CN103035027A - Illumination rendering method for fixed light source - Google Patents

Abstract

The invention relates to an illumination rendering method for a fixed light source. The method comprises a preprocessing stage and a real-time rendering stage. In the preprocessing stage, the diffusion grains of all object models in a scene is traversed in sequence, processing to the diffusion grains is carried out, and the color pattern information corresponding to each pixel point of the diffusion grains of the object models is acquired. In the real-time rendering stage, the illumination effect generated by a fixed light source is calculated according to the color pattern information corresponding to each pixel point of the object models, and the illumination rendering is carried out. Compared with the prior art, the illumination rendering method for the fixed light source transfers most computational process from the real-time rendering stage to the preprocessing stage, greatly reduces the computation amount of the real-time rendering stage, effectively saves the computing resource of a graphics processing unit (GPU), and improves rendering efficiency.

Description

A kind of irradiation rendering method for fixed light source

Technical field

The present invention relates to a kind of information processing method, especially relate to a kind of irradiation rendering method for fixed light source.

Background technology

Illumination calculation is the larger part of the operand in the 3d render process.Because the at present restriction of hardware computing power is to support multiple light courcess in real-time 3d scene.For addressing this problem, that uses at present has several modes such as summit illumination, pixel light photograph, deferred lighting.

Summit illumination is based on summit computing illumination result, and then the illumination result with the summit carries out interpolation in triangle, and it is less that advantage is that calculated amount compares, but may cause the problem that lighting effect is discontinuous and lose high optical information in a lot of situations.

It is to carry out illumination calculation in every pixel that pixel is looked after, and directly obtains the illumination result, and calculated amount increases with the resolution of playing up, over-extraction sample situation and scene organization formula, so calculated amount is larger, but effect is more accurate.Because calculated amount is large, can not support too many light source.

Deferred lighting is that the information that illumination is relevant stores in the buffer zone identical with playing up target resolution, utilizes these information calculations illumination result after scene rendering is finished, and effect is more accurate.Calculated amount is directly proportional with the resolution of playing up target and quantity of light source in this manner.

Summary of the invention

Purpose of the present invention is exactly to provide a kind of irradiation rendering method for fixed light source for the defective that overcomes above-mentioned prior art existence, the method with most computation process from the real-time rendering phase transition to pretreatment stage, large senior general has lacked the operand with the real-time rendering stage, effectively save the calculation resources of GPU, improved rendering efficiency.

Purpose of the present invention can be achieved through the following technical solutions:

A kind of irradiation rendering method for fixed light source, the method comprises the steps:

Pretreatment stage travels through the diffuse texture of all objects model in the scene successively, and described diffuse texture is processed, and obtains the color mode information that each pixel is corresponding on the object model diffuse texture;

The real-time rendering stage, according on the object model every color mode information corresponding to each pixel, calculate the lighting effect that fixed light source produces, carry out illumination and play up.

Described color mode information adopts the form of RGBA to carry out record.

Described pretreatment stage specifically may further comprise the steps:

1) travels through successively the diffuse texture of all objects model in the scene, obtain the corresponding diffuse texture of each object model;

2) each pixel on the traversal object model diffuse texture obtains coordinate, normal and the material information of this homologue body Model position, pixel place;

3) according to step 2) in color mode information corresponding to each pixel of information calculations that obtains.

In the described color mode information, the information of R, G, three passages of B calculates according to following formula:

$K_{\mathrm{RGB}}=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_d\cos \mathrm{\θ}$

In the formula, C ₀, C ₁, C ₂Be three fixed coefficients, d be fixed light source to the distance of irradiation position, θ is the incident angle of light, K _dBe diffuse-reflection factor;

The information of A channel calculates according to following formula:

$K_A=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_s$

In the formula, C ₀, C ₁, C ₂Be three fixed coefficients, d is that fixed light source is to the distance of irradiation position, K _sBe specularity factor.

Described real-time rendering is in the stage, and the lighting effect that fixed light source produces calculates by following formula:

$I=I_p{K}_{\mathrm{RGB}}+I_p{K}_A{\cos }^n\mathrm{\α}=I_p\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_d\cos \mathrm{\θ}+I_p\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_s{\cos }^n\mathrm{\α}$

In the formula, I _pBe incident intensity, C ₀, C ₁, C ₂Be three fixed coefficients, d is that fixed light source is to the distance of irradiation position, K _dBe diffuse-reflection factor, θ is the incident angle of light, K _sBe specularity factor, α is the angle of direction of visual lines and mirror-reflection light direction, and n is the constant relevant with the body surface smoothness.

Compared with prior art, most of computation process of the illumination result of fixed light source is from the real-time rendering phase transition to pretreatment stage among the present invention, larger minimizing at the operand in real-time rendering stage, thereby improved the efficient of real-time rendering, can save more GPU arithmetic capability to realize the smooth degree of more effect or raising real-time rendering, be particularly suitable for processing the effect of fixed position dynamic light sources a large amount of in the urban landscape.

Description of drawings

Fig. 1 is process flow diagram of the present invention;

Fig. 2 is the synoptic diagram of light reflection.

Embodiment

The present invention is described in detail below in conjunction with the drawings and specific embodiments.

Embodiment

As shown in Figure 1, a kind of irradiation rendering method for fixed light source, the method comprises following pretreatment stage and two stages of real-time rendering.

