Save this PDF as:

Size: px
Start display at page:

## Transcription

1 Illumination and Shading Computer Graphics COMP 770 (236) Spring 2007 Instructor: Brandon Lloyd 2/14/07 1

2 From last time Texture mapping overview notation wrapping Perspective-correct interpolation Texture filtering Bilinear interpolation MIP maps Summed-area tables 2/14/07 2

3 Topics for today Light Sources Empirical Illumination Shading Local vs Global Illumination 2/14/07 3

4 Illumination Models Computer Graphics Jargon: Illumination - the transport luminous flux from light sources between surfaces via direct and indirect paths Lighting - the process of computing the luminous intensity reflected from a specified 3-D point Shading - the process of assigning a colors to a pixels Illumination Models: Empirical - simple formulations that approximate observed phenomenon Physically-based - models based on the actual physics of light's interactions with matter 2/14/07 4

5 Two components of illumination Light Sources: Emittance spectrum (color) Geometry (position and direction) Directional attenuation Surface Properties: Reflectance spectrum (color) Geometry (position, orientation, and micro-structure) Absorption Simplifications used by most computer graphics systems: Compute only direct illumination from the emitters to the reflectors of the scene Ignore the geometry of light emitters, and consider only the geometry of reflectors 2/14/07 5

6 Ambient light source Ambient light sources are a simple hack for indirect illumination Incoming ambient illumination (I i,a ) is constant for all surfaces in the scene Reflected ambient illumination (I r,a ) depends only on the surface s ambient reflection coefficient (k a ) and not its position or orientation I r,a = k I a i,a These quantities typically specified as (R, G, B) triples 2/14/07 6

7 Point light sources Point light sources emit rays from a single point a fair approximation to a local light source such as a light bulb The direction to the light changes across the surface p l ˆL = p p p p l l ˆL p 2/14/07 7

8 Directional light sources Light rays are parallel and have no origin Can be considered as a point light at infinity A good approximation for sunlight The direction to the light source is constant over the surface ˆL 2/14/07 8

9 Lights in OpenGL Light positions are specified in homogeneous coordinates They are transformed by the current modelview matrix Directional light sources have w=0 # define a directional light lightdirection = [1, 1, 1, 0] gllightfv(gl_light0, GL_POSITION, lightdirection) glenable(gl_light0) # define a point light lightpoint = [100, 100, 100, 1] gllightfv(gl_light1, GL_POSITION, lightpoint) glenable(gl_light1) # set up light s color gllightfv(gl_light0, GL_AMBIENT, ambientintensity) gllightfv(gl_light0, GL_DIFFUSE, diffuseintensity) gllightfv(gl_light0, GL_SPECULAR, specularintensity) 2/14/07 9

10 Other light sources Spotlights point source whose intensity falls off away from a given direction Area Light Sources occupies a 2-D area (e.g. a polygon or a disk) generates soft shadows Extended Light Sources occupies a 3-D area (e.g. a sphere) generates soft shadows Area and extended often used interchangeably 2/14/07 10

11 Ideal diffuse reflection Ideal diffuse reflectors very rough at the microscopic level microscopic variations in the surface make any direction over the hemisphere equally likely to be the reflected direction of an incoming light ray reflection is view-independent follow Lambert s cosine law Chalk is a good approximation to an ideal diffuse surface 2/14/07 11

12 Lambert s cosine law Lambert s cosine law : the reflected energy from a small surface area from illumination arriving from direction ˆL is proportional to the cosine of the angle between ˆL and the surface normal ˆN Ir Iicosθ θ ˆL I(Nˆ L) ˆ i 2/14/07 12

13 Computing diffuse reflection Constant of proportionality depends on surface properties I = k I(Nˆ L) ˆ r,d The constant k d specifies how much of the incident light I i is diffusely reflected When (Nˆ L) ˆ < 0 the incident light is blocked by the surface itself and the diffuse reflection is 0 d i diffuse reflection for varying light 2/14/07 13

14 Specular reflection Specular reflectors have a bright, view dependent highlight examples polished metal, glossy car finish, a mirror at the microscopic level a specular reflecting surface is very smooth Specular reflection obeys Snell s law: The incoming ray, the surface normal, and the reflected ray all lie in a common plane. The relationship between the angles of the incoming and reflected rays with the normal is given by: nsinθ = n sinθ i i o o ˆL θ i ˆN θ o ˆR n i and n o are the indices of refraction for the incoming and outgoing ray, respectively Reflection is a special case where n i = n o so θ o = θ i 2/14/07 14

