# Recollection. Models Pixels. Model transformation Viewport transformation Clipping Rasterization Texturing + Lights & shadows

Size: px
Start display at page:

## Transcription

1 Recollection Models Pixels Model transformation Viewport transformation Clipping Rasterization Texturing + Lights & shadows Can be computed in different stages 1

2 So far we came to

3 Geometry model 3

4 Surface color 4

6 Important recollections

7 Bilinear interpolation A D P X Q B C 7

8 Bilinear interpolation 4 corner points A,B,C,D with known values 1 internal point X with unknown value P = A + u.(b-a), Q = D + u.(c-d) X = P + v.(q-p) Matrix representation X A 1 v v 1 u, u u 0,1, v 0, 1 B D C 8

9 Application: texture mapping Interpolate D A = P, D C = Q, P Q = X P Q P Q 9

10 Application: texture filtering Consider 4 neighboring texels Weighted average 10

12 General problem For a point in space, calculate lighting conditions and modulate the inherent object color to produce final pixel color 12

13 Lighting and shading What is lighting Computing amount of radiance (per wavelength) reflected from object towards the camera What is shading Creating illusion of space in planar images Usually uses lighting but other options are available too e.g. depth shading 13

14 Lighting

15 Light source types Omnidirectional Spotlight Area Directional Object - what are the differences? 15

16 Elementary theory Light-surface interaction Reflection Refraction Snell s law Surface normal vector Real world is a bit different 16

17 Surface types Reflective Diffuse Lambertian Both 17

18 Light reflection distribution Mirror Matte directional component indirectional component 18

19 Lighting models Empiric e.g. Phong lighting model cheap computation physically incorrect visually plausible Physically-based energy transfer, light propagation closer to real-world physics expensive 19

20 Local illumination models Fast but inaccurate Ignore other objects (i.e. it s not global) Empirical (no physical background) Many physical effects are impossible to achieve Computer games, real-time rendering 20

21 Diffuse light 21

22 Ambient light 22

23 Diffuse + ambient 23

24 Diffuse + ambient + specular 24

25 Phong lighting model Ambient + Diffuse + Specular components without ambient with ambient Simulates global light scattered in the scene and reflected from other objects 25

26 Phong lighting model Ambient + Diffuse + Specular components Lambert law ambient + diffuse I d n l ambient + diffuse + specular 26

27 Phong lighting model Ambient + Diffuse + Specular components Directional view vector I s r v k shine 27

28 Specular component r.v = r. v.cos(rv) absolute parameter k s exponential parameter shininess (gloss) 28

29 Phong lighting model I k a I a k I k I d d s s lights k, I coefficients can depend on wavelength what defines surface lighting properties? k a, k d, k s, k shine 29

30 Other lighting models Blinn-Phong generalization of Phong s model Cook-Torrance microfacets Oren-Nayar rough surfaces Anisotropic microfacet distribution 30

31 Surface normal vector Perpendicular to the surface at the point Computation: Usually from tangent vectors Vector product n u v Depends on the object representation n v u Vector normalization nˆ n n 31

32 Tangent vectors Parametric representation X = x(u,v) Y = y(u,v) Z = z(u,v) Partial derivation by u,v vectors t u, t u Polygonal representation Tangent vectors are edge vectors Mind the orientation! 32

33 Lighting a polygon Scanline rasterization For each pixel evaluate lighting model compute normal vector, view vector, light vector get surface parameters evaluate formula Expensive therefore: shading 33

35 Shading Object color is altered to give impression of light and depth Usually incorporates lighting Often only an approximation of real physics 35

36 Two stages of lighting 1. Evaluate illumination for some points of the object = LIGHTING 2. Use results from (1) to compute illumination of the rest of the object = SHADING 36

37 Flat shading One normal per face Entire face = one color 37

38 Flat (constant) shading 1 normal vector per object face (polygon) 1 lighting value per object face Entire polygon = 1 color 38

