PhD Thesis of Andreas Dieberger (andreas.dieberger@acm.org)
Navigation in Textual Virtual Environments using a City Metaphor

[Contents]--[Abstract]--[1]--[2]--[3]--[4]--[5]--[6]--[7]--[8]--[References]

Navigation in Textual Virtual Environments using a City Metaphor

Andreas Dieberger

A thesis submitted in partial fulfillment of the requirements for the degree of

Doctor of Technical Sciences

Submitted at the Vienna University of Technology
Faculty of Technology and Sciences
November, 1994

advisers:

Univ.Prof. Dr. Peter Fleissner
Department for Design and Assessment of Technology

Univ.Prof. Dr. Andreas Frank
Department for Geoinformation

Vienna, November 1994

About this thesis

This PhD thesis was finished in Fall 1994. After getting a number of requests for it I took the time to put the whole thing on the Web. I did it in a more or less quick and dirty fashion. It still took quite some time to do it but some formatting mistakes may have happened. If you find severe mistakes, please let me know. Please let me know if you like or dislike the thesis, and why.

Note: I split the thesis into 10 Webpages, each of which contains one chapter. Some of the chapters are quite long and contain many figures of significant size. If you have a slow connection you may want to disable automatic image loading and selectively load those pictures you really want to see.

Also note that this is the complete thesis. The only reason that some chapters are not linked in the table of contents is that I was to lazy to create links for every little sub-chapter. Use your scrollbar -- that's what it's there for :)

A pdf version of the thesis is accessible on my other Web site. [go there]

Enjoy, and happy reading.

Andreas Dieberger, 10/31/96 (5/2000, 4/2001)

