# Overview. Pipeline implementation I. Overview. Required Tasks. Preliminaries Clipping. Hidden Surface removal

Size: px
Start display at page:

Transcription

1 Overview Pipeline implementation I Preliminaries Clipping Line clipping Hidden Surface removal Overview At end of the geometric pipeline, vertices have been assembled into primitives Must clip out primitives that are outside the view frustum Algorithms based on representing primitives by lists of vertices Must find which pixels can be affected by each primitive Fragment generation Rasterization or scan conversion Required Tasks Clipping This lecture Rasterization or scan conversion Next lecture Transformations Some tasks deferred until fragment processing Hidden surface removal Antialiasing

2 Rasterization Meta Algorithms Two approaches For every pixel, determine which object that projects on the pixel is closest to the viewer and compute the shade of this pixel Ray tracing paradigm Global effects For every object, determine which pixels it covers and shade these pixels Pipeline approach Must keep track of depths No Global effects Clipping 2D against clipping window 3D against clipping volume Easy for line segments polygons Hard for curves and text Convert to lines and polygons first Clipping 2D Line Segments Brute force approach: compute intersections with all sides of clipping window Inefficient: one division per intersection Cohen-Sutherland Algorithm Idea: eliminate as many cases as possible without computing intersections Start with four lines that determine the sides of the clipping window y = y max x = x min x = x max y = y min

3 The Cases Case 1: both endpoints of line segment inside all four lines Draw (accept) line segment as is x = x min y = y max y = y min x = x max The Cases Case 3: One endpoint inside, one outside Must do at least one intersection Case 4: Both outside May have part inside Must do at least one intersection y = y max Case 2: both endpoints outside all lines and on same side of a line Discard (reject) the line segment x = x min x = x max Defining Outcodes For each endpoint, define an outcode b 0 b 1 b 2 b 3 b 0 = 1 if y > y max, 0 otherwise b 1 = 1 if y < y min, 0 otherwise b 2 = 1 if x > x max, 0 otherwise b 3 = 1 if x < x min, 0 otherwise Using Outcodes Consider the 5 cases below AB: outcode(a) = outcode(b) = 0 Accept line segment Outcodes divide space into 9 regions Computation of outcode requires at most 4 subtractions

4 Using Outcodes CD: outcode (C) = 0, outcode(d) 0 Compute intersection Location of 1 in outcode(d) determines which edge to intersect with Note if there were a segment from A to a point in a region with 2 ones in outcode, we might have to do two interesections Using Outcodes EF: outcode(e) logically ANDed with outcode(f) (bitwise) 0 Both outcodes have a 1 bit in the same place Line segment is outside of corresponding side of clipping window reject Using Outcodes GH and IJ: same outcodes, neither zero but logical AND yields zero Shorten line segment by intersecting with one of sides of window Compute outcode of intersection (new endpoint of shortened line segment) Reexecute algorithm Efficiency In many applications, the clipping window is small relative to the size of the entire data base Most line segments are outside one or more side of the window and can be eliminated based on their outcodes Inefficiency when code has to be reexecuted for line segments that must be shortened in more than one step

5 Cohen Sutherland in 3D Use 6-bit outcodes When needed, clip line segment against planes Liang-Barsky Clipping Consider the parametric form of a line segment p(α) = (1-α)p 1 + αp 2 1 α 0 p 1 p 2 We can distinguish between the cases by looking at the ordering of the values of α where the line determined by the line segment crosses the lines that determine the window Liang-Barsky Clipping In (a): α 4 > α 3 > α 2 > α 1 Intersect right, top, left, bottom: shorten In (b): α 4 > α 2 > α 3 > α 1 Intersect right, left, top, bottom: reject Advantages Can accept/reject as easily as with Cohen- Sutherland Using values of α, we do not have to use algorithm recursively as with C-S Extends to 3D

6 Clipping and Normalization General clipping in 3D requires intersection of line segments against arbitrary plane Example: oblique view Plane-Line Intersections a = n ( po n ( p 2 p1) p ) 1 Normalized Form Polygon Clipping top view before normalization after normalization Not as simple as line segment clipping Clipping a line segment yields at most one line segment Clipping a polygon can yield multiple polygons Normalization is part of viewing (pre clipping) but after normalization, we clip against sides of right parallelepiped Typical intersection calculation now requires only a floating point subtraction, e.g. is x > x max? However, clipping a convex polygon can yield at most one other polygon

