KR20120062542A - Image processing apparatus and method - Google Patents

Image processing apparatus and method Download PDF

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Publication number
KR20120062542A
KR20120062542A KR1020100123843A KR20100123843A KR20120062542A KR 20120062542 A KR20120062542 A KR 20120062542A KR 1020100123843 A KR1020100123843 A KR 1020100123843A KR 20100123843 A KR20100123843 A KR 20100123843A KR 20120062542 A KR20120062542 A KR 20120062542A
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KR
South Korea
Prior art keywords
triangles
model
vpl
importance
shape information
Prior art date
Application number
KR1020100123843A
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Korean (ko)
Inventor
하인우
Original Assignee
삼성전자주식회사
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Priority to KR1020100123843A priority Critical patent/KR20120062542A/en
Publication of KR20120062542A publication Critical patent/KR20120062542A/en

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T15/00—3D [Three Dimensional] image rendering
    • G06T15/04—Texture mapping
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T15/00—3D [Three Dimensional] image rendering
    • G06T15/50—Lighting effects
    • G06T15/55—Radiosity
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2215/00—Indexing scheme for image rendering
    • G06T2215/12—Shadow map, environment map

Abstract

PURPOSE: An image processing apparatus and a method thereof are provided to reduce the amount of VPL(Virtual Point Light)sampling operation in case of sampling VPL for three-dimensional rendering. CONSTITUTION: A first calculation unit(120) applies a plurality of direct light sources to a texture. The first calculation unit calculates illumination about model information. A second calculation unit(130) calculates a CDF(Cumulative Distribution Function) through the illumination. A distribution curve of significance about the model information is accumulated in the CDF. A VPL sampling unit(140) selects the CDF value. The VPL sampling unit samples at least one VPL within a three-dimensional model.

Description

Image processing apparatus and method {IMAGE PROCESSING APPARATUS AND METHOD}

Related to global illumination-based rendering of objects made up of 3D models, and more specifically to how to sample Virtual Point Light (VPL) on 3D models for 3D rendering by Radiosity techniques. do.

As hardware and software evolve, real-time rendering of 3D models in various fields, such as 3-Dimensional (hereinafter simply referred to as "3D") gaming, virtual world animation, and cinema There is a growing interest in.

Among these 3D rendering techniques, the Radiosity technique considering global illumination includes not only direct lighting by a direct light source existing in a 3D model, but also indirect lighting by reflected light or diffuse reflection phenomenon reflected by an object. It is a rendering method that improves rendering quality in consideration of.

In this case, VPL sampling is required to properly position VPLs representing indirect lighting effects at arbitrary locations in the 3D model. In the case where there are a plurality of direct light sources, the amount of computation for VPL sampling is very large, Since redundancy is large because no associations such as spatial proximity between direct light sources are taken into account.

When sampling a VPL for rendering a 3D model including a plurality of direct light sources, an image processing apparatus and a method capable of reducing an operation amount of the VPL sampling are provided.

In 3D rendering of the radiosity technique, an image processing apparatus and method are provided that greatly reduce the amount of computation in a VPL sampling process and greatly improve the possibility of real-time rendering due to an improvement in rendering speed relative to computational resources.

According to one aspect of the invention, the texture generation unit for generating a texture for the shape information of the 3D model using a 3D model, by applying a plurality of direct light sources to the texture, the first to calculate the roughness of the shape information A second calculation unit that calculates a cumulative distribution function (CDF) that accumulates a distribution curve of importance for the shape information using the illuminance, and randomly selects the cumulative distribution function value And a VPL sampling unit for sampling at least one VPL in the 3D model.

The shape information may include a 3D coordinate value of a vertex for each of the plurality of triangles constituting the 3D model.

In this case, the first calculator may calculate illuminance of the plurality of direct light sources with respect to vertices of each of the plurality of triangles.

According to an embodiment of the present invention, the second calculator calculates, for each of the triangles, the importance of each of the triangles in proportion to at least one of the calculated illuminance, triangle width, and triangle color.