15 Computing the reflection vector The vector R can be computed from the incoming light direction and the surface normal as shown below. Rˆ = (2(Nˆ Lˆ))Nˆ Lˆ The diagram below illustrates this relationship. ˆL ˆN ˆR 2(Nˆ L)N ˆ ˆ 2/14/07 15 ˆL

16 Non-ideal reflectors Snell s law applies only to ideal specular reflectors Real materials have microscopic surface variations that cause some of the light to be reflected in directions slightly offset from the the ideal reflected ray Causes highlight to spread out according to roughness Empirical models try to simulate the appearance of this effect, without trying to capture the physics of it ˆL ˆN ˆR 2/14/07 16

17 Phong illumination The Phong model is an empirical model one of the most commonly used illumination models in computer graphics has no physical basis I = k I(cos φ) r,s s i = ki(vˆ R) ˆ si n s n s ˆL ˆN ˆV φ ˆR (V) ˆ is the direction to the viewer (Vˆ R) ˆ is clamped to [0,1] The specular exponent n s controls how quickly the highlight falls off 2/14/07 17

18 Effect of specular exponent How the shape of the highlight changes with varying n s 2/14/07 18

19 Phong examples varying light direction varying specular exponent 2/14/07 19

20 Blinn & Torrance variation Jim Blinn introduced another approach for computing Phonglike illumination based on the work of Ken Torrance: I = k I(Nˆ H) ˆ r,s s i Lˆ Ĥ = Lˆ + Vˆ + Vˆ n s ˆL ˆN Ĥ ˆV Ĥis the half-way vector that bisects the light and viewer directions 2/14/07 20

21 Putting it all together numlights ( ˆ ˆ ˆ ˆ n ) I = k I + I k (N L ) + k (V R ) r a a i,j d j s j j= 1 s 2/14/07 21

22 OpenGL surface properties glmaterialfv(gl_front, GL_AMBIENT, ambientcolor) glmaterialfv(gl_front, GL_DIFFUSE, diffusecolor) glmaterialfv(gl_front, GL_SPECULAR, specularcolor) glmaterialfv(gl_front, GL_SHININESS, nshininess) 2/14/07 22

23 Where do we Illuminate? Illumination can be expensive requires computation and normalizing of vectors for multiple light sources Compute illumination for faces Use face normal If the light is directional then the diffuse contribution is constant across the facet If the eye is infinitely far away and the light is directional then the specular contribution is constant across the facet Compute illumination for vertices Use vertex normals. interpolate illumination across face Compute illumination at each pixel most accurate and expensive interpolate normal across face 2/14/07 23

24 Flat shading The simplest shading method applies only one illumination calculation per face called constant or flat shading Issues: For point light sources the light direction varies over the face For specular reflections the viewer direction varies over the facet Illumination usually computed at the centroid of the face: n 1 centroid = p n i = 1 i 2/14/07 24

25 Need for vertex normals Even when the illumination equation is applied at each pixel, the polygonal nature of the model is still apparent. To overcome this limitation normals are introduced at each vertex. Usually different than the polygon normal Used only for shading (not backface culling or other geometric computations) Better approximates the "real" surface 2/14/07 25

26 Vertex normals If vertex normals are not provided they can often be approximated by averaging the normals of the facets which share the vertex. n v This only works if the polygons reasonably approximate the underlying surface. k = n i= 1 face,i A better approximation can be found using a clustering analysis of the normals on the unit sphere. 2/14/07 26

27 Gouraud shading Gouraud shading applies the illumination model on a subset of surface points and interpolates the intensity of the remaining points on the surface. For a polygonal mesh the illumination model is usually applied at each vertex and linearly interpolated over the polygons Notice that facet artifacts are still visible. 2/14/07 27

28 Phong shading Phong shading (not to be confused with Phong s illumination model), the surface normal is linearly interpolated across polygonal facets, and the Illumination model is applied at every point. Phong shading will usually result in a very smooth appearance, however, evidence of the polygonal model can usually be seen along silhouettes. 2/14/07 28

