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ACTIVITY-ORIENTED CONTEXT MODEL FOR ADAPTIVE MOBILE GIS SYSTEM DESIGN
ABSTRACT
Mobile GIS has been used to support many human activities such as tourism, navigation, and crisis management. One of the challenges of dealing with mobility is the continuous change of contexts, which requires the system to be adaptive. Despite considerable research efforts in context adaptation in the mobile map services, there remain a number of limitations. First, context models are inadequate in a sense that they merely deal with physical factors and fail to take into account the dynamics of cognitive factors. Second, the adaptation mechanisms for geovisualization often deal with context changes in isolation to user’s activity resulting in missing the target of adaptation.
In this study, I believe that geovisualization should be situated in user’s ongoing activities and dynamically present the most relevant information to the user. This thesis advances the science of context-adaptive map services in two related areas. First, I describe an activity-oriented context model and its computational representation based on the theories of situated activity and SharedPlan. The model binds contextual factors with the plans of the ongoing activity and enables the system to reason the effect of a context change on the advances of the whole activity.
Second, I present a method to adapt cartographic visualization based on the above context model. The principles of adapting a mobile map to context change are demonstrated through an analysis of a hypothetical scenario.
Table of Contents
LIST OF FIGURES v
LIST OF TABLES vi
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Statement of the Problem 2
1.3 Objective 3
1.3 Method and Expected Outcome 4
1.4 Thesis Outline 5
Chapter 2 State of the Art 6
2.1 Adaptation and Adaptive mobile system 6
2.2 Adaptive mobile GIS system 8
2.2.1 Mobile activity 8
2.2.2 Mobile Contexts and Context Awareness 9
2.2.3 Adaptation objects 15
2.2.4 Adaptation process 15
2.3 Conclusion 17
Chapter 3 Methodology 19
3.1 Understanding Mobile Activities 19
3.2 Modeling Mobile Activities as SharedPlan 21
3.3 PlanGraph-Based Context Model 23
3.3.1 Structure of the PlanGraph 23
3.3.2 PlanGraph-based context capturing 26
3.3.3 PlanGraph-based context reasoning 26
3.4 PlanGraph-based Adaptive Mobile GeoVisualization Process 27
3.4.1 Basic structure of PlanGraph for mobile visualization 28
3.4.2 PlanGraph-based adaptive geovisualization 29
3.5 The Architecture for System implementation 36
Chapter 4 A Sample Scenario of Adaptive Mobile Adaptation 39
4.1 Deliberation of scenario 39
4.2 Mobile GIS Adaptation Process Based on PlanGraph 45
4.3 Summarization of the scenario 59
Chapter 5 Conclusion 60
5.1 Research Summery 60
5.2 Research Contribution 61
5.3 Future Study and Discussion 62
5.4 Conclusion 62
Bibliography 63
LIST OF FIGURES
Figure 2-1: Basic structure of adaptation system ………………………………………………………….. 7
Figure 2-2: Topologies of context for mobile cartography usage ……………………………………. 10
Figure 3-1: Structure of Activity Theory……………………………………………………………………… 20
Figure 3-2: The hierarchical components of activity……………………………………………………… 21
Figure 3-3: A collaborative paradigm of human computer interaction…………………………….. 24
Figure 3-4: Structure of a PlanGraph. …………………………………………………………………………. 29
Figure 3-5: Structure of a PlanGraph for mobile visualization. ………………………………………. 31
Figure 3-6: Action-based rules for selection of layers. ………………………………………………….. 33
Figure 3-7: Formalization of action-based rule…………………………………………………………….. 33
Figure 3-8: Action-based rules for selection of layers. ………………………………………………….. 34 Figure 3-9: Formalization of activity-based rule…………………………………………………………… 35
Figure 3-10: Constraint-based rules for selection of layers…………………………………………….. 35
Figure 3-11: Formalization of constraint-based rule……………………………………………………… 36
Figure 3-12: Basic architecture of adaptive mobile GIS system……………………………………… 37
Figure 4-1: The process of interactions between Jim and the system. ……………………………… 40
Figure 4-2: Map for selecting touring actions ………………………………………………………………. 46
Figure 4-3: Default map for selection of an attraction. ………………………………………………….. 47
Figure 4-4: A map for selection of landmarks………………………………………………………………. 48
Figure 4-5: Adaptive mobile visualization for selecting the restaurant…………………………….. 49
Figure 4-6: Adaptive mobile visualization for selecting the transportation mode. …………….. 50
Figure 4-7: An adaptive map for selecting the bus route. ………………………………………………. 51
Figure 4-8: The default map for identifying a food type………………………………………………… 54
Figure 4-9: An adaptive map to identify a restaurant…………………………………………………….. 56
Figure 4-10: An adaptive map to identify the transportation mode. ………………………………… 57 Figure 4-11: An adaptive mobile visualization for selecting a sidewalk. …………………………. 58
LIST OF TABLES
Table 2-1: A Summery of Current Adaptive Mobile GIS System. ………………………………….. ….17
Chapter 1
Introduction
1.1 Motivation
Mobile GIS system is an integrated software/hardware framework for accessing geospatial data and services through wireless network (Tsou, 2004). It brought a whole new variety of possibilities of utilizing geospatial information to support real-time mobile activities. could range from basic information services that merely present location-based information to more complex ones that provide functional spatial-related analysis. Currently, the main applications of Location-Based Services include tourism, navigation and crisis management. Despite the great potential of mobile GIS system in supporting multiple user mobile activities, the design of mobile GIS remains to be a difficult task due to the mobility of users, the restriction of mobile devices, the difference contexts of users, and the various user profiles and requirements. To address this challenge, adaptive mobile GIS, as a new field of research, has gained increasing attention from multiple research disciplines, including Geographical
Information Science (GIS), Cartography, Artificial Intelligence (AI) and Human Computer Interaction (HCI); and the knowledge from these disciplines needs to be combined in order to pursue the approach of designing a well-behaved adaptive mobile GIS system.