In this case, when calculating the importance of each of the triangles, the second calculation unit may calculate the importance of each of the triangles in consideration of the visibility at the camera viewpoint to render the 3D model for each of the triangles. have.

The image processing apparatus may further include a rendering unit generating a shadow map for each of the at least one VPL, and rendering a 3D model using a radiosity technique.

According to another aspect of the invention, generating a texture for the shape information of the 3D model using a 3D model, applying a plurality of direct light sources to the texture, calculating the roughness for the shape information, the Computing a cumulative distribution function (CDF) by accumulating the distribution curve of importance for the shape information using the roughness, and randomly selecting the cumulative distribution function value, sampling at least one VPL in the 3D model Provided is an image processing method comprising the steps of.

Since the redundancy is greatly reduced when calculating the scene illumination for each of the plurality of direct light sources, the amount of computation when sampling the VPL is greatly reduced.

In 3D rendering of the Radiosity technique, since the amount of computation in the VPL sampling process is greatly reduced, the rendering speed is increased compared to the computational resources, and the possibility of real-time rendering is greatly increased.

1 illustrates an image processing apparatus according to an embodiment of the present invention.
2 illustrates an exemplary 3D model rendered by an image processing apparatus and method according to an embodiment of the present invention.
3 is a plan view illustrating an object and a light of the 3D model of FIG. 2.
4 is a conceptual diagram illustrating a process of generating a texture for triangles of a 3D model according to an embodiment of the present invention.
5 is a conceptual diagram illustrating a process of calculating illumination of triangles in consideration of a plurality of direct light sources according to an embodiment of the present invention.
6 is a graph illustrating a process of performing VPL sampling after generating a CDF of importance calculated for triangles according to an embodiment of the present invention.
7 illustrates VPLs sampled according to an embodiment of the present invention.
8 illustrates an image processing method according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited or limited by the embodiments. Like reference numerals in the drawings denote like elements.

1 illustrates an image processing apparatus 100 according to an embodiment of the present invention.

According to an embodiment of the present invention, the texture generator 110 generates a texture for triangles constituting shape information of the input 3D model, for example, 3D shape information.

The texture is data including three-dimensional coordinate values of vertices for each of the plurality of triangles constituting the 3D model, and is shape information data for calculating scene illumination by direct light sources.

The texture generation process and the generated texture of the texture generator 110 will be described later in more detail with reference to FIG. 4.

The first calculator 120 of the image processing apparatus 100 calculates a scene illumination of the shape information by applying a plurality of direct light sources included in a 3D model to the texture.

The illuminance calculation process of the first calculation unit 120 will be described later in more detail with reference to FIG. 5.

According to the conventional method, when calculating scene illumination for each of each direct light source, and sampling the virtual point light (VPL) for the indirect lighting effect for each direct light source, the amount of calculation for VPL sampling is large.

For example, there is a big problem in redundancy in the VPL sampling operation when the position of each direct light source is close.

According to an embodiment of the present invention, the first calculator 120 calculates the total scene illumination once in consideration of all the plurality of direct light sources included in the rendering of the 3D model, thereby removing redundancy.

The second calculation unit 130 of the image processing apparatus 100 imports the importance of each triangle constituting the shape information in the 3D model by using the total scene illumination calculated in consideration of the plurality of direct light sources. Calculate

In this case, the second calculator 130 calculates the importance of the triangle as the calculated illuminance for each triangle is larger, the triangle width is wider, and / or the brightness value of the triangle color is larger.

Meanwhile, according to an embodiment of the present invention, when the second calculator 130 calculates the importance of each of the triangles, a camera view for rendering the 3D model for each of the triangles is performed. The importance of each of the triangles can be calculated by considering the visibility in.

That is, in the present embodiment, the second calculation unit 130 calculates the importance of the triangles that are visible at the camera point of view, and calculates the importance of the triangles that are not visible.