29 Local illumination Local illumination models compute the colors of points on surfaces by considering only local properties the position of the point the surface properties the properties of any light sources that affect it No other objects in the scene are considered neither as light blockers nor as reflectors Typical of immediate-mode renders, such as OpenGL 2/14/07 29

30 Global Illumination In the real world, light takes indirect paths Light reflects off of other materials (possibly multiple objects) Light is blocked by other objects Light can be scattered Light can be focused Light can bend Harder to model At each point we must consider not only every light source, but and other point that might have reflected light toward it 2/14/07 30

31 Next time Illumination and shading physically-based models 2/14/07 31

### Topic 9: Lighting & Reflection models 9/10/2016. Spot the differences. Terminology. Two Components of Illumination. Ambient Light Source

Topic 9: Lighting & Reflection models Lighting & reflection The Phong reflection model diffuse component ambient component specular component Spot the differences Terminology Illumination The transport

### Computer Graphics. Illumination and Shading

() Illumination and Shading Dr. Ayman Eldeib Lighting So given a 3-D triangle and a 3-D viewpoint, we can set the right pixels But what color should those pixels be? If we re attempting to create a realistic

### CPSC 314 LIGHTING AND SHADING

CPSC 314 LIGHTING AND SHADING UGRAD.CS.UBC.CA/~CS314 slide credits: Mikhail Bessmeltsev et al 1 THE RENDERING PIPELINE Vertices and attributes Vertex Shader Modelview transform Per-vertex attributes Vertex

### CSE 681 Illumination and Phong Shading

CSE 681 Illumination and Phong Shading Physics tells us What is Light? We don t see objects, we see light reflected off of objects Light is a particle and a wave The frequency of light What is Color? Our

### CS5620 Intro to Computer Graphics

So Far wireframe hidden surfaces Next step 1 2 Light! Need to understand: How lighting works Types of lights Types of surfaces How shading works Shading algorithms What s Missing? Lighting vs. Shading

### ECS 175 COMPUTER GRAPHICS. Ken Joy.! Winter 2014

ECS 175 COMPUTER GRAPHICS Ken Joy Winter 2014 Shading To be able to model shading, we simplify Uniform Media no scattering of light Opaque Objects No Interreflection Point Light Sources RGB Color (eliminating

### Comp 410/510 Computer Graphics. Spring Shading

Comp 410/510 Computer Graphics Spring 2017 Shading Why we need shading Suppose we build a model of a sphere using many polygons and then color it using a fixed color. We get something like But we rather

### Classic Rendering Pipeline

CS580: Classic Rendering Pipeline Sung-Eui Yoon ( 윤성의 ) Course URL: http://sglab.kaist.ac.kr/~sungeui/gcg/ Course Objectives Understand classic rendering pipeline Just high-level concepts, not all the

Illumination & Shading Goals Introduce the types of light-material interactions Build a simple reflection model---the Phong model--- that can be used with real time graphics hardware Why we need Illumination

Shading and Illumination OpenGL Shading Without Shading With Shading Physics Bidirectional Reflectance Distribution Function (BRDF) f r (ω i,ω ) = dl(ω ) L(ω i )cosθ i dω i = dl(ω ) L(ω i )( ω i n)dω

Why we need shading? Suppose we build a model of a sphere using many polygons and color it with glcolor. We get something like But we want Light-material interactions cause each point to have a different

### CSE 167: Lecture #8: Lighting. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011

CSE 167: Introduction to Computer Graphics Lecture #8: Lighting Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011 Announcements Homework project #4 due Friday, October 28 Introduction:

### Three-Dimensional Graphics V. Guoying Zhao 1 / 55

Computer Graphics Three-Dimensional Graphics V Guoying Zhao 1 / 55 Shading Guoying Zhao 2 / 55 Objectives Learn to shade objects so their images appear three-dimensional Introduce the types of light-material

### Illumination. Illumination CMSC 435/634

Illumination CMSC 435/634 Illumination Interpolation Illumination Illumination Interpolation Illumination Illumination Effect of light on objects Mostly look just at intensity Apply to each color channel

### Computer Graphics. Shading. Based on slides by Dianna Xu, Bryn Mawr College

Computer Graphics Shading Based on slides by Dianna Xu, Bryn Mawr College Image Synthesis and Shading Perception of 3D Objects Displays almost always 2 dimensional. Depth cues needed to restore the third

