Feeling C owded Ye ?: C owd Simula ions o VR
Nu ia Pelechano∗
Uni e si a Poli `
ecnica de Ca alunya
Jan M. Allbeck†
Geo ge Mason Uni e si y
ABSTRACT
Wi h ad ances in i ual eali y echnology and i s mul iple applica-
ions, he need o belie able, imme si e i ual en i onmen s is in-
c easing. E en hough cu en compu e g aphics me hods allow us
o de elop highly ealis ic i ual wo lds, he main elemen ailing
o enhance p esence is au onomous g oups o human inhabi an s.
A g ea numbe o c owd simula ion echniques ha e eme ged in
he las decade, bu c i ical de ails in he c owd’s mo emen s and
appea ance do no mee he s anda ds necessa y o con ince VR
pa icipan s ha hey a e p esen in a eal c owd. In his pape , we
e iew ecen ad ances in he c ea ion o imme si e i ual c owds
and discuss a eas ha equi e u he wo k o u n hese simula ions
in o mo e ully imme si e and belie able expe iences.
1 INTRODUCTION
Imme sion desc ibes he ex en o which compu e displays a e ca-
pable o deli e ing an inclusi e, ex ensi e, su ounding and i id
illusion o eali y o he senses o a human pa icipan [27]. In-
c eased imme sion can esul in inc eased p esence in he i ual
wo ld. Sla e and Wilbu de ine p esence as a s a e o conscious-
ness, he (psychological) sense o being in he i ual en i onmen .
S udies show ha inc eased p esence in i ual wo lds can yield
be e aining ans e om hese g aphical en i onmen s o eal
wo ld scena ios [27].
Vi ual c owds ha e po en ial o enhance Vi ual Reali y (VR)
expe iences. The way we pe cei e a i ual c owd s ongly depends
on he medium and on ou ole. Ou expe ience changes based on
whe he we a e a passi e iewe (e.g. mo ies, e en wi h 3D ech-
nology) o an ac i e pa icipan (e.g. ideo games). In VR he
goal becomes con incing he pa icipan ha he/she is expe iencing
some hing eal (i.e. being mo e p esen in he i ual en i onmen
han he eal one) and is su ounded by a i ual c owd. Un o u-
na ely his is whe e ailu es begin. Pa icipan s’ expec a ion o he
i ual c owds a e no me and hei sense o p esence is diminished.
The p oblem is ha we as humans obse e each o he e e y day and
become accus omed o no mal beha io and a une o ecognizing
e en small de ia ions om hese no ms. Any unna u al a i ac s in
ou c owd simula ions become magni ied by he i s pe son pe -
spec i e and imme si e echnologies o VR.
Since we i s explo ed using p esence o e alua e c owd simula-
ions [21], a lo o echnologies ha e been de eloped. VR ha dwa e
has ad anced and become eadily a ailable as consume le el p od-
uc s. C owd simula ions ha e also been g ea ly imp o ed, bu a e
no ye o he le el hey need o be o be e ec i e in VR. Resea ch
ocuses on: making c owds appea mo e pu pose ul, making cha -
ac e s ollow easonable ajec o ies, making anima ions smoo he
and mo e na u al, imp o ing ende ing and so on. Ye when im-
me sed in VR, c owd simula ions a e s ill ound lacking. Jus as we
ix one dis ac ing a i ac , ano he appea s and olls us igh back
in o he uncanny alley. We seem o ide an uncanny alley olle
coas e . E e y ime we manage o imp o e one ea u e, an issue
∗e-mail: [email p o ec ed]
†e-mail: [email p o ec ed]
wi h ano he becomes appa en and d as ically educes ealism ye
again.
So how a a e we om achie ing ou goal o e ec i e c owd
simula ions in VR? Tha is he ocus o his pape . We will e alua e
cu en c owd simula ion esea ch, we will discuss he p og ess o
VR echnology o e he pas eigh yea s, and we will p esen ou
hough s on whe e addi ional e o s a e needed o b ing us close
o ou goal.
2 CROWD SIMULATION METHODS
The e has been a la ge numbe o me hods o simula e c owds o
i ual cha ac e s. Mos o he c owd simula ion wo k ocuses on
simula ing oo ajec o ies using a bounding olume o he en i e
cha ac e o collision a oidance and epulsion o ces. Fo a good
su ey on c owd simula ion me hod we e e he eade o ecen
books in his ield [13, 19, 30]. Simula ing oo ajec o ies p o ides
good esul s in e ms o local mo emen , bu a i ac s appea easily
in he anima ions and ee -g ound con ac , specially as he densi ies
inc ease and ca e ul ee posi ion and anima ion blending becomes
necessa y. In hose si ua ions i is easy o spo oo sliding, ab up
changes in eloci y and o so o ien a ion, as well as jumps be ween
anima ions.