The second calculator 130 arranges each triangle according to an index and calculates a cumulative distribution function (CDF) that accumulates the distribution curve of the importance according to the indexes of the triangles.

The calculation of this cumulative distribution function will be described later in more detail with reference to FIG. 6.

Then, the VPL sampling unit 140 of the image processing apparatus 100 randomly selects the cumulative distribution function value, randomly samples the triangles, and applies at least one VPL to each of the sampled triangles. Sample.

Through this process, one VPL sampling is performed in consideration of a plurality of direct light sources.

The result of the VPL sampling will be described later with reference to FIG. 7.

The renderer 150 generates a shadow map for each of the at least one sampled VPL, and renders the 3D model using a conventional global illumination rendering technique, such as a radiosity technique.

2 illustrates an example 3D model 200 rendered by an image processing apparatus and method according to an embodiment of the present invention.

The 3D model 200 has an exemplary form in which three objects are included in a room in which a part of the facade is open.

Within the example 3D model 200 are objects 210, objects 220 and objects 230.

Of course, the 3D model 200 is merely exemplary for simplicity of explanation, and the present invention should not be construed as limited by the specific embodiments.

The state of the 3D model 200 currently shown in FIG. 2 shows the state seen from the outside to the inside of the room.

The plan view of the 3D model 200 and the positions of the direct light sources will be described later with reference to FIG. 3.

FIG. 3 is a plan view illustrating objects 210 to 230 and direct light sources of the 3D model 200 of FIG. 2.

In this example 3D model 200, the direct light sources that should be considered for rendering are the light source 310 and the light source 320. Of course, the number of direct light sources is merely exemplary, and in fact, a greater number of direct light sources may be included.

The light source 301 and the light source 302 considered for the rendering of the 3D model 200 are located outside the hexahedron room, and the interior objects 210 to 230 of the room through the gaps in the open front of the room. To give light).

The range in which the light of the light source 301 existing outside of the room reaches the inside of the room is represented by the angle 310. In addition, the range in which the light of the light source 302 reaches the inside of the room is represented by the angle 320.

Direct light from the light source 301 does not reach a portion outside the angle 310 inside the room, and direct light from the light source 302 does not reach a portion outside the angle 320. Do not.

In this case, the direct light of both the light source 301 and the light source 302 reaches the object 210, but only the direct light of the light source 302 reaches the object 220, and the light source 301 of the object 230. It can be seen that only the direct light of arrives.

If, according to the conventional method, sampling the VPLs on the 3D model 200 at the viewpoint of the light source 301, and separately sampling the VPLs on the 3D model 200 also at the viewpoint of the light source 302, the object ( The VPL sampling process may overlap on 210.

According to an embodiment of the present invention, the first calculator 120 generates texture data for a VPL sampling operation on the triangles constituting the entire Scene objects of the 3D model 200, and the second calculator ( 130).

Then, the second calculator 130 calculates the scene illumination only once in consideration of the plurality of light sources 301 and 302 for the entire scene of the 3D model 200. Redundancy can be eliminated in this process.

4 is a conceptual diagram illustrating a process of generating a texture for triangles of a 3D model according to an embodiment of the present invention.

The first calculation unit 120 generates the triangles 410 constituting the shape information of the 3D model 200 as the texture 420.

In this process, the X-, Y-, and Z-axis coordinate values of each vertex of each triangle 411-413 are generated as data elements 421-423 in the texture.

Of course, the texture 420 is merely an exemplary and conceptual representation, and according to the computational structure of the image processing apparatus 100 for rendering or the memory structure included therein, the texture of the texture 420 is generated. Can be in other forms.

In the present embodiment, the texture data elements 421 correspond to the triangle 411, the elements 422 to the triangle 412, and the elements 423 to the triangle 413, respectively.

5 is a conceptual diagram illustrating a process of calculating illumination of triangles in consideration of a plurality of direct light sources according to an embodiment of the present invention.

