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DesigningRoomLightingForVideoconferencingThenewDesignGuidefromIESNAistheclosestthingproAVhastoaninternationalstandardforvideoconferencinglightingdesign.Source:PROAVMagazinePublicationdate:December1,2005ByTimCape,CTS-DWhiletheultimategoalinvideoconferencingisgoodinteractivitybetweennear-andfar-endrooms,onecommonlightingdesignproblemcanbesummedupinaquestionthat'sremainedconstantthroughouttheevolutionofvideoconferencingtechnology:Howcanyouprovidegood,comfortablelightingtooptimizethecameraandvideocodecoperationinanarchitecturalenvironmentratherthaninastudio?Althoughit'safairlysimplequestion,theanswercanbequitecomplicated.Theremustbesomelightintheroomofthespaceyou'redesigningjustforthecameratoproduceanimage,butmakingthatimagelookgoodwhilemaintainingagoodprojectedvideoimagecanbeeasiersaidthandone.Ontopofjustgettingthecameratoproduceadecentimage,youalsohavetobeconcernedaboutwhatthecodecwilldotothatimage(particularlyatlowbitrates),puttingmoreconstraintsonnotjustthelightingdesignbutalsotheinteriordesignoftheroomitself—onceagaingoingbeyondthetenetsofabasicAVsystem.Upuntilnow,AVprofessionalshaven'thadmuchconsistentguidanceonvideoconferencingroomlightingdesign,butthenewdesignguide,offeredbytheIlluminatingEngineeringSocietyofNorthAmerica(IESNA),givesthemanauthoritativeplacetostart.ThenewdesignguideIndevelopmentsince2002,the“VideoconferencingLightingDesignGuide,”DG-17-05,isnowavailableforpurchasethroughtheIESNAwebsite().Itincludesawiderangeofrecommendedcriteriaandgeneralrecommendationsforapproachestolightingforvideoconferencingfacilities.It'sspecificallyorientedtowardsmall-tomid-sizedvideoconferencingroomswithasinglecameraaxis(fromdisplaystoseatedparticipants).Itdoesn'tspecificallycoverdual-axisroomsthatincludeapresenternearthedisplaysorlargerfacilities,thoughmuchofthecriteriacanbeappliedtothiswiderrangeofrooms.TheGuideisintendedtosomeextentfordesignersbothwithandwithoutabackgroundinlightingdesign.TheolddesignproblemBeforeansweringthequestionpresentedaboveabouthowtooptimizethecameraandvideocodecoperationinanarchitecturalenvironment,youmustunderstandseveralbasicandsometimesconflictingrequirements.Andit'snotjustabouttheluminairesthatemitthelight,it'sabouttheroom,too.Theprimarytasksintermsoflightingare:Lighttheparticipantsforgoodvideo.Thisinvolveslimitingthevariationinlightlevelenoughtoallowthecameratoreproducethefullrangeoflightandshadowinthepicture.Atthesametime,thereneedstobeenoughvariationinthepicturetokeepitfromlooking“flat”withnoshadowordepth.Lighttheroomtocomplementtheparticipants.Thismeanspayingattentiontothelightingforthewalls,floor,andceilingareasthatmightbeinthecameraview.Coordinatetheroomfinishesfromthestandpointofcolor,contrast,andpattern,andhowtheyrelatetothepeopleinthepicture.Thisalsoinvolvesconsiderationofthetypeoffinish,andhowitmayaffecttheimagepickedupbythecameraandtransmittedtotheremotesite.Forexample,reflective,orspecular,finishessuchaschromecancreateproblemsforthecamerabycreatinganexcessivelybrightspotintheimage.Sometimestherearemoreparticularconstraintsplacedonthelightingsystemwhenspecialcamerasorhigherthannormalcolorrenderingareneededforspecializedapplicationslikeretail,fashion,andsomemilitaryenvironments.However,thebasicsaboveapplytoanyvideoconferenceroomandarediscussedintheGuideThefundamentalsTocreateanenvironmentthatworkswellforvideoconferencing,designersmustaddresssomefundamentallightingparameters.ForthoseinproAV,thismaymeanbecomingfamiliarwithatleastthebasiclightingtermsyou'llencounterinalightingdesignproject.WhiletheAVdesignermaybequalifiedtobethelightingdesignerinsomecases,it'smorelikelythatheorshewillbeprovidingcriteriatoalightingorelectricalconsultantwhowillthendesignthelightingunderaseparatescopeofwork.Ineithercase,theAVdesignerneedsatleastsomebasiclightingknowledge.Tobeginworkingwithlighting,somebasiclightingtermsshouldbeunderstood.Someofthetypicaltermsusedindiscussinganddesigninglightingsystemsarerelatedtothoseforprojectionanddisplaytechnologies.Illuminanceisthelightlevelincidentonasurfaceorplanefromasourceorsources.It'sexpressedinlux(lumenspersquaremeter—thepreferredunitofmeasure)orfootcandles(fc,lumenspersquarefoot—themoreobsoleteunit).Onefootcandleequals10.76lux.It'susefultonotethatexactconversionsshouldbeusedwhenreportingmeasurements,butwhenbotharegivenascriteriaasimpleconversionfactorof10isoftenusedinsteadof10.76.Luminanceistheluminousintensityfromasurfaceinaparticulardirection.Luminancemaybethoughtofinthisdiscussionasthelightreflectedfromasurface.It'sexpressedascandelaspersquaremeter(footlambertsinthemoreobsoleteEnglishunits).Luminairereferstoacompletelightingassemblyincludingthehousing,reflectors,andlamps.Onlywhenit'sinstalledisthiscorrectlyreferredtoasalightfixture.LightReflectanceValue(LRV)isameasurementoftenappliedtopaintedandotherroomfinishesindicatingthepercentageoflightreflectedfromaparticularsurfaceindependentofthecolor.LRVrangesfrom0to100,withhighernumbersindicatinglighterfinishesandlowernumbersindicatingdarkercolors.Luminanceratioandcontrastratiorefertothemathe