These app oaches o en deal wi h a small da abase o anima ions
and ei he limi he mo emen o he cha ac e o he a ailable an-
ima ions [15], o include some echniques o in e pola e be ween
anima ions and apply ime wa ping o sa is y cons ain s be ween
he ee and he en i onmen [20].
Some ecen wo k a emp s o achie e mo e na u al esul s by
planning in he oo domain [31, 25] and hen compu ing he igh
sequence o anima ions and blending o ollow he esul ing ajec-
o y [8].
Ano he aspec o i ual c owds ha equi es a en ion is en-
de ing. O en when la ge c owds a e equi ed, i is necessa y o
use echniques o speed up ende ing while minimizing loss o i-
sual quali y. Bu is ealis ic ende ing eally equi ed o p esence?
The e ha e been s udies on isual ealism a ec ing p esence om
he poin o iew o he en i onmen unde di e en illumina ion
models [32]. F om hose s udies i appea s ha wha ma e s is he
dynamics o he illumina ion model, i.e. changing shadows and e-
lec ions. The quali y o he illumina ion does no seem o a ec
p esence, howe e i esul s in g ea e plausibili y and hus pa ic-
ipan s a e mo e likely o espond o i ual e en s as i hey we e
eal.
This opens he doo o e alua ing he isual appea ance o he
c owd. Wo k by Ja abo e al. [12] s udied how c owd mo emen
cha ac e is ics and di e en illumina ion models a ec ed he pe -
cep ion o c owds. The pu pose o his wo k was o de e mine how
much he illumina ion models could be simpli ied o c owd ende -
ing wi hou being no iceable. This could also ha e an applica ion o
ende ing c owds in IVEs (Imme si e Vi ual En i onmen s). E al-
ua ing p esence unde a a ie y o c owd ende ing echniques [7]
would help us o de e mine he mos ele an condi ions o use each
ype o ende ing and hus o e all sa e esou ces while s ill p o-
iding ealis ic isualiza ion o many cha ac e s. Fo example, in
Figu e 1 we compa e simple ca oonish looking cha ac e s used in
an imme si e i ual c owd expe imen agains a c owd ende ed
wi h a mo e human-like appea ance and shadows ha change dy-
namically as he cha ac e s mo e. The nex le el o isual appea -
© 2016 IEEE. Pe sonal use o his ma e ial is pe mi ed. Pe mission om IEEE mus be ob ained o all o he uses, in any
cu en o u u e media, including ep in ing/ epublishing his ma e ial o ad e ising o p omo ional pu poses,c ea ing
new collec i e wo ks, o esale o edis ibu ion o se e s o lis s, o euse o any copy igh ed componen o his wo k in
o he wo ks. DOI: 10.1109/VHCIE.2016.7563568
ance would be pho o- ealis ic cha ac e s, bu his would mos likely
p esen p oblems wi h he Uncanny Valley.
Figu e 1: C owds ende ed wi h ca oon like cha ac e s and no shad-
ows [22] (le ) o a mo e human-like appea ance and shadows [6]
( igh ).
3 VR TECHNOLOGY
When conside ing he po en ial impac s o c owd simula ions on
i ual eali y and ice e sa, we mus include bo h so wa e and
ha dwa e. Focusing i s on so wa e, he mo e open elease o
games engines like Uni y 3D [1] and he Un eal Engine [2] ha e
p o ided c owd simula ion esea che s access o echnologies and
me hods ha p e iously equi ed g ea e o on hei pa . E en i
he ocus o hei esea ch was on s ee ing o s epping beha io s,
hey needed o de elop so wa e o na iga ion, ende ing, e c. in
o de o show how hei me hods ope a e in a ull c owd simula ion.
While no ye ideal and no ye en i ely simplis ic o u ilize, hese
game engines p o ide a amewo k ha includes a leas udimen-
a y (and in some elemen s mo e ad anced) componen s on which
esea che s can examine and de elop hei simula ions. Func ional-
i y includes, le el design ools, na iga ion meshes, anima ion play-
back and blending, in e se kinema ics, ad anced ende ing ech-
niques, and physics engines. Pushes owa d open sou ce so wa e
has also lessen he ini ial in es men o ime and e o p e iously
needed when beginning c owd simula ion esea ch.