7 Tessellation and Convexity One strategy is to replace nonconvex (concave) polygons with a set of triangular polygons (a tessellation) Also makes fill easier Tessellation code in GLU library Clipping as a Black Box Can consider line segment clipping as a process that takes in two vertices and produces either no vertices or the vertices of a clipped line segment Pipeline Clipping of Line Segments Pipeline Clipping of Polygons Clipping against each side of window is independent of other sides Can use four independent clippers in a pipeline Three dimensions: add front and back clippers Strategy used in SGI Geometry Engine Small increase in latency

8 Bounding Boxes Rather than doing clipping on a complex polygon, we can use an axis-aligned bounding box or extent Smallest rectangle aligned with axes that encloses the polygon Simple to compute: max and min of x and y Bounding boxes Can usually determine accept/reject based only on bounding box accept reject requires detailed clipping Clipping and Visibility Clipping has much in common with hidden-surface removal In both cases, we are trying to remove objects that are not visible to the camera Often we can use visibility or occlusion testing early in the process to eliminate as many polygons as possible before going through the entire pipeline Hidden Surface Removal Object-space approach: use pairwise testing between polygons (objects) partially obscuring can draw independently Worst case complexity O(n 2 ) for n polygons

9 Painter s Algorithm Render polygons a back to front order so that polygons behind others are simply painted over Depth Sort Requires ordering of polygons first O(n log n) calculation for ordering Not every polygon is either in front or behind all other polygons B behind A as seen by viewer Fill B then A Order polygons and deal with easy cases first, harder later Polygons sorted by distance from COP Easy Cases Hard Cases A lies behind all other polygons Can render Polygons overlap in z but not in either x or y Can render independently Overlap in all directions but can one is fully on one side of the other cyclic overlap penetration

10 Back-Face Removal (Culling) face is visible iff 90 θ -90 equivalently cos θ 0 or v n 0 plane of face has form ax + by +cz +d =0 but after normalization n = ( ) T need only test the sign of c In OpenGL we can simply enable culling but may not work correctly if we have nonconvex objects θ Image Space Approach Look at each projector (nm for an n x m frame buffer) and find closest of k polygons Complexity O(nmk) Ray tracing z-buffer z-buffer Algorithm Efficiency Use a buffer called the z or depth buffer to store the depth of the closest object at each pixel found so far As we render each polygon, compare the depth of each pixel to depth in z buffer If less, place shade of pixel in color buffer and update z buffer If we work scan line by scan line as we move across a scan line, the depth changes satisfy a x+b y+c z=0 Along scan line y = 0 z = - a c x In screen space x = 1

11 Visibility Testing In many realtime applications, such as games, we want to eliminate as many objects as possible within the application Reduce burden on pipeline Reduce traffic on bus Partition space with Binary Spatial Partition (BSP) Tree Octrees Portals Simple Example consider 6 parallel polygons top view The plane of A separates B and C from D, E and F BSP Tree Can continue recursively Plane of C separates B from A Plane of D separates E and F Can put this information in a BSP tree Use for visibility and occlusion testing Next time Scan conversion and Rasterization

### Clipping. Angel and Shreiner: Interactive Computer Graphics 7E Addison-Wesley 2015

Clipping 1 Objectives Clipping lines First of implementation algorithms Clipping polygons (next lecture) Focus on pipeline plus a few classic algorithms 2 Clipping 2D against clipping window 3D against

### FROM VERTICES TO FRAGMENTS. Lecture 5 Comp3080 Computer Graphics HKBU

FROM VERTICES TO FRAGMENTS Lecture 5 Comp3080 Computer Graphics HKBU OBJECTIVES Introduce basic implementation strategies Clipping Scan conversion OCTOBER 9, 2011 2 OVERVIEW At end of the geometric pipeline,

### From Vertices To Fragments-1

From Vertices To Fragments-1 1 Objectives Clipping Line-segment clipping polygon clipping 2 Overview At end of the geometric pipeline, vertices have been assembled into primitives Must clip out primitives

### Topics. From vertices to fragments

Topics From vertices to fragments From Vertices to Fragments Assign a color to every pixel Pass every object through the system Required tasks: Modeling Geometric processing Rasterization Fragment processing

