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COMPUTER GRAPHICS: What Is Virtual Reality?
Introduction

"Virtual Reality: A computer system used to create an artificial world in which the user has the impression of being in that world and with the ability to navigate through the world and manipulate objects in the world."
- C. Manetta and R. Blade in "Glossary of Virtual Reality Terminology" in the International Journal of Virtual Reality, Vol.1 Nr.2 1995.


"Virtual Reality allows you to explore a computer generated world by actually being in it"
- B. Sherman and P. Judkins (1992) "Glimpses of Heaven, Visions of Hell: Virtual Reality and its implications" (Hodder and Stoughton: London).

Please see, VR, A Short Introduction for a continued definition of VR.

Real-time Versus Pre-Rendered Graphics

Conceptually, virtual reality (VR) is used by artists to explore an alternate reality while the military, automobile manufacturers, architects, and medical doctors use VR to display real world scenarios and data. Planners need to capitalize on data visualization techniques and utilize the VR platform for exploring alternative "What If" scenarios about the built environment. VR also provides the opportunity to explore conceptual visualization about environmental data.


Real time graphics are rendered (or drawn) in real time as you interact with them while pre-rendered computer graphics are static or in the case of cinematography, a series of rendered images. Real time has many advantages over pre-rendered graphics. The user within a real time display has free range of movement. The user can walk, fly, or examine any object within the scene by moving closer to the object and walking around it. Preselected viewpoints allow the user to travel easily from one place to another. Within a simulation, the user can manipulate buildings by moving and scaling them. If it has been programmed, the user can also swap out buildings to judge the appropriateness of building types. Real time simulations are dynamic. Cars, doors, lights, and sound can be manipulated and immediately address the client's concerns.

Real-time Graphics In Depth

Real-time graphics is part of a computer graphics system. The five major elements are as follows:
1. Processor
2. Memory
3. Frame Buffer
4. Output Devices
5. Input Devices

A raster image is produced and comprised of pixels. Collectively, the pixels are stored in a part of memory called the frame buffer. In high-end systems, the frame buffer is implemented with special types of memory chips—video random-access memory (VRAM) or dynamic random-access memory (DRAM)—that enable fast redisplay of the contents of the frame buffer. The depth of the frame buffer, defined as the number of bits that are used for each pixel, determines properties such as how many colors can be represented on a given system. For example, a 8-bit deep frame buffer allows 256 colors. The resolution (the number of pixels in the fame buffer) determines the detail that you can see in the image.

In a raster system, the graphics system takes pixels from the frame buffer and displays them as points on the surface of the display. The entire contents of the frame buffer are displayed at a rate high enough to avoid flicker. This rate is called the refresh rate.

A low refresh rate is important to avoid. When creating content for the CAVE, you must monitor both your polygon count and texture map file size to avoid a slow refresh rate.

Most graphics systems provide a keyboard and at least one other input device. In the CAVE, a 3D mouse called a wand is used. It has three buttons and a joystick. The buttons’ uses are determined by the program developer, meaning you.

 

Links

Virtual Reality Society
Resources: On the Net
University of Michigan Virtual Reality Lab
Iowa State University virtual Reality Applications Center
Swiss Federal Institute of Technology
 
 
 
 

 

Computer Graphics & Urban Planning
  What is Virtual Reality?
  What is a CAVE and why use it?
  VR & the Web
  Current & Future state of VR
  Ongoing projects
   
Overview of Classes & Program
  Newspace versus EVL computers
   
Project Fundamentals
  Collect Data
  Construct Models
  Apply Textures
  Program Interactivity
  Output to Display Device