Note: This thesis is © Andreas Dieberger, 1994, 2000

Abstract
Acknowledgements
1. Introduction	7
1.1. Spatialization of user interfaces	7
1.2. Researching navigation in a textual virtual environment	9
1.3. Ontology of environmental terms	10
1.4. Structure of this thesis	11
2. Spatial cognition of humans	13
2.1. What is "space"?	13
2.1.1. Philosophical and physical concepts of space	13
2.1.2. The mathematical view of space	14
2.2. Spatial perception	18
2.2.1. Experiencing space using vision	18
2.2.2. Experiencing space using different senses	19
2.2.3. Experiencing space using abstractions and language	20
2.3. Spatial memory	23
2.3.1. Cognitive maps	23
2.3.2. Cognitive collage	24
2.3.3. Spatial mental models	25
2.3.4. The TOUR model	25
2.3.5. Distortions in spatial memory	25
2.4. Navigation as an activity in space	26
2.5. Conclusion	27
3. The city as an area of spatial experience	28
3.1. The navigational task in a city	28
3.2. Elements of the city environment according to Lynch	31
3.2.1. Paths	32
3.2.2. Edges	34
3.2.3. Nodes	35
3.2.4. Districts	36
3.2.5. Landmarks	37
3.2.6. Combinations of city elements	38
3.3. Communicative and social aspects of the environment	40
3.3.1. The environment as information carrier	40
3.3.1.1. Knowledge in the world and Writing on the world	41
3.3.1.2. Unmistakable form	42
3.3.1.3. Navigational infrastructure	43
3.3.1.4. Change in the city environment	44
3.3.2. Communicating about the environment	45
3.3.3. Social aspects of space	45
3.4. Summary of the city environment	48
3.4.1. Structural objects and functionality	48
3.4.2. Information providers	50
3.4.3. Transportation	50
3.4.4. Communication	51
3.4.5. Limits of this environment	51
3.5. Conclusion	52
4. User interfaces and their spatialization	54
4.1. The navigation task in computer systems	54
4.2. The user interface	55
4.2.1. Text-based user interfaces	55
4.2.2. Graphical user interfaces	55
4.2.3. Principles of modern user interfaces	56
4.2.4. User interface metaphors	56
4.2.4.1. The user interface metaphor as a mapping	57
4.2.4.2. Richness in user interface metaphors	59
4.2.4.3. Magic features in user interface metaphors	60
4.3. Spatial user interfaces	61
4.3.1. Why every user interface is an environment	61
4.3.2. The meaning of spatialization	61
4.3.3. Advantages of spatialization	62
4.3.4. Review of spatialized user interfaces and their metaphors	62
4.4. Virtual environments and virtual reality systems	65
4.4.1. Graphical virtual environments	66
4.4.2. Textual virtual environments	68
4.4.3. Non-visual virtual environments	68
4.5. Conclusion	69
5. Navigation in computer environments	70
5.1. Hypertext and Hypermedia	70
5.2. Navigational problems in computer environments in general	74
5.3. The Information City metaphor	76
5.3.1. Overview of the Information City metaphor	76
5.3.2. Metaphorical mapping from a real to a virtual city	78
5.4. Open questions in the Information City	83
5.5. Conclusion	83
6. A study about navigation in a virtual environment	84
6.1. Research in text-based spatial user interfaces	84
6.2. The MUD used in the case study	85
6.2.1. The navigational task in MUDs	85
6.2.2. The center of Igor	87
6.2.3. Areas around the center	89
6.2.4. Navigational problems in MUDs	90
6.3. The study	94
6.3.1. MUD questionnaires	95
6.3.2. MUD interviews	96
6.3.2.1. Realization	96
6.3.2.2. The results	101
6.3.2.3. Pro and Con of the interview approach	104
6.4. Summary	105
7. Interpretation of results	107
7.1. The space concept in the MUD	107
7.1.1. Overall structure	107
7.1.2. Local structure	108
7.1.2.1. The triangulation theorem	108
7.1.2.2. Overlapping rooms and missing rooms	108
7.1.2.3. Undefined space in the MUD	110
7.1.3. Types of connections between rooms	110
7.1.3.1. The standard room exit	110
7.1.3.2. Special exits	111
7.1.4. Perception of sizes and distances	115
7.2. How to describe the environment	117
7.2.1. Room descriptions	117
7.2.2. What makes a room special	120
7.2.3. What makes a room a landmark	121
7.2.4. Other elements of the environment	122
7.3. Navigational infrastructure	125
7.3.1. Transportation	126
7.3.2. Moving rooms	128
7.4. Informational infrastructure	129
7.4.1. Providing information in rooms	129
7.4.2. Communication	133
7.4.3. Change in the environment	133
7.5. Magic features	134
7.5.1. Are magic features useful?	135
7.5.2. Describing magic features	135
7.6. Are design guidelines for MUDs needed?	136
7.7. Summary	137
8. Conclusions and further work	139
8.1. Navigation in MUDs	139
8.1.1. Infrastructure	140
8.1.2. Magic features and the need for enactment	140
8.1.3. Guidelines for the use of spatial metaphors	141
8.2. Consequences for the Information City metaphor	141
8.2.1. Is it realizable?	141
8.2.2. Providing other structures in the city	141
8.2.3. Hierarchical structure	142
8.2.4. Restructuring the city and extending the metaphor	143
8.3. Future work	143
References	146

Abstract (English)

This thesis researches the possibility to support navigation in computer systems with a user interface based on a city metaphor. The task of navigation is reviewed both in real environments and in computer systems, which are seen as virtual environments. Navigation essentially is an activity in space. Therefore the thesis starts with a review of the psychology of spatial perception and spatial memory. The city environment is looked at in more detail and the work of Kevin Lynch and other influential city-planners is reviewed. This review describes properties of the city environment which are important for navigating a virtual environment based on a city metaphor.

Virtual environments and principles of modern user interfaces are described. Spatialized user interfaces are a promising special case of modern user interfaces because humans use spatial organizing principles in their daily lives, are used to navigate space and to communicate easily about space. The city environment forms the basis for a novel spatial user interface metaphor - the Information City metaphor. This metaphor enhances the city metaphor with various "magic features" which provide navigational functionality not available in real cities.