39 Gouraud shading Per-vertex lighting Color is interpolated over the face 39

40 Gouraud shading 1 normal vector per 1 surface vertex i.e. 4 lighting values / quad, 3 values / triangle Rest of the polygon lighting value interpolation Bands Chance of missing specular Realtime 40

41 Example A[0, 0] = 80% intensity B[10, 6] = 20% C[10, 9] = 80% D[0, 10] = 40% Interpolate light intensity at S[5, 8] HINT: Bilinear interpolation A D => P B C => Q P Q => S 41

42 Phong shading NOT Phong lighting model Entire surface normal is interpolated instead of interpolating only the lighting value Per pixel lighting Slower 42

43 Towards photorealism

44 Real world effects light refraction mutual object reflection caustics chromatic aberration color bleeding (soft) shadows

45 Refraction, caustics 45

46 Reflections 46

47 Chromatic aberration 47

48 Color bleeding 48

49 Raytracing 49

50 Raytracing Tracing a beam from viewer s eye through each screen pixel. Find first beam intersection with objects Compute local lighting Trace reflected and refracted beams Combine the results with local result recursively 50

51 Raytracing what s inside Line-object intersection expensive computation speed-up by e.g. scene subdivision (octree) or bounding volumes take the nearest intersection Example intersections: Sphere Triangle 51

52 Line-sphere intersection Line A,p : L = P + t * p Sphere C,r : (S C) 2 = R 2 Intersect: ( P + t * p C ) 2 = R 2 Quadratic equation 0,1,2 roots 52

53 Line-triangle intersection Line P,p : L = P + t * p Triangle K,L,M: T = K + u*(l-k) + v*(m-k) Line-plane intersection Plane: ax + by + cx + d = 0 Check if intersection is inside triangle 53

54 Raytracing what s inside Compute reflected and refracted rays evaluate light coming from their direction Combine with the local lighting result C comb( l. C, r. C, t. C L R T ) 54

55 Let s think the combinations C comb( l. C, r. C, t. C L R T ) 55

56 Raytracing pros and cons No need for polygonal representation works with both volume and boundary rep. works with CSG objects, F-reps, meshes... No explicit rasterization takes place Computationally expensive Does not compute soft shadows 56

57 Examples: POVRAY 57

58 Radiosity Object hit by light is a new light source Energy (light) exchange between objects Indirect illumination 58

59 Real world radiosity Light reflectors in photography 59

60 Radiosity Physically based Object hit by light becomes a new light source Not only object-light interaction But also object-object light interaction Energy exchange between objects 60

61 General situation 61

62 The math behind it Energy is either emitted (E) or bounced (B) All reflections are perfectly diffuse Surface A i radiosity: B i E i p i A B Form factors F ij how two surface elements A i and A j affect each other j j F ij 62

63 Elementary example Problem: B 1 =? B 2 =? Let E 1 =E 2 =0 63

64 Energy preservation Bounced = Emitted + p*received B B E p ( B F B F B F ) p B F B F B F ) ( E 1 p B F B 1 p F ) ( p B F E Repeat for all 3 surfaces 64

65 Result = linear system E 1 = E 2 = 0 E 0 = light source parameter In real tens of thousands of surfaces E E E B B B F p F p F p p F p F p F F p F p F p

66 Radiosity pros and cons Physically correct Extreme computational expenses Indirect light soft realistic shadows Area lights and object lights are easy to do Color bleeding possible too Only diffuse light transfer = Problems with reflections and specular light 66

67 Example Indirect light Color bleeding Soft shadows Area light 67

68 Radiosity example direct illumination indirect illumination 68

70 Questions?

### 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,

### Topic 12: Texture Mapping. Motivation Sources of texture Texture coordinates Bump mapping, mip-mapping & env mapping

Topic 12: Texture Mapping Motivation Sources of texture Texture coordinates Bump mapping, mip-mapping & env mapping Texture sources: Photographs Texture sources: Procedural Texture sources: Solid textures

