond to multiple values in the lookup table. reference brightness values; each reference brightness value in the lookup table is less than or equal to the second brightness threshold. The shadow color corresponding to the reference brightness value matched with the brightness value of each fragment in the shadow area can be searched from the lookup table; according to the shadow color corresponding to the reference brightness value matched with each fragment, the Each fragment in the shaded area is rendered. This way of determining the shade color is called a lookup table based way. If the reference luminance value identical to the luminance value of the fragment is found in the lookup table, the reference luminance value identical to the luminance value of the fragment can be directly determined as the reference luminance value matching the luminance value of the fragment.

If no reference luminance value identical to the luminance value of the fragment is found in the lookup table, the reference luminance value closest to the luminance value of the fragment in the lookup table is determined as the reference luminance value matching the luminance value of the fragment. Alternatively, the average value of multiple reference brightness values in the lookup table whose difference from the brightness value of the fragment is within a preset range may be determined as the reference brightness value matching the brightness value of the fragment.

Further, the larger the reference brightness value stored in the lookup table, the lighter the shadow color corresponding to the reference brightness value; conversely, the smaller the reference brightness value stored in the lookup table, the darker the shadow color corresponding to the reference brightness value. In this way, the effect that the shadow color becomes darker in layers as the brightness value of the fragment decreases can be presented. Of course, the above-mentioned change trend is not necessary, and other methods can also be used to set the shadow color corresponding to each brightness value in the lookup table, so as to obtain other shadow rendering effects.

The first brightness threshold and the second brightness threshold in the above embodiments may be the same or different. The shadow color used for correcting the color of the shadow area may be determined based on any one of brightness subinterval-based manners or look-up table-based manners, or may be determined in combination of the two manners. For example, the shadow color determined based on the brightness sub-interval is called the first shadow color, and the shadow color determined based on the look-up table is called the second shadow color, then the color used for correcting the shadow area The shadow color may be a darker or lighter shadow color among the first shadow color and the second shadow color, or a shadow color obtained by weighting the first shadow color and the second shadow color.

In addition to determining the shadow color using the methods listed above, other methods may also be used to determine the shadow color, which will not be listed here. By using different shadow colors for parts with different brightness values on the 3D model, the rendering effect of different painting styles can be imitated. But the core is to calculate the light and dark distribution, and use the light and dark distribution to partition the shading and rendering of the 3D model, no matter how delicate the partition is.

The rendering process described above may be referred to as flat shading. In some embodiments, the rendering result obtained in step 303 may also be stroked to form a line outline in a two-dimensional rendering effect. The so-called stroke refers to rendering the edge outline of the 3D model with a predetermined stroke color.

The traditional stroke method is generally to perform edge detection on the two-dimensional image after rendering the entire three-dimensional model into a two-dimensional image to determine the edge pixels in the two-dimensional image, and then use the stroke color to render the edge pixels. This stroke method also needs to render the entire 3D model into a 2D image first, and then perform post-processing, and the rendering efficiency is low.

In the embodiment of the present disclosure, the three-dimensional model may be enlarged to obtain an enlarged model, and then the enlarged model may be rendered based on a predetermined stroke color. By overlaying the rendering result in step 303 on the rendering result of the enlarged model, the stroke effect shown in FIG. 6 can be realized.

As an implementation manner, each vertex on the three-dimensional model may be displaced along a direction of a projection vector of a normal of the vertex on a projection plane to obtain an enlarged model. The enlarged model obtained in this way does not need to be displaced, the middle part of the enlarged model will be blocked by the 3D model before the enlargement, and the enlarged part around the 3D model will cover the outside of the 3D model before the enlargement, forming a two-dimensional rendering effect line outline. In addition to the above-mentioned displacement methods, the three-dimensional model may also be enlarged in other ways, which is not limited in the present disclosure.