### CS452/552; EE465/505. Clipping & Scan Conversion

CS452/552; EE465/505 Clipping & Scan Conversion 3-31 15 Outline! From Geometry to Pixels: Overview Clipping (continued) Scan conversion Read: Angel, Chapter 8, 8.1-8.9 Project#1 due: this week Lab4 due:

### Realtime 3D Computer Graphics Virtual Reality

Realtime 3D Computer Graphics Virtual Reality From Vertices to Fragments Overview Overall goal recapitulation: Input: World description, e.g., set of vertices and states for objects, attributes, camera,

### Introduction to Computer Graphics 5. Clipping

Introduction to Computer Grapics 5. Clipping I-Cen Lin, Assistant Professor National Ciao Tung Univ., Taiwan Textbook: E.Angel, Interactive Computer Grapics, 5 t Ed., Addison Wesley Ref:Hearn and Baker,

### Rasterization, Depth Sorting and Culling

Rasterization, Depth Sorting and Culling Rastrerzation How can we determine which pixels to fill? Reading Material These slides OH 17-26, OH 65-79 and OH 281-282, by Magnus Bondesson You may also read

### 3D Rendering Pipeline (for direct illumination)

Clipping 3D Rendering Pipeline (for direct illumination) 3D Primitives 3D Modeling Coordinates Modeling Transformation Lighting 3D Camera Coordinates Projection Transformation Clipping 2D Screen Coordinates

### Renderer Implementation: Basics and Clipping. Overview. Preliminaries. David Carr Virtual Environments, Fundamentals Spring 2005

INSTITUTIONEN FÖR SYSTEMTEKNIK LULEÅ TEKNISKA UNIVERSITET Renderer Implementation: Basics and Clipping David Carr Virtual Environments, Fundamentals Spring 2005 Feb-28-05 SMM009, Basics and Clipping 1

### Incremental Form. Idea. More efficient if we look at d k, the value of the decision variable at x = k

Idea 1 m 0 candidates last pixel Note that line could have passed through any part of this pixel Decision variable: d = x(a-b) d is an integer d < 0 use upper pixel d > 0 use lower pixel Incremental Form

### Examples. Clipping. The Rendering Pipeline. View Frustum. Normalization. How it is done. Types of operations. Removing what is not seen on the screen

Computer Graphics, Lecture 0 November 7, 006 Eamples Clipping Types of operations Accept Reject Clip Removing what is not seen on the screen The Rendering Pipeline The Graphics pipeline includes one stage

### Page 1. Area-Subdivision Algorithms z-buffer Algorithm List Priority Algorithms BSP (Binary Space Partitioning Tree) Scan-line Algorithms

Visible Surface Determination Visibility Culling Area-Subdivision Algorithms z-buffer Algorithm List Priority Algorithms BSP (Binary Space Partitioning Tree) Scan-line Algorithms Divide-and-conquer strategy:

### CSE528 Computer Graphics: Theory, Algorithms, and Applications

CSE528 Computer Graphics: Theory, Algorithms, and Applications Hong Qin State University of New York at Stony Brook (Stony Brook University) Stony Brook, New York 11794--4400 Tel: (631)632-8450; Fax: (631)632-8334

### Computer Graphics. Bing-Yu Chen National Taiwan University The University of Tokyo

Computer Graphics Bing-Yu Chen National Taiwan University The University of Tokyo Hidden-Surface Removal Back-Face Culling The Depth-Sort Algorithm Binary Space-Partitioning Trees The z-buffer Algorithm

### Today. CS-184: Computer Graphics. Lecture #10: Clipping and Hidden Surfaces. Clipping. Hidden Surface Removal

Today CS-184: Computer Graphics Lecture #10: Clipping and Hidden Surfaces!! Prof. James O Brien University of California, Berkeley! V2015-S-10-1.0 Clipping Clipping to view volume Clipping arbitrary polygons

### Hidden Surface Removal

Outline Introduction Hidden Surface Removal Hidden Surface Removal Simone Gasparini gasparini@elet.polimi.it Back face culling Depth sort Z-buffer Introduction Graphics pipeline Introduction Modeling Geom

### Identifying those parts of a scene that are visible from a chosen viewing position, and only process (scan convert) those parts

Visible Surface Detection Identifying those parts of a scene that are visible from a chosen viewing position, and only process (scan convert) those parts Two approaches: 1. Object space methods 2. Image

