# Pedestrians' motion Through the Eyes of Road Users

Martin Bossard, Régis Lobjois, Jean-Marie Pergandi, Mehdi Pierron, Stéphane Caro, Nguyen-Thong Dang, Gilles Montagne, Remy Casanova, Anne-Hélène Olivier

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Martin Bossard, Régis Lobjois, Jean-Marie Pergandi, Mehdi Pierron, Stéphane Caro, et al. Pedestrians' motion Through the Eyes of Road Users. SAP 2024 - ACM Symposium on Applied Perception, Aug 2024, Dublin, Ireland. ACM, 25, pp.1 - 3, 2024, 10.1145/3675231.3678870. hal-04708218

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# Pedestrians' motion Through the Eyes of Road Users

**Martin Bossard**

Univ Gustave Eiffel, COSYS, PICS-L
Marne-la-Vallée, France
martin.bossard@univ-eiffel.fr

**Régis Lobjois**

Univ Gustave Eiffel, COSYS, PICS-L
Marne-la-Vallée, France
regis.lobjois@univ-eiffel.fr

**Jean-Marie Pergandi**

Aix-Marseille Univ, CNRS, ISM
Marseille, France
jean-marie.pergandi@univ-amu.fr

**Medhi Pierron**

Aix-Marseille Univ, CNRS, ISM
Marseille, France
medhi.pierron@univ-amu.fr

**Stéphane Caro**

Univ Gustave Eiffel, COSYS, PICS-L
Marne-la-Vallée, France
stephane.caro@univ-eiffel.fr

**Nguyen-Thong Dang**

Univ Gustave Eiffel, COSYS, PICS-L
Versaille, France
nguyen-thong.dang@univ-eiffel.fr

**Gilles Montagne**

Aix-Marseille Univ, CNRS, ISM
Marseille, France
gilles.montagne@univ-amu.fr

**Remy Casanova**

Aix-Marseille Univ, CNRS, ISM
Marseille, France
remy.casanova@univ-amu.fr

**Anne-Hélène Olivier**

Univ Rennes, Inria, M2S, VirtUs
Rennes, France
anne-helene.olivier@univ-rennes2.fr

<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /><figcaption>**Figure 1:** From pedestrian motion capture to contextual psychological experiment passing by theoretical studies on biological motion perception and interception.</figcaption></figure>

## ABSTRACT

This work introduces PERCEPT-PIETON, a project aiming to understand through the use of virtual reality and inertial motion capture, perceptual-motor and cognitive mechanisms involved during driver-pedestrian interactions from the driver's point of view. We are be particularly interested in how drivers regulate their behaviour and predict pedestrian's intentions based on individual (age, gender, ...) and behavioural (walking speed, trajectory, ...) characteristics of the latter. The objective is threefold : (i) a theoretical scientific contribution to obstacle avoidance literature; (ii) applied scientific knowledge for public decision-makers; and (iii) the creation of a free access library of biological pedestrians movements.

## KEYWORDS

Pedestrians, street-crossing, virtual reality, perception-action, biological motion

## ACM Reference Format:

Martin Bossard, Régis Lobjois, Jean-Marie Pergandi, Medhi Pierron, Stéphane Caro, Nguyen-Thong Dang, Gilles Montagne, Remy Casanova, and Anne-Hélène Olivier. 2024. Pedestrians' motion Through the Eyes of Road Users. In *ACM Symposium on Applied Perception 2024 (SAP '24), August 30-31, 2024, Dublin, Ireland*. ACM, New York, NY, USA, 3 pages. https://doi.org/10.1145/3675231.3678870

## 1 INTRODUCTION

When immersed in a virtual environment, a user's primary characteristic is their interaction with that environment. This includes interacting with static elements of the scenery and, more importantly, with other people (virtual agents) who may be moving around using various modes of locomotion, such as walking, biking, or driving. The careful design of populated virtual environments that consider the interactions between different users and agents is crucial. This is essential not only for ensuring an immersive, realistic experience to the user but also, from the researcher point of view for creating immersive platforms that are relevant for studying human behaviour.

In the project PERCEPT-PIETON, we are interested in the interactions between pedestrians and vehicle, from the driver perspective. For a long time, safety policies have treated the pedestrian as a "moving obstacle in the path of vehicles". Today, however, walking is considered as a real mode of transport with its own travel

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constraints and objectives [Muhirad 2008]. In this respect, it is im-
portant to remind that pedestrians are variable, sensitive to their
environment, sometimes inattentive (e.g. mobile phone) or hesitant,
that their choices are often guided by route optimization objectives
and for these reasons they can ignore signals and take more direct
routes [Fitzpatrick et al. 2015]. It is therefore of main interest to
understand these specificities when interacting with other users,
especially when crossing the street.

