Developing a VR Developing a VR SystemSystem

Developing a VR Developing a VR SystemSystem

Mei Yii LimMei Yii Lim

System Development Life Cycle - Spiral

Model• Problem definition• Preliminary study• System Analysis and Design• System Development• System Testing• System Evaluation• Refinement

Case Study: MY Case Study: MY Virtual Graffiti SystemVirtual Graffiti System

Case Study: MY Case Study: MY Virtual Graffiti SystemVirtual Graffiti System

Introduction• ‘graffiti’ - Greek word ‘graphein’• Modern graffiti - New York, tagging

using water resistant marker• Today - using aerosol spray • Rude, humorous, political or

constituting vandalism and are generally illegal

Problem Objectives• What do you aim to achieve?

– Solution to the problem of illegality– Preserves and documents art works– Virtual spray on virtual buildings– Flexibility and natural interaction– Realistic reproduction of the spray – User-friendly and intuitive interface

CAVE

Problem DefinitionProblem DefinitionProblem DefinitionProblem Definition

Problem Definition• Define the problem you are trying to

solve• What are the major issues?

Project Benefits• What are the benefits of the project?• Why is it so important?

– Expression of opinions, creativity lawfully– Coping with society’s problems– London councils - £13m and graffiti

committee - £100m spent annually on cleaning up graffiti

– New type of art, uncover hidden talent

Project Management• Project scheduling

– Divides work into smaller chunks - Gantt Chart

• Risk Analysis– Degree of uncertainty or potential problems– Eg. lack of knowledge , inappropriate or

difficult to use interaction devices, simulation algorithm, underestimation of time

Project Management continued…

• Risk Planning– Best way for project with users as target -

involve them – Trial and error – Project schedule must be realistic

Preliminary StudyPreliminary StudyPreliminary StudyPreliminary Study

Literature Review• Find out the state-of-the-art• Who has done what• What can be improve• What should be avoided

Literature Review of MYVG

• Eschler & Stricker 03 (Fraunhofer IGD) – projection filled totally by a 2D wall

• Dave Pape - ‘Vandalism’– alter existing artworks, 3D paintings and

sculptures

• Lang– Virtual Graffiti Painter and Light bombing

• MobSpray (mobile application)– http://www.mobspray.com/indexphp

System AnalysisSystem AnalysisSystem AnalysisSystem Analysis

System Analysis• Understand the requirements of the

system you are going to develop• Determine ‘what’ is to be accomplished• To ensure successful system

development• Human Computer Interaction concepts

Rapid Iterative Prototyping

• Offers the best approach for system which accurate requirements can not be defined at its early stage

• Prototype – a mechanism for identifying the actual requirements

• Iterative and corrective cycle

Rapid Prototyping Development Cycle

Requirements Elicitation

• Fact-gathering – active manipulation of conditions or passive observation of people– Researching and reviewing existing

documents– Individual interviews– Mailing list– Observation – demonstration from experts– Questionaires - evaluation

Analysis with Justification

• Every choice must be justified • Why a particular device or methodology

is chosen and not the others?

Analysis Result of the MYVG system

MY Virtual Graffiti System

• CAVE Environment

• Graffiti using VR technologies– 2 sensor gloves (pinch gloves)

sensors

MY Virtual Graffiti System

– Space Orb 360º (6 degree of freedom)

– Stereo glasses

– Tracking system– Dummy spray can

with sensor

Object-Oriented Model• Use cases –

scenarios of usage• Analysis model –

subsystems of the end product

System Requirements Specification

• Hardware requirements• Software requirements• Functionality description• Non-functional requirements• Interface specification• Design constraints• System validation and verification criteria

System DesignSystem DesignSystem DesignSystem Design

System Design• How to accomplish the proposed

functionality?• How are all the VR devices linked

together?• Representation of the system

Architectural Design• UML class diagrams - shows all

available classes

Architectural Design …• Object-relationship model – static

model, reflects the object classes and their relationship

Architectural Design …• State diagram – dynamic model• Describes the behavior of the system,

events

Architectural Design …• Sequence diagram – illustrate each

significant interaction between objects

Algorithm Design• Pseudocode – description of the

program• Example – a method to create scene

METHOD createScene char*(filename) returns pfScene*Generate scene stateAdd lightingSet traversal maskLoad fileRETURN scene

END

Scenegraph

User Interface Design• A useful system with a poor user

interface = non-functional system• HCI golden rules

– Know the user population– Reduce cognitive load– Engineer for errors– Maintain consistency and clarity

WELCOME TO VIRTUAL GRAFFITI !WELCOME TO VIRTUAL GRAFFITI !

