Objectives. Introduce Phong model Introduce modified Phong model Consider computation of required vectors Discuss polygonal shading.
|
|
- Bridget Williamson
- 5 years ago
- Views:
Transcription
1 Shading II 1
2 Objectives Introduce Phong model Introduce modified Phong model Consider computation of required vectors Discuss polygonal shading Flat Smooth Gouraud 2
3 Phong Lighting Model A simple model that can be computed rapidly Has three components Ambient Diffuse Specular Uses four vectors To source (l) To viewer (v) Normal (n) Perfect reflector (r) 3
4 Ambient reflection Amount and color depend on both the color of the light(s) and the material properties of the object I a = k a L a 0<=k a <=1 reflection coef intensity of ambient light 4
5 Diffuse Reflection An ideal diffuse surface is, at the microscopic level, a very rough surface. Chalk is a good approximation to an ideal diffuse surface. Because of the microscopic variations in the surface, an incoming ray of light is equally likely to be reflected in any direction over the hemisphere. 5
6 Lambertian Surface Perfectly diffuse reflector Light scattered equally in all directions Amount of light reflected is proportional to the vertical component of incoming light reflected light ~ cos q cos q= l n if vectors normalized There are also three coefficients, k r, k b, k g that show how much of each color component is reflected 6
7 Lambert's Cosine Law Lambert's law determines how much of the incoming light energy is reflected. Tthe amount of energy that is reflected in any one direction is constant in this model. In other words, the reflected intensity is independent of the viewing direction. 7
8 Illumination effects Shaded using a diffuse-reflection model,from left to right k d =0.4, 0.55, 0.77, 0.85, 1.0. Shaded using a ambient and diffuse-reflection model, I a =I light = 1.0, k d = 0.4. From left to right k a =0.0, 0.15, 0.30, 0.45,
9 Ideal Specular Surfaces Normal is determined by local orientation Angle of incidence = angle of relection The three vectors must be coplanar 9
10 Specular Surfaces Most surfaces are neither ideal diffusers nor perfectly specular (ideal reflectors) Smooth surfaces show specular highlights due to incoming light being reflected in directions concentrated close to the direction of a perfect reflection specular highlight 10
11 Modeling Specular Relections Phong proposed using a term that dropped off as the angle between the viewer (v) and the ideal reflection increased (r) I r ~ k s I cos a f reflected shininess coef intensity incoming intensity absorption coef f 11
12 The Shininess Coefficient Values between 5 and 10 give surface that look like plastic Values of a between 100 and 500 correspond to metals cos a f -90 f 90 12
13 Spheres shaded using phong illumination model 13
14 Distance Terms The light from a point source that reaches a surface is inversely proportional to the square of the distance between them We can add a factor of the form 1/(c 1 +c 2 d L +c 3 d L2 ) to the diffuse and specular terms The constant and linear terms soften the effect of the point source 14
15 Light source attenuation I = I a k a +f att I light k d (N. L) f att =1/d L 2 f att = (1/min((c 1 +c 2 d L +c 3 d L2 ), 1)); Distance C
16 Adding up the Components For each light source and each color component, the Phong model can be written (without the distance terms) as I = k a I a + k d I d l n + k s I s (v r ) a For each color component we add contributions from all sources 16
17 add a distance term 17
18 Light Sources In the Phong Model, we add the results from each light source Each light source has separate diffuse, specular, and ambient terms to allow for maximum flexibility even though this form does not have a physical justification Separate red, green and blue components Hence, 9 coefficients for each point source I dr, I dg, I db I sr, I sg, I sb I ar, I ag, I ab 18
19 Material Properties Material properties match light source properties 9 absorbtion coefficients k dr, k dg, k db k sr, k sg, k sb k ar, k ag, k ab Shininess coefficient a 19
20 Modified Phong Model The specular term in the Phong model is problematic because it requires the calculation of a new reflection vector and view vector for each vertex Blinn suggested an approximation using the halfway vector that is more efficient 20
21 The Halfway Vector h is normalized vector halfway between l and v h = ( l + v )/ l + v 21
22 Let ψ be the angle between the normal and the halfway vector, φ be the angle between the viewer and the reflection angle, and θ be the angle between the normal and the light source. If all the vectors lie in the same plane, the angle between the light source and the viewer can be computer either as φ + 2θ or as 2(θ + ψ). Setting the two equal, we find φ = 2ψ. If the vectors are not coplanar then φ < 2ψ 22