Fu he mo e, hese engines p o ide easy access o a ied inpu
and ou pu de ices. Resea che s no longe need o be conce ned
wi h de eloping de ice d i e s and connec i e so wa e o game
con olle s and Head Moun ed Displays (HMDs). These engines
p o ide au oma ic connec ions wi h consume le el ha dwa e like
wi eless con olle s, acke s (e.g. he Mic oso Kinec ) and he
Occulus Ri . This p omo es much g ea e expe imen a ion a lowe
in es men cos s.
Focusing on VR ha dwa e, i now wo ks and is e en com-
mon place [26]. CAVES now ha e high esolu ion displays wi h
seamless image alignmen s. The e a e e en a numbe o po able
CAVES. HMDs also bene i om high esolu ion as well as wide
ields o iew, ligh e weigh , and lowe cos poin s. The e a e now
simple moun s o sma phones o become HMDs. Head acke s
and whole body acke s, like he Mic oso Kinec , a e common
and o many applica ions ha e he equi ed accu acy and ease o
use. The a ailabili y o hese de ices makes i much mo e easible
o place simula ed c owds in VR and po en ially p o ide new lines
o esea ch in pa icipan in e ac ion wi h c owds.
De ices such as eye acke s and biome ic senso s (e.g. EEGs
and SCRs) ha e also become much mo e pe asi e and a e used
o e alua e VR applica ions including he le els o p esence o he
pa icipan s [28]. Using hese de ices o aid in he de e mina ion
o a subjec ’s le el o p esence in VR wo lds wi h a ying c owd
models could be a iable a enue o c owd simula ion e alua ion.
4 STATE OF THE ART IN IMMERSIVE VIRTUAL CROWDS
Imme si e i ual c owds could o e a g ea po en ial o e alua e
human beha io in di icul o dange ous si ua ions. Vi ual eali y
o e s he possibili y o eplica ing expe imen s wi hou exposing
he pa icipan o a eal dange ous si ua ion. Fo example, he e
has been wo k s udying human beha io s unde a i e eme gency
in a public place [28]. This pa icula s udy was ca ied ou wi h a
ew i ual agen s wi h sc ip ed beha io s and anima ions. Vi ual
c owds in imme si e en i onmen s ha e been p oposed as bo h a
alida ion echnique o c owd simula ion om an egocen ic poin
o iew, and also as a se up o lea n abou human decision-making
in con olled si ua ion [21]. The lea ned da a could be used la e on
o enhance c owd simula ion models.
In o de o be able o bo h alida e and ex ac ele an da a, i is
essen ial o c ea e an en i onmen whe e people eel p esence, and
hus eac in a ealis ic way o i ual e en s. In [21] he au ho s
p esen a s udy based on p esence li e a u e and ea u es ha appea
o en in c owd simula ion models. They discuss how hose ea u es
could enhance o b eak p esence. In a la e expe imen [22] using
a head moun ed display, hey showed ha ha ing some le el o in-
e ac ion wi h he c owds could enhance he eeling o being he e.
Fo example, he i ual agen s we e able o see he pa icipan o
pe o m collision a oidance, hey could also be pushed by he pa -
icipan in case o high densi ies. The pa icipan was imme sed
in a i ual cock ail pa y whe e he c owd would walk a ound and
s op a ables wi h ood and d inks. Agen s would au onomously
decide o s op a ound ables, u n o ace o he agen s, and play idle
beha io s ha included hand ges u es imi a ing being engaged in
con e sa ion. All o hese elemen s combined wi h he backg ound
noise o pla es and con e sa ion helped c ea e a s ong sense o
p esence despi e he ca oonis appea ance o he cha ac e s.
CAVE sys ems ha e also been used o imme se a pa icipan in
i ual c owd o he pu pose o e alua ing new c owd simula ion
me hods [3]. In his wo k he goal was o compa e di e en c owd
simula ion me hods. The pa icipan was s anding in a loca ion
wai ing o a pe son and could obse e he c owds om an ego-
cen ic poin o iew o e alua e hei collision a oidance me hods.
Ques ionnai es we e used a e wa d o ga he in o ma ion abou he
pa icipan s opinion ega ding li e-likeness o he c owd, spa ial
awa eness and com o in he CAVE.
Bo h he wo k by Pelechano e al. [22] and Ahn e al. [3] ound
ha b eaks in p esence o low com o appea when he e is no col-
lision a oidance (i.e. cha ac e s mo ing h ough he pa icipan )
and when he me hod p oduces shaking a i ac s.