Pretreatment stage:

Travel through successively the diffuse texture of all objects model in the scene, described diffuse texture is processed, obtain the color mode information that each pixel is corresponding on the object model diffuse texture.

Concrete process is:

1) travels through successively the diffuse texture of all objects model in the scene, obtain the corresponding diffuse texture of each object model, if the same part of a diffuse texture is used by a plurality of object models, need to be broken down into different diffuse texture and process respectively;

2) each pixel on the traversal object model diffuse texture obtains coordinate, normal and the material information of this homologue body Model position, pixel place.

3) according to step 2) in color mode information corresponding to each pixel of information calculations that obtains, color mode information adopts the form of RGBA to carry out record among the present invention.

Since illumination generally by surround lighting, diffuse, specular light, therefore wherein under actual conditions, surround lighting is generally definite value, and only relevant with the characteristic of body surface, only needs diffusing and specular light calculates.Diffuse and to be expressed as I _d=I _pK _dCos θ, wherein, I _pBe incident intensity, K _dBe diffuse-reflection factor, θ is the incident angle of light, and specular light can represent I _s=I _pK _sCos ⁿα, wherein, I _pBe incident intensity, K _sBe specularity factor, α is the angle of direction of visual lines and mirror-reflection light direction, and n is the constant relevant with the body surface smoothness, and the surface is more smooth, and n is larger, and described angular relationship as shown in Figure 2.Because in practice, incident intensity can reduce with the increase of distance, actual intensity I _p' with incident intensity I in theory _pBetween have a following relation:

${I_p}^{\′}=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})I_p$

In the formula, C ₀, C ₁, C ₂Be three fixed coefficients, d is that fixed light source is to the distance of irradiation position.

Therefore, in color mode information, the information of R, G, three passages of B calculates according to following formula:

$K_{\mathrm{RGB}}=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_d\cos \mathrm{\θ}$

Because mirror-reflection only partly is reduced to for light intensity, rather than for three color components of RGB, so the information of A channel calculates according to following formula:

$K_A=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_s$

Pretreatment stage is finished.

The real-time rendering stage, according on the object model every color mode information corresponding to each pixel, calculate the lighting effect that fixed light source produces, carry out illumination and play up.The lighting effect that fixed light source produces can calculate by following formula:

$I=I_p{K}_{\mathrm{RGB}}+I_p{K}_A{\cos }^n\mathrm{\α}=I_p\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_d\cos \mathrm{\θ}+I_p\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_s{\cos }^n\mathrm{\α}$

Most of computation process of the illumination result of fixed light source is from the real-time rendering phase transition to pretreatment stage among the present invention, larger minimizing at the operand in real-time rendering stage, thereby improved the efficient of real-time rendering, can save more GPU arithmetic capability to realize the smooth degree of more effect or raising real-time rendering, be particularly suitable for processing the effect of fixed position dynamic light sources a large amount of in the urban landscape.

Claims (5)

1. an irradiation rendering method that is used for fixed light source is characterized in that the method comprises the steps:

Pretreatment stage travels through the diffuse texture of all objects model in the scene successively, and described diffuse texture is processed, and obtains the color mode information that each pixel is corresponding on the object model diffuse texture;

The real-time rendering stage, according on the object model every color mode information corresponding to each pixel, calculate the lighting effect that fixed light source produces, carry out illumination and play up.

2. a kind of irradiation rendering method for fixed light source according to claim 1 is characterized in that, described color mode information adopts the form of RGBA to carry out record.

3. a kind of irradiation rendering method for fixed light source according to claim 2 is characterized in that described pretreatment stage specifically may further comprise the steps:

1) travels through successively the diffuse texture of all objects model in the scene, obtain the corresponding diffuse texture of each object model;

2) each pixel on the traversal object model diffuse texture obtains coordinate, normal and the material information of this homologue body Model position, pixel place;

3) according to step 2) in color mode information corresponding to each pixel of information calculations that obtains.

4. a kind of irradiation rendering method for fixed light source according to claim 3 is characterized in that, in the described color mode information, the information of R, G, three passages of B calculates according to following formula:

$K_{\mathrm{RGB}}=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_d\cos \mathrm{\θ}$

In the formula, C ₀, C ₁, C ₂Be three fixed coefficients, d be fixed light source to the distance of irradiation position, θ is the incident angle of light, K _dBe diffuse-reflection factor;

The information of A channel calculates according to following formula:

$K_A=\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_s$

In the formula, C ₀, C ₁, C ₂Be three fixed coefficients, d is that fixed light source is to the distance of irradiation position, K _sBe specularity factor.

5. a kind of irradiation rendering method for fixed light source according to claim 4 is characterized in that, described real-time rendering is in the stage, and the lighting effect that fixed light source produces calculates by following formula:

$I=I_p{K}_{\mathrm{RGB}}+I_p{K}_A{\cos }^n\mathrm{\α}=I_p\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_d\cos \mathrm{\θ}+I_p\min (1,\frac{1}{C_0+C_{1}d+C_2{d}^2})K_s{\cos }^n\mathrm{\α}$

In the formula, I _pBe incident intensity, C ₀, C ₁, C ₂Be three fixed coefficients, d is that fixed light source is to the distance of irradiation position, K _dBe diffuse-reflection factor, θ is the incident angle of light, K _sBe specularity factor, α is the angle of direction of visual lines and mirror-reflection light direction, and n is the constant relevant with the body surface smoothness.

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