### CSE328 Fundamentals of Computer Graphics: Concepts, Theory, Algorithms, and Applications

CSE328 Fundamentals of Computer Graphics: Concepts, Theory, Algorithms, and Applications Hong Qin Stony Brook University (SUNY at Stony Brook) Stony Brook, New York 11794-4400 Tel: (631)632-8450; Fax:

### Clipping and Scan Conversion

15-462 Computer Graphics I Lecture 14 Clipping and Scan Conversion Line Clipping Polygon Clipping Clipping in Three Dimensions Scan Conversion (Rasterization) [Angel 7.3-7.6, 7.8-7.9] March 19, 2002 Frank

### CHAPTER 1 Graphics Systems and Models 3

?????? 1 CHAPTER 1 Graphics Systems and Models 3 1.1 Applications of Computer Graphics 4 1.1.1 Display of Information............. 4 1.1.2 Design.................... 5 1.1.3 Simulation and Animation...........

### Computer Graphics (CS 543) Lecture 9 (Part 2): Clipping. Prof Emmanuel Agu. Computer Science Dept. Worcester Polytechnic Institute (WPI)

Computer Graphics (CS 543) Lecture 9 (Part 2): Clipping Prof Emmanuel Agu Computer Science Dept. Worcester Polytechnic Institute (WPI) OpenGL Stages After projection, several stages before objects drawn

### Hidden surface removal. Computer Graphics

Lecture Hidden Surface Removal and Rasterization Taku Komura Hidden surface removal Drawing polygonal faces on screen consumes CPU cycles Illumination We cannot see every surface in scene We don t want

### Computer Graphics. Bing-Yu Chen National Taiwan University

Computer Graphics Bing-Yu Chen National Taiwan University Visible-Surface Determination Back-Face Culling The Depth-Sort Algorithm Binary Space-Partitioning Trees The z-buffer Algorithm Scan-Line Algorithm

### Werner Purgathofer

Einführung in Visual Computing 186.822 Visible Surface Detection Werner Purgathofer Visibility in the Rendering Pipeline scene objects in object space object capture/creation ti modeling viewing projection

### VISIBILITY & CULLING. Don t draw what you can t see. Thomas Larsson, Afshin Ameri DVA338, Spring 2018, MDH

VISIBILITY & CULLING Don t draw what you can t see. Thomas Larsson, Afshin Ameri DVA338, Spring 2018, MDH Visibility Visibility Given a set of 3D objects, which surfaces are visible from a specific point

### 8. Hidden Surface Elimination

8. Hidden Surface Elimination Identification and Removal of parts of picture that are not visible from a chosen viewing position. 1 8. Hidden Surface Elimination Basic idea: Overwriting Paint things in

### Computer Graphics. - Clipping - Philipp Slusallek & Stefan Lemme

Computer Graphics - Clipping - Philipp Slusallek & Stefan Lemme Clipping Motivation Projected primitive might fall (partially) outside of the visible display window E.g. if standing inside a building Eliminate

### EECE 478. Learning Objectives. Learning Objectives. Rasterization & Scenes. Rasterization. Compositing

EECE 478 Rasterization & Scenes Rasterization Learning Objectives Be able to describe the complete graphics pipeline. Describe the process of rasterization for triangles and lines. Compositing Manipulate

### Computer Graphics. Lecture 9 Hidden Surface Removal. Taku Komura

Computer Graphics Lecture 9 Hidden Surface Removal Taku Komura 1 Why Hidden Surface Removal? A correct rendering requires correct visibility calculations When multiple opaque polygons cover the same screen

### QUESTION BANK 10CS65 : COMPUTER GRAPHICS AND VISUALIZATION

QUESTION BANK 10CS65 : COMPUTER GRAPHICS AND VISUALIZATION INTRODUCTION OBJECTIVE: This chapter deals the applications of computer graphics and overview of graphics systems and imaging. UNIT I 1 With clear

### Spatial Data Structures

CSCI 420 Computer Graphics Lecture 17 Spatial Data Structures Jernej Barbic University of Southern California Hierarchical Bounding Volumes Regular Grids Octrees BSP Trees [Angel Ch. 8] 1 Ray Tracing Acceleration

### Graphics and Interaction Rendering pipeline & object modelling

433-324 Graphics and Interaction Rendering pipeline & object modelling Department of Computer Science and Software Engineering The Lecture outline Introduction to Modelling Polygonal geometry The rendering