The wo k by Ky iakou e al. [14] demons a ed ha showing col-
lision a oidance be ween he use and he i ual agen s wi h some
basic in e ac ion be ween hem could inc ease he sense o p es-
ence. This kind o in e ac ion also helped o make he i ual en i-
onmen appea mo e ealis ic and li elike. In hei s udies hey also
obse ed ha including in e ac ion wi h he i ual c owd could en-
hance p esence. The ypes o in e ac ion used o hei wo k we e
limi ed o ha ing cha ac e s wa ing o e bally salu ing he pa ic-
ipan .
The wo k by B uneau e al. [9] s udied he pa icipan s’ beha io
when walking agains g oups o i ual agen s. The goal was o
de e mine wha elemen s o he c owd ge people o decide o walk
h ough o a ound a g oup o people. The elemen s o he g oup
ha hey es ed whe e based on ela i e mo ion, size, densi y o
appea ance.
P oxemics ha e also been e alua ed wi h small g oups o i ual
cha ac e s walking owa ds he pa icipan [17]. Those expe imen s
ound ha physiological a ousal would inc ease as he cha ac e s
would app oach he pa icipan and also as he numbe o i ual
humans would inc ease om 1 o 4.
These las wo pape s had some in e es ing, i no su p ising, e-
sul s which we e ha in ce ain si ua ions he appea ance o he i -
ual humans did no seem o ha e much e ec on he pa icipan ’s
esponse. Fo example he i s one [9] was e alua ing he pa ic-
ipan s’ decisions o walking h ough o a ound a g oup o i ual
humans. I u ned ou ha whe he he i ual humans we e en-
de ed as o dina y people o zombies had no signi ican di e ences
in he decisions made by pa icipan s. And simila ly, in [17] hey
ound no signi ican di e ences in e ms o physiological a ousal
when being app oached by i ual people o cylinde s. This opens
ques ions ega ding he ex end o which ealis ic isual appea ance
is necessa y and why.
IVE p o ides a pla o m o s udy c owd beha io unde con-
olled condi ions [18]. In his pape hey discuss and e alua e he
use o VR o ca y ou con olled expe imen s o ob ain da a abou
human beha io in e ms o na iga ion. The long e m goal would
be o be able o use VR as an aid in he p ocess o de eloping mo e
accu a e mic oscopic models. The pape aises in e es ing ques-
ions such as: a e ajec o ies in VR simila o hose in eal li e? o ,
is he e any bias induced by he use o locomo ion in e aces?
The answe s o hese ques ions a e s ill un esol ed. Fo ins ance,
pa o he wo k in his ield is ocusing on enhancing p esence in
an a emp o ha e he pa icipan s beha ing as in eal li e. Bu how
close a e eal esponses o i ual e en s om ha ing pa icipan s
pe o ming ealis ic local mo emen ? Gi en ha mo emen i sel
is cons ained in mos VR applica ions, (i.e. cables in HMD o size
o he CAVEs) can we ully us pa icipan mo emen ? In o he
wo ds, is p esence enough o u n VR in o an accu a e pla o m o
cap u e human locomo ion? The e has been a la ge amoun o wo k
ying o ind co ela ions be ween human walking in s a ic i ual
en i onmen s and in eal se ups ha exac ly ma ch he dimensions
o he i ual one. La ely some esea che s ha e been mo ing hese
s udies o dynamic en i onmen s popula ed wi h i ual humans o
ind he simila i ies be ween he eal and he i ual wo ld [24].
Despi e ecen ad ances in VR and he a ailabili y o engines
such as Un eal [2] and Uni y [1] ha acili a e he ask o c ea -
ing i ual en i onmen s, he e is s ill a la ge amoun o manual
wo k equi ed o popula e hose en i onmen s in a belie able man-
ne . The pape by Spanlang e al. [29] p o ides a good o e iew o
he di icul ies in c ea ing a i ual expe imen dealing wi h embod-
imen . Embodimen equi es he eplacemen o he pa icipan ’s
body wi h a i ual cha ac e seen om a i s pe son pe spec i e.
To be belie able, he body ep esen a ion needs o ollow he mo e-
men s o he pa icipan . This implies ha ing a leas one i ual
human, wi h eal- ime mo ion cap u e, cha ac e anima ion, and e-
alis ic ende ing. Ha ing a ew belie able i ual cha ac e s al eady
equi es a la ge amoun o wo k, bu he p oblems escala e as he
numbe o cha ac e s needed inc eases, since i is necessa y o deal
no only wi h he simula ion o each cha ac e bu also wi h he in-
e ac ions be ween hem.
