WO2017039027A1

WO2017039027A1 - Method of processing global illumination and apparatus performing the same

Info

Publication number: WO2017039027A1
Application number: PCT/KR2015/009163
Authority: WO
Inventors: Woo Nam Chung
Original assignee: Siliconarts Inc.
Priority date: 2015-08-31
Filing date: 2015-08-31
Publication date: 2017-03-09
Also published as: KR20180048902A

Abstract

The present invention relates to a rendering technique based on a ray tracing, a method of processing global illumination, includes (a) performing a ray tracing on a certain pixel from a given light source to generate a direct light shading, (b) determining at least one indirect light source on the certain pixel for an indirect light shading and (c) performing a ray tracing on the certain pixel from the at least one indirect light source to generate an indirect light shading.

Description

METHOD OF PROCESSING GLOBAL ILLUMINATION AND APPARATUS PERFORMING THE SAME

[0001] This disclosure relates to a ray-tracing based rendering technique and, more particularly, to a computer executable global illumination processing method and apparatus capable of using a ray tracing in a global illumination with better speed and lesser complexity.

[0002] A graphic processing unit (GPU) is one of fundamental devices for a multimedia environment. A graphic processing process performed in the GPU may be largely classified into animation and rendering procedures. An animation procedure is used for moving an object at each frame and a rendering procedure is used for coating a color on a surface of an object.

[0003] The rendering procedure requires a sufficient understanding for a light dispersion and a light refraction generated by an object when the object is illuminated by a light and also requires a sufficient understanding for an optical property of the light. In such rendering procedures, there are a local illumination based rendering (hereinafter, referred to as "local illumination scheme") and a global illumination based rendering (hereinafter, referred to as "global illumination scheme").

[0004] A local illumination scheme considers a relation between a normal vector of a vertex and a light (that is, a direct relation among an observer, a light source and an object) to calculate a brightness value of a surface of an object. The local illumination scheme may not represent an effect of light such as a shadow because an indirect illumination according to a surrounding circumstance surrounding the face is not considered.

[0005] A global illumination scheme considers a surface, a surrounding circumstance around surfaces, a light optical property and a relation therebetween in an image generation procedure to illustrate a light effect. Because a realistic optical effect such as a shadow generation and a reflection is reflected in the image, the global illumination scheme may provide more realistic image than the local illumination scheme. This global illumination scheme may typically include ray tracing scheme and also, a radiosity scheme and photon map ray tracing scheme.

[0006] Korean Patent Publication NO. 10-2011-0020411 is related to a graphic processing device for supporting global illumination. A graphics processing device for supporting global illumination is provided to offer a realistic brightness value by calculating a brightness value of an object face. A global lighting operation unit(250) produces the entire region lighting operation value about the an object. A local lighting operation unit(210) reads the entire region lighting operation value by the entire local lighting operation value loader command. The local lighting operation unit outputs the final pixel value through the shading of the entire local lighting operation value about the pixel value of the first object. An interfacing unit(230) the local lighting operation unit and the entire region lighting operation unit.

[0007] One embodiment of the present invention proposes a global illumination processing method and apparatus capable of using a ray tracing in a global illumination with better speed and lesser complexity.

[0008] One embodiment of the present invention proposes a global illumination processing method and apparatus capable of independently or sequentially operating a direct light shading and an indirect light shading to process a global illumination.

[0009] One embodiment of the present invention proposes a global illumination processing method and apparatus capable of using an LOS (Line Of Sight) for processing an indirect light shading.

[0010] In some embodiments, a method of processing global illumination includes (a) performing a ray tracing on a certain pixel from a given light source to generate a direct light shading, (b) determining at least one indirect light source on the certain pixel for an indirect light shading and (c) performing a ray tracing on the certain pixel from the at least one indirect light source to generate an indirect light shading.

[0011] The method of processing the global illumination further may further include (d) combining a direct light pixel generated through the direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel.

[0012] In one embodiment, the method of processing global illumination may further include independently performing the steps (a) and the (b).

[0013] The step (a) may include (a1) generating an eye ray and performing a traversal and intersection operation to obtain the certain pixel as a hitting point and (a2) performing a direct shading operation on the certain pixel to generate the direct light pixel.

[0014] The step (b) may include (b1) searching for at least one LOS (Line Of Sight) associated with at least one pixel influencing on a present color of the certain pixel beyond a certain criterion and (b2) determining the at least one pixel as the at least one indirect light source to generate each of the at least one LOS as a shading ray for the certain pixel.

