# SIDH: A Game-Based Architecture for a Training Simulator

Authors: P. Backlund; H. Engström; M. Gustavsson; M. Johannesson; M. Lebram; E. Sjörs
Journal: International Journal of Computer Games Technology
 (2009)

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## Abstract

Game-based simulators, sometimes referred to as “lightweight” simulators, have benefits such as flexible technology and economic feasibility. In this article, we extend the notion of a game-based simulator by introducing multiple screen view and physical interaction. These features are expected to enhance immersion and fidelity. By utilizing these concepts we have constructed a training simulator for breathing apparatus entry. Game hardware and software have been used to produce the application. More important, the application itself is deliberately designed to be a game. Indeed, one important design goal is to create an entertaining and motivating experience combined with learning goals in order to create a serious game. The system has been evaluated in cooperation with the Swedish Rescue Services Agency to see which architectural features contribute to perceived fidelity. The modes of visualization and interaction as well as level design contribute to the usefulness of the system.


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## Body

## 1. Introduction

The
firefighter profession is stressful and dangerous, exposing its practitioners
physically and psychologically highly demanding tasks in extreme environments [1].
One of the most hazardous tasks is to enter a building on fire and to search
for victims. This activity is referred to as breathing apparatus entry (BAE)
and requires a systematic and thorough scanning of the building where the sight
may be extremely limited due to smoke. This in combination with the heat from
fires forces the firefighters to hold a low position. When a victim is found, he/she must be dragged to
a safe environment before the search can continue. The training for BAE is
traditionally carried out in training areas with buildings of different types
where victims are replaced with dummies. These methods have been shown to be
effective but they are not optimal for all situations. First of all, they are
relatively costly as they require trained instructors and access to a dedicated
training area where each type of environment (e.g., hotel, ship, train, gas
station, etc.) requires a separate physical model. If the same persons
participate in repeated exercises they are likely to become familiar with these
models. Simulator training solves the problem of students getting familiar with
the physical models as new virtual models are fairly easy to create.
Furthermore, as live training sessions are costly they need to be well prepared
to create high value. Hence, virtual environments form an effective and efficient
complement and preparation for real-world training [2] in order to increase its
quality.Simulators form a class of systems
which emulate the operational environment, often by means of visual
representations. Various game-based training systems are sometimes referred to
as “lightweight” simulators [3]. Alexander et al. [3] identify a number of
benefits with “lightweight” simulators and the use of video game engines, some
of which are flexible technology, economy, and user control. The system
presented in this paper extends the concept of game-based training systems by
adding multiple screen view and a novel interaction mode. These features add to
immersion and increase the feeling of “being there”. One issue in relation to
all sorts of simulator training, and in particular concerning game-based
simulators, is the transfer of skills and abilities to the real operational
environment. Fidelity refers to the extent which the virtual system emulates
the real world and is hence expected to be an important aspect of the system.SIDH is a game-based firefighter
training simulator developed in cooperation between the University of Skövde
and the Swedish Rescue Services Agency (SRSA). An important property of SIDH, which
differentiate it from traditional simulators, is that it is game-based. Game
technology, hardware, as well as software have been used to produce the
application. More important, the application itself is deliberately designed to
be a game. Indeed, one important design goal is to create an entertaining and
motivating experience combined with learning goals. In this way, learning
becomes self-motivating and the system may be used for off-hour training. SIDH
also utilizes multiple screen view to make the player surrounded
by the virtual world and a novel sensor-based interaction mode to put a
physical load on the player.The aim of this paper is to report
on the architecture of a game based training simulator for BAE and how its
fidelity is perceived by the users. By this we extend the knowledge of how game
technology can be utilized for serious games purposes as well as the practical
usefulness of such a system.


## 2. Background

In this
section, we give a brief account for our view on the concept of serious games
and serious gaming, that is, the activity of using games for purposes other
than entertainment. We also summarize previous work on firefighter simulations and
give a brief background on Swedish firefighter training.


### 2.1. Serious Games

Today, the
term serious games is becoming more and more popular (see, e.g., [4, 5]).
The term itself is established, but there is no current singleton definition of
the concept. Zyda [6, page 26] defines a serious game as follows: “a mental
contest, played with a computer in accordance with specific rules, that uses
entertainment to further government or corporate training, education, health,
public policy, and strategic communication objectives.” Furthermore, Zyda [6]
argues that serious games have more than just story, art, and software. It is
the addition of pedagogy (activities that educate or instruct, thereby
imparting knowledge or skill) that makes games serious. However, he also stresses
that pedagogy must be subordinate to story and that the entertainment component
comes first.In our work, we define serious
games as games that engage the user, and contribute to the achievement of a
defined purpose other than pure entertainment (whether or not the user is
consciously aware of it). A game’s purpose may be formulated by the game’s designer
or by the user her/himself. The desired purpose, that is, a serious game, can
be achieved through a spectrum ranging from the mere utilization of game
technology for nonentertainment purposes to development of specifically
designed games for some nonentertainment purpose or the use and/or adaptation
of commercial games for nonentertainment purposes, which means that also a
commercial off-the-shelf (COTS) game, used for nonentertainment purposes, may
be considered a serious game. We also propose that any combination of the above
would constitute a feasible way to achieve the desired effect.Serious games can be applied to a
broad spectrum of application areas, for example, defense, government,
healthcare, marketing and communications, education, and corporate and industry
[4]. A question of interest concerns the claimed positive effects of such
games, or of applications from related and sometimes overlapping areas such as
e-learning, edutainment, game-based learning, and digital game-based learning. In
addition to obvious advantages, like allowing learners to experience situations
that are impossible in the real world for reasons of safety, cost, time, and so
on [7, 8], serious games, it is argued, can have positive impacts on the
players’ development of certain skills. We also note that some of these
positive effects of gaming are not necessarily associated with any specific
training or information objectives. As discussed by Mitchell and Savill-Smith
[9], analytical and spatial skills, strategic skills and insight, learning and
recollection capabilities, psychomotor skills, visual selective attention, and
so on, may be enhanced by playing computer games. Other reports [10] have also
pointed out the positive effects on motor and spatial skills. More specific
positive impacts have been reported, for example, by Enochsson et al. [11], who
found a positive correlation between experience in computer games and
performance in endoscopic simulation by medical students. The better
performance of gamers is attributed to their three-dimensional perception
experience from computer gaming.  The
positive effects of games may hence be further utilized if we can identify the
correct content and accurately exploit the user’s experience as a driving force
for developing serious games. Swartout and van Lent [12] identify the areas of
experience-based systems and experience-based education as potentially
benefiting from such a game-based approach. The general idea is to influence
users by exposing them to some type of experience. Even though gaming is not a
replacement for simulation, it may well serve as a complement in some regards
[13]. In this sense we find the intersection between gaming and simulation to
be an interesting one.