### Lighting/Shading II. Week 7, Mon Mar 1

University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2010 Tamara Munzner Lighting/Shading II Week 7, Mon Mar 1 http://www.ugrad.cs.ubc.ca/~cs314/vjan2010 News Homework 3 out today Homework

### CEng 477 Introduction to Computer Graphics Fall

Illumination Models and Surface-Rendering Methods CEng 477 Introduction to Computer Graphics Fall 2007 2008 Illumination Models and Surface Rendering Methods In order to achieve realism in computer generated

### Light Sources. Spotlight model

lecture 12 Light Sources sunlight (parallel) Sunny day model : "point source at infinity" - lighting - materials: diffuse, specular, ambient spotlight - shading: Flat vs. Gouraud vs Phong light bulb ambient

### Lighting and Shading. Slides: Tamar Shinar, Victor Zordon

Lighting and Shading Slides: Tamar Shinar, Victor Zordon Why we need shading Suppose we build a model of a sphere using many polygons and color each the same color. We get something like But we want 2

CS 543: Computer Graphics Illumination & Shading I Robert W. Lindeman Associate Professor Interactive Media & Game Development Department of Computer Science Worcester Polytechnic Institute gogo@wpi.edu

Illumination and Shading Illumination (Lighting) Model the interaction of light with surface points to determine their final color and brightness OpenGL computes illumination at vertices illumination Shading

DH2323 DGI15 INTRODUCTION TO COMPUTER GRAPHICS AND INTERACTION LIGHTING AND SHADING Christopher Peters HPCViz, KTH Royal Institute of Technology, Sweden chpeters@kth.se http://kth.academia.edu/christopheredwardpeters

### Shading , Fall 2004 Nancy Pollard Mark Tomczak

15-462, Fall 2004 Nancy Pollard Mark Tomczak Shading Shading Concepts Shading Equations Lambertian, Gouraud shading Phong Illumination Model Non-photorealistic rendering [Shirly, Ch. 8] Announcements Written

### surface: reflectance transparency, opacity, translucency orientation illumination: location intensity wavelength point-source, diffuse source

walters@buffalo.edu CSE 480/580 Lecture 18 Slide 1 Illumination and Shading Light reflected from nonluminous objects depends on: surface: reflectance transparency, opacity, translucency orientation illumination:

Illumination and Shading Illumination (Lighting)! Model the interaction of light with surface points to determine their final color and brightness! The illumination can be computed either at vertices or

### CENG 477 Introduction to Computer Graphics. Ray Tracing: Shading

CENG 477 Introduction to Computer Graphics Ray Tracing: Shading Last Week Until now we learned: How to create the primary rays from the given camera and image plane parameters How to intersect these rays

### Lighting and Shading Computer Graphics I Lecture 7. Light Sources Phong Illumination Model Normal Vectors [Angel, Ch

15-462 Computer Graphics I Lecture 7 Lighting and Shading February 12, 2002 Frank Pfenning Carnegie Mellon University http://www.cs.cmu.edu/~fp/courses/graphics/ Light Sources Phong Illumination Model

### Lighting affects appearance

Lighting affects appearance 1 Source emits photons Light And then some reach the eye/camera. Photons travel in a straight line When they hit an object they: bounce off in a new direction or are absorbed

### Ambient reflection. Jacobs University Visualization and Computer Graphics Lab : Graphics and Visualization 407

Ambient reflection Phong reflection is a local illumination model. It only considers the reflection of light that directly comes from the light source. It does not compute secondary reflection of light

### Methodology for Lecture. Importance of Lighting. Outline. Shading Models. Brief primer on Color. Foundations of Computer Graphics (Spring 2010)

Foundations of Computer Graphics (Spring 2010) CS 184, Lecture 11: OpenGL 3 http://inst.eecs.berkeley.edu/~cs184 Methodology for Lecture Lecture deals with lighting (teapot shaded as in HW1) Some Nate

### Raytracing CS148 AS3. Due :59pm PDT

Raytracing CS148 AS3 Due 2010-07-25 11:59pm PDT We start our exploration of Rendering - the process of converting a high-level object-based description of scene into an image. We will do this by building

### CSE 167: Lecture #7: Color and Shading. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011

CSE 167: Introduction to Computer Graphics Lecture #7: Color and Shading Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2011 Announcements Homework project #3 due this Friday,