### Topic 11: Texture Mapping 11/13/2017. Texture sources: Solid textures. Texture sources: Synthesized

Topic 11: Texture Mapping Motivation Sources of texture Texture coordinates Bump mapping, mip mapping & env mapping Texture sources: Photographs Texture sources: Procedural Texture sources: Solid textures

### Topic 11: Texture Mapping 10/21/2015. Photographs. Solid textures. Procedural

Topic 11: Texture Mapping Motivation Sources of texture Texture coordinates Bump mapping, mip mapping & env mapping Topic 11: Photographs Texture Mapping Motivation Sources of texture Texture coordinates

### 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

### 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

### Topic 9: Lighting & Reflection models. Lighting & reflection The Phong reflection model diffuse component ambient component specular component

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. 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

### Simple Lighting/Illumination Models

Simple Lighting/Illumination Models Scene rendered using direct lighting only Photograph Scene rendered using a physically-based global illumination model with manual tuning of colors (Frederic Drago and

### 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

### Consider a partially transparent object that is illuminated with two lights, one visible from each side of the object. Start with a ray from the eye

Ray Tracing What was the rendering equation? Motivate & list the terms. Relate the rendering equation to forward ray tracing. Why is forward ray tracing not good for image formation? What is the difference

### 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

### Introduction to Computer Graphics 7. Shading

Introduction to Computer Graphics 7. Shading National Chiao Tung Univ, Taiwan By: I-Chen Lin, Assistant Professor Textbook: Hearn and Baker, Computer Graphics, 3rd Ed., Prentice Hall Ref: E.Angel, Interactive

### 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

### Introduction to Visualization and Computer Graphics

Introduction to Visualization and Computer Graphics DH2320, Fall 2015 Prof. Dr. Tino Weinkauf Introduction to Visualization and Computer Graphics Visibility Shading 3D Rendering Geometric Model Color Perspective

Illumination Models & Shading Lighting vs. Shading Lighting Interaction between materials and light sources Physics Shading Determining the color of a pixel Computer Graphics ZBuffer(Scene) PutColor(x,y,Col(P));

Reflection and Shading R. J. Renka Department of Computer Science & Engineering University of North Texas 10/19/2015 Light Sources Realistic rendering requires that we model the interaction between light

### Illumination & Shading: Part 1

Illumination & Shading: Part 1 Light Sources Empirical Illumination Shading Local vs Global Illumination Lecture 10 Comp 236 Spring 2005 Computer Graphics Jargon: Illumination Models Illumination - the

University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2007 Tamara Munzner Shading, Advanced Rendering Week 7, Wed Feb 28 http://www.ugrad.cs.ubc.ca/~cs314/vjan2007 Reading for Today and Tomorrow

### Rendering: Reality. Eye acts as pinhole camera. Photons from light hit objects

Basic Ray Tracing Rendering: Reality Eye acts as pinhole camera Photons from light hit objects Rendering: Reality Eye acts as pinhole camera Photons from light hit objects Rendering: Reality Eye acts as

### CS130 : Computer Graphics Lecture 8: Lighting and Shading. Tamar Shinar Computer Science & Engineering UC Riverside

CS130 : Computer Graphics Lecture 8: Lighting and Shading Tamar Shinar Computer Science & Engineering UC Riverside Why we need shading Suppose we build a model of a sphere using many polygons and color

### Lighting. To do. Course Outline. This Lecture. Continue to work on ray programming assignment Start thinking about final project

To do Continue to work on ray programming assignment Start thinking about final project Lighting Course Outline 3D Graphics Pipeline Modeling (Creating 3D Geometry) Mesh; modeling; sampling; Interaction

Computergrafik Matthias Zwicker Universität Bern Herbst 2009 Today Introduction Local shading models Light sources strategies Compute interaction of light with surfaces Requires simulation of physics Global

### 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

Lighting and Shading Today: Local Illumination Solving the rendering equation is too expensive First do local illumination Then hack in reflections and shadows Local Shading: Notation light intensity in,