### 2.2. Immersive Visualization

There are
several ways of visualizing virtual worlds in order to offer a more immersive
experience to the viewer than can be achieved using ordinary computer displays.
The choice of visualization system depends on in what purpose it will be used
and, what resources in terms of time, space, and finances are available.The term head-mounted display (HMD)
is used on a category of visualization systems which presents a virtual world
directly in front of the viewer’s eyes, via one or two small displays. Used
with a head tracking system the viewer is able to look at different parts of
the world by turning his/her head. There are many different types of HMDs in
the market, for instance helmets, goggles, and lightweight glasses. There are
also a number of features which may be supported by an HMD device, such as
stereoscopic vision and semitransparent displays. A common property of HMDs is,
however, relatively low resolution and a small field of view.A CAVE is an, usually supercomputer-based,
environment for visualization of, and interaction with virtual models and
worlds. The first CAVE Automatic Virtual Environment (CAVE) was developed by
Electronic Visualization Laboratory [14]. The purpose was to build a system for
scientific visualization, with high demands on performance [15]. The original
CAVE had three walls, consisting of screens for rear projection, and measures
2.5×2.5×2.5 meters. On the walls and the floor, stereoscopic scenes are
presented for a viewer whose head movements are tracked in order to correct the
projection in real time. The viewer is also able to interact with the virtual
world, for instance, by using a special glove. Several variations of CAVE have
been built since 1991. One example is the six-sided VR-CUBE which was built at
the Royal Institute of Technology in Stockholm
in 1998 [16]. Here the viewer is completely surrounded by video and audio from
the virtual world—in all
directions.


### 2.3. Virtual Environments for Firefighter Training

The SRSA is
the government authority responsible for the training of fire and rescue
operatives. All municipal fire and rescue services staff are trained and
certified by the SRSA. BAE is one of the tasks a firefighter has to perform. It
is of crucial importance that the firefighter can remain orientated with very
limited or no vision in a building. Traditionally the firefighter students practice
search methods with and without smoke in different physical buildings.As firefighters have to handle
extreme tasks there is a continuous need to develop training programs to
prepare for such tasks [17]. There exist a number of reports of the use of
virtual environments for firefighter training in the literature.Tate et al. [2] present a study
where a virtual environment training system was used to prepare shipboard
firefighters for a mission. The virtual environment allowed users, equipped
with an HMD device, to navigate in a 3D model of the ex-USS Shadwell fire
research and test ship. A group of 12 trained firefighters participated in a
study where their performance in a firefighting training mission was evaluated.
Half the group was offered traditional mission preparation and the other half
prepared using the virtual environment. The result of the evaluation showed
that the second group had a better performance than the group using traditional
preparation.In a different study, Julien and
Shaw [18] present a virtual firefighter command training environment which
allows its users to inspect a house on fire and to command virtual
firefighters. The fire is extinguished by issuing the correct sequence of
commands to the firefighters. Perdigau et al. [19] present an application for
managing virtual reality scenarios and their main scenario is a firefighter training
simulation used for crisis situations training and understanding.There are also examples of
commercial simulation software used for firefighter training. The tactical
command trainer is a tool from VectorCommand Ltd. [20] which allows users to
train emergency management.


### 2.4. Fidelity in Games and Visualization

Buy-in, that
is, how a person recognizes that an experience is relevant for their training
is related to the amount of fidelity and perceived realism. It is often thought
that high fidelity and realism will increase the chances of buy-in. Alexander
et al. [3] describe how realism can be perceived important even though it has
no particular bearing on the task to be trained.Fidelity and transfer are crucial
factors in simulation training. The fidelity aspect implies that the necessary
level of fidelity in a simulator must be compared with the training goals. A
low level of fidelity can be sufficient when the simulation training is part of
a larger context; whereas a high level of fidelity is needed when the training
goals includes features that are too dangerous or to expensive to practice in
real life [21]. Fidelity can be divided in to three categories: physical, functional, and psychological fidelity. Physical fidelity is defined as the degree to which the physical
simulation looks, sounds, and feels like the operational environment in terms
of visual displays, controls, and audio. Functional fidelity is defined as the
degree to which the simulation acts like the operational equipment in reacting
to the tasks executed by the trainee. Psychological
fidelity is the degree to which the simulation replicates the psychological
factors (i.e., stress, fear) experienced in the real-world environment, and engaging
the trainee in the same manner as the actual equipment would in the real world
[3].A major issue concerning simulation training or game-based training is
about the absence of a surrounding context where the knowledge will be used.
According to Alexander et al. [3], it is a fact that real environments create
stress and excitement that cannot be recreated in a virtual environment. When
it comes to learning new abilities it can some times be necessary to try to
reach the same levels of stress and excitement in the simulator as in the
“real” world. If we could reach this relationship it would be named as high
psychological fidelity. Alexander et al. [3], also claim, in connection to this
line of argument, that both negative stress and positive stress are shown to improve retain and
transfer of knowledge from the virtual environment to the “real” world. In a study
of game-based training and its effects on American soldiers made by Morris et
al. [22], it emerged that soldiers who where exposed to stress during the
military training performed better in a “real” situation, than the soldiers who
where not exposed to stress. In fact the group that was exposed to stress got
considerably higher points during the following practice. The higher points were
due to the fact that they managed to administer time better and they also
avoided enemy fire to a higher extent.Concerning fidelity, there is a
focus on what is needed in terms of complexity and graphic realism and how the
users will be able to use the things they learn in the virtual reality
situation in the “real” world. According to Linderoth [23], this means that
fidelity and transfer covary. Within the fidelity element there is a
relationship between functional, physical, and psychological fidelity.
Functional and physical fidelity form the largest impact on the transfer
element. Psychological fidelity is defined after how well the simulator can
recreate the psychological factors, that is, stress and fear, which the user
later will meet in the “real” world [3]. The psychological fidelity has a
rather small amount of impact on the transfer element since it is a rather
abstract element.


## 2.1. Serious Games

Today, the
term serious games is becoming more and more popular (see, e.g., [4, 5]).
The term itself is established, but there is no current singleton definition of
the concept. Zyda [6, page 26] defines a serious game as follows: “a mental
contest, played with a computer in accordance with specific rules, that uses
entertainment to further government or corporate training, education, health,
public policy, and strategic communication objectives.” Furthermore, Zyda [6]
argues that serious games have more than just story, art, and software. It is
the addition of pedagogy (activities that educate or instruct, thereby
imparting knowledge or skill) that makes games serious. However, he also stresses
that pedagogy must be subordinate to story and that the entertainment component
comes first.In our work, we define serious
games as games that engage the user, and contribute to the achievement of a
defined purpose other than pure entertainment (whether or not the user is
consciously aware of it). A game’s purpose may be formulated by the game’s designer
or by the user her/himself. The desired purpose, that is, a serious game, can
be achieved through a spectrum ranging from the mere utilization of game
technology for nonentertainment purposes to development of specifically
designed games for some nonentertainment purpose or the use and/or adaptation
of commercial games for nonentertainment purposes, which means that also a
commercial off-the-shelf (COTS) game, used for nonentertainment purposes, may
be considered a serious game. We also propose that any combination of the above
would constitute a feasible way to achieve the desired effect.Serious games can be applied to a
broad spectrum of application areas, for example, defense, government,
healthcare, marketing and communications, education, and corporate and industry
[4]. A question of interest concerns the claimed positive effects of such
games, or of applications from related and sometimes overlapping areas such as
e-learning, edutainment, game-based learning, and digital game-based learning. In
addition to obvious advantages, like allowing learners to experience situations
that are impossible in the real world for reasons of safety, cost, time, and so
on [7, 8], serious games, it is argued, can have positive impacts on the
players’ development of certain skills. We also note that some of these
positive effects of gaming are not necessarily associated with any specific
training or information objectives. As discussed by Mitchell and Savill-Smith
[9], analytical and spatial skills, strategic skills and insight, learning and
recollection capabilities, psychomotor skills, visual selective attention, and
so on, may be enhanced by playing computer games. Other reports [10] have also
pointed out the positive effects on motor and spatial skills. More specific
positive impacts have been reported, for example, by Enochsson et al. [11], who
found a positive correlation between experience in computer games and
performance in endoscopic simulation by medical students. The better
performance of gamers is attributed to their three-dimensional perception
experience from computer gaming.  The
positive effects of games may hence be further utilized if we can identify the
correct content and accurately exploit the user’s experience as a driving force
for developing serious games. Swartout and van Lent [12] identify the areas of
experience-based systems and experience-based education as potentially
benefiting from such a game-based approach. The general idea is to influence
users by exposing them to some type of experience. Even though gaming is not a
replacement for simulation, it may well serve as a complement in some regards
[13]. In this sense we find the intersection between gaming and simulation to
be an interesting one.


