Crowd perception is very important for learning about group
behavior, in which observers can see interpersonal interaction
on a collective level [17]. The area of crowd perception has
grown in recent years in several scientific researches (both
through psychology and computing), such as perception of
different models of agents in crowd simulations [18], percep-
tion of geometric and cultural features in virtual crowds [19],
[20], perception of density in virtual crowds from two points
of view [21], effects on users during interaction with a
virtual crowd in an immersive virtual reality environment [22],
studies of social categorization and emotions in crowds using
ensemble coding [17], [23], among other researches. However,
these methods do not focus on the perception of interactions
between agents, between agent and user, and the impact of
geometric personalities and emotions (that is, no facial and
body expressions) on the perception of these interactions. In
this work, we define three hypotheses we want to answer:
•H01defining that people with only observational control
of agents in the crowd (do not interfere with crowd
dynamics) perceive interactions similarly to people with
control of agents in the crowd (the user is considered a
crowd agent);
•H02defining that people with only observational control
of crowd agents perceive different personalities and emo-
tions similarly to people with control of crowd agents.
In this case, as in our work we only use extraversion
personality trait, different personalities mean that an agent
can or cannot be extraverted;
•H03defining that the perception of interactions in crowds
is not related to the perception of different personalities
and emotions;
To try to answer the hypotheses, we created three scenarios
with virtual crowds: i) Scenario 1, in which a user controlled
a first-person camera throughout the entire scenario, without
interfering with the agents’ behavior; ii) Scenario 2, in which a
user also controlled a first-person camera throughout the entire
scenario, but he/she is considered as one agent of the simulated
crowd, using the BioCrowds [24] model; iii) Scenario 3, in
which a user is also an agent in the crowd, but the simulated
crowd is different from Scenario 2 because we use an exten-
sion of BioCrowds model, called Normal Life behaviors [25],
i.e., people are not in emergent situation. As the contribution
of this paper, we introduced in BioCrowds the Extraversion
factor to be distributed among the agents, so they are impacted
by their levels of extraversion when applying their motion.
Such factor is inspired in the personality traits methods, as
proposed by Durupinar et al. [11]. From the observations
and interactions with the scenarios, people answered questions
about how they perceive the agents’ interactions, and their
different personalities and emotions, as discussed in this paper.
This paper is organized as follows: Section II presents
the related work, while Section III presents the methodology
proposed. Section IV presents the results achieved with our
method and evaluation with subjects. Finally, Section VI
presents the final considerations and future work of our
method.
II. RELATED WORK
This section discusses some work related to pedestrian
and crowd behavioral analysis, focusing on personality traits,
emotion, and perception. Knob et al. [26] presented work
related to visualizing interactions between pedestrians in video
sequences and virtual agents in crowd simulations. OCEAN-
based factors gave interactions for each pedestrian and agent.
OCEAN [27], [28] is the most commonly used personality
trait model for this type of analysis, also known as the
Big-Five: O - Openness to experience: “the active seeking
and appreciation of new experiences”; C - Conscientiousness:
“degree of organization, persistence, control, and motivation
in goal directed-behavior”; E - Extraversion: “quantity and
intensity of energy directed outwards in the social world”; A -
Agreeableness: “the kinds of interaction an individual prefers
from compassion to tough-mindedness”; N - Neuroticism:
“how much prone to psychological distress the individual
is” [29]. Durupinar et al. [30] also used OCEAN to visually
represent personality traits.
Visual representation of agents is given in various ways,
for example, the animations of agents are based on these two
cultural features (OCEAN and emotion). If an agent is sad,
the animation will represent that emotion. Yang et al. [21]
conducted a study analyzing perception to determine the
impact of groups at various densities, using two points of view:
top and first-person. In addition to that, they examined what
kind of camera position might be best for density perception.
Regarding realism perception, the work proposed by Araujo
et al. [31] investigated people’s perception of characters cre-
ated using CG, comparing if they feel more comfortable with
more recent CG characters or older ones. The authors found
out that the perceived comfort about newer CG characters was
more significant than the perception of comfort about older CG
characters. Also, people’s perception of comfort in 2020 was
greater than people’s perception in 2012.
In another work [19], [20], the authors evaluate the hu-
man perception regarding geometric features, personalities,
and emotions in avatars. Results indicate that, even without
explaining to the participants the concepts of cultural features
and how they were calculated (considering the geometric fea-
tures), in most cases, the participants perceived the personality
and emotion expressed by avatars, even without faces and body
expressions.
The work proposed by Volonte et al. [22] examined the
effects on users during interaction with a virtual human crowd
in an immersive virtual reality environment. They found that
the users’ were able to interpret the verbal and non-verbal
behaviors of the virtual human characters where Positive
emotional crowds elicit the highest scores in the variables
related to interaction with the virtual characters.
Next, we present the proposed model to generate virtual
agents with personality traits (in this case, we just used
the extraversion personality trait) and how we evaluate the
people’s perception.