An RFID-based Infrastructure for Automatically Det

AnRFID-basedInfrastructureforAutomaticallyDeterminingthePositionandOrientationofGameObjectsinTabletopGames1SteveHinske1andMarcLangheinrich11InstituteforPervasiveComputing,ETHZurichClausiusstr.59,8092Zurich,Switzerland{steve.hinske,marc.langheinrich}@inf.ethz.chAbstract.RadioFrequencyIdentification(RFID)technologyalreadyplaysamajorroleinmanyareas.Inbusinessapplications,forexample,theideaofsmartshelvesortablesequippedwithRFIDtechnologyhasbeenaroundforsometimenow,especiallyforretailing.Currentsolutions,however,aredesignedtoonlyidentifyobjectsinrange,whichissufficientformostoftheenvisionedshopapplications.Forotheruses,however,notonlytheidentification,butalsotheexactpositionandorientationofobjectswouldbeinteresting,ifnotnecessary.Agoodexampleareminiaturewargames,wherethecurrentgamestateusuallydependsonwhatobjectsarelocatedwhere,and,insomecases,howtheseobjectsareoriented.Inthisarticle,wepresentanapproachtodeterminethepositionandorientationof(multi-tagged)objects.Weintroducetheconceptualidea,aswellasthetechnicalrealizationbasedontheexampleofanaugmentedminiaturewargame.Wethendescribeourfindingssofarandsummarizeournextsteps.Keywords:AugmentedGames,PervasiveGames,TabletopGames,MiniatureWarGames,Localization,Radio-FrequencyIdentification(RFID).1IntroductionDespitetherecord-breakingsalesofconsolesandvideo-games,traditionaltabletopgamescontinuetofindmanyplayers.Miniaturewargamesareaparticularlypopulartypeoftabletopgames,inwhichtwoormoreplayersengageinbattlewitheachother,commandinganarmyofnumerousgameobjectsrepresentingcombatunits,usuallywiththegoalofeliminatingtheadversarialforces.Warfareinsuchgamesverymuchdependsontheexactlocationandorientationofgamepieces,inordertoproperlyassessthevisibilityofenemies,ortherangeandeffectofanattacker'sweapons.Computingtheseeffectsiscurrentlyalaboriousandtime-consumingtask,whereplayersuserulersandgoniometerstomeasurethedistancesandanglesbetweenunitsandtheirorientation.Ourgoalistosupportplayersofsuchgamesbyautomatically1Partsofthisarticlearebasedonearlierpublicationsbytheauthors[9].capturingthisinformationandprovidingittotheminanautomatedandunobtrusivefashion.Wedevelopedaninfrastructurefortabletopgamesingeneral(andminiaturewargamesinparticular)thatenablestheautomaticandrelativelyprecisetrackingofthelocationandorientationofgameobjectsontheplayingfield.Ourdesignfollowstwomaingoals:Firstly,thetechnologyshouldbeintegratedunobtrusively,sothatthenaturalgameexperienceisnotdisturbednorrenderedunusableifthetechnologyfails(i.e.,thegamecanstillbeusedinthetraditionalway).Secondly,therichsocialinteractionoftabletopgamesshouldnotbenegativelyinfluencedbythesystem.Bothgoalshavesomeimplicationsonwhatkindoftechnologyistobeusedandhowitshouldbeimplemented.Thefirstgoalrequires•Aninvisibleintegrationofthetechnologyintothegameenvironment,•Analmostmaintenance-freeoperation,and•Providingplayerswithsimpleandefficientaccesstoinformation.Thesecondgoaladditionallyemphasizes•Minimizingsecondaryuserinterfacessuchasgraphicaldisplays(GUIs).Ideally,thegameobjectsremainthemajor(tangible)userinterfaces(TUI),inordertoavoidshiftingtheplayers'focustoscreensandothermethodsofinput(e.g.,keyboardsormice)[11,33].WemettheserequirementsbyemployingRadioFrequencyIdentification(RFID)technology,asemi-maturetechnologyforunobtrusivelyidentifyingtaggedartefactspassingthroughanantennafield.Byincreasingthenumberanddensityofantennasandtags,wearetryingtoexploitadditionalinformationfromoverlappingreadrangesandtagsightingstoprovideimprovedtrackingandorientationdetection.Theresultisaninfrastructurethatsupportsplayersbyprovidingthemwithinformationthattheyotherwisewouldhavetogatherthemselvesexecutingrathercumbersometasks(i.e.,measuring),withouttheneedforadditionalstepsontheplayers'behalf.Thisarticlepresentsourinitialprototypesystemandisstructuredasfollows:Chapter2introducestheproblemofdeterminingthepositionandorientationofgameobjects,usingtheexampleofapopularminiaturewargame,“Warhammer40,000”(or,“Warhammer40k”).Chapter3discussesseveraltechniquesofusingRFIDtechnologytodeterminethelocationandorientationofobjects.Inthischapter,wealsocompareRFIDtechnologytoothertechnologies.Chapter4thenpresentstheresultsofourpreliminaryevaluationanddiscussessystemperformance(andpotentialimprovements).Chapter5summarizesthemainideasandcontributions,andoutlinesfuturework.2AugmentingMiniatureWarGamesPeoplehaveenjoyedplayinggamesforrecreationalpurposesandamusementforthousandsofyears.Amongallevolvedandexistentgames,tabletopgamescertainlybelongtothemostpopularandmostoftenplayedgames.Inrecentyears,severalprojectshaveaddressedtheissueofaugmentingtabletopgameswithvariouskindsoftechnology.Equippingtabletopgameswithpervasivecomputingtechnologiestoenhancethegamingexperiencehasledtointerestingnewapplications,e.g.[1,6,13,15-18,21,22],alsocf.Chap.3.1.Tabletopgamesaregamesthataretypicallyplayedonatableoramoreorlessflatsurface.Theycanbefurthersubdividedintothefollowingcategories:•Miniaturewargames,•Boardgames,•Cardgames,and•Dicegames.Forthepurposeofthispaper,wewillfocusonMiniatureWarGame