23 Using the halfway vector Replace (v r ) a by (n h ) b b is chosen to match shineness Note that halway angle is half of angle between r and v if vectors are coplanar Resulting model is known as the modified Phong or Blinn lighting model Specified in OpenGL standard 23
24 Example Only differences in these teapots are the parameters in the modified Phong model 24
25 Computation of Vectors l and v are specified by the application Can computer r from l and n Problem is determining n how we determine n differs depending on underlying representation of surface OpenGL leaves determination of normal to application Exception for GLU quadrics and Bezier surfaces (Chapter 11) glnormal3f(nx, ny, nz) 25
26 Plane Normals Equation of plane: ax+by+cz+d = 0 we know that plane is determined by three points p 0, p 2, p 3 or normal n and p 0 Normal can be obtained by n = (p 2 -p 0 ) (p 1 -p 0 ) 26
27 Implicit function Implicit function f(x,y,z)=0 the gradient vector the approximation is the equation of a plane whose normal is the gradient. 27
28 Normal to Sphere Sphere f(p)=p p - 1 n = [ f/ x, f/ y, f/ z] T =p the normal at every point on the surface of the sphere points directly out of the sphere, that is, in a direction from the origin through the point. For the unit sphere, the normalized result is n=p 28
29 Parametric Form For sphere x=x(u,v)=cos u sin v y=y(u,v)=cos u cos v z= z(u,v)=sin u Tangent plane determined by vectors p/ u = [ x/ u, y/ u, z/ u] T p/ v = [ x/ v, y/ v, z/ v] T Normal given by cross product n = p/ u p/ v 29
30 General Case We can compute parametric normals for other simple cases Quadrics Parameteric polynomial surfaces Bezier surface patches (Chapter 11) In OpenGL, the current normal vector is part of the state glnormal3f(nx, ny, nz); glnormal3fv(pointer_to_normal); 30
31 the reflection vector R =Ncosq + S =Ncosq + Ncosq - L =2N (N.L) - L Calculating N. H instead of R. V, in which H = (L+V)/ L+V 31
32 Although the fixed-function Open GL pipeline uses the modified Phong model and thus avoids having to calculate the reflection vector programmable shaders can use the reflection vector. 32
33 Polygonal Shading Shading calculations are done for each vertex Vertex colors become vertex shades By default, vertex shades are interpolated across the polygon glshademodel(gl_smooth); If we use glshademodel(gl_flat); the color at the first vertex will determine the shade of the whole polygon 33
34 Flat shading Flat shading of polygonal mesh Step chart 34
35 Polygon Normals Polygons have a single normal Shades at the vertices as computed by the Phong model can be almost same Identical for a distant viewer (default) or if there is no specular component Consider model of sphere Want different normals at each vertex even though this concept is not quite correct mathematically 35
36 Smooth Shading We can set a new normal at each vertex Easy for sphere model If centered at origin n = p Now smooth shading works Note silhouette edge 36
37 Mesh Shading The previous example is not general because we knew the normal at each vertex analytically For polygonal models, Gouraud proposed we use the average of the normals around a mesh vertex n = (n 1 +n 2 +n 3 +n 4 )/ n 1 +n 2 +n 3 +n 4 37
38 38
39 39
40 40
41 Gouraud V.S. Phong Gouraud shading Cheap but gives poor highlights Phong shading Slightly more expensive, but gives high quality highlights 41
42 Gouraud and Phong Shading Gouraud Shading Find average normal at each vertex (vertex normals) Apply modified Phong model at each vertex Interpolate vertex shades across each polygon Phong shading Find vertex normals Interpolate vertex normals across edges Interpolate edge normals across polygon Apply modified Phong model at each fragment 42
43 Comparison If the polygon mesh approximates surfaces with a high curvatures, Phong shading may look smooth while Gouraud shading may show edges Phong shading requires much more work than Gouraud shading Until recently not available in real time systems Now can be done using fragment shaders (see Chapter 9) Both need data structures to represent meshes so we can obtain vertex normals 43
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 informationShading. 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 informationWHY 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 informationShading II. Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts University of New Mexico
Shading II Ed Angel Professor of Computer Science, Electrical and Computer Engineering, and Media Arts University of New Mexico 1 Objectives Continue discussion of shading Introduce modified Phong model
More informationOverview. 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 informationIntroduction 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 informationThree-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 informationComp 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 informationIllumination & 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 informationComputer 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 informationLessons Learned from HW4. Shading. Objectives. Why we need shading. Shading. Scattering