## 2.2. Immersive Visualization

There are
several ways of visualizing virtual worlds in order to offer a more immersive
experience to the viewer than can be achieved using ordinary computer displays.
The choice of visualization system depends on in what purpose it will be used
and, what resources in terms of time, space, and finances are available.The term head-mounted display (HMD)
is used on a category of visualization systems which presents a virtual world
directly in front of the viewer’s eyes, via one or two small displays. Used
with a head tracking system the viewer is able to look at different parts of
the world by turning his/her head. There are many different types of HMDs in
the market, for instance helmets, goggles, and lightweight glasses. There are
also a number of features which may be supported by an HMD device, such as
stereoscopic vision and semitransparent displays. A common property of HMDs is,
however, relatively low resolution and a small field of view.A CAVE is an, usually supercomputer-based,
environment for visualization of, and interaction with virtual models and
worlds. The first CAVE Automatic Virtual Environment (CAVE) was developed by
Electronic Visualization Laboratory [14]. The purpose was to build a system for
scientific visualization, with high demands on performance [15]. The original
CAVE had three walls, consisting of screens for rear projection, and measures
2.5×2.5×2.5 meters. On the walls and the floor, stereoscopic scenes are
presented for a viewer whose head movements are tracked in order to correct the
projection in real time. The viewer is also able to interact with the virtual
world, for instance, by using a special glove. Several variations of CAVE have
been built since 1991. One example is the six-sided VR-CUBE which was built at
the Royal Institute of Technology in Stockholm
in 1998 [16]. Here the viewer is completely surrounded by video and audio from
the virtual world—in all
directions.


## 2.3. Virtual Environments for Firefighter Training

The SRSA is
the government authority responsible for the training of fire and rescue
operatives. All municipal fire and rescue services staff are trained and
certified by the SRSA. BAE is one of the tasks a firefighter has to perform. It
is of crucial importance that the firefighter can remain orientated with very
limited or no vision in a building. Traditionally the firefighter students practice
search methods with and without smoke in different physical buildings.As firefighters have to handle
extreme tasks there is a continuous need to develop training programs to
prepare for such tasks [17]. There exist a number of reports of the use of
virtual environments for firefighter training in the literature.Tate et al. [2] present a study
where a virtual environment training system was used to prepare shipboard
firefighters for a mission. The virtual environment allowed users, equipped
with an HMD device, to navigate in a 3D model of the ex-USS Shadwell fire
research and test ship. A group of 12 trained firefighters participated in a
study where their performance in a firefighting training mission was evaluated.
Half the group was offered traditional mission preparation and the other half
prepared using the virtual environment. The result of the evaluation showed
that the second group had a better performance than the group using traditional
preparation.In a different study, Julien and
Shaw [18] present a virtual firefighter command training environment which
allows its users to inspect a house on fire and to command virtual
firefighters. The fire is extinguished by issuing the correct sequence of
commands to the firefighters. Perdigau et al. [19] present an application for
managing virtual reality scenarios and their main scenario is a firefighter training
simulation used for crisis situations training and understanding.There are also examples of
commercial simulation software used for firefighter training. The tactical
command trainer is a tool from VectorCommand Ltd. [20] which allows users to
train emergency management.


## 2.4. Fidelity in Games and Visualization

Buy-in, that
is, how a person recognizes that an experience is relevant for their training
is related to the amount of fidelity and perceived realism. It is often thought
that high fidelity and realism will increase the chances of buy-in. Alexander
et al. [3] describe how realism can be perceived important even though it has
no particular bearing on the task to be trained.Fidelity and transfer are crucial
factors in simulation training. The fidelity aspect implies that the necessary
level of fidelity in a simulator must be compared with the training goals. A
low level of fidelity can be sufficient when the simulation training is part of
a larger context; whereas a high level of fidelity is needed when the training
goals includes features that are too dangerous or to expensive to practice in
real life [21]. Fidelity can be divided in to three categories: physical, functional, and psychological fidelity. Physical fidelity is defined as the degree to which the physical
simulation looks, sounds, and feels like the operational environment in terms
of visual displays, controls, and audio. Functional fidelity is defined as the
degree to which the simulation acts like the operational equipment in reacting
to the tasks executed by the trainee. Psychological
fidelity is the degree to which the simulation replicates the psychological
factors (i.e., stress, fear) experienced in the real-world environment, and engaging
the trainee in the same manner as the actual equipment would in the real world
[3].A major issue concerning simulation training or game-based training is
about the absence of a surrounding context where the knowledge will be used.
According to Alexander et al. [3], it is a fact that real environments create
stress and excitement that cannot be recreated in a virtual environment. When
it comes to learning new abilities it can some times be necessary to try to
reach the same levels of stress and excitement in the simulator as in the
“real” world. If we could reach this relationship it would be named as high
psychological fidelity. Alexander et al. [3], also claim, in connection to this
line of argument, that both negative stress and positive stress are shown to improve retain and
transfer of knowledge from the virtual environment to the “real” world. In a study
of game-based training and its effects on American soldiers made by Morris et
al. [22], it emerged that soldiers who where exposed to stress during the
military training performed better in a “real” situation, than the soldiers who
where not exposed to stress. In fact the group that was exposed to stress got
considerably higher points during the following practice. The higher points were
due to the fact that they managed to administer time better and they also
avoided enemy fire to a higher extent.Concerning fidelity, there is a
focus on what is needed in terms of complexity and graphic realism and how the
users will be able to use the things they learn in the virtual reality
situation in the “real” world. According to Linderoth [23], this means that
fidelity and transfer covary. Within the fidelity element there is a
relationship between functional, physical, and psychological fidelity.
Functional and physical fidelity form the largest impact on the transfer
element. Psychological fidelity is defined after how well the simulator can
recreate the psychological factors, that is, stress and fear, which the user
later will meet in the “real” world [3]. The psychological fidelity has a
rather small amount of impact on the transfer element since it is a rather
abstract element.


## 3. SIDH: An Architecture for a Game-Based Simulator

The main goal
with SIDH was to develop a cave-based simulator game for training some aspects
of BAE. The project was carried out by expertise in game development and
serious games, in close cooperation with expertise in firefighter training from
SRSA. The game is not intended to replace conventional training, but rather to
be used as a complement with focus on search strategies and ability to orient
in unknown premises.The game is to resemble real-world
BAE in as many aspects as possible. This means that the player’s task is to
completely search different premises, with higher or lower complexity of the
architecture, and rescue any persons inside. It should be possible to fill the
premises with smoke, which, similar to real smoke, should be thinner close to
the floor than close to the roof. The player should also be exposed to heat and
physical and psychological stresses, which are characteristic parts of BAE.
Furthermore, in respect of the educational purpose, it is crucial to record the
player’s actions during a game session for later analysis.To reduce overhead time in the
developing process, it was decided that the game was to be developed as a
modification of a COTS game. In this way, the developers can focus on game
content and specific features without first having to create an infrastructure
from scratch. A feasibility study was committed in order to choose one of three
common games—FarCry, Quake2,
and Half-Life 2. All candidates were successfully modified to run in the cave
environment. However, due to the realistic indoor environments and the ease of
use of the level editor, Half-Life 2 was chosen as a platform for SIDH.


