15-volumes

15-volumes - 1 Volumes Lecture 15 CPSC 578/478 Spring 2005...

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Unformatted text preview: 1 Volumes Lecture 15 CPSC 578/478 Spring 2005 NOTES: Reading: text, chap 19 and 23 Jianye’s office hours : 6-9pm TONIGHT ASSIGNMENT #2 : Due March 4 11:00 AM FAQ has been posted on the Materials Page Assignment #2 • Make sure your zip file is < 10 Mb (delete obj’s) • Include source, exe and sample images, notes. • Send email to JIANYE and me after uploading • Make file accessible on pantheon as well • Get confirmation from JIANYE that your file was readable. 9 Volumes for depth effect (OpenGL”fog”) 9 Global illumination for realistic scattering 9 Volume rendering data: 9 understanding structures 9 Volumes for modeling shape NY Times Grand Central Fog in real life – gives a sense of depth 2 Close objects seen with their own color The greater the fog thickness, the less the object color is seen, and more the fog color is seen Open Gl fog Generating photorealistic volumes of scattering media Henrik Wann Jensen Alex Keller Participating Media: Transport Equation ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) , ( ) , ( 4 ) ( ) ( ) ( ) ( t t s a 4 i i o i s e a x L x x J x x L x x L x d ω ω ω p ω x L π x x L x dx x dL π κ κ κ κ κ κ − = − − + = ∫ r r r Absorption Emission In-scattering Out-scattering function source the ) ( function phase the ) , ( ts coefficien media , , i o s a t s a x J ω ω p r r κ κ κ κ κ + = being 3 SCATTERING AND OUT SCATTERING AND Absorption Out-scattering Emission In-scattering Light Ray Tracing Volumes Stop at opaque surface Light Ray Tracing Volumes Stop at opaque surface Compute intensity of direct illumination Light Ray Tracing Volumes Need to reduce intensity if viewed through a volume dI/dt = - σ I n n n tI I I n ∆ − = + σ 1 density thickness Light Ray Tracing Volumes Stop at opaque surface ∆ t L I n n n tI I I n ∆ − = + σ 1 L L tI I I ∆ − = 1 1 σ 1 2 1 2 tI I I ∆ − = σ March along ray reducing light intensity as a function of the volume density Light Ray Tracing Volumes 1 1 1 tI I I s ∆ − = σ I s Need to march from surface to eye reducing intensiy 4 Light Ray Tracing Volumes ' 1 , 1 1 1 s tI tI I I s s ∆ + ∆ − = σ σ I s Also need to add “in scattered” light so cloud is visible Light Ray Tracing Volumes ' 1 , 1 1 1 s tI tI I I s s ∆ + ∆ − = σ σ I s Also need to add “in scattered” light so cloud is visible Need to march along and attenuate this ray also Light Ray Tracing Volumes Also need to add “in scattered” light so cloud is visible Even more rays needed to account for general scattering Alex Keller Joe Kniss Volume Data Visualization 3D independent variable – x,y, z in space 1D dependent variable – f(x,y,z) Want to see structure of f(x,yz,) Where does volume data come from?...
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This note was uploaded on 11/21/2009 for the course CPSC 478 taught by Professor Hollyrushmeier during the Spring '05 term at Yale.

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15-volumes - 1 Volumes Lecture 15 CPSC 578/478 Spring 2005...

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