Radiance Radiance Workflow 1 - TU Wien · Radiance vs. Path Tracer 14 Textures and Refraction A lexandrW ik 15 Out- & Indoor Rendering AlexandrW ilk 16 ... Vray Example A lexandrW

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VO RenderingSS 2005

Unit 8: Rendering Systems

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Overview Radiance Maya 3DS Brazil RenderPark Lightwave ART

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Radiance Development started 1988 Major systems paper: SIGGRAPH 1994 Principal author: Greg Ward-Larson Provided as free UNIX binaries by LLBL An open source project (!) A collection of command-line C

programs designed to work in concert ~60.000 lines of code as of ´94

http://radsite.lbl.gov 4Alexander Wilkie

Radiance Workflow 1 Modelling is usually done in an external

CAD program Import filters for a wide variety of

applications (AutoCAD etc.) exists Filters operate autonomously on well-

structured 3D data Scene properties – textures etc. – are

added to object descriptions obtainedfrom CAD files by the user

Native Radiance modelling also possible

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Radiance Workflow 2 Completed scene description is then

processed by oconv -> octree scene file Interactive preview of camera position in

rview viewer rpict renderer generates intermediate

image pfilt performs tone mapping and filtering Finished image can be viewed by any

image display program & falsecolor

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Radiance in Practice rad command-line front-end takes care

of almost everything from CAD data tofinal image

Several packages are based on oraround Radiance, e.g. ADELINE

„Native“ Windows front-end currently instate of development, but useable

Radiance is showing it‘s age, but it is stillthe gold standard for architects

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Radiance Technical Specs Radiance is basically a highly accurate

stochastic raytracer Tristimulus renderer – CIE XYZ Physical quantities are used for

luminance Sophisticated reflectance models can be

used Several acceleration strategies are

used, and as a tradeoff no caustics arecomputed

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Radiance Acceleration Techniques Hybrid deterministic/stochastic raytracing Cached irradiance gradients Adaptive sampling of lightsources

Unimportant sources are not used at all Automatic generation of virtual

lightsources User-directed secondary lightsources Hierarchical octrees Parallel processing

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Irradiance Gradients

Distribution ray-tracing is done forthe blue pixels

Information isinterpolated in theareas inbetween

Sample points arechosen based ongeometry and light

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Irradiance Gradient Example

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Genuine Radiance

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Falsecolor Output

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Radiance vs. Path Tracer

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Textures and Refraction

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Out- & Indoor Rendering

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Radiance Improvements

Radiance AutoCad integration Done at Lawrence Livermore labs

Perceptually-based ray terminationGaze-directed realtime rendering University of Bristol - original codebase

Parallel, spectral Radiance University of Bristol New codebase - work in progress

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Maya, 3D Studio Similar, with different capabilities: Maya is

somewhat more powerful Primarily geared towards a creative user

interface, rendering technology comessecond -> primary renderer is usuallyshader based OpenGL / scanline hybrid

However: experienced artists can deliverstunning results using these tools

Plus: rendering engine can be exchangedby a third-party plug-in

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Brazil Commercial product: third party global

illumination plugin for 3DS & possiblylater Maya

Finished product Stochastic ray-based renderer with

subsurface scattering One of the first commercial GI rendering

systems. Others are VRay, FinalRender,Raymax, (Entropy – cancelled by Exluna)

http://www.splutterfish.com/

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Brazil Example #1

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Brazil Example #2

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Brazil Example #3

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Vray Example

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Mental Ray The premier raytracing backend for the

entire CG industry Extremely reliable and fast – only

geometric primitive is the triangle Is dependent on preprocessing for

geometry Supports photon mapping as add-on

and custom shaders Not a native global illumination renderer

http://www.mentalray.com/ 24Alexander Wilkie

MentalRay Example

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POVRay Persistence of Vision Raytracer Ancient by computer science standards The tool for hobbyists and certain artists Comparatively primitive – no tone

mapping, RGB colour space rendering Software structure a catastrophe Highly configurable, several subversions

exist (most notably MegaPOV) In the hands of a good artist it still is a

formidable tool

http://www.povray.org/ 26Alexander Wilkie

POVRay Example

http://www.oyonale.com/

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RenderPark Developed at the KU Leuven / Belgium Primary target: image synthesis

algorithm testbed Will eventually be a general purpose

toolkit C++ libraries and applications Under development since 1993 Snapshots available for download

http://www.renderpark.be/ 28Alexander Wilkie

RenderPark Features

Wide variety of patch- and ray-basedglobal illumination methods. Alsofeatures OpenGL and AR output

MGF and VRML97 input X-Windows interface Tone mapping support Can act as a plug-in for other

applications

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RPK Examples #1

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RPK Examples #2

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PBRT

Devloped by Matt Pharr, GregHumphires and others

Stochastic rendering research toolkit Path tracing, stochastic raytracing Large selection of reflectancy models

Extensive documentation in book form Covers a wide range of the topic in this

lecture by example

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PBRT Example

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Graphics Toolkits @ ICGA The grandfather: RISS – Realistic Image

Synthesis System. VAX Pascal, 1987 –1991, chief architect Michael Gervautz

The bastard child: FLIRT – Faster thanLIght RayTracer. ANSI C, 1991 – 1996,Tobler, Stürzlinger, Traxler et. al.

The stillborn child: VEGA / BaBeL. C++,1995-1998, Löffelmann & Tobler.Discontinued due to language & designlimitations

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RISS Images

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FLIRT DCG Image

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Advanced Rendering Toolkit Aim: a general-purpose rendering toolkit

for graphics research and use Under development since 1996 2 core developers, ~10 students Written in Objective C, ~180k LOC Highly modularized Currently command-line only Runs on a large variety of platforms:

Solaris, Linux, Windows, IRIX, OS X, ...

http://www.artoolkit.org/

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ART Features #1 Modelling: CSG, NURBS, subdivision

surfaces, CSG and SDS automata Turing-complete shading language,

cellular automata Modular imaging pipeline with

intermediary spectral images and tonemapping

Spectral rendering incl. polarization andfluorescence

(Realistic skylight and water models)

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ART Features #2 Renderers: Open GL, edge tracer,

visibility raytracer, lightmap photontracer, path tracer

Intelligent selection of parser moduleson input -> potentially capable of multi-format input

Different colour types for internalcalculations are supported – RGB, CIEXYZ, Spectra with 8,16,45,450 samples

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ART Structure Code is grouped into a set of 20 libraries Several command-line applications use

these classes Protocols (in Java: interfaces) are used

to group objects by functional hierarchyinstead of inheritance hierarchy

Categories are used to split classes intodifferent libraries where appropriate, e.g.according to rendering technology

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ART Libraries Basics Colour Graphics Image Material Math Node Objective OpenGL Parser

ShootingExpansion Raycasting GatheringExpansion Rendering Shape Surface Trafo User Value

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ART: Status Global structure more or less finished Tons of detail work are left Numerous highly advanced features are

implemented, while minor details have notbeen done

Goal: public availability under the GPL Code is still a bit too unfinished for public

beta release CVS server used for internal development

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Historic ART Example

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Project: A Complex Model

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Battleship Model

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Battleship Closeup

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ART: Praktikums- and Other Topics (Maintenance work on the surface models) Leaf surface and volume model Implementation of a new tone mapping

operator, or maintenance of the existingtone mapping operators

Documentation writing (Demo suite)

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Rendering VO Unit 8

Thank you for your attention!