### Color and Light. CSCI 4229/5229 Computer Graphics Summer 2008

Color and Light CSCI 4229/5229 Computer Graphics Summer 2008 Solar Spectrum Human Trichromatic Color Perception Are A and B the same? Color perception is relative Transmission,Absorption&Reflection Light

Shaders Oscar 1/43 Apodaca and Gritz, Advanced RenderMan Pixel Color Irradiance measures the power per unit area hitting a pixel E = න L i cos θ i dω i (obtained by integrating an equation form last class)

### Lighting affects appearance

Lighting affects appearance 1 Source emits photons Light And then some reach the eye/camera. Photons travel in a straight line When they hit an object they: bounce off in a new direction or are absorbed

### Orthogonal Projection Matrices. Angel and Shreiner: Interactive Computer Graphics 7E Addison-Wesley 2015

Orthogonal Projection Matrices 1 Objectives Derive the projection matrices used for standard orthogonal projections Introduce oblique projections Introduce projection normalization 2 Normalization Rather

### Shading, lighting, & BRDF Theory. Cliff Lindsay, PHD

Shading, lighting, & BRDF Theory Cliff Lindsay, PHD Overview of today s lecture BRDF Characteristics Lights in terms of BRDFs Classes of BRDFs Ambient light & Shadows in terms of BRDFs Decomposing Reflection

### CS 5625 Lec 2: Shading Models

CS 5625 Lec 2: Shading Models Kavita Bala Spring 2013 Shading Models Chapter 7 Next few weeks Textures Graphics Pipeline Light Emission To compute images What are the light sources? Light Propagation Fog/Clear?

Computer Graphics (Fall 2008) COMS 4160, Lecture 19: Illumination and Shading 2 http://www.cs.columbia.edu/~cs4160 Radiance Power per unit projected area perpendicular to the ray per unit solid angle in

Fall 2017 CSCI 420: Computer Graphics 5.2 Shading in OpenGL Hao Li http://cs420.hao-li.com 1 Outline Normal Vectors in OpenGL Polygonal Shading Light Sources in OpenGL Material Properties in OpenGL Example:

### 03 RENDERING PART TWO

03 RENDERING PART TWO WHAT WE HAVE SO FAR: GEOMETRY AFTER TRANSFORMATION AND SOME BASIC CLIPPING / CULLING TEXTURES AND MAPPING MATERIAL VISUALLY DISTINGUISHES 2 OBJECTS WITH IDENTICAL GEOMETRY FOR NOW,

Lessons Learned from HW Shading CS Interactive Computer Graphics Prof. David E. Breen Department of Computer Science Only have an idle() function if something is animated Set idle function to NULL, when

### So far, we have considered only local models of illumination; they only account for incident light coming directly from the light sources.

11 11.1 Basics So far, we have considered only local models of illumination; they only account for incident light coming directly from the light sources. Global models include incident light that arrives

### CSE 167: Lecture #8: GLSL. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2012

CSE 167: Introduction to Computer Graphics Lecture #8: GLSL Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2012 Announcements Homework project #4 due Friday, November 2 nd Introduction:

Illumination and Shading Illumination and Shading z Illumination Models y Ambient y Diffuse y Attenuation y Specular Reflection z Interpolated Shading Models y Flat, Gouraud, Phong y Problems CS4451: Fall

### How do we draw a picture?

1 How do we draw a picture? Define geometry. Now what? We can draw the edges of the faces. Wireframe. We can only draw the edges of faces that are visible. We can fill in the faces. Giving each object

### Deferred Rendering Due: Wednesday November 15 at 10pm

CMSC 23700 Autumn 2017 Introduction to Computer Graphics Project 4 November 2, 2017 Deferred Rendering Due: Wednesday November 15 at 10pm 1 Summary This assignment uses the same application architecture

### Introduction to Computer Graphics. Farhana Bandukwala, PhD Lecture 14: Light Interacting with Surfaces

Introduction to Computer Graphics Farhana Bandukwala, PhD Lecture 14: Light Interacting with Surfaces Outline Computational tools Reflection models Polygon shading Computation tools Surface normals Vector

### Surface Reflection Models

Surface Reflection Models Frank Losasso (flosasso@nvidia.com) Introduction One of the fundamental topics in lighting is how the light interacts with the environment. The academic community has researched

### Rendering Light Reflection Models

Rendering Light Reflection Models Visual Imaging in the Electronic Age Donald P. Greenberg October 3, 2017 Lecture #13 Program of Computer Graphics, Cornell University General Electric - 167 Cornell in