As shown in Figure 5, the circle shown by the solid line represents the three-dimensional model before the enlargement, A, B and C are the three vertices on the three-dimensional model before the enlargement respectively, and f _A , f _B and f _C represent the vertex A respectively , the directions of the projection vectors of the normals corresponding to vertices B and C on the projection plane. By displacing each vertex outward for a certain distance along the direction of the projection vector, an enlarged three-dimensional model as indicated by the circular dotted line is obtained. Those skilled in the art can understand that the three-dimensional model before the enlargement also includes other vertices, which are not shown one by one in the figure. The displacement of each vertex can be the same or different. Under the condition that the displacement of each vertex is the same, the whole three-dimensional model can be uniformly enlarged, that is, the enlargement degree of each part of the three-dimensional model is the same. In the case that there are vertices with different displacement amounts, the magnification degree corresponding to the vertex with a larger displacement amount is larger than that of a vertex with a smaller displacement amount. By enlarging different vertices to different degrees, different stroke effects can be achieved. The amount of displacement of the vertices is related to the desired width of the edge profile. If you need to render a wider edge outline, you can set a larger displacement; if you need to render a narrower edge outline, you can set a smaller displacement. That is, the amount of displacement is positively correlated with the width of the rendered edge outline. The desired edge profile width can be input in advance, and the displacement of each vertex is automatically determined based on the input width.

After getting the enlarged model, the 3D model can be rendered with the stroke color. For example, the entire enlarged 3D model can be rendered with the stroke color, or only the part outside the enlarged 3D model can be rendered. The former rendering method can effectively avoid the gap between the stroke rendering result and the flat shading rendering result, which will affect the rendering effect. The aforementioned stroke color may be a single color or a gradient color. The stroke color can be pre-specified by the user, or one of multiple colors can be randomly selected, or the default color can be used. In order to highlight the difference between the edge outline and the bright area, you can select a color that is greater than the preset difference value from the bright area as the stroke color.

In some embodiments, the front face of each fragment in the bright area may be rendered based on the color of the three-dimensional model, and the front face of each fragment in the shadow area may be rendered based on a predetermined shadow color. In other words, only the front faces of the fragments in the bright area and the front faces of the shadows in the shadow area may be rendered, but not the back faces of the fragments in the bright area and the shadows in the shadow area Render the back of the . This rendering method is called culling backface rendering. The back surface of each fragment in the enlarged model may also be rendered based on a predetermined stroke color. That is to say, only the backside of each fragment in the enlarged model may be rendered, but the front side of each fragment in the enlarged model may not be rendered. This rendering method is called culling front-facing rendering.

Wherein, the front face of a fragment is the face obtained by connecting multiple vertices on the fragment along the first direction, and the back face of a fragment is the face obtained by connecting multiple vertices on the fragment along the second direction On the other hand, the first direction is opposite to the second direction. For example, the front face of a fragment can be defined as a face formed by connecting multiple vertices in a clockwise manner, and the back face of a fragment can be defined as a face formed by connecting multiple vertices in a counterclockwise manner. Of course, the front and the back can also be defined in other ways according to actual needs.

As shown in Figure 7, in the rendering method of excluding the back surface, a, b, and c represent three vertices of a fragment, and the direction of the arrow represents the connection order of the vertices. Only render the surface (7-1) formed by connecting the three vertices a, b, and c in a clockwise direction, but not render the surface (7-2) formed by connecting the three vertices a, b, and c in a counterclockwise direction. In the rendering method of excluding the front face, only the surface (7-3) formed by connecting the three vertices a, b, and c in a counterclockwise direction is rendered, and the surface (7-3) formed by connecting the three vertices a, b, and c in a clockwise direction is not rendered. Face (7-4). By using different culling methods to render the three-dimensional model before enlargement and the three-dimensional model after enlargement, the occlusion effect of the three-dimensional model before enlargement on the three-dimensional model after enlargement can be better realized.

In some embodiments, before rendering the enlarged three-dimensional model based on a predetermined stroke color, the enlarged model may be moved in a direction away from the rendering camera. This step can avoid the problem of magnified model and 3D model penetrating in places where the thickness of the model is small, resulting in wrong rendering effects. As shown in FIG. 8 , assuming that the distance between the enlarged model and the rendering camera before moving is d1, the enlarged model can be moved to a position d2 away from the rendering camera, where d2 is greater than d1.

The above two processes of flat shading and stroke can be realized by using different rendering passes (Pass). The processes on the two rendering passes can be executed in parallel, or the flat shading can be performed through the first rendering pass first, and after the flat shading process is completed , and then stroke through the second rendering pass.