### 3.1. Cave Visualization

The cave is
constructed from standard consumer electronics components. The purpose is to
create a flexible environment for 360 degrees visualizations of, for example,
games and films. The four walls are each 160 cm wide and 210 cm high. The upper
120 cm of the walls consists of screens for rear projection. Each screen is
projected by a standard LCD projector, connected to a PC (Figure1). These
computers are interconnected in an Ethernet network together with another
computer which acts as a server. All five computers are standard gaming PCs
with regular graphics cards. The internal sound card of the server has been complemented
with an external 5.1 sound card which delivers sound to four loudspeakers, one
in each of the corners of the cave (Figure 1).Figure 1
Schematic
view of the cave.Half-Life 2 [24] is a multiplayer
game which means that there is native network functionality for distributing
information about the current state of the game objects. When playing a
multiplayer game, one of the computers acts as a server responsible for
controlling and synchronizing the progress of the game. When a server is
running other computers in the network are able to connect and thereby become
participating instances of the game running on the server.When playing SIDH in the cave, the
actual game, that is, the instance responsible for player input and game logic,
is running on the server computer. The task of the four-client-computers is to
visualize the game running on the server, why the clients always have to be
updated about the player’s position and the state of the world. To achieve
this, a native multiplayer feature called spectator mode is used. The original
purpose of this feature is to make it possible for connected, but nonparticipating,
clients to automatically follow and observe an active player. In that manner,
the instances of the game running on the cave computers are observers, following
the player on the server and hence showing the same view as the server without
actually interacting with the game. The screens of the cave are however not to
be clones of the server screen. Instead, they should present the world in four
different directions, one direction for each screen, with the same origin as
the server player. In the implementation, the game view is defined by a camera
which acts as the eyes of the player (or the spectator). The position and
orientation of this camera decides what is shown on the screen. By setting the
orientation of a client’s camera to a certain fixed direction, the client view
will always show the world from that angle, regardless of the player
orientation. Each view is thus rotated 90 degrees with respect to the adjacent
screens. To produce the final 360 degree projection in the cave, the field-of-view
(FOV) for the cameras was adjusted to 90 degrees. This is important since two
adjacent views will overlap with a greater FOV value, and with a lesser value
all parts of the world will not be visible at the same time.


### 3.2. Interaction Model

One of the
goals with SIDH has been to make the player’s interaction with the game as
natural as possible. The player has to be able to move and look around in the
virtual world, crouching as well as in a raised position. Moreover, it has to
be possible to pick up and drop victims and control the game flow.


#### 3.2.1. Navigation

One problem with
navigating in a cave environment is the lack of obvious directions in terms of
forward, backward, left, and right. Normally, when playing a first-person game,
forward is defined by the center of the display, that is, the direction in
which the player is currently looking. Pressing the forward key on the keyboard
will always move the player in the desired direction since the world is
rotating around the player and the keyboard. In the cave, however, it is not
possible to use a single forward key since the directions are fixed to the real
world. Hence, in order to decide what direction is forward for a cave player it
is necessary for the software to keep track of the player’s current
orientation. In SIDH, this problem is solved by using a GameTrak [25], which is
an USB device working as a joystick with a string to pull as Z-axis. The
GameTrak [25] is placed centered in the top of the cave, top down, with the
string attached to the fogfighter nozzle (Figure 2). In this way, the nozzle’s
position in 3D space can be calculated. Since there may be some discrepancy
between the direction expected by the player and the calculated direction (due
to player deviation from the center of the cave), the calculated forward
direction is visualized as a marker on the screens.Figure 2
The
string of the GameTrak (top right) is attached to
the fogfighter nozzle (bottom right). N.B., only one of the GameTrak’s [25] two controls is
used.SIDH also calculates the nozzle’s
distance to the floor in order to decide whether the player is crouching (to
increase the sight in smoke-filled areas) or not. Since a low position is
depending on the player’s height, the crouching
threshold is dynamically adapted based on the highest nozzle position recorded
during a mission. The information about the distance to the floor is also used
to record so called markings. A marking is done by touching the floor with the
nozzle, and is an action with different meanings in different phases of the
game:(i)
to start the game in the
beginning of a level,(ii)
to pick up found victims,(iii)
to drop rescued victims,(iv)
to confirm a completed
search task.


#### 3.2.2. Movement

For the player
to be able to move inside the cave, a device named Stepometer has been
developed. The idea with the Stepometer is that the player moves forward in the
game by walking or running on the spot. The device consists of two
accelerometer-based sensors which are attached to the player’s feet, and a
central unit processing the sensor signals and reporting steps to the server
computer. The central unit is based on the Atmega8 microprocessor which, among
other advantages, has native support for RS232 serial communication. The
Stepometer is using this protocol over Bluetooth for wireless communication
with the server computer.A physical-based model is used to compute the speed,v, of the
player. The updating of player speed is handled in the main loop of the game
and the delay since last update is given by dt. For each update, the
algorithm determines if the player has taken a step since last update, denoted
with s. With s=1 the player has taken a step and with s=0 no step has been taken. The Stepometer has a sensor for each leg and the player
has to alternate between left and right leg for the steps to be recorded. For
each recorded step, the player speed is increased with an impulse, Istep, which is computed based on the players speed:(1)Istep=Imax−k1*vwherek1isaconstant.This means that speed will increase quickly when the player starts to
move, but as the speed increases each step will give a smaller and smaller
contribution. The maximum speed of a player is hence given byImax/k1.The player speed is, in addition, decreased by a damping force,Idamp,
proportional to the delay since the last step, denoted tprev.
The damping is given by(2)Idamp=tprev2*k2*dtwherek2isaconstant.The quadratic nature ofIdamp implies that
the damping is very low when steps are frequent but the damping grows quickly
when the player stops moving. The speed is never allowed to become negative.Combining the above, the speed is updated according to the following
formula:(3)v(t+dt)=max[0,s*(Imax−k1*vt)+tprev2*k2*dt].When the player is crouching the
speed is divided by 2, which means that the step frequency has to be higher
compared to when in a raised position, in order to keep up the speed. When
carrying a victim, the speed is divided by 4, why the step frequency has to be
very high for the player to advance forward. This results in a significant increase
of the physical strain, in analogy with carrying a victim in a real situation.


