Upload
lekhanh
View
219
Download
0
Embed Size (px)
Citation preview
1
VO RenderingSS 2005
Unit 8: Rendering Systems
2Alexander Wilkie
Overview Radiance Maya 3DS Brazil RenderPark Lightwave ART
3Alexander Wilkie
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
5Alexander Wilkie
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
6Alexander Wilkie
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
2
7Alexander Wilkie
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
8Alexander Wilkie
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
9Alexander Wilkie
Irradiance Gradients
Distribution ray-tracing is done forthe blue pixels
Information isinterpolated in theareas inbetween
Sample points arechosen based ongeometry and light
10Alexander Wilkie
Irradiance Gradient Example
11Alexander Wilkie
Genuine Radiance
12Alexander Wilkie
Falsecolor Output
3
13Alexander Wilkie
Radiance vs. Path Tracer
14Alexander Wilkie
Textures and Refraction
15Alexander Wilkie
Out- & Indoor Rendering
16Alexander Wilkie
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
17Alexander Wilkie
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
18Alexander Wilkie
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/
4
19Alexander Wilkie
Brazil Example #1
20Alexander Wilkie
Brazil Example #2
21Alexander Wilkie
Brazil Example #3
22Alexander Wilkie
Vray Example
23Alexander Wilkie
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
5
25Alexander Wilkie
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/
27Alexander Wilkie
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
29Alexander Wilkie
RPK Examples #1
30Alexander Wilkie
RPK Examples #2
6
31Alexander Wilkie
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
32Alexander Wilkie
PBRT Example
33Alexander Wilkie
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
34Alexander Wilkie
RISS Images
35Alexander Wilkie
FLIRT DCG Image
36Alexander Wilkie
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/
7
37Alexander Wilkie
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)
38Alexander Wilkie
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
39Alexander Wilkie
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
40Alexander Wilkie
ART Libraries Basics Colour Graphics Image Material Math Node Objective OpenGL Parser
ShootingExpansion Raycasting GatheringExpansion Rendering Shape Surface Trafo User Value
41Alexander Wilkie
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
42Alexander Wilkie
Historic ART Example
8
43Alexander Wilkie
Project: A Complex Model
44Alexander Wilkie
Battleship Model
45Alexander Wilkie
Battleship Closeup
46Alexander Wilkie
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)
47Alexander Wilkie
Rendering VO Unit 8
Thank you for your attention!