# Lighting. Figure 10.1

Size: px
Start display at page:

Download "Lighting. Figure 10.1"

## Transcription

1 We have learned to build three-dimensional graphical models and to display them. However, if you render one of our models, you might be disappointed to see images that look flat and thus fail to show the three-dimensional nature of the model. This appearance is a consequence of our unnatural assumption that each surface is colored with a single color. Under this assumption, the orthographic projection of a sphere is rendered as a uniformly colored circle, and the rendering of a cube appears as a flat hexagon. If we look at a photograph of a lit sphere, we do not see a uniformly colored circle but rather a circular shape with many gradations or shades of color. It is these gradations that give two-dimensional images the appearance of being threedimensional. When we look at a point on an object, the color that we see is determined by multiple interactions among light sources and reflective surfaces. These interactions can be viewed as a recursive process. Consider the simple scene illustrated in Figure 10.1 Some light from the source that reaches surface A is scattered. Some of this reflected light reaches surface B, and some of it is then scattered back to A, where some of it is again reflected back to B, and so on. Figure 10.1 There are various approximate approaches, such as radiosity and ray tracing, each of which is an excellent approximation to the rendering equation for particular types of surfaces. We follow rays of light from light-emitting (or self-luminous) surfaces that we call light sources. There are two independent parts of the problem. First, we must model the light sources in the scene. Then we must build a reflection model that describes the

2 interactions between materials and light. To get an overview of the process, we can start following rays of light from a point source, as shown in Figure Figure 10.2 Light and Surfaces Interactions : The interactions between light and materials can be classified into the three groups depicted in Figure Specular surfaces : appear shiny because most of the light that is reflected or scattered is in a narrow range of angles close to the angle of reflection. Mirrors are perfectly specular surfaces; the light from an incoming light ray may be partially absorbed, but all reflected light emerges at a single angle, obeying the rule that the angle of incidence is equal to the angle of reflection. 2. Diffuse surfaces : are characterized by reflected light being scattered in all directions. Walls painted with matte or flat paint are diffuse reflectors, as are many natural materials, such as terrain viewed from an airplane or a satellite. Perfectly diffuse surfaces scatter light equally in all directions and thus appear the same to all viewers. 3. Translucent surfaces : allow some light to penetrate the surface and to emerge from another location on the object. This process of refraction characterizes glass and water. Some incident light may also be reflected at the surface.

3 Figure 10.3 Light Sources : If we consider a source such as the one shown in Figure 10.4, we can look at it as an object with a surface. Each point (x, y, z) on the surface can emit light that is characterized by the direction of emission ( ) and the intensity of energy emitted at each wavelength. Thus, a general light source can be characterized by a six-variable illumination function I(x, y, z ), Figure Figure 10.4 Figure 10.5 For most applications, we can thus model light sources as having three components red, green, and blue and can use each of the three color sources to obtain the corresponding color component that a human observer sees. Thus, we can describe a color source through a three-component intensity or illumination function:

4 1. Ambient Light In many situations, such as in classrooms or kitchens, the lights have been designed and positioned to provide uniform illumination throughout the room. Often such illumination is achieved through large sources that have diffusers whose purpose is to scatter light in all directions. We could create an accurate simulation of such illumination, at least in principle, by modeling all the distributed sources and then integrating the illumination from these sources at each point on a reflecting surface. We can look at the desired effect of the sources: to achieve a uniform light level in the room. This uniform lighting is called ambient light. Ambient light depends on the color of the light sources in the environment. For example, a red light bulb in a white room creates red ambient light. 2. Point Sources An ideal point source emits light equally in all directions. We can characterize a point source located at a point p0 by a three-component color function We use I (p0 ) to refer to any of the components. The intensity of illumination received from a point source located at p0 at a point p is proportional to the inverse square of the distance from the source. Hence, at a point p (Figure 10.6), any component of the intensity of light received from the point source is given by function of the form Figure 10.6

5 3. Spotlights Spotlights are characterized by a narrow range of angles through which light is emitted. We can construct a simple spotlight from a point source by limiting the angles at which light from the source can be seen. We can use a cone whose apex is at p s, which points in the direction Is, and whose width is determined by an angle, as shown in Figure If = 180, the spotlight becomes a point source. Figure Distant Light Sources Most shading calculations require the direction from the point on the surface to the light source position. As we move across a surface, calculating the intensity at each point, we should recompute this vector repeatedly a computation that is a significant part of the lighting calculation. However, if the light source is far from the surface, the vector does not change much as we move from point to point, just as the light from the sun strikes all objects that are in close proximity to one another at the same angle. Figure 10.7