The embodiments of the present disclosure can be applied to scenarios such as 2D-style 3D games, 2D-style 3D stickers of anchors, or 3D virtual anchor rendering of 2D-style. Taking a 3D virtual anchor rendering scene in a two-dimensional style as an example, the 3D model is the 3D model of the anchor. During the live broadcast process of the anchor, the image of the anchor can be obtained in real time, and the three-dimensional modeling of the anchor can be performed based on the image of the anchor to obtain the three-dimensional model of the anchor. Then, the three-dimensional model of the anchor is rendered in real time by using the rendering method of the embodiment of the present disclosure, so as to obtain a virtual anchor image in a two-dimensional style. Since the rendering method of the embodiment of the present disclosure does not require post-processing and has high real-time performance, it can be applied to the above-mentioned scenarios.

As shown in FIG. 9A , the embodiment of the present disclosure also provides another method for rendering a three-dimensional model, and the method includes steps 901 to 902 .

Step 901: In a first rendering pass, render the bright area of the 3D model based on the color of the 3D model, and render the shadow area of the 3D model based on a predetermined shadow color.

Step 902: In the second rendering pass, enlarge the 3D model to obtain an enlarged model, render the enlarged model based on a predetermined stroke color, and the middle area of the enlarged model is blocked by the 3D model .

The embodiments of the present disclosure respectively perform flat shading and stroke through two rendering passes, wherein the flat shading process is implemented by rendering a 3D model, and the stroke process is implemented by rendering an enlarged model. Since both the flat shading process and the stroke process are directly rendered with the determined color, there is no need to render the 3D model into a 2D image before post-processing, thus improving the rendering efficiency.

The processing of the first pass above is called flat shading, and the processing of the second pass is called stroke. Referring to FIG. 9B , FIG. 9B shows a specific process of performing flat shading through the first rendering pass and a specific process of performing model strokes through the second rendering pass.

Perform flat shading through the first rendering pass, including steps (1-1) to steps (1-6):

(1-1) Obtain the input for rendering, such as the shadow map of the 3D model, the direction of light, the normal map of the 3D model, and the position of the rendering camera.

(1-2) Determine the first light and dark distribution of the 3D model under the perspective of the rendering camera due to the direction of the light through the direction of the light, the normal map and the position of the rendering camera.

(1-3) Determine the second light and dark distribution on the 3D model due to shadow occlusion through the shadow map.

(1-4) Superimpose the second light and dark distribution on the 3D model due to shadow occlusion and the first light and dark distribution caused by the light direction to obtain the final light and dark distribution (that is, the light and dark distribution of the 3D model under the rendering camera perspective dark distribution).

(1-5) Divide the final light-dark distribution into two parts, the bright area and the shadow area, using a predefined brightness threshold.

(1-6) Color the bright area and shadow area separately: draw the original diffuse reflection map color of the 3D model in the bright area; adjust the original diffuse reflection map of the 3D model according to the predefined shadow color in the shadow area Then draw the adjusted color in the shadow area, so as to realize the rendering effect of the secondary color in the two-dimensional style.

Stroke the model through the second rendering pass, including step (2-1) to step (2-5):

(2-1) Obtain the input for rendering, such as vertex position, projection matrix of rendering camera, model matrix, bone data, vertex normal of 3D model, etc.; among them, the projection matrix is the distance between the rendering camera coordinate system and the world coordinate system The transformation matrix, the model matrix is used to describe the displacement and rotation of the 3D model, the bone data is used to represent the deformation of the 3D model with bones (for example, a 3D model of a character), and for a 3D model without bones (for example, a table), input Skeleton data may not be included.

(2-2) Calculate the position and normal information of each vertex of the 3D model in the world coordinate system through the vertex position, vertex normal and model matrix of the 3D model. Since the position of the light source is generally represented by the position in the world coordinate system, the purpose of this step is to project the 3D model to the world coordinate system, so that the 3D model and the light source are in the same coordinate system. In addition to converting the 3D model to the world coordinate system, you can also convert the light source to the rendering camera coordinate system, or convert both the 3D model and the rendering camera to other coordinate systems, as long as they are in the same coordinate system.

(2-3) Model enlargement: using the position and normal information of the 3D model, and the projection matrix of the rendering camera, each vertex of the model is moved outward along the normal in the projection direction of the projection plane, so that the model is on the projection plane Zoom in, that is, to make the model "bigger".

(2-4) Move the enlarged model slightly in a direction away from the rendering camera. This step can avoid the problem that the zoomed-in model and the original model are penetrated in places where the thickness of the model is small, resulting in wrong rendering effects.

(2-5) Render the enlarged model with the pre-specified stroke color by excluding the front (the shadow area and bright area of the original 3D model are rendered by excluding the back). In this way, the middle part of the enlarged model will be blocked by the original 3D model, and the enlarged peripheral part will cover the outside of the original 3D model, forming the outline of the lines in the 2D rendering effect.