The second calculation unit 130 calculates illuminance for the triangle T1 of the 3D model 200 in consideration of the data L1 of the light source 301 and the data L2 of the light source 302. The second calculator 130 calculates an illuminance in consideration of the data L1 and the data L2 of the light source 302 for all the triangles constituting the 3D model 200, such as the triangle T2 and the triangle T3.

Through this process, the total scene illumination calculation considering the plurality of direct light sources is performed.

In addition, the second calculation unit 130 may consider each of the triangles T1 to T3 in consideration of the illumination calculation value, the width of each triangle, and / or the color of the triangle (eg, the brightness (brightness) of the color). The importance of the entire triangles of the 3D model 200).

In calculating the importance, according to an embodiment of the present invention, the second calculator 130 may consider the visibility at the camera viewpoint to render the 3D model 200 together.

6 is a graph 600 for explaining a process of performing VPL sampling after generating a CDF of importance calculated for triangles according to an embodiment of the present invention.

According to an embodiment of the present invention, the second calculator 130 calculates a cumulative distribution function (CDF) of importance of each triangle in the X-axis direction indicating a triangle index. The Y axis of graph 600 corresponds to the CDF value.

The VPL sampling unit 140 randomly (or uniformly) samples any of these CDF values (values of 0 to 1).

Then, the triangle indexes corresponding to the sampled S1 to S4 and the like are identified to sample the triangles.

The VPL sampling unit 140 samples one or more VPLs at a center of gravity in each of the sampled triangles or at any point in each triangle.

7 illustrates VPLs sampled according to an embodiment of the present invention.

Referring to the exemplary sampling result 700, on an object 210 that receives light directly from both of the two direct light sources 301 and 302, it is possible to see more than another object 220 or 230 or other space in the 3D model 200. It can be seen that more VPLs (eg, VPL 710) have been sampled.

Through this VPL sampling process, redundancy is greatly reduced as compared with the case of performing VPL sampling for each direct light source.

When the VPLs to be used for rendering are determined, the rendering unit 150 of the image processing apparatus 100 renders an image of the camera viewpoint 302 by using a radiosity technique using the determined VPLs.

8 illustrates an image processing method according to an embodiment of the present invention.

In operation 810, the texture generator 110 of the image processing apparatus 100 generates a texture for each triangle of the input 3D model.

The texture generation process and an exemplary conceptual diagram are as described above with reference to FIG. 4.

In operation 820, the first calculator 120 of the image processing apparatus 100 may apply a plurality of direct light sources included in a 3D model to the texture to obtain scene illumination of the shape information. Calculate

The illuminance calculation process of the first calculation unit 120 is as described above with reference to FIG. 5.

In operation 830, the second calculator 130 of the image processing apparatus 100 may configure shape information in the 3D model using total scene illumination calculated in consideration of the plurality of direct light sources. Calculate Importance for the triangles of.

In this case, the importance is calculated that the greater the calculated illuminance for each triangle, the wider the triangular width, and / or the larger the value of the triangular color, the higher the value. As described above.

Furthermore, according to an embodiment of the present invention, when the second calculator 130 calculates the importance of each of the triangles, a camera view to render the 3D model for each of the triangles is performed. The importance of each of the triangles can be calculated by considering the visibility in.

In addition, in this step, the second calculator 130 arranges each triangle according to an index to calculate a cumulative distribution function (CDF) that accumulates the distribution curve of the importance according to the indexes of the triangles.

Such CDF is as described above with reference to FIG. 6.

Then, in step 840, the VPL sampling unit 140 of the image processing apparatus 100 randomly selects the cumulative distribution function value, randomly samples the triangles, and each of the triangles thus sampled. Sample at least one VPL inside.

The results of the VPL sampling have been described above with reference to FIG. 7.

In operation 850, the rendering unit 150 generates a shadow map for each of the at least one sampled VPL, and uses a conventional global illumination rendering technique, such as a radiosity technique. Render the 3D model.