6 LIGHT SOURCES IN OPENGL OpenGL supports the four types of light sources point, spotlight, ambient, and distant that we described previously and allows at least eight light sources in a program. Each must be individually specified and enabled. Although there are many parameters that must be specified, they are exactly the parameters required by the modified-phong lighting model. The OpenGL functions: Specify the required vector and scalar parameters, respectively. There are four vector parameters that we can set: the position (or direction) of the light source and the amount of ambient, diffuse, and specular light associated with the source. For example, suppose that we wish to specify the first source GL_LIGHTO and to locate it at the point (1.0, 2.0, 3.0). We specify its position as a point in homogeneous coordinates as follows : With the fourth component set to zero, the point source becomes a distant source with direction vector. For our single light source, if we want a white specular component and red ambient and diffuse components, we can use the following code:

7 Note that we must enable both lighting and the particular source. We can also add a global ambient term that is independent of any of the sources. For example, if we want a small amount of white light, even when all light sources are turned off or disabled, we can use the following code:

### 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

More information

### 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

More information

### 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

More information

### Lecture 15: Shading-I. CITS3003 Graphics & Animation

Lecture 15: Shading-I CITS3003 Graphics & Animation E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012 Objectives Learn that with appropriate shading so objects appear as threedimensional

More information

### 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

More information

### WHY WE NEED SHADING. Suppose we build a model of a sphere using many polygons and color it with glcolor. We get something like.

LIGHTING 1 OUTLINE Learn to light/shade objects so their images appear three-dimensional Introduce the types of light-material interactions Build a simple reflection model---the Phong model--- that can

More information

### Shading. Why we need shading. Scattering. Shading. Objectives

Shading Why we need shading Objectives Learn to shade objects so their images appear three-dimensional Suppose we build a model of a sphere using many polygons and color it with glcolor. We get something

More information

### 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

More information

### Illumination & Shading

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

More information

### CHAPTER5. We have learned to build three-dimensional graphical models and to LIGHTING AND SHADING

LIGHTING AND SHADING CHAPTER5 We have learned to build three-dimensional graphical models and to display them. However, if you render one of our models, you might be disappointed to see images that look

More information

### Shading Intro. Shading & Lighting. Light and Matter. Light and Matter

Shading Intro Shading & Lighting Move from flat to 3-D models Orthographic view of sphere was uniformly color, thus, a flat circle A circular shape with many gradations or shades of color Courtesy of Vincent

More information

### 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

More information

### 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

More information

### 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

More information

### Module 5: Video Modeling Lecture 28: Illumination model. The Lecture Contains: Diffuse and Specular Reflection. Objectives_template

The Lecture Contains: Diffuse and Specular Reflection file:///d /...0(Ganesh%20Rana)/MY%20COURSE_Ganesh%20Rana/Prof.%20Sumana%20Gupta/FINAL%20DVSP/lecture%2028/28_1.htm[12/30/2015 4:22:29 PM] Diffuse and

More information

### CS452/552; EE465/505. Intro to Lighting

CS452/552; EE465/505 Intro to Lighting 2-10 15 Outline! Projection Normalization! Introduction to Lighting (and Shading) Read: Angel Chapter 5., sections 5.4-5.7 Parallel Projections Chapter 6, sections

More information

### 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

More information

### 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

More information

### 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

More information

### w Foley, Section16.1 Reading

Shading w Foley, Section16.1 Reading Introduction So far, we ve talked exclusively about geometry. w What is the shape of an object? w How do I place it in a virtual 3D space? w How do I know which pixels

More information

### 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

More information

### Color and Light CSCI 4229/5229 Computer Graphics Fall 2016

Color and Light CSCI 4229/5229 Computer Graphics Fall 2016 Solar Spectrum Human Trichromatic Color Perception Color Blindness Present to some degree in 8% of males and about 0.5% of females due to mutation

More information

### Illumination in Computer Graphics

Illumination in Computer Graphics Ann McNamara Illumination in Computer Graphics Definition of light sources. Analysis of interaction between light and objects in a scene. Rendering images that are faithful

More information

### 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

More information

### 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

More information

### 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

More information

### 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

More information

### Overview. Shading. Shading. Why we need shading. Shading Light-material interactions Phong model Shading polygons Shading in OpenGL

Overview Shading Shading Light-material interactions Phong model Shading polygons Shading in OpenGL Why we need shading Suppose we build a model of a sphere using many polygons and color it with glcolor.