After the rendering of the above two passes, the result is a celluloid-style two-dimensional rendering effect with edge outlines and secondary coloring.

In addition to using the normal information of the vertices, the stroke effect in this process can also use the tangent to indirectly calculate the normal of the smooth transition, and then enlarge it, so as to achieve smoother strokes and avoid the appearance of strokes on sharp corners. The problem of fracture, but the core is to draw a reverse model that is larger than the original model to simulate the effect of stroke. Compared with the post-processing method, the rendering result of the method of the embodiment of the present disclosure is a two-dimensional drawing style, which saves the steps and time of post-processing.

For details of this embodiment, refer to the foregoing embodiment of the rendering method for a three-dimensional model, and details are not repeated here.

As shown in FIG. 10 , the embodiment of the present disclosure also provides another method for rendering a 3D model, and the method includes steps 1001 to 1002 .

Step 1001: Enlarge the three-dimensional model to obtain an enlarged model, and the middle area of the enlarged model is blocked by the three-dimensional model.

Step 1002: Render the enlarged model based on a predetermined stroke color.

The embodiment of the present disclosure directly uses the stroke color to render the enlarged model. Compared with the traditional rendering method in which the entire 3D model is first rendered into a 2D image, and then edge segmentation is performed through post-processing, the embodiment of the present disclosure can effectively Improve rendering efficiency.

In some embodiments, the amplifying the three-dimensional model to obtain the enlarged model includes: displacing each vertex on the three-dimensional model along the direction of the projection vector of the normal of the vertex on the projection plane , to obtain the enlarged model. The middle area of the enlarged model obtained in this way can be directly blocked by the three-dimensional model before the enlargement without displacement, and the processing complexity is low.

In some embodiments, before rendering the enlarged model based on a predetermined stroke color, the method further includes: moving the enlarged model in a direction away from the rendering camera. This step can avoid the problem of magnified model and 3D model penetrating in places where the thickness of the model is small, resulting in wrong rendering effects.

In some embodiments, the method further includes: rendering a bright area of the three-dimensional model based on a color of the three-dimensional model, and rendering a shaded area of the three-dimensional model based on a predetermined shade color. In the embodiments of the present disclosure, it is not necessary to first render the entire 3D model into a 2D image, but can directly obtain the final rendering effect. Compared with the rendering method in which the 3D model to be rendered is first drawn to a 2D image and then post-processed, the rendering method of the embodiment of the present disclosure has higher rendering efficiency and is more suitable for real-time rendering scenarios.

In some embodiments, rendering the bright area of the 3D model based on the color of the 3D model, and rendering the shaded area of the 3D model based on a predetermined shadow color includes: pairing the color of the 3D model based on rendering the front of each fragment in the bright area, and rendering the front of each fragment in the shadow area based on a predetermined shadow color; rendering the enlarged model based on a predetermined stroke color, including : Render the back of each fragment in the enlarged model based on a predetermined stroke color; wherein, the front of a fragment is a surface obtained by connecting multiple vertices on the fragment along the first direction, and a The back surface of the fragment is a surface obtained by connecting multiple vertices on the fragment along a second direction, and the first direction is opposite to the second direction. In this way, the influence of the stroke color on the color of the bright area and the shadow area of the 3D model can be reduced, and the rendering effect can be improved.

This disclosure relates to the field of augmented reality. By acquiring the image information of the target object in the real environment, and then using various visual correlation algorithms to detect or identify the relevant features, states and attributes of the target object, and thus obtain the image information that matches the specific application. AR effect combining virtual and reality. Exemplarily, the target object may involve faces, limbs, gestures, actions, etc. related to the human body, or markers and markers related to objects, or sand tables, display areas or display items related to venues or places. Vision-related algorithms can involve visual positioning, SLAM, 3D reconstruction, image registration, background segmentation, object key point extraction and tracking, object pose or depth detection, etc. Specific applications can not only involve interactive scenes such as guided tours, navigation, explanations, reconstructions, virtual effect overlays and display related to real scenes or objects, but also special effects processing related to people, such as makeup beautification, body beautification, special effect display, virtual Interactive scenarios such as model display. The relevant features, states and attributes of the target object can be detected or identified through the convolutional neural network. The above-mentioned convolutional neural network is a network model obtained by performing model training based on a deep learning framework.

