BPC: Art and Computation – Fall 2006BPC: Art and Computation – Fall 2006

Introduction to virtual environmentsIntroduction to virtual environments

Glenn Bresnahan

glenn@bu.edu

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OutlineOutline

High level overview of VR hardware and software (details will be covered throughout the year)– Demonstration of a VR world– 3D Display Wall – how we see in 3D– Animation– Rendering– DAFFIE VR software environment

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Intro to demo – physical environmentIntro to demo – physical environment

3D Display Wall– Stereoscopic– 3D glasses

Navigation– Game controller– Left joystick:

• Moves U/D• Moves R/L

– Right joystick:• Moves F/B• Turns P(L)/S(R)

– Start button: reset

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Intro to demo - virtual environmentIntro to demo - virtual environment

Multi-person, multi-site shared virtual space– Navigation– Avatar representation– Telephony

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3D Display – stereopsis3D Display – stereopsis

Stereoscopic display– Stereopsis – left and right eye view

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Stereoscopic display Stereoscopic display

Viewmaster

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3D display - polarization3D display - polarization

Light is a wave

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3D display - polarization3D display - polarization

Polarization aligns light in a plane

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3D display - polarization3D display - polarization

Polarizing filters used to align light Filters rotated 90 degrees block light

Two projectors, one per eye view– Polarizing filters rotated 90 degrees– Matching glasses

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3D stereoscopic displays – other 3D stereoscopic displays – other techniquestechniquesColored (red-blue) glasses

– Anaglyph

Circular polarizerShuttered glassesDual (head-mounted) display

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AnimationAnimation

What is animation?

Animate: to give life to; to bring to life

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AnimationAnimation

What is animation?Traditionally applied to

cartoonsCreation of apparent

motion from still images

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Animation – pictures in motionAnimation – pictures in motion

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Animation – component images Animation – component images

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Animation - principlesAnimation - principles

Creating moving image from a sequence of still images– Each image is displayed for a fraction of

a secondBasis for film,

video, computer graphics, etc.

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Animation – traditionalAnimation – traditional

Each image (cell) was hand drawn

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Animation – film and videoAnimation – film and video

Film – individual images (frames) are photographically reproduced on film strip

Video – individual images (frames) are recorded or transmitted as electrical signals

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Animation – computer graphicsAnimation – computer graphics

Computer generates individual images (frames) and displays them rapidly on a monitor– Technology is very similar to video– Images may also be recorded to film

(e.g. CG special effects) or video

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RenderingRendering

Creation of a pictorial representation– Generally applied to a realistic depiction

of a 3D scene or objectTypes of rendering

– Artistic rendering– Photographic rendering– Computer rendering

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Artistic renderingArtistic rendering

Rendering realistic images (perspective)

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Artistic renderingArtistic rendering

Trompe l’oeil Gone bad

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Photographic renderingPhotographic rendering

Camera and film

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Photographic renderingPhotographic rendering

Camera obscura

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Computer rendering (3D)Computer rendering (3D)

Computer creates an image from a model

A model is a (mathematical) description of the 3D object

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Computer rendered imageComputer rendered image

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Computer rendering (3D)Computer rendering (3D)

Computer takes into account the position of the object, as well as the position of the viewer (simulated or virtual camera).

Computer will shade the objects based on position of lights and the surface's material properties.

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Computer rendering processComputer rendering process

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Computer modelsComputer models

Conceptually like a blueprint

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Computer modelsComputer models