[0015] The step (b1) may include calculating an influence levels for the certain pixel based on material properties and material distances of corresponding pixels, being on intersected points with shortest lines from the certain pixel.

[0016] In another embodiment, the method may further include sequentially performing the step (a) and then the step (b).

[0017] The step (a) may include (a1) generating an eye ray and performing a traversal and intersection operation to obtain the certain pixel as a hitting point, (a2) performing a shading operation on the certain pixel to generate the direct light pixel and (a3) storing the LOS between the certain pixel and the given light source.

[0018] The step (b) may include searching for at least one LOS (Line Of Sight) associated with at least one pixel, each being located within a predetermined angle range toward the given light source at a center of the stored direct LOS and each influencing on a present color of the certain pixel and generating at least one first pixel as at least one primary indirect light source to determine the at least one primary indirect light shading ray for the certain pixel, the at least one first pixel including a pixel forming an LOS from the given light source among the at least one pixel.

[0019] The step (b) may include when a current amount of operations is below a predetermined criterion, generating at least one second pixel as at least one secondary indirect light source to determine the at least one secondary indirect light shading ray for the certain pixel.

[0020] In some embodiments, a global illumination apparatus includes a direct light shading generation unit configured to perform a ray tracing on a certain pixel from given light source to generate a direct light shading, an indirect light source determination unit configured to determine at least one indirect light source on the certain pixel for an indirect light shading and an indirect light shading generation unit configured to perform a ray tracing on the certain pixel from the at least one indirect light source to generate an indirect light shading.

[0021] The global illumination apparatus may further include a final pixel generation unit configured to combine a direct light pixel generated through the direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel.

[0022] A global illumination processing method and apparatus according to one embodiment of the present invention may use a ray tracing in a global illumination with better speed and lesser complexity.

[0023] A global illumination processing method and apparatus according to one embodiment of the present invention may independently or sequentially operate a direct light shading and an indirect light shading to process a global illumination.

[0024] A global illumination processing method and apparatus according to one embodiment of the present invention may use an LOS (Line Of Sight) for processing an indirect light shading.

[0025] FIG. 1 is a block diagram illustrating a global illumination apparatus according to an example embodiment of the present invention.

[0026] FIG. 2 is a flowchart illustrating one example of a global illumination procedure in FIG. 1.

[0027] FIG. 3 is a flowchart illustrating another example of a global illumination procedure in FIG. 1.

[0028] FIG. 4 is a conceptual diagram illustrating a global illumination procedure in FIG. 1.

[0029] Explanation of the present invention is merely an embodiment for structural or functional explanation, so the scope of the present invention should not be construed to be limited to the embodiments explained in the embodiment. That is, since the embodiments may be implemented in several forms without departing from the characteristics thereof, it should also be understood that the described embodiments are not limited by any of the details of the foregoing description, unless otherwise 20 specified, but rather should be construed broadly within its scope as defined on the appended claims. Therefore, various changes and modifications that fall within the scope of the claims, or equivalents of such scope are therefore intended to be embraced by the appended claims.

[0030] Terms described in the present disclosure may be understood as follows.

[0031] While terms such as "first" and "second," etc., may be used to describe various components, such components must not be understood as being limited to the above terms. The above terms are used to distinguish one component from another. For example, a first component may be referred to as a second component without departing from the scope of rights of the present invention, and likewise a second component may be referred to as a first component.

[0032] It will be understood that when an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly connected to" another element, no intervening elements are present. In addition, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising," will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. Meanwhile, other expressions describing relationships between components such as "between?,“immediately between" or "adjacent to" and "directly adjacent to" may be construed similarly.

[0033] Singular forms "a", "an" and "the" in the present disclosure are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that terms such as "including" or "having," etc., are intended to indicate the existence of the features, numbers, operations, actions, components, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, operations, actions, components, parts, or combinations thereof may exist or may be added.

[0034] Identification letters (e.g., a, b, c, etc.) in respective steps are used for the sake of explanation and do not described order of respective steps. The respective steps may be changed from a mentioned order unless specifically mentioned in context. Namely, respective steps may be performed in the same order as described, may be substantially simultaneously performed, or may be performed in reverse order.

[0035] The present invention may be implemented as machine-readable codes on a machine-readable medium. The machine-readable medium includes any type of recording device for storing machine-readable data. Examples of the machine readable recording medium include a read-only memory (ROM), a random access memory (RAM), a compact disk-read only memory (CD-ROM), a magnetic tape, a floppy disk, and optical data storage. The medium may also be carrier waves (e.g., Internet transmission). The computer-readable recording medium may be distributed among networked machine systems which store and execute machine-readable codes in a de-centralized manner.