Method according to an embodiment of the present invention is implemented in the form of program instructions that can be executed by various computer means may be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

100: image processing device
110: texture generator
120: first calculation unit
130: second calculation unit
140: VPL sampling unit
150: renderer

Claims (13)

A texture generator for generating a texture of shape information of the 3D model using a 3D model;
A first calculator configured to apply a plurality of direct light sources to the texture to calculate roughness of the shape information;
A second calculator configured to calculate a cumulative distribution function (CDF) that accumulates a distribution curve of importance for the shape information using the illuminance; And
A VPL sampling unit for randomly selecting the cumulative distribution function value and sampling at least one VPL in the 3D model
Image processing apparatus comprising a. The method of claim 1,
The shape information includes a three-dimensional coordinate value of a vertex for each of the plurality of triangles constituting the 3D model. The method of claim 2,
The first calculation unit,
And for the vertices of each of the plurality of triangles, illuminance by the plurality of direct light sources. The method of claim 1,
The second calculation unit,
For each of the triangles, the importance of each of the triangles is calculated in proportion to at least one of the calculated illuminance, triangle width, and triangle color. The method of claim 4, wherein
The second calculation unit,
When calculating the importance of each of the triangles, the importance of each of the triangles is calculated in consideration of the visibility at the camera viewpoint to render the 3D model for each of the triangles. The method of claim 1,
A rendering unit generating a shadow map for each of the at least one VPL and rendering a 3D model using a radiosity technique.
Further comprising, the image processing device. Generating a texture for shape information of the 3D model using a 3D model;
Calculating a roughness of the shape information by applying a plurality of direct light sources to the texture;
Calculating a cumulative distribution function (CDF) in which a distribution curve of importance for the shape information is accumulated using the illuminance; And
Sampling at least one VPL in the 3D model by randomly selecting the cumulative distribution function value
Image processing method comprising a. The method of claim 7, wherein
The shape information includes a three-dimensional coordinate value of a vertex for each of the plurality of triangles constituting the 3D model. The method of claim 8,
Calculating the roughness for the shape information,
Computing illuminance by the plurality of direct light sources for the vertices of each of the plurality of triangles. The method of claim 7, wherein
Computing the cumulative distribution function (CDF),
For each of the triangles, the importance of each of the triangles is calculated in proportion to at least one of the calculated illuminance, triangle width, and triangle color. The method of claim 10,
Computing the cumulative distribution function (CDF),
When calculating the importance of each of the triangles, calculating the importance of each of the triangles in consideration of the visibility from the camera viewpoint to render the 3D model for each of the triangles. The method of claim 7, wherein
Generating a shadow map for each of the at least one VPL and rendering a 3D model using a radiosity technique
Further comprising, the image processing method. A computer-readable recording medium containing a program for performing the image processing method of any one of claims 7 to 12.
KR1020100123843A 2010-12-06 2010-12-06 Image processing apparatus and method KR20120062542A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150128536A (en) * 2014-05-09 2015-11-18 삼성전자주식회사 Method and apparatus for processing image
CN108427777A (en) * 2017-02-14 2018-08-21 常州星宇车灯股份有限公司 A kind of analog analysing method of halogen lens module self-focusing
US10157494B2 (en) 2014-02-20 2018-12-18 Samsung Electronics Co., Ltd. Apparatus and method for processing virtual point lights in an image
US10403034B2 (en) 2014-05-09 2019-09-03 Samsung Electronics Co., Ltd. Image processing method and apparatus for rendering an image based on virtual point light (VPL) samplings

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10157494B2 (en) 2014-02-20 2018-12-18 Samsung Electronics Co., Ltd. Apparatus and method for processing virtual point lights in an image
KR20150128536A (en) * 2014-05-09 2015-11-18 삼성전자주식회사 Method and apparatus for processing image
US10403034B2 (en) 2014-05-09 2019-09-03 Samsung Electronics Co., Ltd. Image processing method and apparatus for rendering an image based on virtual point light (VPL) samplings
CN108427777A (en) * 2017-02-14 2018-08-21 常州星宇车灯股份有限公司 A kind of analog analysing method of halogen lens module self-focusing

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