Mos o he ime hese i ual cha ac e s ollow s ic ly sc ip ed
beha io s and hei appa en in e ac ion simply ollows he Wiz-
a d o Oz me apho . Anima ions a e mo ion cap u ed and ca e ully
cleaned and adjus ed o he inal scena io. In such expe imen s,
he e is li le oom o au onomous beha io , and he i ual hu-
mans a e like he ac o s in a mo ie wi h li le oom o in e ac ion
wi h he pa icipan . When we deal wi h imme si e c owds, he job
o edi ing scena ios wi h such le el o de ail becomes un easible,
and hus mo e esea ch is needed o mo e p esence expe imen a-
ion in o he c owd simula ion ield.
5 SOWHAT’SMISSING?
In [26] Sla e discusses g and challenges in i ual en i onmen s,
a eas ha need u he esea ch. One opic highligh ed is acking
and he need o be e body acking o e wide a eas wi h high
accu acy and low la ency. Such ad ancemen s in acking could
posi i ely impac c owd simula ion esea ch on wo on s. One,
i would enable pa icipan s imme sed in a i ual c owd o mo e
mo e na u ally and mo e eely. I could also enable be e da a
collec ion o inpu o c owd simula ions and o e alua e hem.
Sla e also discusses plausibili y illusion. Pa icipan s ca y ex-
pec a ions abou hei en i onmen and he people in i om he
eal wo ld in o he i ual wo lds. This calls o mo e ealis ic hu-
man beha io s including he beha io s o c owds and hei in e ac-
ions wi h he en i onmen . Said in e ac ions equi e a high le el
o domain knowledge, he c ea ion o which is edious and ime
consuming. Recen esea ch has explo ed au oma ing he c ea ion
o elemen s o domain knowledge [23, 5], bu addi ional e o is
needed.
The plausibili y illusion also calls o esea che s o a oid he
Uncanny Valley. When pa icipan expec a ions a e no me , p es-
ence can be b oken. When pa icipan expec a ions a e se oo high
by one aspec o he simula ion, lowe quali y in ano he aspec can
b eak p esence. Along hese lines, he e a e a eas o ac i e esea ch
ha need con inued imp o emen o c owd simula ions in VR o
be success ul. We need be e anima ion and blending ools, be e
ende ing o la ge c owds, be e ing s epping and na iga ion algo-
i hms (pa icula ly in clu e ed en i onmen s). In ac anima ion
bugs and gli ches end o be e y no iceable in VR and e y dis-
ac ing. We also need o calib a e he speed o cha ac e s when
placed in VR. We ha e obse ed ha hey end o be pe cei ed as
mo ing mo e quickly han hey should.
Acco ding o Sla e , ano he challenge o i ual en i onmen s
is hap ics. While he e a e an a ay o hap ic de ices a ailable,
none can eplica e all, o pe haps e en any, o he ouches and eels
we expe ience daily. Sla e poin s ou ha esea ch in he a ea o
hap ics has o con end wi h and is limi ed by he laws o physics,
making i pa icula ly challenging. A lack o ealis ic hap ic eed-
back is p oblema ic when imme sing pa icipan s in c owds. The
lack o ac ile eedback om e en ela i ely mino collisions wi h
indi iduals in he c owd may g ea ly dec ease p esence. Absence
o he o ces and p essu es no mally expe ienced in dense c owds
would g ea ly dec ease a pa icipan ’s sense o p esence. Resea ch
on how o eplica e he eeling o being imme sed in a c owd is s ill
needed. Do ad ances in neu oscience hold he solu ions?
Ano he challenge is enabling people nai e o p og amming o
c ea e and modi y en i onmen s. Cu en so wa e amewo ks like
he game engines discussed in Sec ion 3 ha e begun add essing his
challenge. They p o ide ools o impo ing models, designing le -
els, blending anima ions, designing simple AIs, e c. They do no ,
howe e , p o ide ools o he c ea ion and con ol o i ual hu-
man popula ions. While we ha e explo ed au ho ing he beha io s
o popula ions om a limi ed numbe o easy o au ho ac ion ypes
(See igu e 2) [19, 16, 4], addi ional esea ch is needed.
Figu e 2: Simple GUIs o au ho ing eac i e, s ochas ic, and need-
based ac ions (le ) and Mic oso Ou look calenda s o au ho ing
scheduled ac ions ( igh ).
Cummings e al., who s udied imme sion and p esence h ough
a me a-analysis o p e ious esea ch [11], discussed di e en ypes
o p esence. They indica e ha social p esence would be inc eased
h ough be e communica ion and social ac o s. Ce ainly his is
an elemen o c owd simula ions ha could use addi ional esea ch.
