László Szirmay-Kalos

Budapesti University of Technology and EconomicsDepartment of Control Engineering and Information Technology

andGraphisoft R&D

Photorealistic Image Synthesisin CAD Systems

(IKTA3 00101/2000)

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The Project• A research project between BUTE and Graphisoft• Research topic: global illumination in architectural CAD

systems• January 2001 – April 2002• Homepage: www.iit.bme.hu/~szirmay/ikta/index.html• Participants:

– Project leader: dr. László Szirmay-Kalos (BUTE)– Advisors: dr. László Szirmay-Kalos (BUTE) and László

Sparing (Graphisoft)– PhD students: György Antal, Ferenc Csonka (Graphisoft),

László Kovács (BUTE), Benedek Balazs (BUTE), Szécsi László (BUTE)

– Others: dr. Horváth Tamás (BUTE), Csaba Kelemen• The main results: scientific research and a new framework

called RenderX for testing and implementing global illumination algorithms

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Graphisoft and ArchiCAD• Graphisoft was promoted in 1982• It is the third software company in the

AEC sector (Architecture, Engineering and Construction)

• The leading product of Graphisoft is the ArchiCAD, which is an object oriented, 3D design software for the architecture and building industry

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Outlines

• Objective of the project

• Photorealistics image synthesis fundamentals

• The result of the project

• Products and applications

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Goal of the project

• Global illumination image synthesis– Must be physically accurate– Solving the rendering equation– Identify all potential light paths– Conventional methods took hours to render

• Interactive naviagation and animation– must produce new images in seconds

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The aim of image synthesis

• In the virtual world, a virtual camera makes the photo of the scene.

The camera looks into the world through a window

The camera sees the scene like this

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The rendering equation

L= Le+ T L

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How does the Nature work?• 100 W light bulb emits 1042 photon per second

• The calculation of the intersected patches, that the photons hit is determined parallel with the speed of light

• The photons are absorbed randomly or reflected into a random direction

• Very little fraction of the emitted photons arrive finally to the eye

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Local Illumination

Top: sharp (left) and soft (right) shadows on local illumination imagesDown: the global illumination image

(H. W. Jensen, 1996)

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Global Illumination

• Identify all the possible light paths via multiple reflections, from the light source to the eye

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Global Illumination• Follow the light paths from the camera to the eye

with another method

(Szirmay-Kalos László, 2000)

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Results• Publications in 2001:

– László Szirmay-Kalos, Ferenc Csonka, György Antal: Global Illumination as a Combination of Continuous Random Walk and FiniteElement Based Iteration, Eurographics Conference, 2001

– Csaba Kelemen, László Szirmay-Kalos: A Microfacet Based Coupled Specular-Matte BRDF Model with Importance Sampling,Eurographics Conference, 2001

– Csaba Kelemen, László Szirmay-Kalos: Simple and Robust Mutation Strategy for Metropolis Light Transport Algorithm, Dagstuhl Seminar on Monte-Carlo Methods in Rendering, 2001

– György Antal, László Szirmay-Kalos, Ferenc Csonka, Csaba Kelemen: Multiple Strategy Stochastic Iteration for Architectural Walkthroughs, Dagstuhl Seminar on Monte-Carlo Methods in Rendering, 2001

– Ferenc Csonka, László Szirmay-Kalos György Antal: Cost-Driven Multiple Importance Sampling for Monte-Carlo Rendering, MCM Conference, Salzburg, 2001

– György Antal, László Szirmay-Kalos, Ferenc Csonka, Csaba Kelemen: Multiple Strategy Stochastic Iteration for Architectural Walkthroughs, Technical Report, TR-186-2-01-17, Vienna, 2001

– Csaba Kelemen, László Szirmay-Kalos: Simple and Robust Mutation Strategy for Metropolis Light Transport Algorithm, Technical Report, TR-186-2-01-18, Vienna, 2001

– Ferenc Csonka, László Szirmay-Kalos György Antal: Cost-Driven Multiple Importance Sampling for Monte-Carlo Rendering, MCM Conference, Technical Report, TR-186-2-01-19, Vienna, 2001

– László Szirmay-Kalos, László Kovács, Ali Mohamed Abbas: Testing Global Illumination Methods with Analytically Computable Scenes Winter School of Computer Graphics Conf., 2001

– Roel Martínez, László Szirmay-Kalos, Mateu Sbert, Ali Mohamed Abbas: Parallel Implementation of Stochastic Iteration Algorithms, Winter School of Computer Graphics Conf., 2001

– László Szirmay-Kalos, György Antal, Mateu Sbert: Progressive Light Path Development, Winter School of Computer Graphics Conf., 2001

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Results• Publications in 2002:

– György Antal, László Szirmay-Kalos, Ferenc Csonka: Weighted Multipass Method Based on Stochastic Iteration and Random Walk Methods, Winter School Of Computer Graphics Conference, 2002

– Csaba Kelemen, László Szirmay-Kalos, György Antal, Ferenc Csonka: Simple and Robust Mutation Strategy for Metropolis Light Transport Algorithm, Eurographics Conference, 2002

– György Antal, László Szirmay-Kalos, Ferenc Csonka: Hemicube Shooting for Non-Diffuse Global Illumination, Spring Conference on Computer Graphics, 2002

– László Szirmay-Kalos, Vlastimil Havran, Balázs Benedek, László Szécsi: On the Efficiency of Ray-shooting Acceleration Schemes, Spring Conference on Computer Graphics, 2002

• Submitted papers:– György Antal, László Szirmay-Kalos, Ferenc Csonka, Csaba Kelemen: Multiple Strategy Stochastic Iteration for

Architectural Walkthroughs– Ferenc Csonka, László Szirmay-Kalos, György Antal: Cost-Driven Multiple Importance Sampling for Monte-Carlo

Rendering– Ferenc Csonka, László Szirmay-Kalos, Csaba Kelemen, György Antal: Dependent Tests driven Filtering in Monte-Carlo

Global Illumination– György Antal, Ferenc Csonka: An Efficient And Robust Framework for Global Illumination Algorithms, 1st Hungarian

Conference on Computer Graphics, 2002– Ferenc Csonka, György Antal: A Multi-Phase Energy Preserving Filtering Method for Architectural Scenes, 1st Hungarian

Conference on Computer Graphics, 2002

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Applications• The CAD programs connect to the global illumination application via 3D File

formats: SCE, 3DS, VRML, MGF.

RayBundle

RenderX

SCE

3DS, VRML,MGF,...

SceWriterArchiCAD

3D Studio

Maya

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RenderX

SCE3DSVRMLMGF

WireframeLocal IlluminationRay-TracingRay Bundles (Gouraud)Ray Bundles (Phong)Path TracingBidirectional Path TracingMetropolis...

ScalingWardetc.

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Stochastic Iteration Finite element methods

15 K patches5 seconds1220

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Stochastic Iteration with Phong shading

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Production qualityMonte-Carlo methods

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Walkthrough Animation• Place camera

keyframes in ArchiCAD,

• save scene, • calculate global

illumination animation in RenderX