Those skilled in the art can understand that in the above method of specific implementation, the writing order of each step does not mean a strict execution order and constitutes any limitation on the implementation process. The specific execution order of each step should be based on its function and possible The inner logic is OK.

As shown in Fig. 11 , an embodiment of the present disclosure also provides a rendering device for a 3D model, the device includes: a determining module 1101, configured to determine the light and dark distribution of the 3D model under the viewing angle of the rendering camera, and the light and dark distribution is used to represent The luminance value of each fragment on the 3D model; the division module 1102, used to divide the 3D model into bright areas and shadow areas based on the light and dark distribution; the rendering module 1103, used to color the 3D model based on The bright area is rendered, and the shadow area is rendered based on a predetermined shadow color.

As shown in FIG. 12 , an embodiment of the present disclosure also provides a three-dimensional model rendering device, which includes: a first rendering module 1201, configured to, in the first rendering pass, adjust the brightness of the three-dimensional model based on the color of the three-dimensional model The region is rendered, and the shadow region of the three-dimensional model is rendered based on a predetermined shadow color; the second rendering module 1202 is configured to enlarge the three-dimensional model in a second rendering pass to obtain an enlarged model, based on The predetermined stroke color renders the enlarged model, and the middle area of the enlarged model is blocked by the three-dimensional model.

As shown in Fig. 13 , the embodiment of the present disclosure also provides a rendering device for a three-dimensional model, the device includes: an enlargement module 1301, configured to enlarge the three-dimensional model to obtain an enlarged model, the middle area of the enlarged model is covered by the three-dimensional Model occlusion; a rendering module 1302, configured to render the enlarged model based on a predetermined stroke color.

In some embodiments, the functions or modules included in the device provided by the embodiments of the present disclosure can be used to execute the methods described in the method embodiments above, and its specific implementation can refer to the description of the method embodiments above. For brevity, here No longer.

The embodiment of this specification also provides a computer device, which at least includes a memory, a processor, and a computer program stored on the memory and operable on the processor, wherein, when the processor executes the program, the computer program described in any of the preceding embodiments is implemented. described method.

FIG. 14 shows a schematic diagram of a more specific hardware structure of a computing device provided by the embodiment of this specification. The device may include: a processor 1401 , a memory 1402 , an input/output interface 1403 , a communication interface 1404 and a bus 1405 . The processor 1401 , the memory 1402 , the input/output interface 1403 and the communication interface 1404 are connected to each other within the device through the bus 1405 .

The processor 1401 may be implemented by a general-purpose CPU (Central Processing Unit, central processing unit), a microprocessor, an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), or one or more integrated circuits, and is used to execute related programs to realize the technical solutions provided by the embodiments of this specification. The processor 1401 may also include a graphics card, and the graphics card may be an Nvidia titan X graphics card or a 1080Ti graphics card.

The memory 1402 can be implemented in the form of ROM (Read Only Memory, read-only memory), RAM (Random Access Memory, random access memory), static storage device, dynamic storage device, etc. The memory 1402 can store operating systems and other application programs. When implementing the technical solutions provided by the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 1402 and invoked by the processor 1401 for execution.

The input/output interface 1403 is used to connect the input/output module to realize information input and output. The input/output/module can be configured in the device as a component (not shown in the figure), or can be externally connected to the device to provide corresponding functions. The input device may include a keyboard, mouse, touch screen, microphone, various sensors, etc., and the output device may include a display, a speaker, a vibrator, an indicator light, and the like.

The communication interface 1404 is used to connect a communication module (not shown in the figure), so as to realize the communication interaction between the device and other devices. The communication module can realize communication through wired means (such as USB, network cable, etc.), and can also realize communication through wireless means (such as mobile network, WIFI, Bluetooth, etc.).

Bus 1405 includes a path for transferring information between the various components of the device (eg, processor 1401, memory 1402, input/output interface 1403, and communication interface 1404).

It should be noted that although the above device only shows the processor 1401, the memory 1402, the input/output interface 1403, the communication interface 1404, and the bus 1405, in the implementation process, the device may also include other necessary components for normal operation. components. In addition, those skilled in the art can understand that the above-mentioned device may only include components necessary to implement the solutions of the embodiments of this specification, and does not necessarily include all the components shown in the figure.

An embodiment of the present disclosure further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method described in any one of the foregoing embodiments is implemented.