### CS4620/5620: Lecture 14 Pipeline

CS4620/5620: Lecture 14 Pipeline 1 Rasterizing triangles Summary 1! evaluation of linear functions on pixel grid 2! functions defined by parameter values at vertices 3! using extra parameters to determine

### Computer Graphics II

Computer Graphics II Autumn 2017-2018 Outline Visible Surface Determination Methods (contd.) 1 Visible Surface Determination Methods (contd.) Outline Visible Surface Determination Methods (contd.) 1 Visible

### Visible Surface Detection Methods

Visible urface Detection Methods Visible-urface Detection identifying visible parts of a scene (also hidden- elimination) type of algorithm depends on: complexity of scene type of objects available equipment

### Clipping & Culling. Lecture 11 Spring Trivial Rejection Outcode Clipping Plane-at-a-time Clipping Backface Culling

Clipping & Culling Trivial Rejection Outcode Clipping Plane-at-a-time Clipping Backface Culling Lecture 11 Spring 2015 What is Clipping? Clipping is a procedure for spatially partitioning geometric primitives,

### COMP30019 Graphics and Interaction Scan Converting Polygons and Lines

COMP30019 Graphics and Interaction Scan Converting Polygons and Lines Department of Computer Science and Software Engineering The Lecture outline Introduction Scan conversion Scan-line algorithm Edge coherence

### CSE 167: Lecture #5: Rasterization. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2012

CSE 167: Introduction to Computer Graphics Lecture #5: Rasterization Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2012 Announcements Homework project #2 due this Friday, October

### Clipping Algorithms; 8-5. Computer Graphics. Spring CS4815

Computer Graphics Spring 2016-2017 Outline Clipping Algorithms; 8-5 1 Clipping Algorithms; 8-5 Announcements Mid-term: Week07?? Clipping: Introduction It is common for a region to be defined so that only

### 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

### Culling. Computer Graphics CSE 167 Lecture 12

Culling Computer Graphics CSE 167 Lecture 12 CSE 167: Computer graphics Culling Definition: selecting from a large quantity In computer graphics: selecting primitives (or batches of primitives) that are

### Two basic types: image-precision and object-precision. Image-precision For each pixel, determine which object is visable Requires np operations

walters@buffalo.edu CSE 480/580 Lecture 21 Slide 1 Visible-Surface Determination (Hidden Surface Removal) Computationaly expensive Two basic types: image-precision and object-precision For n objects and

### Spatial Data Structures and Speed-Up Techniques. Tomas Akenine-Möller Department of Computer Engineering Chalmers University of Technology

Spatial Data Structures and Speed-Up Techniques Tomas Akenine-Möller Department of Computer Engineering Chalmers University of Technology Spatial data structures What is it? Data structure that organizes

### Spatial Data Structures

CSCI 480 Computer Graphics Lecture 7 Spatial Data Structures Hierarchical Bounding Volumes Regular Grids BSP Trees [Ch. 0.] March 8, 0 Jernej Barbic University of Southern California http://www-bcf.usc.edu/~jbarbic/cs480-s/

### Spatial Data Structures

15-462 Computer Graphics I Lecture 17 Spatial Data Structures Hierarchical Bounding Volumes Regular Grids Octrees BSP Trees Constructive Solid Geometry (CSG) April 1, 2003 [Angel 9.10] Frank Pfenning Carnegie

### 9. Visible-Surface Detection Methods

9. Visible-Surface Detection Methods More information about Modelling and Perspective Viewing: Before going to visible surface detection, we first review and discuss the followings: 1. Modelling Transformation:

### Spatial Data Structures

15-462 Computer Graphics I Lecture 17 Spatial Data Structures Hierarchical Bounding Volumes Regular Grids Octrees BSP Trees Constructive Solid Geometry (CSG) March 28, 2002 [Angel 8.9] Frank Pfenning Carnegie

### 8. Hidden Surface Elimination

-04-8 Hidden Surface Elimination To eliminate edges and surfaces not visible to the viewer Two categories: Object space methods: Image space methods: deal with object definitions directly Order the surfaces

### Visibility: Z Buffering

University of British Columbia CPSC 414 Computer Graphics Visibility: Z Buffering Week 1, Mon 3 Nov 23 Tamara Munzner 1 Poll how far are people on project 2? preferences for Plan A: status quo P2 stays