#### 3.2.3. BAE Gear

Since the
interaction is not depending on any fine motor activity, it is possible to let
the SIDH player play the game using the same equipment as in BAE, that is,
coat, trousers, gloves, boots, helmet, and air mask. Due to the look, feel, and
smell of the equipment this may be used to increase the player’s sense of
realism. Since heat has a great influence on both physical and psychological
stress during BAE, there was initially a discussion about placing infrared
heaters on top of the cave. This would result in a realistic heat distribution
which would force the player to crouch in order to decrease heat exposure.
However, the computers and the projectors produced enough heat to make the room
uncomfortably hot. This temperature and the fact that the equipment preserved
the body heat (resulting from the player’s physical effort) led to the decision
that adding more heat would be a disadvantage concerning the entertaining
aspects of the game.The air mask (Figure3) is equipped
with a radio receiver through which instructions from the virtual instructor is
presented. To avoid interfering with the radio frequencies used by SRSA, the
original radio system is replaced by two budget walkie-talkies. The other
walkie-talkie works as a transmitter, which is connected to the internal sound card of the
server. A slight modification of the software makes it possible to direct the
voice of the instructor to this sound card, while all other sound effects are
played back in the regular sound system.Figure 3
Air mask with radio unit.


### 3.3. Level Design

The levels for
SIDH have been created in the Hammer world editor which is included in the Half
Life 2 edition [24]. The Hammer world editor is a powerful tool. Apart from
facilities for easy creation and texturing of elementary building blocks such
as walls, floors, roofs, and ceilings the editor also gives access to a number
of prefabricated models of humans, furniture, and other furnishing items. The
prefabricated items have facilitated development work by reducing the number of
specific models necessary to create for SIDH. Furthermore, the editor supports
the manipulation of light, sound, smoke, and fire to alter environments.The game flow is controlled by timers
and triggers. Triggers are invisible objects which can be used to activate
other objects or events such as, for example, a fire to flare or a new level to
start. As an example, a trigger may be activated when the player approaches it.
All levels in the SIDH game must have a specific setup of triggers and timers
to handle the game flow. Important elements to game functionality are recycled
in all levels, thus reducing the overhead when creating new tracks.13 different levels (Table1) have
been developed in close cooperation with the SRSA. There is also a tutorial in
which the player gets to learn the game and the interaction mode and two bonus
levels. The game covers a variety of flats, warehouses, shops, and industry
facilities to provide a relevant sample of environments for rescue personnel to
train in. Each level provides new challenges with respect to size, complexity,
and smoke. The difficulty is also increased by shorter time limits and the
degree of harm made to the player by smoke and fire. Furthermore, the game
provides challenges in terms of unexpected situations, such as victims hidden
in closets and rooms difficult to locate. Other elements of stress are alarms,
sirens, screaming victims, and explosions.Table 1
Game levels
and their learning objectives.
LevelDescriptionObjective0TutorialTo handle the interaction model and game goals1Two-room apartmentTo get a first contact with the game2Club buildingTo realize that time is limited3GarageTo realize the advantage of crouching in smoke-filled areas4Bonus levelTo get a break5One-room apartmentTo look in closets6Youth hostelTo handle large number of rooms7Office spaceTo handle complex corridor architecture, closet8Grocery storeTo handle areas divided by shelves9Three-room apartmentTo handle heavy fire, closet, and limited time10Large apartmentTo handle extremely limited sight in complex architecture11Basement storage areaTo handle fenced areas filled with junk12Four-room apartmentTo handle doors at unexpected positions13Hotel corridorTo handle numerous identical doors14Butcher shopTo handle veiled areas15Bonus levelTo finish the gameEach level starts with a female
virtual instructor introducing the game task. The virtual instructor’s voice is
personified by an instructor from the SRSA, and the texture of the prefabricated
models has been modified to resemble a real rescue personnel outfit. Each level
ends in a debriefing room (Figure4) where the player receives oral and visual
feedback concerning his/her result.Figure 4
The
debriefing room. The board presents achieved score and an overview of the
premises. The bright fields in the map represent areas visited by the player.A level is completed when all rooms
and areas have been scanned and all victims rescued within time limit and with
preserved player stamina. If the result is unsatisfying, the virtual instructor
will inform the player of this and the player gets a new chance. The number of
trials on each level is maximized to three in order to expose the player to a
variety of environments.When a level is successfully
completed the player will get a score based on the proportion of the facilities
that has been searched, time spent on the task, and whether it was the first,
second, or third trial. If the area covered by the search exceeds 90%, the
player will be awarded a star bonus which will also generate a bonus score on
the following level.


### 3.4. Source Modification

Besides
implementing cave visualization and the interaction model, the source code had
to be modified in order to implement required features and the specialized game
flow. An example of such a modification is concerning the player’s health
level, which is constantly decreasing when acting in smoke-filled areas. When
the player is in the room where the instructor is, that is, outside the hostile
premises, the health level is recharged.Furthermore, a supervising feature
had to be implemented. SIDH is using the game engine’s native functionality for
recording metadata of a game to a file. This makes it possible to review the
game exactly as it appeared on the screen when played. Hence, the feature works
like screen capture except that the recording does not contain any image data,
which requires a lot more storage space. The compact format allows SIDH to
record every game without instantly filling the hard disk.In addition to the native recording
feature, a more specific logging functionality concerning the state and the
activities of the player has been implemented. The player’s position,
orientation, and health level are logged ten times per second, and the markings
are logged when committed. Together with information about the level geometry,
this data is processed by an external tool which has been developed. This tool
creates an orthographic image which shows not only what parts of the level the
player has visited but also what parts actually have been seen. The algorithm
for deciding the player’s sight is based on information about the player’s
orientation, if there is smoke at the current position, the density of the
smoke, and if the player is crouching or not. The image created is loaded into
the game as a texture which is shown in the debrief room described above. The
tool can also be used standalone to present an orthographic animation of the
player’s actions during the game.It is worth mentioning that the
modifications regarding interaction and cave visualization are implemented as
additions to the original game features. Hence, it is possible to play SIDH on
a single PC using standard input devices.


## 3.1. Cave Visualization

The cave is
constructed from standard consumer electronics components. The purpose is to
create a flexible environment for 360 degrees visualizations of, for example,
games and films. The four walls are each 160 cm wide and 210 cm high. The upper
120 cm of the walls consists of screens for rear projection. Each screen is
projected by a standard LCD projector, connected to a PC (Figure1). These
computers are interconnected in an Ethernet network together with another
computer which acts as a server. All five computers are standard gaming PCs
with regular graphics cards. The internal sound card of the server has been complemented
with an external 5.1 sound card which delivers sound to four loudspeakers, one
in each of the corners of the cave (Figure 1).Figure 1
Schematic
view of the cave.Half-Life 2 [24] is a multiplayer
game which means that there is native network functionality for distributing
information about the current state of the game objects. When playing a
multiplayer game, one of the computers acts as a server responsible for
controlling and synchronizing the progress of the game. When a server is
running other computers in the network are able to connect and thereby become
participating instances of the game running on the server.When playing SIDH in the cave, the
actual game, that is, the instance responsible for player input and game logic,
is running on the server computer. The task of the four-client-computers is to
visualize the game running on the server, why the clients always have to be
updated about the player’s position and the state of the world. To achieve
this, a native multiplayer feature called spectator mode is used. The original
purpose of this feature is to make it possible for connected, but nonparticipating,
clients to automatically follow and observe an active player. In that manner,
the instances of the game running on the cave computers are observers, following
the player on the server and hence showing the same view as the server without
actually interacting with the game. The screens of the cave are however not to
be clones of the server screen. Instead, they should present the world in four
different directions, one direction for each screen, with the same origin as
the server player. In the implementation, the game view is defined by a camera
which acts as the eyes of the player (or the spectator). The position and
orientation of this camera decides what is shown on the screen. By setting the
orientation of a client’s camera to a certain fixed direction, the client view
will always show the world from that angle, regardless of the player
orientation. Each view is thus rotated 90 degrees with respect to the adjacent
screens. To produce the final 360 degree projection in the cave, the field-of-view
(FOV) for the cameras was adjusted to 90 degrees. This is important since two
adjacent views will overlap with a greater FOV value, and with a lesser value
all parts of the world will not be visible at the same time.