Objectives Shading in OpenGL Introduce the OpenGL shading methods - per vertex shading vs per fragment shading - Where to carry out Discuss polygonal shading - Flat - Smooth - Gouraud CITS3003 Graphics

### Lets assume each object has a defined colour. Hence our illumination model is looks unrealistic.

Shading Models There are two main types of rendering that we cover, polygon rendering ray tracing Polygon rendering is used to apply illumination models to polygons, whereas ray tracing applies to arbitrary

### Computer Graphics. Lecture 13. Global Illumination 1: Ray Tracing and Radiosity. Taku Komura

Computer Graphics Lecture 13 Global Illumination 1: Ray Tracing and Radiosity Taku Komura 1 Rendering techniques Can be classified as Local Illumination techniques Global Illumination techniques Local

### Illumination and Reflection in OpenGL CS 460/560. Computer Graphics. Shadows. Photo-Realism: Ray Tracing. Binghamton University.

Binghamton University EngiNet State University of New York EngiNet Thomas J. Watson School of Engineering and Applied Science WARNING All rights reserved. No Part of this video lecture series may be reproduced

### Interpolation using scanline algorithm

Interpolation using scanline algorithm Idea: Exploit knowledge about already computed color values. Traverse projected triangle top-down using scanline. Compute start and end color value of each pixel

### CS Illumination and Shading. Slide 1

CS 112 - Illumination and Shading Slide 1 Illumination/Lighting Interaction between light and surfaces Physics of optics and thermal radiation Very complex: Light bounces off several surface before reaching

### CGT520 Lighting. Lighting. T-vertices. Normal vector. Color of an object can be specified 1) Explicitly as a color buffer

CGT520 Lighting Lighting Color of an object can be specified 1) Explicitly as a color buffer Bedrich Benes, Ph.D. Purdue University Department of Computer Graphics 2) Implicitly from the illumination model.

### The Rasterization Pipeline

Lecture 5: The Rasterization Pipeline Computer Graphics and Imaging UC Berkeley CS184/284A, Spring 2016 What We ve Covered So Far z x y z x y (0, 0) (w, h) Position objects and the camera in the world

Illumination and Shading Light sources emit intensity: assigns intensity to each wavelength of light Humans perceive as a colour - navy blue, light green, etc. Exeriments show that there are distinct I

### Precomputed Radiance Transfer: Theory and Practice

1 Precomputed Radiance Transfer: Peter-Pike Sloan Microsoft Jaakko Lehtinen Helsinki Univ. of Techn. & Remedy Entertainment Jan Kautz MIT 2 Introduction Jan Kautz MIT 3 Introduction We see here an example

### Illumination Models and Surface-Rendering Methods. Chapter 10

Illumination Models and Surface-Rendering Methods Chapter 10 Illumination and Surface- Rendering Given scene specifications object positions, optical properties of the surface, viewer position, viewing

### COMP environment mapping Mar. 12, r = 2n(n v) v

Rendering mirror surfaces The next texture mapping method assumes we have a mirror surface, or at least a reflectance function that contains a mirror component. Examples might be a car window or hood,

### Turn on the Lights: Reflectance

Turn on the Lights: Reflectance Part 2: Shading Tuesday, October 15 2012 Lecture #14 Goal of Shading Model simple light sources Point light sources Extended light sources Ambient lighting Model lighting

### Computer Graphics. Lecture 10. Global Illumination 1: Ray Tracing and Radiosity. Taku Komura 12/03/15

Computer Graphics Lecture 10 Global Illumination 1: Ray Tracing and Radiosity Taku Komura 1 Rendering techniques Can be classified as Local Illumination techniques Global Illumination techniques Local

### The Rasterization Pipeline

Lecture 5: The Rasterization Pipeline Computer Graphics and Imaging UC Berkeley What We ve Covered So Far z x y z x y (0, 0) (w, h) Position objects and the camera in the world Compute position of objects

### Photorealism: Ray Tracing

Photorealism: Ray Tracing Reading Assignment: Chapter 13 Local vs. Global Illumination Local Illumination depends on local object and light sources only Global Illumination at a point can depend on any

