Prefiltered Anti-Aliasing on Parallel Hardware Thomas Auzinger Institute of Computer Graphics and...

Prefiltered Anti-Aliasing on Parallel Hardware

Thomas Auzinger

Institute of Computer Graphics and Algorithms

Vienna University of Technology

Motivation

Rasterization

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Vector inputRaster grid Rastered outputBetter output quality

?

Examples

Font Rendering

Vector Graphics Display

Mesh Rendering

Thomas Auzinger 3smashingmagazine.comserver.arcgis.comtecharp.com

Design Choices

Which filter?

How to evaluate it?

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Performance Quality

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Filter Choice

Downsampling to half resolution:

Delta filter

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Filter Choice

Downsampling to half resolution:

Box filter Hat filter Gaussian filter

Design Choices

Simple Higher Order

Which filter?

How to evaluate it?

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Performance Quality

Motivation – Filter Evaluation

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Motivation – Filter Evaluation

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1 sample per pixel4 samples per pixel16 samples per pixel256 samples per pixelPrefilteringGround truth

Design Choices

Simple Higher Order

Which filter?

How to evaluate it?

Sampling Supersampling Prefiltering

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Performance Quality

Publications

TA*, Gabriel Mistelbauer*, I. Baclija, R. Schernthaner, Eduard Gröller, Stefan Bruckner

Vessel Visualization using Curved Surface ReformationSciVis 2013 (IEEE Trans. Vis. Comp. Graph.)

TA, Michael Guthe, Stefan Jeschke

Analytic Anti-Aliasing of Linear Functions on PolytopesEurographics 2012 (Comp. Graph. Forum)

TA, Michael Wimmer, Stefan Jeschke

Analytic Visibility on the GPUEurographics 2013 (Comp. Graph. Forum)

TA, Przem Musialski, Reinhold Preiner, Michael Wimmer

Non-Sampled Anti-AliasingVMV 2013

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Publications









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Design Choices

Simple Higher Order

Which filter?

How to evaluate it?


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Performance Quality

Curved Surface Reformation

Sampling visibility

Supersampling shading

Interactive performance

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View direction

Curved Surface Reformation

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mpCPR CR CSR

Publications









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Publications









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Design Choices

Simple Higher Order

Which filter?

How to evaluate it?


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Performance Quality

Publications









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Prefiltering Overview

Overview:

Mesh inputSample positionsFilter supports Output

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Prefiltering in 2D

Filter convolution:

yyxyx d)v( )( )(

Sample locationMesh dataFilter function

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Prefiltering in 2D

Filter convolution:

yyxyx d)v( )( )(

Complicated integration domain

Intersection area Subdivision Integration domains

... ...,

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Prefiltering in 2D

Filter convolution:

yyxyx d)(v )( )( 1

yyxyx d)(v )( )( 2

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Prefiltering in 2D

Filter convolution:

Sample location

yyxyx d)v( )( )(

Mesh data & filter

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Bonus: Prefiltering in 3D

Filter convolution:

yyxyx d)v( )( )(

Decomposition:

Intersection volume Subdivision Integration domains

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Results

Alias-free sampling of complex scenes:

2M tetrahedraat different filter radii

(shown right)

Area filtering

Gaussian filtering

32.52

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Publications









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Traditional Analytic

Pipeline

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Vector

Raster

Vertex Geometry

Tessellation

Visibility

Discretization(Rasterizer)

ShadingAnti-aliasing

Output

Input

Visibility

ShadingAnti-aliasing

Discretization(Integrator)

Output

Vertex Geometry

Tessellation

Input

Analytic Filtering

Visible edges not enough boundary completion

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Results

Single zone plate

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Results

Another (white) zone plate below

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1 sample per pixelAnalytic rasterization

Publications









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Limitations

Shading prefiltering

Needs closed-form solution

Only possible for simple shading modelsLinear gradients in image space

No perspective interpolation

No non-linear illumination models

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Our Contribution

Analytic RasterizationVisibility prefiltering


Non-Sampled Anti-Aliasing (NSAA)Visibility prefiltering

Shading sampling

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Our Contribution

Analytic RasterizationVisibility prefiltering


Non-Sampled Anti-Aliasing (NSAA)Visibility prefiltering

Shading sampling

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Pipeline

DesignFragment gathering

Weight computation

Final blending

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Polygon input

Fragment gathering

Weight computation

Final blending

Raster image

Pipeline – Fragment Gathering

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Polygon input

Fragment gathering

Weight computation

Final blending

Raster image

Pipeline – Fragment Gathering

Steps

Fragment count (DX)

Scan (GPGPU)

Fragment gathering (DX)

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0 1 2 1 0

1 2 2 1 1

1 2 2 2 1

0 1 1 1 0

0 0 1 3 4 4 5 ...

B B G G G G B B G ...

fragment histogram

offset buffer

primitive ID buffer

Pipeline – Weight Computation

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Polygon input

Fragment gathering

Weight computation

Final blending

Raster image


StepsParallel hidden surface elimination (GPGPU)

Parallel visibility prefiltering (GPGPU)

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analytic convolutionanalytic visibility


StepsParallel hidden surface elimination (GPGPU)

Parallel visibility prefiltering (GPGPU)

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B B G G G G B B G ...

primitive ID buffer

0.1 0.2 0.2 0.7 0.2 0.4 0.3 0.6 0.4 ...

weight buffer

Pipeline – Final Blending

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Polygon input

Fragment gathering

Weight computation

Final blending

Raster image

Pipeline – Final Blending

StepsCompute shading (DX)

Weighted blending (DX)

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0.1 0.2 0.2 0.7 0.2 0.4 0.3 0.6 0.4 ...

weight buffer

shading values

...+

Pipeline

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Polygon input

Fragment gathering

Weight computation

Final blending

Raster image

Results

Zone plate

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NSAAMSAA8

Results

Log grid

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NSAAMSAA8

Results – Filter Comparison

Radial filters

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Radial box GaussRadial tent

Timings

Bunny model at different LoDs

Implementation in CUDA

Output resolution: 1024²

GPU: Nvidia GTX 680

Timings in milliseconds

3-4 orders of magnitudeslower than super-sampling

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# triangles visibility integration

7k 25 9.1

26k 50 21

70k 121 51

Conclusions

We presented methods for

High-performance sampling

Perfect-quality prefiltering

Future work

Supersampled shading

Polynomial shader interpolation

Transparency effects

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Fin

Thank you for your attention!

Any questions?

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In parallel for all edges

Unordered output global sort

Scan-based visible edge determination

Intersection

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Tiling

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Related Work

Josiah Manson and Scott SchaeferAnalytic Rasterization of Curves with Polynomial FiltersEurographics 2013 (Comp. Graph. Forum)

Josiah Manson and Scott SchaeferWavelet RasterizationEurographics 2010 (Comp. Graph. Forum)

G. Mistelbauer, A. Varchola, H. Bouzari, J. Starinsky, A. Köchl, R. Schernthaner, D. Fleischmann, E. Gröller, M. SrámekCenterline Reformations of Complex Vascular StructuresPacific Visualization Symposium 2012

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Prefiltered Anti-Aliasing on Parallel Hardware Thomas Auzinger Institute of Computer Graphics and...

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