### Chapter 8: Implementation- Clipping and Rasterization

Chapter 8: Implementation- Clipping and Rasterization Clipping Fundamentals Cohen-Sutherland Parametric Polygons Circles and Curves Text Basic Concepts: The purpose of clipping is to remove objects or

### Hidden Surfaces II. Week 9, Mon Mar 15

University of British Columbia CPSC 314 Computer Graphics Jan-Apr 2010 Tamara Munzner Hidden Surfaces II Week 9, Mon Mar 15 http://www.ugrad.cs.ubc.ca/~cs314/vjan2010 ews yes, I'm granting the request

### Painter s HSR Algorithm

Painter s HSR Algorithm Render polygons farthest to nearest Similar to painter layers oil paint Viewer sees B behind A Render B then A Depth Sort Requires sorting polygons (based on depth) O(n log n) complexity

### INFOGR Computer Graphics. J. Bikker - April-July Lecture 11: Visibility. Welcome!

INFOGR Computer Graphics J. Bikker - April-July 2016 - Lecture 11: Visibility Welcome! Smallest Ray Tracers: Executable 5692598 & 5683777: RTMini_minimal.exe 2803 bytes 5741858: ASM_CPU_Min_Exe 994 bytes

### Motivation. Culling Don t draw what you can t see! What can t we see? Low-level Culling

Motivation Culling Don t draw what you can t see! Thomas Larsson Mälardalen University April 7, 2016 Image correctness Rendering speed One day we will have enough processing power!? Goals of real-time

### S U N G - E U I YO O N, K A I S T R E N D E R I N G F R E E LY A VA I L A B L E O N T H E I N T E R N E T

S U N G - E U I YO O N, K A I S T R E N D E R I N G F R E E LY A VA I L A B L E O N T H E I N T E R N E T Copyright 2018 Sung-eui Yoon, KAIST freely available on the internet http://sglab.kaist.ac.kr/~sungeui/render

### CEng 477 Introduction to Computer Graphics Fall 2007

Visible Surface Detection CEng 477 Introduction to Computer Graphics Fall 2007 Visible Surface Detection Visible surface detection or hidden surface removal. Realistic scenes: closer objects occludes the

### CSE 167: Introduction to Computer Graphics Lecture #9: Visibility. Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2018

CSE 167: Introduction to Computer Graphics Lecture #9: Visibility Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2018 Announcements Midterm Scores are on TritonEd Exams to be

### Determination (Penentuan Permukaan Tampak)

Visible Surface Determination (Penentuan Permukaan Tampak) Visible Surface Determination 1/26 Outline Definisi VSD Tiga Kelas Algoritma VSD Kelas : Conservative Spatial Subdivison Bounding Volume Back

### CS 498 VR. Lecture 18-4/4/18. go.illinois.edu/vrlect18

CS 498 VR Lecture 18-4/4/18 go.illinois.edu/vrlect18 Review and Supplement for last lecture 1. What is aliasing? What is Screen Door Effect? 2. How image-order rendering works? 3. If there are several

### Visible Surface Detection. (Chapt. 15 in FVD, Chapt. 13 in Hearn & Baker)

Visible Surface Detection (Chapt. 15 in FVD, Chapt. 13 in Hearn & Baker) 1 Given a set of 3D objects and a viewing specifications, determine which lines or surfaces of the objects should be visible. A

### graphics pipeline computer graphics graphics pipeline 2009 fabio pellacini 1

graphics pipeline computer graphics graphics pipeline 2009 fabio pellacini 1 graphics pipeline sequence of operations to generate an image using object-order processing primitives processed one-at-a-time

### CSE 167: Introduction to Computer Graphics Lecture #10: View Frustum Culling

CSE 167: Introduction to Computer Graphics Lecture #10: View Frustum Culling Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2015 Announcements Project 4 due tomorrow Project

### Visible-Surface Detection Methods. Chapter? Intro. to Computer Graphics Spring 2008, Y. G. Shin

Visible-Surface Detection Methods Chapter? Intro. to Computer Graphics Spring 2008, Y. G. Shin The Visibility Problem [Problem Statement] GIVEN: a set of 3-D surfaces, a projection from 3-D to 2-D screen,

### graphics pipeline computer graphics graphics pipeline 2009 fabio pellacini 1

graphics pipeline computer graphics graphics pipeline 2009 fabio pellacini 1 graphics pipeline sequence of operations to generate an image using object-order processing primitives processed one-at-a-time