## 3.2. Interaction Model

One of the
goals with SIDH has been to make the player’s interaction with the game as
natural as possible. The player has to be able to move and look around in the
virtual world, crouching as well as in a raised position. Moreover, it has to
be possible to pick up and drop victims and control the game flow.


### 3.2.1. Navigation

One problem with
navigating in a cave environment is the lack of obvious directions in terms of
forward, backward, left, and right. Normally, when playing a first-person game,
forward is defined by the center of the display, that is, the direction in
which the player is currently looking. Pressing the forward key on the keyboard
will always move the player in the desired direction since the world is
rotating around the player and the keyboard. In the cave, however, it is not
possible to use a single forward key since the directions are fixed to the real
world. Hence, in order to decide what direction is forward for a cave player it
is necessary for the software to keep track of the player’s current
orientation. In SIDH, this problem is solved by using a GameTrak [25], which is
an USB device working as a joystick with a string to pull as Z-axis. The
GameTrak [25] is placed centered in the top of the cave, top down, with the
string attached to the fogfighter nozzle (Figure 2). In this way, the nozzle’s
position in 3D space can be calculated. Since there may be some discrepancy
between the direction expected by the player and the calculated direction (due
to player deviation from the center of the cave), the calculated forward
direction is visualized as a marker on the screens.Figure 2
The
string of the GameTrak (top right) is attached to
the fogfighter nozzle (bottom right). N.B., only one of the GameTrak’s [25] two controls is
used.SIDH also calculates the nozzle’s
distance to the floor in order to decide whether the player is crouching (to
increase the sight in smoke-filled areas) or not. Since a low position is
depending on the player’s height, the crouching
threshold is dynamically adapted based on the highest nozzle position recorded
during a mission. The information about the distance to the floor is also used
to record so called markings. A marking is done by touching the floor with the
nozzle, and is an action with different meanings in different phases of the
game:(i)
to start the game in the
beginning of a level,(ii)
to pick up found victims,(iii)
to drop rescued victims,(iv)
to confirm a completed
search task.


### 3.2.2. Movement

For the player
to be able to move inside the cave, a device named Stepometer has been
developed. The idea with the Stepometer is that the player moves forward in the
game by walking or running on the spot. The device consists of two
accelerometer-based sensors which are attached to the player’s feet, and a
central unit processing the sensor signals and reporting steps to the server
computer. The central unit is based on the Atmega8 microprocessor which, among
other advantages, has native support for RS232 serial communication. The
Stepometer is using this protocol over Bluetooth for wireless communication
with the server computer.A physical-based model is used to compute the speed,v, of the
player. The updating of player speed is handled in the main loop of the game
and the delay since last update is given by dt. For each update, the
algorithm determines if the player has taken a step since last update, denoted
with s. With s=1 the player has taken a step and with s=0 no step has been taken. The Stepometer has a sensor for each leg and the player
has to alternate between left and right leg for the steps to be recorded. For
each recorded step, the player speed is increased with an impulse, Istep, which is computed based on the players speed:(1)Istep=Imax−k1*vwherek1isaconstant.This means that speed will increase quickly when the player starts to
move, but as the speed increases each step will give a smaller and smaller
contribution. The maximum speed of a player is hence given byImax/k1.The player speed is, in addition, decreased by a damping force,Idamp,
proportional to the delay since the last step, denoted tprev.
The damping is given by(2)Idamp=tprev2*k2*dtwherek2isaconstant.The quadratic nature ofIdamp implies that
the damping is very low when steps are frequent but the damping grows quickly
when the player stops moving. The speed is never allowed to become negative.Combining the above, the speed is updated according to the following
formula:(3)v(t+dt)=max[0,s*(Imax−k1*vt)+tprev2*k2*dt].When the player is crouching the
speed is divided by 2, which means that the step frequency has to be higher
compared to when in a raised position, in order to keep up the speed. When
carrying a victim, the speed is divided by 4, why the step frequency has to be
very high for the player to advance forward. This results in a significant increase
of the physical strain, in analogy with carrying a victim in a real situation.


### 3.2.3. BAE Gear

Since the
interaction is not depending on any fine motor activity, it is possible to let
the SIDH player play the game using the same equipment as in BAE, that is,
coat, trousers, gloves, boots, helmet, and air mask. Due to the look, feel, and
smell of the equipment this may be used to increase the player’s sense of
realism. Since heat has a great influence on both physical and psychological
stress during BAE, there was initially a discussion about placing infrared
heaters on top of the cave. This would result in a realistic heat distribution
which would force the player to crouch in order to decrease heat exposure.
However, the computers and the projectors produced enough heat to make the room
uncomfortably hot. This temperature and the fact that the equipment preserved
the body heat (resulting from the player’s physical effort) led to the decision
that adding more heat would be a disadvantage concerning the entertaining
aspects of the game.The air mask (Figure3) is equipped
with a radio receiver through which instructions from the virtual instructor is
presented. To avoid interfering with the radio frequencies used by SRSA, the
original radio system is replaced by two budget walkie-talkies. The other
walkie-talkie works as a transmitter, which is connected to the internal sound card of the
server. A slight modification of the software makes it possible to direct the
voice of the instructor to this sound card, while all other sound effects are
played back in the regular sound system.Figure 3
Air mask with radio unit.


## 3.2.1. Navigation

One problem with
navigating in a cave environment is the lack of obvious directions in terms of
forward, backward, left, and right. Normally, when playing a first-person game,
forward is defined by the center of the display, that is, the direction in
which the player is currently looking. Pressing the forward key on the keyboard
will always move the player in the desired direction since the world is
rotating around the player and the keyboard. In the cave, however, it is not
possible to use a single forward key since the directions are fixed to the real
world. Hence, in order to decide what direction is forward for a cave player it
is necessary for the software to keep track of the player’s current
orientation. In SIDH, this problem is solved by using a GameTrak [25], which is
an USB device working as a joystick with a string to pull as Z-axis. The
GameTrak [25] is placed centered in the top of the cave, top down, with the
string attached to the fogfighter nozzle (Figure 2). In this way, the nozzle’s
position in 3D space can be calculated. Since there may be some discrepancy
between the direction expected by the player and the calculated direction (due
to player deviation from the center of the cave), the calculated forward
direction is visualized as a marker on the screens.Figure 2
The
string of the GameTrak (top right) is attached to
the fogfighter nozzle (bottom right). N.B., only one of the GameTrak’s [25] two controls is
used.SIDH also calculates the nozzle’s
distance to the floor in order to decide whether the player is crouching (to
increase the sight in smoke-filled areas) or not. Since a low position is
depending on the player’s height, the crouching
threshold is dynamically adapted based on the highest nozzle position recorded
during a mission. The information about the distance to the floor is also used
to record so called markings. A marking is done by touching the floor with the
nozzle, and is an action with different meanings in different phases of the
game:(i)
to start the game in the
beginning of a level,(ii)
to pick up found victims,(iii)
to drop rescued victims,(iv)
to confirm a completed
search task.