### 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

### 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

### CPSC GLOBAL ILLUMINATION

CPSC 314 21 GLOBAL ILLUMINATION Textbook: 20 UGRAD.CS.UBC.CA/~CS314 Mikhail Bessmeltsev ILLUMINATION MODELS/ALGORITHMS Local illumination - Fast Ignore real physics, approximate the look Interaction of

Computergrafik Thomas Buchberger, Matthias Zwicker Universität Bern Herbst 2008 Today Introduction Local shading models Light sources strategies Compute interaction of light with surfaces Requires simulation

### 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?

### Topics and things to know about them:

Practice Final CMSC 427 Distributed Tuesday, December 11, 2007 Review Session, Monday, December 17, 5:00pm, 4424 AV Williams Final: 10:30 AM Wednesday, December 19, 2007 General Guidelines: The final will

### Computer Graphics. Illumination and Shading

Rendering Pipeline modelling of geometry transformation into world coordinates placement of cameras and light sources transformation into camera coordinates backface culling projection clipping w.r.t.

### Computer Graphics. Lecture 14 Bump-mapping, Global Illumination (1)

Computer Graphics Lecture 14 Bump-mapping, Global Illumination (1) Today - Bump mapping - Displacement mapping - Global Illumination Radiosity Bump Mapping - A method to increase the realism of 3D objects

Illumination and Shading Computer Graphics COMP 770 (236) Spring 2007 Instructor: Brandon Lloyd 2/14/07 1 From last time Texture mapping overview notation wrapping Perspective-correct interpolation Texture

### 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:

### Global Illumination. COMP 575/770 Spring 2013

Global Illumination COMP 575/770 Spring 2013 Final Exam and Projects COMP 575 Final Exam Friday, May 3 4:00 pm COMP 770 (and 575 extra credit) Projects Final report due by end of day, May 1 Presentations:

### Global Illumination CS334. Daniel G. Aliaga Department of Computer Science Purdue University

Global Illumination CS334 Daniel G. Aliaga Department of Computer Science Purdue University Recall: Lighting and Shading Light sources Point light Models an omnidirectional light source (e.g., a bulb)

### Global Rendering. Ingela Nyström 1. Effects needed for realism. The Rendering Equation. Local vs global rendering. Light-material interaction

Effects needed for realism Global Rendering Computer Graphics 1, Fall 2005 Lecture 7 4th ed.: Ch 6.10, 12.1-12.5 Shadows Reflections (Mirrors) Transparency Interreflections Detail (Textures etc.) Complex

### 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

### Today s class. Simple shadows Shading Lighting in OpenGL. Informationsteknologi. Wednesday, November 21, 2007 Computer Graphics - Class 10 1

Today s class Simple shadows Shading Lighting in OpenGL Wednesday, November 21, 27 Computer Graphics - Class 1 1 Simple shadows Simple shadows can be gotten by using projection matrices Consider a light

### CPSC / Illumination and Shading

CPSC 599.64 / 601.64 Rendering Pipeline usually in one step modelling of geometry transformation into world coordinate system placement of cameras and light sources transformation into camera coordinate

### Rendering Part I (Basics & Ray tracing) Lecture 25 December 1, 2015

Rendering Part I (Basics & Ray tracing) Lecture 25 December 1, 2015 What is rendering? Generating an image from a 3D scene model Ingredients Representation of 3D geometry Specification for camera & lights

### CS 325 Computer Graphics

CS 325 Computer Graphics 04 / 02 / 2012 Instructor: Michael Eckmann Today s Topics Questions? Comments? Illumination modelling Ambient, Diffuse, Specular Reflection Surface Rendering / Shading models Flat

### Local Illumination. CMPT 361 Introduction to Computer Graphics Torsten Möller. Machiraju/Zhang/Möller

Local Illumination CMPT 361 Introduction to Computer Graphics Torsten Möller Graphics Pipeline Hardware Modelling Transform Visibility Illumination + Shading Perception, Interaction Color Texture/ Realism