More information

### Why we need shading?

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

More information

### Illumination Models & Shading

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));

More information

### 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

More information

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

Computer Graphics Ray Tracing Based on slides by Dianna Xu, Bryn Mawr College Ray Tracing Example Created by Anto Matkovic Ray Tracing Example Ray Tracing Example Ray Tracing Most light rays do not reach

More information

### C O M P U T E R G R A P H I C S. Computer Graphics. Three-Dimensional Graphics V. Guoying Zhao 1 / 65

Computer Graphics Three-Dimensional Graphics V Guoying Zhao 1 / 65 Shading Guoying Zhao 2 / 65 Objectives Learn to shade objects so their images appear three-dimensional Introduce the types of light-material

More information

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

Global Illumination CMPT 361 Introduction to Computer Graphics Torsten Möller Reading Foley, van Dam (better): Chapter 16.7-13 Angel: Chapter 5.11, 11.1-11.5 2 Limitation of local illumination A concrete

More information

### Reflection and Shading

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

More information

### Computer Graphics (CS 4731) Lecture 16: Lighting, Shading and Materials (Part 1)

Computer Graphics (CS 4731) Lecture 16: Lighting, Shading and Materials (Part 1) Prof Emmanuel Agu Computer Science Dept. Worcester Polytechnic Institute (WPI) Why do we need Lighting & shading? Sphere

More information

### Computer Graphics (CS 543) Lecture 7b: Intro to lighting, Shading and Materials + Phong Lighting Model

Computer Graphics (CS 543) Lecture 7b: Intro to lighting, Shading and Materials + Phong Lighting Model Prof Emmanuel Agu Computer Science Dept. Worcester Polytechnic Institute (WPI) Why do we need Lighting

More information

### Shading. Brian Curless CSE 557 Autumn 2017

Shading Brian Curless CSE 557 Autumn 2017 1 Reading Optional: Angel and Shreiner: chapter 5. Marschner and Shirley: chapter 10, chapter 17. Further reading: OpenGL red book, chapter 5. 2 Basic 3D graphics

More information

### Today. Global illumination. Shading. Interactive applications. Rendering pipeline. Computergrafik. Shading Introduction Local shading models

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

More information

### CS230 : Computer Graphics Lighting and Shading. Tamar Shinar Computer Science & Engineering UC Riverside

CS230 : Computer Graphics Lighting and Shading Tamar Shinar Computer Science & Engineering UC Riverside General light source Illumination function: [Angel and Shreiner] integrate contributions from all

More information

### Today we will start to look at illumination models in computer graphics

1 llumination Today we will start to look at illumination models in computer graphics Why do we need illumination models? Different kinds lights Different kinds reflections Basic lighting model 2 Why Lighting?

More information

### 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

More information

### Illumination and Shading

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

More information

### CS 4600 Fall Utah School of Computing

Lighting CS 4600 Fall 2015 Utah School of Computing Objectives Learn to shade objects so their images appear three-dimensional Introduce the types of light-material interactions Build a simple reflection

More information

### 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)

More information

### Today. Global illumination. Shading. Interactive applications. Rendering pipeline. Computergrafik. Shading Introduction Local shading models

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

More information

### Lighting and Shading

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,

More information

### 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

More information

### Shading. Reading. Pinhole camera. Basic 3D graphics. Brian Curless CSE 557 Fall Required: Shirley, Chapter 10

Reading Required: Shirley, Chapter 10 Shading Brian Curless CSE 557 Fall 2014 1 2 Basic 3D graphics With affine matrices, we can now transform virtual 3D objects in their local coordinate systems into

More information

### 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

More information

### 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

More information

### 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

More information

### Introduction. Lighting model Light reflection model Local illumination model Reflectance model BRDF

Shading Introduction Affine transformations help us to place objects into a scene. Before creating images of these objects, we ll look at models for how light interacts with their surfaces. Such a model

More information

### 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

More information

### 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

More information

### 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

More information

### Global Illumination. Global Illumination. Direct Illumination vs. Global Illumination. Indirect Illumination. Soft Shadows.

CSCI 480 Computer Graphics Lecture 18 Global Illumination BRDFs Raytracing and Radiosity Subsurface Scattering Photon Mapping [Ch. 13.4-13.5] March 28, 2012 Jernej Barbic University of Southern California

More information

### 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

More information

### CMSC427 Shading Intro. Credit: slides from Dr. Zwicker

CMSC427 Shading Intro Credit: slides from Dr. Zwicker 2 Today Shading Introduction Radiometry & BRDFs Local shading models Light sources Shading strategies Shading Compute interaction of light with surfaces

More information

### 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

More information

### Global Illumination. Global Illumination. Direct Illumination vs. Global Illumination. Indirect Illumination. Soft Shadows.