Cha ac e s in c owds end o be exp essionless and la gely non e-
ac i e. While hey may espond o a oid collisions and o a ew
sc ip ed e en s, hey end o appea a he li eless. They possess
limi ed communica ion models and ew social ea u es. E en he
addi ion o models o a en ion would p o ide mo e li elike qual-
i ies. Cha ac e s should look whe e hey a e going and a in e -
es ing objec s and e en s in he wo ld. Indi iduals in c owds ha
mee he eye o he pa icipan om ime o ime could help o in-
c ease social p esence. Cha ac e s should eac o each o he and
o he pa icipan in a na u al manne . Figu e 3 shows ha e en in
a a he p imi i e c owd simula ion and VR se up, pa icipan s can
be posi i ely in luenced by e en unin en ional cha ac e ac ions. To
inc ease social p esence, cha ac e s should exhibi su p ise, cu ios-
i y, and e en ange . They should exhibi di e en pe sonali ies and
a i udes. They should appea ...human.
Figu e 3: A pa icipan in a VR expe imen on p esence eac ing o
a pe cei ed wa e om a i ual cha ac e by s a ing o wa e back
(mo emen o le hand).
In e ms o spa ial p esence hey ound acking le el, s e e-
oscopy, and ield-o - iew o be mo e impac ul han image qual-
i y, esolu ion, and sound. T acking p o ides pa icipan s wi h a
sense o sel -loca ion, be e na iga ion, and addi ional ac ion pos-
sibili ies. S e eoscopy p o ides g ea e spa ial p esence h ough in-
c eased dep h pe cep ion and ce ainly wide ields-o - iew aid in
sel loca ion. They ound ha he abili y o na iga e a ound he en-
i onmen is key o inc easing spa ial p esence. Na iga ion is mo e
di icul in c owds, especially dense c owds. Will including c owds
in VR inhe en ly dec ease le els o spa ial p esences o will pa ic-
ipan s ha e lowe expec a ions o na iga ion in c owds and ha e
hei le els o p esence emain high?
Ano he elemen o c owd simula ions ha has no ecei ed
much a en ion is sound. Adding ealis ic, localized sound o he
cha ac e s in a simula ion may imp o e he pa icipan ’s le el o
p esence. They would be less s a led by cha ac e s suddenly ap-
pea ing in hei ield-o - iew. The cha ac e s hemsel es could e-
ac o noises in he en i onmen , making hem appea mo e li elike.
Finally, elemen s o s o y and game play wi hin c owd simula-
ions may inc ease imme sion and p esence. I pa icipan s a e en-
h alled by a s o y o ac i i y wi hin he i ual en i onmen , hey
may no ice ewe anomalies and be less impac ed by hem. Pe haps
elemen s o s o y and game play need o be add essed in c owd
simula ion esea ch.
6 CONCLUSION
VR can bene i om ad ances in c owd simula ion echniques and
c owd simula ion esea ch can bene i om ad ances in VR ech-
nology. Popula ions o i ual humans can make imme si e i -
ual wo lds mo e ealis ic, in e es ing, and compelling. The c owd
simula ion communi y con inues o explo e ways o e alua ing and
alida ing hei echniques. VR is an e e mo e iable enue o
imme sing pa icipan s in a c owd and examining hei beha io al
eac ions and o e all le els o p esence. Howe e , as ou lined in
his pape c owd simula ions mus s ill imp o e o mee he s an-
da ds needed o achie e high le els o p esence.
Since VR p esen s an ideal pla o m o s udy human beha io in
c owds, i is hus impo an o ocus ou esea ch e o s in de e -
mining how we can achie e ealis ic imme si e c owds. One way
ha we ound e y aluable o make p og ess is o ob ain mo e
in o ma ion om he pa icipan s a e he expe imen s. So o in-
s ance, once all he esul s om ques ionnai es and physiological
esponse ha e been ga he ed, we can ask he pa icipan s o gi e us
gene al commen s abou he expe imen . Wha was he mos com-
pelling? Wha did hey ind was missing? Wha b oke he eeling
o in e ac ing wi h a eal c owd? Thei answe s can help he e-
sea che s o hink ou side he box by no icing wha he a e age pe -
son may be expe iencing as opposed o wha he esea che eels
is missing. I also p o ides ele an in o ma ion ega ding wha
he a e age pe son may no ca e abou ha he esea che s do. Fo
example, when playing ideo games, people ge so imme sed and
exci ed abou he game ha hey olun a ily decide o igno e he
a i ac s (i.e. low [10]). So he playe does no s op chasing he en-
emy jus because he/she obse ed a bad blending, an ab up change
in di ec ion, o some oo sliding. Could pa icipan s in a p esence
en i onmen wi h an imme si e c owd also adap o he ci cum-
s ances and decide o igno e ce ain a i ac s? Maybe as long as he
i ual humans appea eal by alking o hem, wa ing o showing
emo ions, he pa icipan would ea hem as eal people.