### Computer Vision Systems. Viewing Systems Projections Illuminations Rendering Culling and Clipping Implementations

Computer Vision Systems Viewing Systems Projections Illuminations Rendering Culling and Clipping Implementations Viewing Systems Viewing Transformation Projective Transformation 2D Computer Graphics Devices

### 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

Complex Shading Algorithms CPSC 414 Overview So far Rendering Pipeline including recent developments Today Shading algorithms based on the Rendering Pipeline Arbitrary reflection models (BRDFs) Bump mapping

### CSE 167: Introduction to Computer Graphics Lecture #6: Lights. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2014

CSE 167: Introduction to Computer Graphics Lecture #6: Lights Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2014 Announcements Project 2 due Friday, Oct. 24 th Midterm Exam

### Lecture 18: Primer on Ray Tracing Techniques

Lecture 18: Primer on Ray Tracing Techniques 6.172: Performance Engineering of Software Systems Joshua Slocum November 16, 2010 A Little Background Image rendering technique Simulate rays of light - ray

### Rendering. Illumination Model. Wireframe rendering simple, ambiguous Color filling flat without any 3D information

llumination Model Wireframe rendering simple, ambiguous Color filling flat without any 3D information Requires modeling interaction of light with the object/surface to have a different color (shade in

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

### Virtual Reality for Human Computer Interaction

Virtual Reality for Human Computer Interaction Appearance: Lighting Representation of Light and Color Do we need to represent all I! to represent a color C(I)? No we can approximate using a three-color

CT4510: Computer Graphics Illumination and Shading BOCHANG MOON Photorealism The ultimate goal of rendering is to produce photo realistic images. i.e., rendered images should be indistinguishable from

### CS770/870 Spring 2017 Color and Shading

Preview CS770/870 Spring 2017 Color and Shading Related material Cunningham: Ch 5 Hill and Kelley: Ch. 8 Angel 5e: 6.1-6.8 Angel 6e: 5.1-5.5 Making the scene more realistic Color models representing the

### Visualisatie BMT. Rendering. Arjan Kok

Visualisatie BMT Rendering Arjan Kok a.j.f.kok@tue.nl 1 Lecture overview Color Rendering Illumination 2 Visualization pipeline Raw Data Data Enrichment/Enhancement Derived Data Visualization Mapping Abstract

### 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

### Homework #2. Shading, Ray Tracing, and Texture Mapping

Computer Graphics Prof. Brian Curless CSE 457 Spring 2000 Homework #2 Shading, Ray Tracing, and Texture Mapping Prepared by: Doug Johnson, Maya Widyasari, and Brian Curless Assigned: Monday, May 8, 2000

### Computer Graphics. Si Lu. Fall uter_graphics.htm 11/22/2017

Computer Graphics Si Lu Fall 2017 http://web.cecs.pdx.edu/~lusi/cs447/cs447_547_comp uter_graphics.htm 11/22/2017 Last time o Splines 2 Today o Raytracing o Final Exam: 14:00-15:30, Novermber 29, 2017

### 6. Illumination, Lighting

Jorg s Graphics Lecture Notes 6. Illumination, Lighting 1 6. Illumination, Lighting No ray tracing in OpenGL! ray tracing: direct paths COP interreflection: soft shadows, color bleeding. umbra, penumbra,

### 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

### 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

### CS580: Ray Tracing. Sung-Eui Yoon ( 윤성의 ) Course URL:

CS580: Ray Tracing Sung-Eui Yoon ( 윤성의 ) Course URL: http://sglab.kaist.ac.kr/~sungeui/gcg/ Recursive Ray Casting Gained popularity in when Turner Whitted (1980) recognized that recursive ray casting could

### Supplement to Lecture 16

Supplement to Lecture 16 Global Illumination: View Dependent CS 354 Computer Graphics http://www.cs.utexas.edu/~bajaj/ Notes and figures from Ed Angel: Interactive Computer Graphics, 6 th Ed., 2012 Addison