[0036] The terms used in the present application are merely used to describe particular embodiments, and are not intended to limit the present invention. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meanings as those generally understood by those with ordinary knowledge in the field of art to which the present invention belongs. Such terms as those defined on a generally used dictionary are to be interpreted to have the meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted to have ideal or excessively formal meanings unless clearly defined on the present application.

[0037]

[0038] The present invention is supported by Seoul Industry Promotion Institute in 2013 as 「Technology Development Supporting Project For Patent Technology Commercialization」 and is a result of the project "Software Kit Development For Developing Ray Tracing Rendering Contents" from September 1, 2013 to August 31, 2014 by SILICONARTS, INC.

[0039] [National R&D Project Supporting the present invention]

[0040] [Project Serial Number] PA130017

[0041] [Department] Seoul Special City

[0042] [Research Management Organization] Seoul Industry Promotion Institute

[0043] [Research Project Name] Seoul Industry-academic Cooperative Project (Technology Development Supporting Project For Patent Technology Commercialization in 2013)

[0044] [Research Subject Name] Software Kit Development For Developing Ray Tracing Rendering Contents

[0045] [Contribution Ratio] 1/1

[0046] [Leading Organization] SILICONARTS, INC.

[0047] [Research Period] September 1, 2013 ~ August 31, 2014

[0048]

[0049] FIG. 1 is a block diagram illustrating a global illumination apparatus according to an example embodiment of the present invention. FIG. 4 is a conceptual diagram illustrating a global illumination procedure in FIG. 1.

[0050] Referring to FIG. 1, a global illumination apparatus 100 includes a direct light shading generation unit 110, an indirect light source determination unit 120, an indirect light shading generation unit 130, a final pixel generation unit 140, a frame buffer unit 150 and a control unit 160.

[0051] A direct light shading generation unit 110 performs a ray tracing on a certain pixel 410 in a target object 412 from a given light source (e.g., direct light source 420) to generate a direct light shading. In one embodiment, in the ray tracing, an eye ray may be generated based on a position of a camera or a viewpoint and an eye ray position may be changed according to a user manipulation. In one embodiment, the direct light shading may be mainly influenced by a brightness strength and a light color of the direct light source 420 and a material property of the certain pixel 410 in the target object 412 viewed by a camera.

[0052] An indirect light source determination unit 120 determinates at least one indirect light source 430 on the certain pixel 410 for an indirect light shading. In one embodiment, the at least one indirect light source 430 may be generated by at least one object 432 other than the target object 412 and the at least one object 432 may be scattered in a space around the target object 412. In one embodiment, the at least one indirect light source 430 may be determined as a region in one of the at least one object 432 and the region may be selected as a point group in a visible shortest path from a viewpoint of the target object 412.

[0053] An indirect light shading generation unit 130 performs a ray tracing on the certain pixel 410 from the at least one indirect light source 430 to generate an indirect light shading. In one embodiment, the at least one indirect light source 430 may be respectively considered as another direct light source with its own brightness strength and light color for the ray tracing. In one embodiment, the at least one indirect light shading may be mainly influenced by a material property such as a material ingredient, a reflection degree, a refraction degree and a color and a material distance. For example, the material ingredient may indicate a metal property, a glass property and/or a plastic property. For example, the reflection degree may indicate an optical reflectivity of the certain pixel 410. The reflection degree may be influenced by the material ingredient and may be changed according to a surface roughness. For example, the refraction degree may indicate an amount of a change in direction of propagation of a wave due to a change in its transmission medium and may be changed according to a wavelength of the indirect light source 430. For example, the color may indicate a color of the indirect light source 430. For example, the material distance may indicate a distance between the certain pixel 410 and the at least one indirect light source 430.

[0054] A final pixel generation unit 140 combines a direct light pixel generated through the direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel. In one embodiment, the combination weight of the direct light pixel and the indirect light pixel may be determined by weighing (i) relative distances of the direct light source 420 and each of the at least one indirect light source 430, (ii) relative color of the direct light source 420 and each of the at least one indirect light source 430 and (iii) relative offset relation among

light sources

420 and 430 that may be generated by light waves in the certain pixel 410. In one embodiment, the final pixel generation unit may calculate an intensity of the direct light source 420 and each of the at least one indirect light source 430 to generate a color of the target object 412. For example, a combination of a red light, a blue light and a green light may generate a white light.

[0055] A frame buffer unit 150 may include storage regions in a memory and may temporarily store an image illustrating on a display screen. In one embodiment, each of the storage regions in the frame buffer 150 may indicate one frame.