Mo e esea ch is needed.
7 ACKNOWLEDGMENTS
This wo k has been pa ially unded by he Spanish Minis y o
Science and Inno a ion and FEDER unde g an TIN2014-52211-
C2-1-R.
REFERENCES
[1] Uni y Game Engine 5. h p://uni y3d.com/es/, 2016.
[2] Un eal Engine 4. h ps://www.un ealengine.com/wha -is-un eal-
engine-4, 2016.
[3] J. Ahn, N. Wang, D. Thalmann, and R. Boulic. Wi hin-c owd imme -
si e e alua ion o collision a oidance beha io s. In P oceedings o he
11 h ACM SIGGRAPH In e na ional Con e ence on Vi ual-Reali y
Con inuum and I s Applica ions in Indus y, VRCAI ’12, pages 231–
238, New Yo k, NY, USA, 2012. ACM.
[4] J. M. Allbeck. CAROSA: A ool o au ho ing NPCs. In Mo ion in
Games, pages 182–193. Sp inge Be lin Heidelbe g, 2010.
[5] T. Balin and J. Allbeck. Au oma ed Gene a ion o Plausible Agen
Objec In e ac ions. In W.-P. B inkman, J. B oekens, and D. Heylen,
edi o s, In elligen Vi ual Agen s, olume 9238 o Lec u e No es in
Compu e Science, pages 295–309. Sp inge In e na ional Publishing,
2015.
[6] A. Beacco, C. Anduja , N. Pelechano, and B. Spanlang. E icien en-
de ing o anima ed cha ac e s h ough op imized pe -join impos o s.
Compu e Anima ion and Vi ual Wo lds, 23(1):33–47, 2012.
[7] A. Beacco, N. Pelechano, and C. Andja . A su ey o eal- ime c owd
ende ing. Compu e G aphics Fo um, pages n/a–n/a, 2015.
[8] A. Beacco, N. Pelechano, M. Kapadia, and N. I. Badle . Foo s ep
pa ame e ized mo ion blending using ba ycen ic coo dina es. Com-
pu e s & G aphics, 47:105 – 112, 2015.
[9] J. B uneau, A.-H. Oli ie , and J. Pe e. Going h ough, going a ound:
a s udy on indi idual a oidance o g oups. Visualiza ion and Com-
pu e G aphics, IEEE T ansac ions on, 21(4):520–528, 2015.
[10] M. Csikszen mihalyi. Flow: The Psychology o Op imal Expe ience.
Ha pe Pe ennial Mode n Classics, 2008.
[11] J. J. Cummings and J. N. Bailenson. How imme si e is enough? a
me a-analysis o he e ec o imme si e echnology on use p esence.
Media Psychology, pages 1–38, 2015.
[12] A. Ja abo, T. V. Eyck, V. Sunds ed , K. Bala, D. Gu ie ez, and
C. O’Sulli an. C owd ligh : E alua ing he pe cei ed ideli y o illu-
mina ed dynamic scenes. Compu e G aphics Fo um, 31(2p 3):565–
574, 2012.
[13] M. Kapadia, N. Pelechano, J. Allbeck, and N. Badle . Vi ual c owds:
S eps owa d beha io al ealism. Syn hesis Lec u es on Visual Com-
pu ing: Compu e G aphics, Anima ion, Compu a ional Pho og aphy,
and Imaging, 7(4):1–270, 2015.
[14] M. Ky iakou, X. Pan, and Y. Ch ysan hou. In e ac ion wi h i ual
agen s. compa ison o he pa icipan s’ expe ience be ween an i and
a semi-i sys em. In Vi ual Reali y (VR), 2015 IEEE, pages 217–218.
IEEE, 2015.
[15] M. Lau and J. J. Ku ne . P ecompu ed sea ch ees: Planning o
in e ac i e goal-d i en anima ion. In P oceedings o he 2006 ACM
SIGGRAPH/Eu og aphics Symposium on Compu e Anima ion, SCA
’06, pages 299–308, Ai e-la-Ville, Swi ze land, Swi ze land, 2006.