### Summary. What is Computer Graphics? IRISA 2. Coordinate systems. 4. Geometric transformations for display

Summary Basic Computer Graphics Kadi Bouatouch IRISA Email: kadi@irisa.fr 1. Introduction 2. Coordinate systems 3. Geometric transformations 4. Geometric transformations for display 5. Choosing the camera

### CMSC427 Advanced shading getting global illumination by local methods. Credit: slides Prof. Zwicker

CMSC427 Advanced shading getting global illumination by local methods Credit: slides Prof. Zwicker Topics Shadows Environment maps Reflection mapping Irradiance environment maps Ambient occlusion Reflection

### Lecture 4: Reflection Models

Lecture 4: Reflection Models CS 660, Spring 009 Kavita Bala Computer Science Cornell University Outline Light sources Light source characteristics Types of sources Light reflection Physics-based models

### Lecture outline Graphics and Interaction Surface rendering and shading. Shading techniques. Introduction. Surface rendering and shading

Lecture outline 433-324 Graphics and Interaction Surface rendering and shading Department of Computer Science and Software Engineering The Introduction Surface rendering and shading Gouraud shading Phong

### Ray Optics. Lecture 23. Chapter 34. Physics II. Course website:

Lecture 23 Chapter 34 Physics II Ray Optics Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Today we are going to discuss: Chapter 34: Section 34.1-3 Ray Optics Ray Optics Wave

### Basic Computer Graphics. Kadi Bouatouch IRISA

Basic Computer Graphics Kadi Bouatouch IRISA Email: kadi@irisa.fr 1 Summary 1. Introduction 2. Coordinate systems 3. Geometric transformations 4. Geometric transformations for display 5. Choosing the camera

### 3D Programming. 3D Programming Concepts. Outline. 3D Concepts. 3D Concepts -- Coordinate Systems. 3D Concepts Displaying 3D Models

3D Programming Concepts Outline 3D Concepts Displaying 3D Models 3D Programming CS 4390 3D Computer 1 2 3D Concepts 3D Model is a 3D simulation of an object. Coordinate Systems 3D Models 3D Shapes 3D Concepts

### Chapter 32 Light: Reflection and Refraction. Copyright 2009 Pearson Education, Inc.

Chapter 32 Light: Reflection and Refraction Units of Chapter 32 The Ray Model of Light Reflection; Image Formation by a Plane Mirror Formation of Images by Spherical Mirrors Index of Refraction Refraction:

### Objectives. Introduce the OpenGL shading Methods 1) Light and material functions on MV.js 2) per vertex vs per fragment shading 3) Where to carry out

Objectives Introduce the OpenGL shading Methods 1) Light and material functions on MV.js 2) per vertex vs per fragment shading 3) Where to carry out 1 Steps in OpenGL shading Enable shading and select

### Chapter 26 Geometrical Optics

Chapter 26 Geometrical Optics 1 Overview of Chapter 26 The Reflection of Light Forming Images with a Plane Mirror Spherical Mirrors Ray Tracing and the Mirror Equation The Refraction of Light Ray Tracing

### Computergrafik. Matthias Zwicker Universität Bern Herbst 2016

Computergrafik Matthias Zwicker Universität Bern Herbst 2016 Today More shading Environment maps Reflection mapping Irradiance environment maps Ambient occlusion Reflection and refraction Toon shading

### Chapter 3. Illumination Models and Surface-Rendering Methods. Department of Computer Science and Engineering

Chapter 3 Illumination Models and Surface-Rendering Methods 3-1 3.1 Overview For a realistic display of a scene the lighting effects should appear naturally. An illumination model, also called a lighting

### CS452/552; EE465/505. Lighting & Shading

CS452/552; EE465/505 Lighting & Shading 2-17 15 Outline! More on Lighting and Shading Read: Angel Chapter 6 Lab2: due tonight use ASDW to move a 2D shape around; 1 to center Local Illumination! Approximate

### Rendering Algorithms: Real-time indirect illumination. Spring 2010 Matthias Zwicker

Rendering Algorithms: Real-time indirect illumination Spring 2010 Matthias Zwicker Today Real-time indirect illumination Ray tracing vs. Rasterization Screen space techniques Visibility & shadows Instant

### specular diffuse reflection.

Lesson 8 Light and Optics The Nature of Light Properties of Light: Reflection Refraction Interference Diffraction Polarization Dispersion and Prisms Total Internal Reflection Huygens s Principle The Nature