### Level of Details in Computer Rendering

Level of Details in Computer Rendering Ariel Shamir Overview 1. Photo realism vs. Non photo realism (NPR) 2. Objects representations 3. Level of details Photo Realism Vs. Non Pixar Demonstrations Sketching,

### 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

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

### 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

### Chapter 10. Surface-Rendering Methods. Somsak Walairacht, Computer Engineering, KMITL

Computer Graphics Chapter 10 llumination Models and Surface-Rendering Methods Somsak Walairacht, Computer Engineering, KMTL 1 Outline Light Sources Surface Lighting Effects Basic llumination Models Polygon

### Pipeline Operations. CS 4620 Lecture 10

Pipeline Operations CS 4620 Lecture 10 2008 Steve Marschner 1 Hidden surface elimination Goal is to figure out which color to make the pixels based on what s in front of what. Hidden surface elimination

### Local vs. Global Illumination & Radiosity

Last Time? Local vs. Global Illumination & Radiosity Ray Casting & Ray-Object Intersection Recursive Ray Tracing Distributed Ray Tracing An early application of radiative heat transfer in stables. Reading

### Introduction Ray tracing basics Advanced topics (shading) Advanced topics (geometry) Graphics 2010/2011, 4th quarter. Lecture 11: Ray tracing

Lecture 11 Ray tracing Introduction Projection vs. ray tracing Projection Ray tracing Rendering Projection vs. ray tracing Projection Ray tracing Basic methods for image generation Major areas of computer

### Introduction Rasterization Z-buffering Shading. Graphics 2012/2013, 4th quarter. Lecture 09: graphics pipeline (rasterization and shading)

Lecture 9 Graphics pipeline (rasterization and shading) Graphics pipeline - part 1 (recap) Perspective projection by matrix multiplication: x pixel y pixel z canonical 1 x = M vpm per M cam y z 1 This

### Computer Graphics. Illumination Models and Surface-Rendering Methods. Somsak Walairacht, Computer Engineering, KMITL

Computer Graphics Chapter 10 llumination Models and Surface-Rendering Methods Somsak Walairacht, Computer Engineering, KMTL Outline Light Sources Surface Lighting Effects Basic llumination Models Polygon

### Sung-Eui Yoon ( 윤성의 )

CS380: Computer Graphics Ray Tracing Sung-Eui Yoon ( 윤성의 ) Course URL: http://sglab.kaist.ac.kr/~sungeui/cg/ Class Objectives Understand overall algorithm of recursive ray tracing Ray generations Intersection

### Graphics for VEs. Ruth Aylett

Graphics for VEs Ruth Aylett Overview VE Software Graphics for VEs The graphics pipeline Projections Lighting Shading VR software Two main types of software used: off-line authoring or modelling packages

Illumination & Shading Light Sources Empirical Illumination Shading Lecture 15 CISC440/640 Spring 2015 Illumination Models Computer Graphics Jargon: Illumination - the transport luminous flux from light

### 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

### Questions??? Announcements Assignment 3 due today

Announcements Assignment 3 due today Questions??? Remember that you have late days (if you haven t used them yet ) Problem set 3 out at the end of the day Movie for Assignment 2 at the end of class 1 Ray

### The Rasterizer Stage. Texturing, Lighting, Testing and Blending

1 The Rasterizer Stage Texturing, Lighting, Testing and Blending 2 Triangle Setup, Triangle Traversal and Back Face Culling From Primitives To Fragments Post Clipping 3 In the last stages of the geometry

### CS 130 Final. Fall 2015

CS 130 Final Fall 2015 Name Student ID Signature You may not ask any questions during the test. If you believe that there is something wrong with a question, write down what you think the question is trying

### Global Illumination. CSCI 420 Computer Graphics Lecture 18. BRDFs Raytracing and Radiosity Subsurface Scattering Photon Mapping [Ch