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Computer modelsComputer models begin ./table/items <default> setxfm 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.000000e+00 putprp cull 1 begin ./table/items/cube polygon setxfm 1.500000e+00 0.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.500000e+00 0.000000e+00 0.000000e+00 0.000000e+00 0.000000e+00 1.500000e+00 0.000000e+00 2.000000e+00 -1.500000e+00 -1.250000e+00 1.000000e+00 defpnt 1 -1.000000e+00 -1.000000e+00 -1.000000e+00 defpnt 2 -1.000000e+00 1.000000e+00 -1.000000e+00 defpnt 3 1.000000e+00 1.000000e+00 -1.000000e+00 defpnt 4 1.000000e+00 -1.000000e+00 -1.000000e+00 defpnt 5 -1.000000e+00 -1.000000e+00 1.000000e+00 defpnt 6 -1.000000e+00 1.000000e+00 1.000000e+00 defpnt 7 1.000000e+00 1.000000e+00 1.000000e+00 defpnt 8 1.000000e+00 -1.000000e+00 1.000000e+00 defpoly 1 2 3 4 0 defpoly 8 7 6 5 0 defpoly 3 7 8 4 0 defpoly 2 1 5 6 0 defpoly 2 6 7 3 0 defpoly 1 4 8 5 0 putprp color 3ff end ./table/items/cube

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Computer animationComputer animation

Generate multiple images by changing the viewing (i.e. camera) position

Reposition one or more objects between frames

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Computer animationComputer animation

Render a sequence of models

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Computer animationComputer animation

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DAFFIE SoftwareDAFFIE Software

DDistributed AApplications FFramework

FFor IImmersive EEnvironments

Glenn BresnahanErik Brisson

Robert Putnam

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What is VR/VEWhat is VR/VE

Definitions– Immersive, natural interaction, believable

Characteristics– 3D appearance– Stereoscopic display– Large display, wide field of view– 1st person view– Navigation within 3d space (natural interface)– Response to physical position of viewer– Realistic audio

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DAFFIE WorldsDAFFIE Worlds

Multiple participants– Represented by an avatar– Interact with each other

• Telephony

– Interact with virtual objectsShared virtual space

– All participants experience the same virtual world

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DAFFIE WorldsDAFFIE Worlds

Shared space divide into roomsrooms Doorways (portalsportals) between rooms Rooms contains objectsobjects Objects

– 3D appearance (3D modelmodel)– May be animated (sequencessequences of models)– May have an appliquéd (2D) image (texturestextures) – May have associated sounds (digital audioaudio)– May react to avatars (people) or other objects

(behaviors via agentsagents)

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DAFFIE Worlds – Using imagesDAFFIE Worlds – Using images

Images may be appliquéd to the surface of an object

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DAFFIE Worlds – Using imagesDAFFIE Worlds – Using images

Objects may be flat or curved

Images may be animated by using a sequence of images

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DAFFIE Software ComponentsDAFFIE Software Components

3D viewer Sound server

– Telephony– Audio mixer & player

Navigation Behavior agents Audio/video generators/processors Object generators/manipulators DAFFIE components communicate over

the network

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DAFFIE Software EnvironmentDAFFIE Software Environment

viewerbehavior

agent

soundplayer

viewer

telephony

telephonysoundplayer

behavioragent

behavioragent event event

serverserver

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DAFFIE ViewerDAFFIE Viewer

Supports multiple display devices from workstations to CAVEs

Directly supports advanced input devices (3D trackers, wands, etc).

Simple script-based world description– Geometric models– Animation– Sounds

Many 3D model formats Local control of time-sensitive animation and sound Broadcasts avatar motion and object state

information to other components

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DAFFIE Sound ServerDAFFIE Sound Server

Provides telephony between participants Mixes and plays multiple sound sources

– Real-time audio streams (e.g. telephony)– Prerecorded object sound files

Sound is localized in 3D space– Originates at 3D virtual object location– Heard relative to the avatar’s position– Played relative to listener position in physical space

(when tracked) Sound player output

– Multi-channel localized audio signals which can be played into a speaker array

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DAFFIE NavigationDAFFIE Navigation

Advanced device support built-in to the viewer

Windows-based navigation client– Game controllers– Hand-held pointing devices (Gyro Pointer)– Mouse– Keyboard

Can control one or more avatars

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DAFFIE Behavior AgentsDAFFIE Behavior Agents

Control object behaviorProximity triggersPortalsDevice interfaces

– Kinematic sculpturesVideo sourcing (camera)Audio and video processing