1.2 Statement of the Problem
Context awareness is a key feature of adaptive mobile GIS system. It refers to the idea that the system should be aware of and adapt to context factors that are related to the ongoing activity. Towards context awareness, considerable efforts have been made to develop mechanisms to capture and model context (Strang & Linnhoff-Popien, 2004). Most of them focus on isolated context factors of single actions but fail to consider the effects of these contexts to the whole embedded activity. As a result, the adaptation is likely to be simple and rigid and the target of the whole activity is missed during the process of adaptive geovisualization. To address this challenge, several research questions need to be answered.
- What is the scope of context that should be considered for mobile context adaptation? Context is information describing the situation of an entity. Two main categories of context include environmental and human context. So far, many context factors have been recognized and utilized for mobile context adaptation, such as location, human preference and history. However, besides of these well-known and frequently used contextual factors, I assume other context should also be important for consideration. As mobile activities are always driven and influenced by cognitive states of mobile users, I regards human cognitive state can be an important piece of context for mobile adaptation.
- How to capture key context factors and model them in computational system? The usage of context should be analyzed under certain situations. For an activity, there are potentially a large number of factors influencing the accomplishment of an activity. It is important to understand how to select and model those significant contextual factors according to the activity in focus.
- How to utilize context for adaptive geovisualization? Geovisualization is an integral component of mobile GIS system. It should be adaptive to the continuously changing context and presents geo-related information according to the current state of an activity. Due to different context surroundings related to an activity, the information to provide to the user should be adaptive and dynamically changing. As for geovisualization, it is important to know how to provide appropriate geographical information for mobile users.
1.3 Objective
The main object of this study is to generate tailored visual representations to support ongoing user activities. Current systems have not been fully developed to achieve this goal, because their adaptations focus on environmental context but rarely consider the target of the activity (Abowd, et al, 1997; Amendola, et al, 2004; Malaka and Zipf, 2000; Pospischil, 2002). By maintaining the context awareness of ongoing activities, this study aims to make an improvement to generate activity-situated visual representation. To approach this main goal, several sub-objectives can be identified corresponding to the identified questions:
- Human intention should be captured and modeled as a piece of context for adaptation to an activity. During a mobile activity, context continuously changes including both environmental and human context. It is important to detect this change to trigger the process of context adaptation. Human intentions help the system to be aware of the influence of the change to the activity. By capturing human intentions, the system can better understand the user’s requirement and hence enables itself to select appropriate strategies for adaptation.
- An activity-oriented context modeling mechanism should be developed to maintain the awareness of the ongoing activities. Single actions are always embedded in activities and their executions should be conducted according to the current state of activity. An action should comply with updated constraints of the activity, such as time left for the rest of the activity.
Besides, its execution should consider the influence from previous/subsequent actions. Therefore, to support adaptation to a current action, the adaptive system should be capable of tracking the whole activity and maintain the updated contextual information of activities.
- An adaptive methods for geovisualization should be developed based on activityoriented context model and generate tailored visual representations. To support the user activity, it is essential for the system to provide appropriate geographical contents to the user at real-time. From this standpoint, this study will work on the selection of layers, that is, what geographical content should be provided to mobile users to support their activities.
1.3 Method and Expected Outcome
To approach the objectives, this study follows two steps. First, an activity-oriented context model is developed with supports from two theories: 1) Activity theory is used to understand the mobile activity. It introduces the hierarchical structure of mobile activity; declares mobile activity as a goal-directed developmental process; and helps identify the related context factors of the mobile activity. 2) Then, coherent to Activity Theory, the SharedPlan theory is utilized to model the mobile activity in computational system. By adopting a mental state view, it helps the system to analyze and capture both environment and human context according to the
activity.
Based on the activity-oriented context model, the adaptive geovisualization can be achieved through a rule-based approach. According to the rules, the contextual information in the context model can be linked to the decision-making of the geovisualization. The system can obtain the information through tracing back the context model and the rule is selected by matching the obtained information with the conditions of the rule. In the large scope of issues of geovisualization, this study focuses on the adaptive selection of geographical content (map layers) for the activity; so specific rules are designed for selecting the layers.
According to method of activity-centric adaptation supported by the context model, the process of geovisualization is expected to be coherent with the ongoing activity, dynamically adapt its geographical content to the user’s need at real-time.
1.4 Thesis Outline
This thesis is organized into five chapters. Chapter 1 (this chapter) aims to provide a big view of this study. It identifies the research question; illustrates the object of this study; and briefly demonstrates the method and expected outcome.
Chapter 2 reviews the related studies to this work. A basic structure of adaptive system is introduced, and based on it, an in-depth discussion on existing adaptive mobile GIS system are made to demonstrate why the existing approaches of adaptation among the systems are insufficient to support user mobile activities.
Chapter 3 describes the method of activity-oriented context adaptation for mobile geovisualization. Activity theory and SharedPlan theory are introduced to build an activityoriented context model. Then based on the model, the process of adaptive geovisualization is illustrated.
Chapter 4 introduces a scenario to test the feasibility of this study and demonstrates the advantages of this study compared to existing ones.
Finally, Chapter 5 makes a conclusion of this study with suggestion for future research.