Curiously, no study has focused on understanding and measuring
driver dynamic behaviour when confronted with a pedestrian about
to cross the street, specifically on the effect of pedestrian dynamic
behaviour and locomotor pattern. Conversely, pedestrians-drivers
interaction in road crossing tasks has been largely studied from the
pedestrian's point of view [Dommes et al. 2021; O'Neal et al. 2018].
Other studies have focused on drivers' [Louveton et al. 2018] or
cyclists' [Plumert et al. 2004] behaviour while they interact with
others road users but still not during interactions with pedestrians.

One of the reasons why road user behaviour when facing a pedes-
trian has not been studied is probably technological [Day et al. 2019].
Pedestrian simulation models presented in 3D environments are
sometimes far from the behaviours and motor signatures that can
be observed in natural environments. In most cases, pedestrians
are represented by virtual agents whose movements are based on
models of locomotor patterns. In PERCEPT-PIETON, on the other
hand, we will confront road users with virtual agents whose ani-
mation is based on previously captured motion and thus represents
biologically plausible movements.

2 OBJECTIVES

The objectives of the PERCEPT-PIETION project are threefold: (i) to
bring theoretical scientific contributions to the literature on obstacle
avoidance and biological motion perception; (ii) to produce useful
and operational knowledge for public policy makers by improving
scientific knowledge on pedestrian safety, focusing on the way
drivers perceive pedestrians' intentions and crossing behaviour;
(iii) to create a library of biological pedestrian movements that
will be freely available to the community for awareness raising,
scientific experimentation or exploitation.

3 DESIGN AND IMPLEMENTATION

To achieve these objectives, we plan to immerse participants in a
driving scenario in a virtual environment in which they will face
digital twins of pedestrians presenting biological motion charac-
teristics taken directly from motion capture - i.e. the reproduction
of the motion performed by real pedestrians, as opposed to virtual
agents walking around according to a model of locomotor patterns.
While the drivers are confronted with different types of pedestrians
(e.g. age, gender, etc.) with different behaviours (e.g. attentive or
not, hesitant or not) and with more or less locomotor abilities, their
behaviour will be recorded. Several experiments will be conducted
using virtual reality headsets. They will drive through a virtual
urban environment, more or less rich in visual information, until
the appearance of a pedestrian about to cross the road.

Two types of task are tested to measure decision making and
regulation of driver behaviour. In the first situation, the scene will
freeze and the participant will be asked to indicate whether they

would have had time to pass by avoiding the collision with the vir-
tual pedestrian (decision task). In the second task, while driving, the
participant will have the opportunity to adjust their speed, direc-
tion or both at times in order to pass before or after the pedestrian
(behaviour regulation task). At the same time, the headsets used
will allow us to measure the participants’ eye movements in order
to inform us about their visual information gathering strategy.

In particular, we will look at the effect of individual pedestrian
characteristics, such as age or gender; the effect of the level of at-
tention that the pedestrian pays to the road and to the approaching
driver, for example whether there is behavioural coupling or com-
munication (formal or not) between these two users [Sucha 2014];
and the effect of pedestrian hesitation when approaching the road
on driver behaviour [Jay et al. 2020].

We will focus on other factors identified in theoretical studies
as important in the perception of moving objects [Casanova et al.
2022] or in the perception of biological motion [Hülemeier and
Lappe 2020; Mayer et al. 2019] during the observer's self-motion.
The speed, the angle of approach and the moment of appearance of
the pedestrians will be variables to which we will pay particular
attention. As has been shown for interception tasks, we hypothesise
that these three parameters lead to changes in drivers' behaviour,
and in particular influence their decision making, the way they
gather visual information, or the way they regulate their approach
speed and direction.

ACKNOWLEDGMENTS

This work is supported by the Road Safety Department from the
French Ministry of the Interior awarded to Martin Bossard and by
the National Research Agency under grants ANR-21-ESRE-0030
(Equipex+ CONTINUUM).

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Brian Day, Elham Ebrahimi, Leah S Hartman, Christopher C Pagano, Andrew C Robb, and Sabarish V Babu. 2019. Examining the effects of altered avatars on perception-action in virtual reality. *Journal of Experimental Psychology: Applied* 25, 1 (2019), 1.

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