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Perception, Illusion and VR

HNRS 299, Spring 2008Lecture 13

Introduction to Virtual Reality

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Switching Gears

We have learned something about visual perception.We will now learn how we can use that knowledge to create alternate, imaginary worlds with which we can interact.

Topics for the second half of the course:• What is Virtual Reality• Computer Graphics• Virtual Reality applications• Virtual Reality and society.

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Topics in Computer Graphics

Because current virtual reality systems rely heavily on computer graphics, we will spend several lectures learning about how computer graphics are generated.

Topics:• What is a computer graphic?

• How are graphics represented in computer memory?• How are graphics displayed on the monitor?

• How are computer graphics generated?• Modeling 3D objects• Transformations• Animation• Lighting and Shading

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Interaction with the Virtual World

We will also explore methods that allow users to interact with objects and people in the virtual world:

• Use of mice and joysticks• Use of Data gloves• Allowing people to actually walk around in the virtual environment.

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Computer Science Virtual Reality: The Ideal

The ideal virtual reality would be a computer-generated world in which the user experiences:1) Immersion2) Navigation3) Interaction

As in "The Matrix," the ideal virtual reality is a world that is completely computer generated. The user is "immersed" in the world and experiences it with all his or her senses.

The user can interact with objects in the world.The user can move about in and explore the world.

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The Current State of Virtual Reality

Many virtual reality systems use a Head mounted display (HMD).

•The user only sees the scene generated by the computer.•When the user moves his or her head, the computer adjusts the image so the world appears stable.•One can add auditory effects with headphones.

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Walking AroundSome advanced set-ups allow the user to walk around in the virtual world.

The Virtual Environment Navigation Laboratory (VENLab) at Brown University.

(We will visit this in April).

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Interacting with ObjectsInteraction with objects can be accomplished with a data glove.

The computer can keep track of the position of the hand and fingers. It can compute whether the position intersects with an object's position.

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Limitations of Current Virtual Reality Systems

1. Mostly just sight and hand position.2. Scenes must be fairly simple:

• Adjusting the image in real time means that the computer performs the calculations as the user moves through the world.

• The updates must be fast enough so that there is no significant delay in what the user sees.

• Updating and redrawing complex scenes takes too long.3. The exact physics of the world is too complex to fully represent virtual

worlds• When someone drops a glass and it shatters, the motions of the

pieces are too complex to compute in real time.• The physics of light is too complex to compute in real time.

Lighting and shading is accomplished with simplified models of light behavior.

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Limited Forms of VRMany computer applications have some of the requirements of VR, but not all.

Example: Viewing things on a computer monitor is not completely immersive, but it can be very engaging. A given application can allow users to navigate through a world and interact with objects.

Discussion: What are some examples of more limited VR on computers? (Think about navigation and interaction)

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Non-computer Virtual Reality?Discussion:Are movies a form of Virtual Reality? Why or why not?

Are books a form of Virtual Reality? Why or why not?

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Benefits of VR

Virtual Reality provides a variety of benefits:1) Computer Aided Design (CAD) is useful for:

• Designing machines (e.g. cars and airplanes)• Designing complex structures (e.g. chemical plants)• Architecture

2) Training Simulations can be used for training:• Pilots (flight simulators)• Surgeons (surgical simulation)• People learning to perform dangerous tasks

3) Entertainment• VR games are compelling and very entertaining.Question: Are they always a good thing? (we will discuss

this later in the semester).