CSCI 420 Computer Graphics Lecture 18 Global Illumination Jernej Barbic University of Southern California BRDFs Raytracing and Radiosity Subsurface Scattering Photon Mapping [Angel Ch. 11] 1 Global Illumination

More information

### Shading II. CITS3003 Graphics & Animation

Shading II CITS3003 Graphics & Animation Objectives Introduce distance terms to the shading model. More details about the Phong model (lightmaterial interaction). Introduce the Blinn lighting model (also

More information

### 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

More information

### Objectives. Continue discussion of shading Introduce modified Phong model Consider computation of required vectors

Objectives Continue discussion of shading Introduce modified Phong model Consider computation of required vectors 1 Lambertian Surface Perfectly diffuse reflector Light scattered equally in all directions

More information

### 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

More information

### 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

More information

### Global Illumination. Why Global Illumination. Pros/Cons and Applications. What s Global Illumination

Global Illumination Why Global Illumination Last lecture Basic rendering concepts Primitive-based rendering Today: Global illumination Ray Tracing, and Radiosity (Light-based rendering) What s Global Illumination

More information

### Virtual Reality for Human Computer Interaction

Virtual Reality for Human Computer Interaction Appearance: Lighting Representation of Light and Color Representation of Light and Color Do we need to represent all I! to represent a color C(I)? Representation

More information

### 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

More information

### 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,

More information

### 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

More information

### 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

More information

### Reading. Shading. An abundance of photons. Introduction. Required: Angel , 6.5, Optional: Angel 6.4 OpenGL red book, chapter 5.

Reading Required: Angel 6.1-6.3, 6.5, 6.7-6.8 Optional: Shading Angel 6.4 OpenGL red book, chapter 5. 1 2 Introduction An abundance of photons So far, we ve talked exclusively about geometry. Properly

More information

### 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?

More information

### 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

More information

### 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

More information

### Understanding Variability

Understanding Variability Why so different? Light and Optics Pinhole camera model Perspective projection Thin lens model Fundamental equation Distortion: spherical & chromatic aberration, radial distortion

More information

### 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

More information

### 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

More information

### Objectives. Introduce Phong model Introduce modified Phong model Consider computation of required vectors Discuss polygonal shading.

Shading II 1 Objectives Introduce Phong model Introduce modified Phong model Consider computation of required vectors Discuss polygonal shading Flat Smooth Gouraud 2 Phong Lighting Model A simple model

More information

### 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

More information

### 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

More information

### Sung-Eui Yoon ( 윤성의 )

CS380: Computer Graphics Illumination and Shading Sung-Eui Yoon ( 윤성의 ) Course URL: http://sglab.kaist.ac.kr/~sungeui/cg/ Course Objectives (Ch. 10) Know how to consider lights during rendering models

More information

### 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

More information

### 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

More information

### Illumination. The slides combine material from Andy van Dam, Spike Hughes, Travis Webb and Lyn Fong

INTRODUCTION TO COMPUTER GRAPHIC S Illumination The slides combine material from Andy van Dam, Spike Hughes, Travis Webb and Lyn Fong Andries van Dam October 29, 2009 Illumination Models 1/30 Outline Physical

More information

### 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

More information

### 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

More information

### Illumination. Michael Kazhdan ( /657) HB Ch. 14.1, 14.2 FvDFH 16.1, 16.2

Illumination Michael Kazhdan (601.457/657) HB Ch. 14.1, 14.2 FvDFH 16.1, 16.2 Ray Casting Image RayCast(Camera camera, Scene scene, int width, int height) { Image image = new Image(width, height); for

More information

### 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

More information

### Shading. Shading = find color values at pixels of screen (when rendering a virtual 3D scene).

Light Shading Shading Shading = find color values at pixels of screen (when rendering a virtual 3D scene). Shading Shading = find color values at pixels of screen (when rendering a virtual 3D scene). Same

More information

### At the interface between two materials, where light can be reflected or refracted. Within a material, where the light can be scattered or absorbed.

At the interface between two materials, where light can be reflected or refracted. Within a material, where the light can be scattered or absorbed. The eye sees by focusing a diverging bundle of rays from

More information

### 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:

More information

### Interactive Real-Time Raycasting

Interactive Real-Time Raycasting CS184 AS4 Due 2009-02-26 11:00pm We start our exploration of Rendering - the process of converting a high-level object-based description into a graphical image for display.

More information

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

Recollection Models Pixels Model transformation Viewport transformation Clipping Rasterization Texturing + Lights & shadows Can be computed in different stages 1 So far we came to Geometry model 3 Surface

More information

### Assignment 2 Ray Tracing

Assignment 2 Ray Tracing Overview The concept of ray tracing: a technique for generating an image by tracing the path of light through pixels in an image plane and simulating the effects of its encounters

More information

### Reading. Shading. Introduction. An abundance of photons. Required: Angel , Optional: OpenGL red book, chapter 5.

Reading Required: Angel 6.1-6.5, 6.7-6.8 Optional: Shading OpenGL red book, chapter 5. 1 2 Introduction So far, we ve talked exclusively about geometry. What is the shape of an obect? How do I place it

More information

### 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

More information

### 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

More information

### 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

More information