### Last Time: Acceleration Data Structures for Ray Tracing. Schedule. Today. Shadows & Light Sources. Shadows

Last Time: Acceleration Data Structures for Ray Tracing Modeling Transformations Illumination (Shading) Viewing Transformation (Perspective / Orthographic) Clipping Projection (to Screen Space) Scan Conversion

### Pipeline 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

### Visibility and Occlusion Culling

Visibility and Occlusion Culling CS535 Fall 2014 Daniel G. Aliaga Department of Computer Science Purdue University [some slides based on those of Benjamin Mora] Why? To avoid processing geometry that does

### 2D Viewing. Viewing Pipeline: Window-Viewport Transf.

Viewing Pipeline: Window-Viewport Transf. 2D Viewing yw max clipping window: what to display viewport: where to be viewed translation, rotation, scaling, clipping,... Clipping Window yv max Viewport yv

### Interactive Computer Graphics A TOP-DOWN APPROACH WITH SHADER-BASED OPENGL

International Edition Interactive Computer Graphics A TOP-DOWN APPROACH WITH SHADER-BASED OPENGL Sixth Edition Edward Angel Dave Shreiner Interactive Computer Graphics: A Top-Down Approach with Shader-Based

### From 3D World to 2D Screen. Hendrik Speleers

Hendrik Speleers Overview Synthetic camera Rendering pipeline World window versus viewport Clipping Cohen-Sutherland algorithm Rasterizing Bresenham algorithm Three different actors in a scene Objects:

### Computer Graphics. Rendering. by Brian Wyvill University of Calgary. cpsc/enel P 1

Computer Graphics Rendering by Brian Wyvill University of Calgary cpsc/enel P Rendering Techniques Wire Frame Z Buffer Ray Tracing A Buffer cpsc/enel P 2 Rendering Visible Surface Determination Many Algorithms,

Last Time? The Traditional Graphics Pipeline Participating Media Measuring BRDFs 3D Digitizing & Scattering BSSRDFs Monte Carlo Simulation Dipole Approximation Today Ray Casting / Tracing Advantages? Ray

### Direct Rendering of Trimmed NURBS Surfaces

Direct Rendering of Trimmed NURBS Surfaces Hardware Graphics Pipeline 2/ 81 Hardware Graphics Pipeline GPU Video Memory CPU Vertex Processor Raster Unit Fragment Processor Render Target Screen Extended

### Pipeline 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

### VIII. Visibility algorithms (II)

VIII. Visibility algorithms (II) Hybrid algorithsms: priority list algorithms Find the object visibility Combine the operations in object space (examples: comparisons and object partitioning) with operations

### Two-Dimensional Viewing. Chapter 6

Two-Dimensional Viewing Chapter 6 Viewing Pipeline Two-Dimensional Viewing Two dimensional viewing transformation From world coordinate scene description to device (screen) coordinates Normalization and

### Part IV. 2D Clipping

Part IV 2D Clipping The Liang-Barsky algorithm Boolean operations on polygons Outline The Liang-Barsky algorithm Boolean operations on polygons Clipping The goal of clipping is mainly to eliminate parts

### Computer Graphics Viewing

Computer Graphics Viewing What Are Projections? Our 3-D scenes are all specified in 3-D world coordinates To display these we need to generate a 2-D image - project objects onto a picture plane Picture

### CSE 167: Introduction to Computer Graphics Lecture #4: Vertex Transformation

CSE 167: Introduction to Computer Graphics Lecture #4: Vertex Transformation Jürgen P. Schulze, Ph.D. University of California, San Diego Fall Quarter 2013 Announcements Project 2 due Friday, October 11

### CS184 : Foundations of Computer Graphics Professor David Forsyth Final Examination

CS184 : Foundations of Computer Graphics Professor David Forsyth Final Examination (Total: 100 marks) Figure 1: A perspective view of a polyhedron on an infinite plane. Cameras and Perspective Rendering

### CSCI 4620/8626. Computer Graphics Clipping Algorithms (Chapter 8-5 )

CSCI 4620/8626 Computer Graphics Clipping Algorithms (Chapter 8-5 ) Last update: 2016-03-15 Clipping Algorithms A clipping algorithm is any procedure that eliminates those portions of a picture outside