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
More informationC 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 informationObjectives. Shading II. Distance Terms. The Phong Reflection Model
Shading II Objectives Introduce distance terms to the shading model. More details about the Phong model (lightmaterial interaction). Introduce the Blinn lighting model (also known as the modified Phong
More informationLighting and Shading II. Angel and Shreiner: Interactive Computer Graphics 7E Addison-Wesley 2015
Lighting and Shading II 1 Objectives Continue discussion of shading Introduce modified Phong model Consider computation of required vectors 2 Ambient Light Ambient light is the result of multiple interactions
More informationWhy 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 informationCS 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 informationShading 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 informationShading 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 informationCS452/552; 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
More informationLecture 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 informationIllumination 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 informationComputer 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 informationTopic 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 informationComputer 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 informationToday. 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 informationTopic 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 informationIntroduction 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
More informationIllumination 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 informationIllumination & 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 informationCS 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
More informationECS 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 informationToday. 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 informationComputer 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
More informationCSE 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 informationCS452/552; 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 informationIllumination and Shading
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
More informationCS5620 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 informationReflection 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 informationw 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 informationRendering. 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 informationOrthogonal 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 informationCPSC 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
More informationIllumination and Shading
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
More informationIntroduction to Computer Graphics with WebGL
Introduction to Computer Graphics with WebGL Ed Angel Classical Viewing Computer Graphics with WebGL Ed Angel, 204 Classical Viewing Viewing requires three basic elements - One or more objects - A viewer
More informationLighting 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 informationIllumination & Shading I
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
More informationCMSC427 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 informationLecture 17: Shading in OpenGL. CITS3003 Graphics & Animation
Lecture 17: Shading in OpenGL CITS3003 Graphics & Animation E. Angel and D. Shreiner: Interactive Computer Graphics 6E Addison-Wesley 2012 Objectives Introduce the OpenGL shading methods - per vertex shading
More informationObjectives. 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
More informationCS130 : 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 informationUniversity of Victoria CSC 305 Shading. Brian Wyvill 2016
University of Victoria CSC 305 Shading Brian Wyvill 2016 The illuminating Hemisphere Energy and Intensity Energy is the intensity integrated over the solid angle through which it acts. Intensity is not
More informationGraphics 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
More informationCHAPTER5. 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 informationGraphics for VEs. Ruth Aylett
Graphics for VEs Ruth Aylett Overview VE Software Graphics for VEs The graphics pipeline Projections Lighting Shading Runtime VR systems Two major parts: initialisation and update loop. Initialisation
More informationCSE 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,
More informationComputer 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.