## 3.2.2. Movement

For the player
to be able to move inside the cave, a device named Stepometer has been
developed. The idea with the Stepometer is that the player moves forward in the
game by walking or running on the spot. The device consists of two
accelerometer-based sensors which are attached to the player’s feet, and a
central unit processing the sensor signals and reporting steps to the server
computer. The central unit is based on the Atmega8 microprocessor which, among
other advantages, has native support for RS232 serial communication. The
Stepometer is using this protocol over Bluetooth for wireless communication
with the server computer.A physical-based model is used to compute the speed,v, of the
player. The updating of player speed is handled in the main loop of the game
and the delay since last update is given by dt. For each update, the
algorithm determines if the player has taken a step since last update, denoted
with s. With s=1 the player has taken a step and with s=0 no step has been taken. The Stepometer has a sensor for each leg and the player
has to alternate between left and right leg for the steps to be recorded. For
each recorded step, the player speed is increased with an impulse, Istep, which is computed based on the players speed:(1)Istep=Imax−k1*vwherek1isaconstant.This means that speed will increase quickly when the player starts to
move, but as the speed increases each step will give a smaller and smaller
contribution. The maximum speed of a player is hence given byImax/k1.The player speed is, in addition, decreased by a damping force,Idamp,
proportional to the delay since the last step, denoted tprev.
The damping is given by(2)Idamp=tprev2*k2*dtwherek2isaconstant.The quadratic nature ofIdamp implies that
the damping is very low when steps are frequent but the damping grows quickly
when the player stops moving. The speed is never allowed to become negative.Combining the above, the speed is updated according to the following
formula:(3)v(t+dt)=max[0,s*(Imax−k1*vt)+tprev2*k2*dt].When the player is crouching the
speed is divided by 2, which means that the step frequency has to be higher
compared to when in a raised position, in order to keep up the speed. When
carrying a victim, the speed is divided by 4, why the step frequency has to be
very high for the player to advance forward. This results in a significant increase
of the physical strain, in analogy with carrying a victim in a real situation.


## 3.2.3. BAE Gear

Since the
interaction is not depending on any fine motor activity, it is possible to let
the SIDH player play the game using the same equipment as in BAE, that is,
coat, trousers, gloves, boots, helmet, and air mask. Due to the look, feel, and
smell of the equipment this may be used to increase the player’s sense of
realism. Since heat has a great influence on both physical and psychological
stress during BAE, there was initially a discussion about placing infrared
heaters on top of the cave. This would result in a realistic heat distribution
which would force the player to crouch in order to decrease heat exposure.
However, the computers and the projectors produced enough heat to make the room
uncomfortably hot. This temperature and the fact that the equipment preserved
the body heat (resulting from the player’s physical effort) led to the decision
that adding more heat would be a disadvantage concerning the entertaining
aspects of the game.The air mask (Figure3) is equipped
with a radio receiver through which instructions from the virtual instructor is
presented. To avoid interfering with the radio frequencies used by SRSA, the
original radio system is replaced by two budget walkie-talkies. The other
walkie-talkie works as a transmitter, which is connected to the internal sound card of the
server. A slight modification of the software makes it possible to direct the
voice of the instructor to this sound card, while all other sound effects are
played back in the regular sound system.Figure 3
Air mask with radio unit.


## 3.3. Level Design

The levels for
SIDH have been created in the Hammer world editor which is included in the Half
Life 2 edition [24]. The Hammer world editor is a powerful tool. Apart from
facilities for easy creation and texturing of elementary building blocks such
as walls, floors, roofs, and ceilings the editor also gives access to a number
of prefabricated models of humans, furniture, and other furnishing items. The
prefabricated items have facilitated development work by reducing the number of
specific models necessary to create for SIDH. Furthermore, the editor supports
the manipulation of light, sound, smoke, and fire to alter environments.The game flow is controlled by timers
and triggers. Triggers are invisible objects which can be used to activate
other objects or events such as, for example, a fire to flare or a new level to
start. As an example, a trigger may be activated when the player approaches it.
All levels in the SIDH game must have a specific setup of triggers and timers
to handle the game flow. Important elements to game functionality are recycled
in all levels, thus reducing the overhead when creating new tracks.13 different levels (Table1) have
been developed in close cooperation with the SRSA. There is also a tutorial in
which the player gets to learn the game and the interaction mode and two bonus
levels. The game covers a variety of flats, warehouses, shops, and industry
facilities to provide a relevant sample of environments for rescue personnel to
train in. Each level provides new challenges with respect to size, complexity,
and smoke. The difficulty is also increased by shorter time limits and the
degree of harm made to the player by smoke and fire. Furthermore, the game
provides challenges in terms of unexpected situations, such as victims hidden
in closets and rooms difficult to locate. Other elements of stress are alarms,
sirens, screaming victims, and explosions.Table 1
Game levels
and their learning objectives.
LevelDescriptionObjective0TutorialTo handle the interaction model and game goals1Two-room apartmentTo get a first contact with the game2Club buildingTo realize that time is limited3GarageTo realize the advantage of crouching in smoke-filled areas4Bonus levelTo get a break5One-room apartmentTo look in closets6Youth hostelTo handle large number of rooms7Office spaceTo handle complex corridor architecture, closet8Grocery storeTo handle areas divided by shelves9Three-room apartmentTo handle heavy fire, closet, and limited time10Large apartmentTo handle extremely limited sight in complex architecture11Basement storage areaTo handle fenced areas filled with junk12Four-room apartmentTo handle doors at unexpected positions13Hotel corridorTo handle numerous identical doors14Butcher shopTo handle veiled areas15Bonus levelTo finish the gameEach level starts with a female
virtual instructor introducing the game task. The virtual instructor’s voice is
personified by an instructor from the SRSA, and the texture of the prefabricated
models has been modified to resemble a real rescue personnel outfit. Each level
ends in a debriefing room (Figure4) where the player receives oral and visual
feedback concerning his/her result.Figure 4
The
debriefing room. The board presents achieved score and an overview of the
premises. The bright fields in the map represent areas visited by the player.A level is completed when all rooms
and areas have been scanned and all victims rescued within time limit and with
preserved player stamina. If the result is unsatisfying, the virtual instructor
will inform the player of this and the player gets a new chance. The number of
trials on each level is maximized to three in order to expose the player to a
variety of environments.When a level is successfully
completed the player will get a score based on the proportion of the facilities
that has been searched, time spent on the task, and whether it was the first,
second, or third trial. If the area covered by the search exceeds 90%, the
player will be awarded a star bonus which will also generate a bonus score on
the following level.


## 3.4. Source Modification

Besides
implementing cave visualization and the interaction model, the source code had
to be modified in order to implement required features and the specialized game
flow. An example of such a modification is concerning the player’s health
level, which is constantly decreasing when acting in smoke-filled areas. When
the player is in the room where the instructor is, that is, outside the hostile
premises, the health level is recharged.Furthermore, a supervising feature
had to be implemented. SIDH is using the game engine’s native functionality for
recording metadata of a game to a file. This makes it possible to review the
game exactly as it appeared on the screen when played. Hence, the feature works
like screen capture except that the recording does not contain any image data,
which requires a lot more storage space. The compact format allows SIDH to
record every game without instantly filling the hard disk.In addition to the native recording
feature, a more specific logging functionality concerning the state and the
activities of the player has been implemented. The player’s position,
orientation, and health level are logged ten times per second, and the markings
are logged when committed. Together with information about the level geometry,
this data is processed by an external tool which has been developed. This tool
creates an orthographic image which shows not only what parts of the level the
player has visited but also what parts actually have been seen. The algorithm
for deciding the player’s sight is based on information about the player’s
orientation, if there is smoke at the current position, the density of the
smoke, and if the player is crouching or not. The image created is loaded into
the game as a texture which is shown in the debrief room described above. The
tool can also be used standalone to present an orthographic animation of the
player’s actions during the game.It is worth mentioning that the
modifications regarding interaction and cave visualization are implemented as
additions to the original game features. Hence, it is possible to play SIDH on
a single PC using standard input devices.