Computer-readable media includes both volatile and non-volatile, removable and non-removable media, and can be implemented by any method or technology for storage of information. Information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Flash memory or other memory technology, Compact Disc Read-Only Memory (CD-ROM), Digital Versatile Disc (DVD) or other optical storage, Magnetic tape cartridge, tape magnetic disk storage or other magnetic storage device or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media excludes transitory computer-readable media, such as modulated data signals and carrier waves.

It can be known from the above description of the implementation manners that those skilled in the art can clearly understand that the embodiments of this specification can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the essence of the technical solutions of the embodiments of this specification or the part that contributes to the prior art can be embodied in the form of software products, and the computer software products can be stored in storage media, such as ROM/RAM, A magnetic disk, an optical disk, etc., include several instructions to enable a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this specification.

The systems, devices, modules or units described in the above embodiments may be realized by computer chips or entities, or by products with certain functions. A typical implementing device is a computer, which may take the form of a personal computer, laptop computer, cellular phone, camera phone, smart phone, personal digital assistant, media player, navigation device, e-mail device, game control device, etc. desktops, tablets, wearables, or any combination of these.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and for relevant parts, please refer to part of the description of the method embodiments. The device embodiments described above are only illustrative, and the modules described as separate components may or may not be physically separated, and the functions of each module may be integrated in the same or multiple software and/or hardware implementations. Part or all of the modules can also be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without creative effort.

The above is only the specific implementation of the embodiment of this specification. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the embodiment of this specification, some improvements and modifications can also be made. These Improvements and modifications should also be regarded as the scope of protection of the embodiments of this specification.

Claims

A method for rendering a three-dimensional model, comprising:

Determine the light and dark distribution of the three-dimensional model under the viewing angle of the rendering camera, where the light and dark distribution is used to represent the brightness value of each fragment on the three-dimensional model;

dividing the three-dimensional model into a bright area and a shadow area based on the light and dark distribution;

The bright area is rendered based on the color of the three-dimensional model, and the shaded area is rendered based on a predetermined shade color.
The method according to claim 1, wherein determining the light and dark distribution of the 3D model under the viewing angle of the rendering camera comprises:

Determine a first light and dark distribution of the 3D model under the viewing angle of the rendering camera based on the illumination direction, the normal map of the 3D model and the position of the rendering camera, the normal map is used to characterize the 3D model The normal of each vertex on the model;

Based on the shadow map of the 3D model, determine a second light and dark distribution of the 3D model under the viewing angle of the rendering camera;

Determine the light and dark distribution of the three-dimensional model under the rendering camera viewing angle based on the first light and dark distribution and the second light and dark distribution.
The method according to claim 2, wherein determining the light and dark distribution of the 3D model under the rendering camera viewing angle based on the first light and dark distribution and the second light and dark distribution comprises:

For each fragment of the 3D model under the viewing angle of the rendering camera, determine the first brightness value of the fragment based on the first light and dark distribution, and determine the brightness value of the fragment based on the second light and dark distribution second brightness value;

Determine the brightness value of the slice according to the first brightness value and the second brightness value.
The method according to claim 1, wherein dividing the three-dimensional model into a bright area and a shadow area based on the light and dark distribution comprises:

determining an area on the three-dimensional model whose brightness value satisfies a first preset brightness condition as the bright area;

An area on the three-dimensional model whose brightness value satisfies a second preset brightness condition is determined as the shaded area.
The method according to claim 4, wherein the second preset brightness condition comprises that the brightness value is less than or equal to a first brightness threshold;

The predetermined shadow color includes a plurality of shadow colors, and the plurality of shadow colors respectively correspond to a plurality of different brightness sub-intervals; The brightness interval is divided into;

Rendering the shadow area based on the predetermined shadow color includes:

determining the luminance subinterval to which the luminance value of each fragment in the shaded area belongs;

Each fragment in the shadow area is rendered according to the shadow colors corresponding to the brightness sub-intervals to which the brightness value of each fragment belongs.
The method according to claim 4, wherein the second preset brightness condition comprises that the brightness value is less than or equal to a second brightness threshold;

The predetermined shadow color includes a plurality of shadow colors, and the plurality of shadow colors respectively correspond to a plurality of reference brightness values in the lookup table; the plurality of reference brightness values in the lookup table are all less than or equal to the first Two brightness thresholds;

Rendering the shadow area based on the predetermined shadow color includes:

Finding, from the lookup table, shadow colors corresponding to reference brightness values respectively matched with the brightness values of the fragments in the shadow area;

Each fragment in the shadow area is rendered according to the shadow color corresponding to the reference brightness value respectively matched with each fragment.
The method of claim 1, wherein rendering the bright region based on the color of the 3D model comprises:

determining the color of the bright region based on the diffuse reflection map corresponding to the three-dimensional model;

The bright region is rendered based on the color of the bright region.
The method of claim 1, wherein rendering the shaded region based on the predetermined shade color comprises:

determining the color of the shadow area based on the diffuse reflection map corresponding to the three-dimensional model;

correcting the color of the shaded area based on the predetermined shaded color to obtain a corrected color of the shaded area;

The shaded area is rendered based on the corrected color.
The method according to any one of claims 1 to 8, further comprising:

Enlarging the three-dimensional model to obtain an enlarged model, the middle area of the enlarged model is blocked by the three-dimensional model;

The enlarged model is rendered based on a predetermined stroke color.
The method according to claim 9, wherein amplifying the three-dimensional model to obtain the amplified model comprises:

Each vertex on the three-dimensional model is displaced along the direction of the projection vector of the normal of the vertex on the projection plane to obtain the enlarged model.
The method of claim 9, wherein rendering the bright region based on a color of the 3D model and rendering the shadow region based on a predetermined shade color comprises:

rendering the front face of each fragment in the bright area based on the color of the three-dimensional model, and rendering the front face of each fragment in the shadow area based on the predetermined shadow color;

Rendering the enlarged model based on a predetermined stroke color includes:

rendering the back of each fragment in the enlarged model based on a predetermined stroke color;

Wherein, the front face of a fragment is the face obtained by connecting multiple vertices on the fragment along the first direction, and the back face of a fragment is the face obtained by connecting multiple vertices on the fragment along the second direction On the other hand, the first direction is opposite to the second direction.
The method according to claim 9, wherein, before rendering the enlarged model based on the predetermined stroke color, the method further comprises:

and moving the enlarged model in a direction away from the rendering camera.
A method for rendering a three-dimensional model, comprising:

In a first rendering pass, rendering a bright region of the 3D model based on a color of the 3D model, and rendering a shadow region of the 3D model based on a predetermined shadow color;

In the second rendering pass, the three-dimensional model is enlarged to obtain an enlarged model, and the enlarged model is rendered based on a predetermined stroke color, and a middle area of the enlarged model is blocked by the three-dimensional model.
The method of claim 13, wherein rendering the bright regions of the 3D model based on the color of the 3D model and rendering the shaded regions of the 3D model based on the predetermined shadow color comprises :

rendering the front face of each fragment in the bright area based on the color of the three-dimensional model, and rendering the front face of each fragment in the shadow area based on the predetermined shadow color;

Rendering the enlarged model based on the predetermined stroke color includes:

rendering the back of each fragment in the enlarged model based on a predetermined stroke color;

Wherein, the front face of a fragment is the face obtained by connecting multiple vertices on the fragment along the first direction, and the back face of a fragment is the face obtained by connecting multiple vertices on the fragment along the second direction On the other hand, the first direction is opposite to the second direction.
A rendering device for a three-dimensional model, comprising:

A determining module, configured to determine the light and dark distribution of the three-dimensional model under the viewing angle of the rendering camera, where the light and dark distribution is used to characterize the brightness value of each fragment on the three-dimensional model;

a division module, configured to divide the three-dimensional model into bright areas and shadow areas based on the light and dark distribution;

A rendering module, configured to render the bright area based on the color of the 3D model, and render the shadow area based on a predetermined shadow color.
A rendering device for a three-dimensional model, comprising:

A first rendering module, configured to render a bright region of the 3D model based on a color of the 3D model in a first rendering pass, and render a shadow region of the 3D model based on a predetermined shadow color;

The second rendering module is configured to enlarge the three-dimensional model in a second rendering pass to obtain an enlarged model, render the enlarged model based on a predetermined stroke color, and the middle area of the enlarged model is drawn The 3D model occlusion described above.
A computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the method according to any one of claims 1 to 14 is realized.
A computer device comprising a memory, a processor, and a computer program stored in the memory and operable on the processor, the processor implementing the method according to any one of claims 1 to 14 when executing the program.
A computer program product comprising a computer program which, when executed by a processor, implements the method of any one of claims 1 to 14.