Yu-Ting Wu Retrospect

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Retrospect

Digital Image Synthesis

Yu-Ting Wu

(2)

So far we have learned:

• Geometry and transforms

• Shapes

• Accelerators

• Color and radiometry

• Cameras

• Sampling and reconstruction

• Reflection models

• Materials

• Textures

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Recap: the process of rendering

Cameras

orthogonal, perspective, environment, realistic …

Sampling

random, stratified, low-discrepancy, best candidate …

Reconstruction

box, triangle, sinc, Gaussian, Mitchell …

GenerateRay

Intersect

Shapes

sphere, disk, cylinder, triangle meshes,

subdivision surfaces …

Intersection

DifferentialGeometry BSDFs

Materials

matte, plastic, mix, measured, metal, substrate …

Lights

point, distant, spot, area, environment …

Accelerators

grid, bvh, kdtree …

 ω ) p,

(

_o

L

o

L

_e

( p , ω

_o

)

ω

i

2

d



s

 f ( p, ω

_o

, ω

_i

) L

_i

( p, ω

_i

) cos θ

_i

GetBSDF

(4)

Cameras

• GenerateRay

– Given a sample on the image film (in raster space), generate the corresponding camera ray (in world space) according to the type of camera.

environment

(5)

Cameras

• Depth-of-field and motion blur

Depth-of-field

Motion blur

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Shapes

• Intersect (used for radiance ray)

• Given a ray, does it has intersection with the shape?

• If yes, fill the information in DifferentialGeometry

• IntersectP (used for shadow ray)

– Given a ray, does it has intersection with the shape?

Intersect Intersect

IntersectP

scene

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Materials, textures

and reflectance models

• Materials

– GetBSDF

• Reflectance models (BxDFs)

– f

– Sample_f

• Textures

– Evaluate

Material Texture

Spatially-varying parameters

BxDFs

reflectance models

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Accelerators

• Construction

• Traversal

• Intersect (used for radiance ray) – IntersectP (used for shadow ray)

BVH Uniform grid Octree Kdtree BSP tree

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Sampling and reconstruction

• Use sub-pixel samples for

– Antialiasing

– Distributed effects

• Depth-of-field

• Motion blur

• Soft shadows

• Glossy reflection

• Global illumination

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Sampling and reconstruction

• Sampling patterns

random stratified uniform stratified jittered

Halton Hammersley best candidate

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Call stack in pbrt

Renderer::Render

RenderTask::Run

Camera::Film::WriteImage

RenderTask::Run

Camera::GenerateRay Renderer::Li

Renderer::Li

Scene::Intersect

if there is an intersection SurfaceIntegrator::Li else

Light::Le

VolumeIntegrator::Li return T Li + Lvi*

[render a block of pixels]

[output an image]

[obtain a camera ray for each camera sample]

[compute the radiance carried by the camera ray]

[obtain the intersection of the ray and the scene]

[compute the surface reflectance along the ray]

[possibly add emittance from all lights]

[compute volume contribution and transmittance]

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Call stack in pbrt

Scene::Intersect

Aggregate::Intersect

SurfaceIntegrator::Li

Intersection::GetBSDF

<Do shading based on the shading geometry and BSDF>

Intersection::GetBSDF Primitive::GetBSDF

Primitive::GetBSDF

Shape::GetShadingGeometry Material::GetBSDF

[call acceleration structure for intersection]

[get BSDF for shading]

[call the intersected primitive to fill the BSDF ]

[call shape to get shading geometry]

[do bump mapping if necessary, call material to get BSDF]

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Remaining components:

• Lights

• Monte Carlo

• Surface integrators

• Volume integrators

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Recap: the process of rendering

Cameras

Sampling

Reconstruction

GenerateRay

Intersect

Shapes

Intersection

Materials

Lights

Accelerators

Li

How much radiance reflected from surface?

 Surface Integrators

GetBSDF

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Recap: the process of rendering

Cameras

Sampling

Reconstruction

GenerateRay

Intersect

Accelerators

Shapes

How much radiance absorbed and scattered by the media?

 Volume Integrators

Intersection

Materials

Lights

GetBSDF

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Recap: the process of rendering

• Are we close to this beautiful image?

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