### Background: Physics and Math of Shading

Background: Physics and Math of Shading Naty Hoffman 2K Hi. Over the next 25 minutes or so I ll be going from the physics underlying shading, to the math used to describe it in the kind of shading models

### Ø Sampling Theory" Ø Fourier Analysis Ø Anti-aliasing Ø Supersampling Strategies" Ø The Hall illumination model. Ø Original ray tracing paper

CS 431/636 Advanced Rendering Techniques Ø Dr. David Breen Ø Korman 105D Ø Wednesday 6PM 8:50PM Presentation 6 5/16/12 Questions from ast Time? Ø Sampling Theory" Ø Fourier Analysis Ø Anti-aliasing Ø Supersampling

### Lecture Outline Chapter 26. Physics, 4 th Edition James S. Walker. Copyright 2010 Pearson Education, Inc.

Lecture Outline Chapter 26 Physics, 4 th Edition James S. Walker Chapter 26 Geometrical Optics Units of Chapter 26 The Reflection of Light Forming Images with a Plane Mirror Spherical Mirrors Ray Tracing

### Computer Graphics 1. Chapter 7 (June 17th, 2010, 2-4pm): Shading and rendering. LMU München Medieninformatik Andreas Butz Computergraphik 1 SS2010

Computer Graphics 1 Chapter 7 (June 17th, 2010, 2-4pm): Shading and rendering 1 The 3D rendering pipeline (our version for this class) 3D models in model coordinates 3D models in world coordinates 2D Polygons

### Materials & Shadows. Steve Rotenberg CSE168: Rendering Algorithms UCSD, Winter 2017

Materials & Shadows Steve Rotenberg CSE168: Rendering Algorithms UCSD, Winter 2017 Diffuse Surfaces In an earlier lecture, we discussed diffuse surfaces We looked at the idealized Lambertian diffuse case

### Lecture 17: Recursive Ray Tracing. Where is the way where light dwelleth? Job 38:19

Lecture 17: Recursive Ray Tracing Where is the way where light dwelleth? Job 38:19 1. Raster Graphics Typical graphics terminals today are raster displays. A raster display renders a picture scan line

### Lecture 7 - Path Tracing

INFOMAGR Advanced Graphics Jacco Bikker - November 2016 - February 2017 Lecture 7 - I x, x = g(x, x ) ε x, x + S ρ x, x, x I x, x dx Welcome! Today s Agenda: Introduction Advanced Graphics 3 Introduction

### rendering equation computer graphics rendering equation 2009 fabio pellacini 1

rendering equation computer graphics rendering equation 2009 fabio pellacini 1 physically-based rendering synthesis algorithms that compute images by simulation the physical behavior of light computer

### SAMPLING AND NOISE. Increasing the number of samples per pixel gives an anti-aliased image which better represents the actual scene.

SAMPLING AND NOISE When generating an image, Mantra must determine a color value for each pixel by examining the scene behind the image plane. Mantra achieves this by sending out a number of rays from

### CS4670/5760: Computer Vision Kavita Bala Scott Wehrwein. Lecture 23: Photometric Stereo

CS4670/5760: Computer Vision Kavita Bala Scott Wehrwein Lecture 23: Photometric Stereo Announcements PA3 Artifact due tonight PA3 Demos Thursday Signups close at 4:30 today No lecture on Friday Last Time:

### Announcement. Lighting and Photometric Stereo. Computer Vision I. Surface Reflectance Models. Lambertian (Diffuse) Surface.

Lighting and Photometric Stereo CSE252A Lecture 7 Announcement Read Chapter 2 of Forsyth & Ponce Might find section 12.1.3 of Forsyth & Ponce useful. HW Problem Emitted radiance in direction f r for incident

### Computer Graphics I. Assignment 3

UNIVERSITÄT DES SAARLANDES Dr.-Ing. Hendrik P.A. Lensch Max Planck Institut Informatik Art Tevs (tevs@mpi-inf.mpg.de) Boris Ajdin (bajdin@mpi-inf.mpg.de) Matthias Hullin (hullin@mpi-inf.mpg.de) 12. November

### SEOUL NATIONAL UNIVERSITY

Fashion Technology 5. 3D Garment CAD-1 Sungmin Kim SEOUL NATIONAL UNIVERSITY Overview Design Process Concept Design Scalable vector graphics Feature-based design Pattern Design 2D Parametric design 3D