[0056] A control unit 160 controls operations among a direct light shading generation unit 110, an indirect light source determination unit 120, an indirect light shading generation unit 130, a final pixel generation unit 140 and a frame buffer unit 150.

[0057] In one embodiment, the global illumination apparatus 100 may be implemented as a single processor such as CPU (Central Processing Unit) and GPU (Graphic Processing Unit). When the global illumination apparatus 100 is implemented as the GPU, the GPU may cooperate with the CPU and also be in another board to be electrically coupled to the CPU.

[0058] FIG. 2 is a flowchart illustrating one example of a global illumination procedure in FIG. 1.

[0059] In FIG. 2, the global illumination apparatus 100 independently performs a direct light shading generation procedure and an indirect light shading generation procedure, and then combines a direct light pixel generated through a direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel.

[0060] The direct light shading generation unit 110 performs a ray tracing on the certain pixel 410 for a given light source 420 to generate a direct light shading pixel (Step S210). In one embodiment, the direct light shading generation unit 110 may generate an eye ray and perform a traversal and intersection operation to obtain the certain pixel 410 as a hitting point to be hit with a trajectory of the eye ray. The direct light shading generation unit 110 may perform a direct light shading operation on the certain pixel 410 to generate the direct light shading pixel. That is, the direct light shading generation unit 110 may generate the direct light pixel on the certain pixel 410 through the direct light shading operation.

[0061] The indirect light source determination unit 120 determines at least one indirect light source 430 (Step S220) and the indirect light shading unit 130 performs a ray tracing on the certain pixel 410 for the at least one indirect light source 430 to generate an indirect light shading pixel (Step S230). In one embodiment, the indirect light source determination unit 120 may search for at least one LOS (Line Of Sight) associated with at least one pixel influencing on a present color of the certain pixel 410 and may determine the at least one pixel as the at least one indirect light source 430 to generate the at least one indirect light shading ray for the certain pixel 410. In detail, the indirect light source determination unit 120 may calculate influence factors for the certain pixel 410 based on material properties and material distances of corresponding pixels. The corresponding pixels may be on intersected points with shortest lines from the certain pixel 410. Herein, the material property may include a material ingredient, a reflection degree, a refraction degree and a color of a corresponding intersected point and the material distance may include a distance between the certain point 410 and the corresponding intersected point. The indirect light shading generation unit 130 may generate an indirect light shading ray and may perform a traversal and intersection operation to obtain the certain pixel 410 as a hitting point to be hit with a trajectory of the indirect light shading ray. That is, the indirect light shading generation unit 130 may perform an indirect light shading operation on the certain pixel 410 to generate the indirect light shading pixel.

[0062] The final pixel generation unit 140 combines the direct light pixel generated through a direct light shading and the indirect light pixel generated through the indirect light shading to generate a final pixel (Step S240).

[0063] FIG. 3 is a flowchart illustrating another example of a global illumination procedure in FIG. 1.

[0064] In FIG. 3, the global illumination apparatus 100 sequentially performs a direct light shading generation procedure and an indirect light shading generation procedure, and then combines a direct light pixel generated through a direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel.

[0065] The direct light shading generation unit 110 performs a ray tracing on the certain pixel 410 for a given light source 420 to generate a direct light shading pixel and to store an LOS (Line Of Sight) between the certain pixel 410 and the given light source 420 (hereinafter, referred to as "a direct LOS") (Step S310). In one embodiment, the direct light shading generation unit 110 may generate an eye ray and perform a traversal and intersection operation to obtain the certain pixel 410 as a hitting point to be hit with a trajectory of the eye ray. The direct light shading generation unit 110 may perform a direct light shading operation on the certain pixel 410 to generate the direct light shading pixel. That is, the direct light shading generation unit 110 may generate the direct light pixel on the certain pixel 410 through the direct light shading operation. Then the direct light shading generation unit 110 may store the direct LOS.

[0066] The indirect light source determination unit 120 uses the stored direct LOS to determine at least one primary indirect light source 430a and 430b and at least one secondary indirect light source 430c and 430d (Step S320) and the indirect light shading unit 130 performs a ray tracing on the certain pixel 410 for the at least one primary indirect light source 430a and 430b and if necessary, the at least one secondary indirect light source 430c and 430d to generate an indirect light shading pixel (Step S330). In one embodiment, the indirect light source determination unit 120 may search for at least one LOS (Line Of Sight) associated with at least one pixel. The at least one pixel is located within a predetermined angle range toward the given light source 420 at a center of the stored direct LOS and influences on a present color of the certain pixel 410. The indirect light source determination unit 120 may generate at least one first pixel as at least one primary indirect light source 430a and 430b to determine the at least one primary indirect light shading ray for the certain pixel 410. The at least one first pixel include a pixel forming an LOS from the given light source 410 among the at least one pixel. Also, when a current amount of operations is below a predetermined criterion, the indirect light source determination unit 120 may generate at least one second pixel as at least one secondary indirect light source 430c and 430d to determine the at least one secondary indirect light shading ray for the certain pixel 410.