CSCI 420 Computer Graphics Lecture 18 Global Illumination Jernej Barbic University of Southern California BRDFs Raytracing and Radiosity Subsurface Scattering Photon Mapping [Ch. 13.4-13.5] 1 Global Illumination

### GLOBAL ILLUMINATION. Christopher Peters INTRODUCTION TO COMPUTER GRAPHICS AND INTERACTION

DH2323 DGI17 INTRODUCTION TO COMPUTER GRAPHICS AND INTERACTION GLOBAL ILLUMINATION Christopher Peters CST, KTH Royal Institute of Technology, Sweden chpeters@kth.se http://kth.academia.edu/christopheredwardpeters

### Shading I Computer Graphics I, Fall 2008

Shading I 1 Objectives Learn to shade objects ==> images appear threedimensional Introduce types of light-material interactions Build simple reflection model Phong model Can be used with real time graphics

### 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

### Problem Set 4 Part 1 CMSC 427 Distributed: Thursday, November 1, 2007 Due: Tuesday, November 20, 2007

Problem Set 4 Part 1 CMSC 427 Distributed: Thursday, November 1, 2007 Due: Tuesday, November 20, 2007 Programming For this assignment you will write a simple ray tracer. It will be written in C++ without

### OpenGl Pipeline. triangles, lines, points, images. Per-vertex ops. Primitive assembly. Texturing. Rasterization. Per-fragment ops.

OpenGl Pipeline Individual Vertices Transformed Vertices Commands Processor Per-vertex ops Primitive assembly triangles, lines, points, images Primitives Fragments Rasterization Texturing Per-fragment

### Ray-Tracing. Misha Kazhdan

Ray-Tracing Misha Kazhdan Ray-Tracing In graphics, we often represent the surface of a 3D shape by a set of triangles. Goal: Ray-Tracing Take a collection of triangles representing a 3D scene and render

### Computer Graphics. Lecture 9 Environment mapping, Mirroring

Computer Graphics Lecture 9 Environment mapping, Mirroring Today Environment Mapping Introduction Cubic mapping Sphere mapping refractive mapping Mirroring Introduction reflection first stencil buffer

### 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

### CSE 167: Introduction to Computer Graphics Lecture #6: Lights. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2016

CSE 167: Introduction to Computer Graphics Lecture #6: Lights Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2016 Announcements Thursday in class: midterm #1 Closed book Material

### COMPLETION OF Z-buffer Graphics Pipeline

Z-buffer algorithm for each polygon in model project vertices of polygon onto viewing plane for each pixel inside the projected polygon calculate pixel colour calculate pixel z-value compare pixel z-value

### Chapter 2 A top-down approach - How to make shaded images?

Chapter 2 A top-down approach - How to make shaded images? Comp. Graphics (U), Chap 2 Global View 1 CGGM Lab., CS Dept., NCTU Jung Hong Chuang Graphics API vs. application API Graphics API Support rendering

### 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

### CS 130 Exam I. Fall 2015

S 3 Exam I Fall 25 Name Student ID Signature You may not ask any questions during the test. If you believe that there is something wrong with a question, write down what you think the question is trying

### Chapter 7 - Light, Materials, Appearance

Chapter 7 - Light, Materials, Appearance Types of light in nature and in CG Shadows Using lights in CG Illumination models Textures and maps Procedural surface descriptions Literature: E. Angel/D. Shreiner,

### COMP371 COMPUTER GRAPHICS

COMP371 COMPUTER GRAPHICS SESSION 15 RAY TRACING 1 Announcements Programming Assignment 3 out today - overview @ end of the class Ray Tracing 2 Lecture Overview Review of last class Ray Tracing 3 Local

### Rendering. Converting a 3D scene to a 2D image. Camera. Light. Rendering. View Plane

Rendering Pipeline Rendering Converting a 3D scene to a 2D image Rendering Light Camera 3D Model View Plane Rendering Converting a 3D scene to a 2D image Basic rendering tasks: Modeling: creating the world