### Lecture 11: Ray tracing (cont.)

Interactive Computer Graphics Ray tracing - Summary Lecture 11: Ray tracing (cont.) Graphics Lecture 10: Slide 1 Some slides adopted from H. Pfister, Harvard Graphics Lecture 10: Slide 2 Ray tracing -

### 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

### Computer Graphics Geometry and Transform

! Computer Graphics 2014! 5. Geometry and Transform Hongxin Zhang State Key Lab of CAD&CG, Zhejiang University 2014-10-11! Today outline Triangle rasterization Basic vector algebra ~ geometry! Antialiasing

### Scene Management. Video Game Technologies 11498: MSc in Computer Science and Engineering 11156: MSc in Game Design and Development

Video Game Technologies 11498: MSc in Computer Science and Engineering 11156: MSc in Game Design and Development Chap. 5 Scene Management Overview Scene Management vs Rendering This chapter is about rendering

### Spatial Data Structures

Spatial Data Structures Hierarchical Bounding Volumes Regular Grids Octrees BSP Trees Constructive Solid Geometry (CSG) [Angel 9.10] Outline Ray tracing review what rays matter? Ray tracing speedup faster

### CS184 : Foundations of Computer Graphics Professor David Forsyth Final Examination (Total: 100 marks)

CS184 : Foundations of Computer Graphics Professor David Forsyth Final Examination (Total: 100 marks) Cameras and Perspective Figure 1: A perspective view of a polyhedron on an infinite plane. Rendering

Final Projects Proposals due Thursday 4/8 Proposed project summary At least 3 related papers (read & summarized) Description of series of test cases Timeline & initial task assignment The Traditional Graphics

### Rendering the Teapot 1

Rendering the Teapot 1 Utah Teapot 2 Angel and Shreiner: Interactive Computer Graphics 7E Addison-Wesley 2015 vertices.js var numteapotvertices = 306; var vertices = [ vec3(1.4, 0.0, 2.4), vec3(1.4, -0.784,

### CS 563 Advanced Topics in Computer Graphics Culling and Acceleration Techniques Part 1 by Mark Vessella

CS 563 Advanced Topics in Computer Graphics Culling and Acceleration Techniques Part 1 by Mark Vessella Introduction Acceleration Techniques Spatial Data Structures Culling Outline for the Night Bounding

Last Time? The Traditional Graphics Pipeline Reading for Today A Practical Model for Subsurface Light Transport, Jensen, Marschner, Levoy, & Hanrahan, SIGGRAPH 2001 Participating Media Measuring BRDFs

### Last class. A vertex (w x, w y, w z, w) - clipping is in the - windowing and viewport normalized view volume if: - scan conversion/ rasterization

Lecture 6 Last class Last lecture (clip coordinates): A vertex (w x, w y, w z, w) - clipping is in the - windowing and viewport normalized view volume if: - scan conversion/ rasterization normalized view

### Course Title: Computer Graphics Course no: CSC209

Course Title: Computer Graphics Course no: CSC209 Nature of the Course: Theory + Lab Semester: III Full Marks: 60+20+20 Pass Marks: 24 +8+8 Credit Hrs: 3 Course Description: The course coversconcepts of

### Sung-Eui Yoon ( 윤성의 )

CS380: Computer Graphics Clipping and Culling Sung-Eui Yoon ( 윤성의 ) Course URL: http://sglab.kaist.ac.kr/~sungeui/cg/ Class Objectives Understand clipping and culling Understand view-frustum, back-face

### CSCI 420 Computer Graphics Lecture 14. Rasterization. Scan Conversion Antialiasing [Angel Ch. 6] Jernej Barbic University of Southern California

CSCI 420 Computer Graphics Lecture 14 Rasterization Scan Conversion Antialiasing [Angel Ch. 6] Jernej Barbic University of Southern California 1 Rasterization (scan conversion) Final step in pipeline:

### The Graphics Pipeline. Interactive Computer Graphics. The Graphics Pipeline. The Graphics Pipeline. The Graphics Pipeline: Clipping

Interactive Computer Graphics The Graphics Pipeline: The Graphics Pipeline Input: - geometric model - illumination model - camera model - viewport Some slides adopted from F. Durand and B. Cutler, MIT

### Models and Architectures

Models and Architectures Objectives Learn the basic design of a graphics system Introduce graphics pipeline architecture Examine software components for an interactive graphics system 1 Image Formation