[0067] The indirect light shading generation unit 130 may generate a primary indirect light shading ray and may perform a traversal and intersection operation to obtain the certain pixel 410 as a hitting point to be hit with a trajectory of the primary indirect light shading ray. If necessary, the indirect light shading generation unit 130 may generate a secondary indirect light shading ray and may perform a traversal and intersection operation to obtain the certain pixel 410 as a hitting point to be hit with a trajectory of the secondary indirect light shading ray. That is, the indirect light shading generation unit 130 may perform an indirect light shading operation on the certain pixel 410 to generate the indirect light shading pixel.

[0068] The final pixel generation unit 140 combines a direct light pixel generated through a direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel (Step S340).

[0069] While the disclosure has been described in terms of exemplary embodiments, those skilled in the art will recognize that the disclosure can be practiced with modifications in the spirit and scope of the appended claims.

100: GLOBAL ILLUMINATION APPARATUS

120: INDIRECT LIGHT SOURCE DETERMINATION UNIT

130: INDIRECT LIGHT SHADING GENERATION UNIT

140: FINAL PIXEL GENERATION UNIT

150: FRAME BUFFER UNIT

160: CONTROL UNIT

Claims

A method of processing global illumination comprising:

(a) performing a ray tracing on a certain pixel from a given light source to generate a direct light shading;

(b) determining at least one indirect light source on the certain pixel for an indirect light shading; and

(c) performing a ray tracing on the certain pixel from the at least one indirect light source to generate an indirect light shading.
The method of claim 1, further comprising:

(d) combining a direct light pixel generated through the direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel.
The method of claim 1, further includes independently performing the steps (a) and the (b).
The method of claim 3, wherein the step (a) includes

(a1) generating an eye ray and performing a traversal and intersection operation to obtain the certain pixel as a hitting point; and

(a2) performing a direct shading operation on the certain pixel to generate the direct light pixel.
The method of claim 1, wherein the step (b) includes

(b1) searching for at least one LOS (Line Of Sight) associated with at least one pixel influencing on a present color of the certain pixel beyond a certain criterion; and

(b2) determining the at least one pixel as the at least one indirect light source to generate each of the at least one LOS as a shading ray for the certain pixel.
The method of claim 5, wherein the step (b1) includes calculating an influence levels for the certain pixel based on material properties and material distances of corresponding pixels, being on intersected points with shortest lines from the certain pixel.
The method of claim 1, further includes sequentially performing the step (a) and then the step (b).
The method of claim 7, wherein the step (a) includes

(a1) generating an eye ray and performing a traversal and intersection operation to obtain the certain pixel as a hitting point;

(a2) performing a shading operation on the certain pixel to generate the direct light pixel; and

(a3) storing the LOS between the certain pixel and the given light source.
The method of claim 8, wherein the step (b) includes

searching for at least one LOS (Line Of Sight) associated with at least one pixel, each being located within a predetermined angle range toward the given light source at a center of the stored direct LOS and each influencing on a present color of the certain pixel; and

generating at least one first pixel as at least one primary indirect light source to determine the at least one primary indirect light shading ray for the certain pixel, the at least one first pixel including a pixel forming an LOS from the given light source among the at least one pixel.
The method of claim 9, wherein the step (b) includes

when a current amount of operations is below a predetermined criterion, generating at least one second pixel as at least one secondary indirect light source to determine the at least one secondary indirect light shading ray for the certain pixel.
A global illumination apparatus comprising:

a direct light shading generation unit configured to perform a ray tracing on a certain pixel from given light source to generate a direct light shading;

an indirect light source determination unit configured to determine at least one indirect light source on the certain pixel for an indirect light shading; and

an indirect light shading generation unit configured to perform a ray tracing on the certain pixel from the at least one indirect light source to generate an indirect light shading.
The global illumination apparatus of claim 10, further comprising:

a final pixel generation unit configured to combine a direct light pixel generated through the direct light shading and an indirect light pixel generated through the indirect light shading to generate a final pixel.