## 4. Fidelity in SIDH

This section reports on the results
of an analysis of the perceived usefulness of the game as a training tool with
respect to its fidelity. Data was collected from 32 students and one teacher
during spring of 2008.
The students participated in two questionnaires; the first one asked them about
their expectations on simulator training and the second one captured their
opinion after the simulator session. We observed training sessions for 11
students and carried out interviews with 10 students. Finally, the teacher in
charge of the training sessions was interviewed. All data was compiled and we
used a qualitative analysis approach to categorize it [26]. We focus on the
aspect of fidelity even though complementary data was collected.In the first questionnaire we asked
a set of general questions concerning general data such as age and gender. We
also asked the following questions (translated from Swedish). “How much do you
play computer games on your spare time? How big is your experience from
computer games? Do you think that it is possible to learn things from computer
games? What is your prior knowledge of BAE entry? What is your prior knowledge
of simulator training? In what ways do you think that simulator training can
affect your performance in live exercises? In what other ways do you think that
games and simulators can be used in your training?”In the follow-up questionnaire: we
asked the students questions about how their perception of the concept had
changed. We also asked the following questions about their perception of the
sessions and the usefulness of the simulator (translated form Swedish). “To
what extent is fidelity important for the simulator to be useful? In which
situations should simulator training be used? Would you consider using the
simulator off-hours? What did you learn from your sessions? Did you learn
anything which was useful during the live exercises? Do you think that the
effect would be the same form playing in a single screen mode on a PC? What is
the teacher’s role during simulator training?”The interviews were carried out following
an interview guide which was adapted depending on the answers from the
questionnaire. The questions concerned the participants’ opinions on transfer
(i.e., to what extent can knowledge from the simulator sessions be transferred
to other situations?); fidelity (i.e., how did the participants perceive the
simulator sessions with respect to the fidelity measures identified?), and
motivation (i.e., in what ways can games and simulators affect motivation for
training in a general sense?).Fidelity is perceived to be a
crucial part for the learning aspect and a high level of fidelity is necessary
for the simulator to work in a proper way. We also claim that there is a
connection between the construction of the simulator and what level of
seriousness it will be perceived to have. One student argued that the higher
the fidelity, the higher is the chance to learn something properly. Another
student argues that a high level of fidelity supports the learning since it
constitutes a chance to operate in a “close to real life” environment. In
general, there was a positive perception of SIDH in terms of graphical
appearance, sound, and user interaction. However, the teacher, being more
conscious about the limitations of fidelity, was more inclined to see it as a
complementary tool to live training. He highlights the fact that SIDH is useful
to mediate search strategies for different types of environments.The psychological strain was an
important learning factor during the simulator training sessions. The students
maintained that they learned how they, as individuals, react under stress and
time pressure, and that the simulator sessions require concentration and
presence of mind. Our findings also indicate that the simulator sessions
require the person to be structured and calm during the minutes that they spend
in the simulator. This is one important aspect of correctly carrying out a
search strategy. Hence, our results indicate psychological fidelity in that the
simulator recreates some of the stress and time pressure present in the
original task. Game features, such as time pressure and pressure of saving
lives, may hence be utilized to increase psychological fidelity.One student suggested that
simulator sessions should be used between the theoretical parts of the course
and live training. He claimed that by doing this the student would be given a
smoother transitional stage between the two parts. From a pedagogical
perspective it makes sense that the students prepare for live training in order
to increase its quality. This approach helps the students to get better results
in live training since they got a chance to practice the procedure (i.e.,
technique for scanning a fire area) in virtual reality first. The majority of
the students also claimed that the foremost thing they had learned in the
simulator was a strategy for scanning a fire area.The generation of smoke in SIDH has
some resemblance to real smoke behavior [27]. The smoke will actually fill the
room from the ceiling and down making it necessary to crouch in order to get a
better view. Even though visually similar some of the participants commented
negatively on the naturalness of the smoke claiming that sight was actually too
good. One potentially negative aspect of this is that the students tend to
trust visual stimuli at the expense of tactile stimuli, which is actually a
poor strategy in many cases.SIDH is a fix-based system with
multiple screens which means that the virtual world is fixed and the player
uses her/his sense of direction to navigate as opposed to a single-screen
solution where the player sits still and the virtual world rotates. This
feature, to some extent, adds to immersion. A majority of the observed
participants felt a sense of misdirection and got lost.The interaction mode of SIDH adds
to the physical fidelity to some extent as game sessions become physically
straining. The current version of SIDH does not utilize heat which would add to
physical fidelity. However, as the participants wore full turn-out gear during the experiment some similarity to the real task was achieved. A majority of the participants experienced physical strain.


## 5. Conclusion

The main
contribution from the presented work is a training simulator with good enough
fidelity developed with relatively simple means. We have demonstrated the
feasibility and usefulness of an architecture for a game-based immersive
training simulator (Table2). The novel interaction mode adds to immersion by
introducing physical aspects into the game. We have also shown that inherent
game functionality can be used and extended to create a variety of levels with
distinct learning goals. Specific logging functionality concerning the state
and the activities of the player has been implemented. This feature adds to the
pedagogical usefulness of the system.Table 2
Architectural
features of SIDH.
Cave visualization–
Flexible
system wrt screens and software–
Utilizing
native functionality in softwareInteraction model–
Fixed-based
system–
Track of current
orientation and distance from ceiling–
Stepometer
with Bluetooth communication–
Physical-based
model to compute speed–
Original
task equipment (including radio communication)Level design– Utilizes
native editor– Timers and
triggers to control game flow–
Levels with
distinct learning objectivesSource mod– Expanding
native functionality to better suit the training taskSIDH is a firefighter training
game, which, according to personnel and students of SRSA, is entertaining as
well as effective regarding learning of the intended tasks [28].One important aspect of the
usefulness of a game-based simulator is the level of fidelity. It is important
that the fidelity is in line with the intentions of how the simulator should be
used. A reasonable level of fidelity is enough in situations where the (game-based)
simulator constitutes a complement to other exercises. This is the situation
with SIDH. Its main goal is to teach search strategies, that is, a demarcated
part of the entire BAE task. Table3 sums up how fidelity was perceived.Table 3
Fidelity
of SIDH features.
Physical fidelity– Visualization
and immersion by multiple screens– Fixed-based
system navigation– Physical
strain– Smoke
behavior requiring low positionPsychological
fidelity– Stress– Time
pressure– Resource
managementFunctional
fidelity– Search
strategiesThe focus on search strategies and
the ability to orient in unknown premises were regarded as the most important
gains from simulator training, due to the limited possibility of varying
physical premises in the real world. Using the Hammer world editor to create
premises for SIDH, the options are virtually unlimited.



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*Source: 472672-2009-03-17.xml*