More informationIllumination and Shading
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
More informationObjectives Shading in OpenGL. Front and Back Faces. OpenGL shading. Introduce the OpenGL shading methods. Discuss polygonal shading
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
More informationShading 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 informationIllumination and Shading
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
More informationComputer 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 informationCS230 : 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 informationLighting 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 informationSimple 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 informationIllumination and Shading ECE 567
Illumination and Shading ECE 567 Overview Lighting Models Ambient light Diffuse light Specular light Shading Models Flat shading Gouraud shading Phong shading OpenGL 2 Introduction To add realism to drawings
More informationColor 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 informationToday 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 informationComputer 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 informationVirtual 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 informationSung-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 informationCS Computer Graphics: Illumination and Shading I
CS 543 - Computer Graphics: Illumination and Shading I by Robert W. Lindeman gogo@wpi.edu (with help from Emmanuel Agu ;-) Illumination and Shading Problem: Model light/surface point interactions to determine
More informationCS Computer Graphics: Illumination and Shading I
CS 543 - Computer Graphics: Illumination and Shading I by Robert W. Lindeman gogo@wpi.edu (with help from Emmanuel Agu ;-) Illumination and Shading Problem: Model light/surface point interactions to determine
More informationPipeline Operations. CS 4620 Lecture 14
Pipeline Operations CS 4620 Lecture 14 2014 Steve Marschner 1 Pipeline you are here APPLICATION COMMAND STREAM 3D transformations; shading VERTEX PROCESSING TRANSFORMED GEOMETRY conversion of primitives
More informationChapter 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 informationCSE 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 informationToday 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
More informationColor 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 informationDisplay Issues Week 5
CS 432/637 INTERACTIVE COMPUTER GRAPHICS Display Issues Week 5 David Breen Department of Computer Science Drexel University Based on material from Ed Angel, University of New Mexico Objectives Consider
More informationTSBK 07! Computer Graphics! Ingemar Ragnemalm, ISY
1(84) Information Coding / Computer Graphics, ISY, LiTH TSBK 07 Computer Graphics Ingemar Ragnemalm, ISY 1(84) Lecture 5 3D graphics part 3 Illumination Illumination applied: Shading Surface detail: Mappings
More informationMach band effect. The Mach band effect increases the visual unpleasant representation of curved surface using flat shading.
Mach band effect The Mach band effect increases the visual unpleasant representation of curved surface using flat shading. A B 320322: Graphics and Visualization 456 Mach band effect The Mach band effect
More informationPipeline Operations. CS 4620 Lecture Steve Marschner. Cornell CS4620 Spring 2018 Lecture 11
Pipeline Operations CS 4620 Lecture 11 1 Pipeline you are here APPLICATION COMMAND STREAM 3D transformations; shading VERTEX PROCESSING TRANSFORMED GEOMETRY conversion of primitives to pixels RASTERIZATION
More informationShading. Brian Curless CSE 457 Spring 2017
Shading Brian Curless CSE 457 Spring 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 informationsurface: 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:
More informationGraphics and Visualization
International University Bremen Spring Semester 2006 Recap Hierarchical Modeling Perspective vs Parallel Projection Representing solid objects Displaying Wireframe models is easy from a computational
More informationShading and 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
More informationINF3320 Computer Graphics and Discrete Geometry
INF3320 Computer Graphics and Discrete Geometry Visual appearance Christopher Dyken and Martin Reimers 23.09.2009 Page 1 Visual appearance Real Time Rendering: Chapter 5 Light Sources and materials Shading
More informationLocal 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 informationReading. 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 informationOpenGl 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 informationCPSC / 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
More informationCGT520 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.
More informationIntroduction. 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 informationVisualisatie 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 informationIllumination & Shading
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
More informationCSE 167: Introduction to Computer Graphics Lecture #6: Colors. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013
CSE 167: Introduction to Computer Graphics Lecture #6: Colors Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013 Announcements Homework project #3 due this Friday, October 18
More informationShading. 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 informationIllumination. 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 informationIllumination and Shading
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
More informationVirtual 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 informationRecollection. 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