Page 112 - DCAP313_LAB_ON_COMPUTER_GRAPHICS

Lab on Computer Graphics Kumar Vishal, Lovely Professional University

Notes Unit 7: Implementation of Hidden Surface in 2D

CONTENTS
Objectives
Introduction
7.1 Visibility Algorithm Categorization
7.1.1 Line Visibility Algorithms
7.1.2 Apple Algorithm
7.2 Hidden Surface Removal Algorithms
7.2.1 Z-buffering
7.2.2 Painter’s Algorithm
7.2.3 Binary Space Partitioning (BSP)
7.2.4 Ray Tracing
7.2.5 The Warnock Algorithm
7.3 Summary
7.4 Keywords
7.5 Review Questions
7.6 Further Readings

Objectives

After studying this unit, you will be able to:
• Discuss visibility algorithm categorization
• Define the hidden surface removal algorithms

Introduction

The term rendering has many meanings in dissimilar perspectives. In computer graphics,
rendering is the process of creating an image from a model. The model holds the essential
information concerning the geometry and position of the objects in the scene, the visual
attributes of the objects such as colour and reflection properties, and the needed lighting and
screening information. In the early years of computer graphics, much attention was spent on
how to perform rendering efficiently. The relatively slow processing speeds of early processors
meant the amount of scene complexity that could be rendered in a reasonable amount of time
was highly dependent on the speed of the rendering algorithm. When producing 30 frame-per-
second animations, even moderate savings in individual frame rendering time was significant. In
today’s high-speed multi-core processor machines, speed and efficiency are not as critical, and
complex models can be easily processed on desktop machines. With the advent of hundreds of
specialized Graphics Processing Units on a display board, it is common to render high quality
images of complex environments in real time for applications such as gaming and simulations.

Rendering can be divided into two basic processes:
1. Determining what surface, or more precisely point on a surface, is visible at each pixel.
2. Shading the point based on surface properties, lighting conditions, viewing parameters,
and other elements in the scene.

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