Eu og aphics Associa ion.
[16] W. Li and J. M. Allbeck. Popula ions wi h pu pose. In Mo ion in
Games, pages 132–143. Sp inge Be lin Heidelbe g, 2011.
[17] J. Llobe a, B. Spanlang, G. Ru ini, and M. Sla e . P oxemics wi h
mul iple dynamic cha ac e s in an imme si e i ual en i onmen .
ACM T ans. Appl. Pe cep ., 8(1):3:1–3:12, No . 2010.
[18] A.-H. Oli ie , J. B uneau, G. Ci io, and J. Pe ´
e. A i ual eali y
pla o m o s udy c owd beha io s. T anspo a ion Resea ch P oce-
dia, 2:114–122, 2014.
[19] N. Pelechano, J. M. Allbeck, and N. I. Badle . Vi ual c owds: Me h-
ods, simula ion, and con ol. Syn hesis Lec u es on Compu e G aph-
ics and Anima ion, 3(1):1–176, 2008.
[20] N. Pelechano, B. Spanlang, and A. Beacco. A a a locomo ion in
c owd simula ion. In e na ional Jou nal o Vi ual Reali y, 10(1):13,
2011.
[21] N. Pelechano, C. S ocke , J. Allbeck, and N. Badle . Feeling c owded?
explo ing p esence in i ual c owds. In P oceedings o PRESENCE
2007. The 10 h annual In e na ional Wo kshop on P esence, pages
373–376, 2007.
[22] N. Pelechano, C. S ocke , J. Allbeck, and N. Badle . Being a pa o he
c owd: Towa ds alida ing c owds using p esence. In P oceedings
o he 7 h In e na ional Join Con e ence on Au onomous Agen s and
Mul iagen Sys ems - Volume 1, AAMAS ’08, pages 136–142, Rich-
land, SC, 2008. In e na ional Founda ion o Au onomous Agen s and
Mul iagen Sys ems.
[23] C. Pelkey and J. M. Allbeck. Popula ing Vi ual Seman ic En i on-
men s. Compu e Anima ion and Vi ual Wo lds, 24(3):405–414, May
2014.
[24] J. Pe ine , A.-H. Oli ie , and J. Pe ´
e. Walk wi h me: In e ac ions
in emo ional walking si ua ions, a pilo s udy. In P oceedings o he
ACM Symposium on Applied Pe cep ion, SAP ’13, pages 59–66, New
Yo k, NY, USA, 2013. ACM.
[25] S. Singh, M. Kapadia, G. Reinman, and P. Falou sos. Foo s ep na i-
ga ion o dynamic c owds. Compu e Anima ion and Vi ual Wo lds,
22(2-3):151–158, 2011.
[26] M. Sla e . G and challenges in i ual en i onmen s. F on ie s in
Robo ics and AI, 1(3), 2014.
[27] M. Sla e and S. Wilbu . A amewo k o imme si e i ual en i on-
men s ( i e): Specula ions on he ole o p esence in i ual en i on-
men s. P esence: Teleope a o s and i ual en i onmen s, 6(6):603–
616, 1997.
[28] B. Spanlang, T. F ¨
ohlich, V. F. Descalzo, A. An ley, and M. Sla e .
The making o a p esence expe imen : Responses o i ual i e. In
Annual In e na ional Wo kshop on P esence, pages 303–307, 2007.
[29] B. Spanlang, J.-M. No mand, D. Bo land, K. Kil eni, E. Giannopou-
los, A. Pomes, M. Gonzalez-F anco, D. P ez Ma cos, J. A oyo Pala-
cios, X. N. Muncunill, and M. Sla e . How o build an embodimen
lab: Achie ing body ep esen a ion illusions in i ual eali y. F on-
ie s in Robo ics and AI, 1(9), 2014.
[30] D. Thalmann and S. R. Musse. C owd simula ion. 2013.
[31] B. J. H. an Bas en, S. A. S ¨
u el, and A. Egges. A hyb id in e po-
la ion scheme o oo p in -d i en walking syn hesis. In P oceedings
o G aphics In e ace 2011, GI ’11, pages 9–16, School o Compu e
Science, Uni e si y o Wa e loo, Wa e loo, On a io, Canada, 2011.
Canadian Human-Compu e Communica ions Socie y.
[32] I. Yu, J. Mo ensen, P. Khanna, B. Spanlang, and M. Sla e . Vi-
sual ealism enhances ealis ic esponse in an imme si e i ual
en i onmen -pa 2. Compu e G aphics and Applica ions, IEEE,
32(6):36–45, 2012.