SPRAY MODE BUTTON A / LEFT PINKIESPRAY MODE BUTTON A / LEFT PINKIE

CLEAR BUTTON BCLEAR BUTTON B

SAVE BUTTON C / LEFT MIDDLESAVE BUTTON C / LEFT MIDDLE

NAVIGATE BUTTON D, PS / RIGHT INDEXNAVIGATE BUTTON D, PS / RIGHT INDEX

RESET BUTTON ERESET BUTTON E

EXIT BUTTON FEXIT BUTTON F

CLOSE MENU RIGHT PINKIECLOSE MENU RIGHT PINKIE

SPRAYING MODESPRAYING MODE

SPRAYING RIGHT MIDDLESPRAYING RIGHT MIDDLE

COLOUR LEFT MIDDLECOLOUR LEFT MIDDLE

NOZZLE LEFT RINGNOZZLE LEFT RING

MAIN MENU LEFT PINKIEMAIN MENU LEFT PINKIE

NAVIGATE RIGHT INDEX NAVIGATE RIGHT INDEX

CLEAR RIGHT RING / BUTTON BCLEAR RIGHT RING / BUTTON B

CLOSE MENU RIGHT PINKIECLOSE MENU RIGHT PINKIE

3D icon that appears while spraying

• Denote the size of the nozzle

• Denote the color of the nozzle

System Development System Development and Testingand Testing

System Development System Development and Testingand Testing

System Development• Programming• Example of Challenges

– Format incompatibility– Incorrect hit points

Correct RayBounding

Plane Abox

Number of rays

• Single ray • Multiple rays

System Testing• Tedious but essential for quality

assurance• Formal technical review • Unit testing • Integration testing

Risk Monitoring• Throughout the whole life cycle to

ensure that everything is under control

• Users’ opinions were checked • Project progress was monitored

System System Implementation and Implementation and

EvaluationEvaluation

System System Implementation and Implementation and

EvaluationEvaluation

System Implementation

• Putting the system into operation• Prototyping approach – implementation

is parallel with the development and testing phases

System Evaluation• Acquire feedback for eventual

improvement• Formative evaluation – usability

evaluation• Can be repetitive• Each evaluation process serves as

guide for changes in subsequent iterations

Bar Chart Representing Result of Initial Evaluation

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Evaluation Attributes

Rating

Engagement toenvironmentInteractiondevicesMenus

Commands

Spraying action

Navigation

Spray paintsimulationSpeed ofadjustmentReal-timeresponseComfortableinteractionResemblanceto real graffiti

Example – Initial Evaluation

• Half a dozen subjects

Refinement• Menu shift and simplification• User manual was provided• More flexible interaction – Space Orb or

pinch gloves• Dummy spray can• Allow deactivation of menu• Bigger paint particles for wider

coverage

Comparison Between Initial Evaluation Result and Final Evaluation Result

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Engagement to environment

Interaction devices

Menus

CommandsUser manualSpraying action

Navigation

Spray paint simulationSpeed of adjustmentReal-time response

Comfortable interaction

Resemblance to real graffiti

Evlauation Attributes

RatingInitialEvaluation

FinalEvaluatian

Final System Evaluation• Twenty subjects

Conclusion and Conclusion and Future WorkFuture Work

Conclusion and Conclusion and Future WorkFuture Work

Achievements• On schedule• Improvement of skills• Expansion of knowledge• Chance to experiment with VR devices

Lessons Learned and Experiences

• Every development cycle should account for unexpected events– Eg. Tools unavailability, lack of knowledge,

system failure, power failure

Future Enhancements• Wireless and pressure sensitive devices• More attractive and user-friendly menu

– entails more extensive user involvement

• Collision detection and sound feedback

The System in Action

Further information• http://www.macs.hw.ac.uk/~myl/

MSC_DISSERTATION.htm