Textual virtual environments are virtual environments that are based entirely on textual descriptions. An example of such environments are networked adventure games commonly played on the Internet. These environments use city metaphors to support navigation and commonly make use of magic features like planned for the Information City. These environment are the ideal research ground to research magic features in a virtual city. A study about navigation in such environments is described. Results from this work can be used to improve text-based virtual environments including a text-based implementation of the Information City metaphor.

Abstract (German)

Diese Dissertation untersucht die Möglichkeit, Navigation in Computersystemen durch eine Benutzerschnittstelle zu unterstützen, die auf einer Stadtmetapher beruht. Der Vorgang des Navigierens wird sowohl in realen Umgebungen als auch in Computersystemen untersucht. Computersysteme werden als virtuelle Umgebungen gesehen. Navigation ist eine Aktivität im Raum und diese Arbeit beginnt daher mit einer Besprechung der räumlichen Wahrnehmung und des räumlichen Gedächtnisses. Die Stadt als räumliche Umgebung wird detailliert beschrieben und die Arbeiten von Kevin Lynch und anderen bedeutenden Städteplanern wird besprochen. Diese Besprechung konzentriert sich auf jene Eigenschaften der Stadt, die auf die Navigation einer virtuellen Stadt Einfluß haben.

Virtuelle Umgebungen und Prinzipien moderner Benutzerschnittstellen werden beschrieben. Räumliche Benutzerschnittstellen sind ein vielversprechender Spezialfall, weil Menschen daran gewöhnt sind, räumliche Organisationsprinzipien anzuwenden, räumliche Umgebungen zu navigieren und über räumliche Zusammenhänge zu kommunizieren. Die Stadt dient als Basis für die Informationsstadt-metapher, eine Metapher für räumliche Benutzerschnittstellen. Diese erweitert die reine Stadtmetapher um "magische Eigenschaften" (magic features), die in realen Städten nicht existente Navigationsfunktionen zur Verfügung stellen.

Textbasierte virtuelle Umgebungen sind virtuelle Umgebungen, die nur auf textuellen Beschreibungen basieren. Beispiel sind Netzwerk-basierte Abenteuerspiele (adventure games), die über das Internet gespielt werden. Diese Systeme bauen ebenfalls auf Stadtmetaphern für die Navigation auf und sehen häufig "magische Eigenschaften", wie sie für die Informationsstadt vorgesehen sind, vor. Sie sind daher ein ideales Experimentierfeld zur Untersuchung dieser Navigationsfunktionen in einer virtuellen Stadt. Eine Navigationsstudie über textbasierte virtuelle Umgebungen wird beschrieben. Die Ergebnisse dienen der Implementierung einer Informationsstadt und der Verbesserung des Designs textbasierter virtueller Umgebungen.

Acknowledgements

At the beginning of this work stands a keynote lecture during the European Conference on Hypertext in 1992, held by Jay Bolter. During this lecture the idea of the Information City was born. Without Prof. Bolter's inspiring talk I would have written a different, and probably less interesting thesis.
I would like to thank my advisers, Prof. Peter Fleissner and Prof. Andrew Frank for their continuing support of this work. Especially Prof. Frank stimulated many ideas and gave my work a new direction.
I also greatly appreciate the support by Werner Kuhn, Sabine Timpf and Adrijana Car.
Jolanda Tromp influenced this thesis in many talks and email discussions. I am especially thankful to her for bringing the potential of textual virtual environments to my attention.
The study described in this thesis would have been impossible without the cooperation of many MUD players in the Igor system, be it in interviews or general talks about the MUD.
There are many others who provided valuable insights, thoughts, discussions and sometimes literature that triggered new ideas and solutions. For brevity they are listed alphabetically: Keith Andrews, Vivienne Begg, Matt Belge, Mark Bernstein, Amy Bruckman, Thomas Grechenig, Bob Horn, Roswitha Lacina, Daniel Montello, Sabine Musil, Strata Rose, Bruce Tognazzini, Margit Pohl, Peter Purgathofer, Kaisa Väänäänen, and John Waterworth.
Last, but definitely not least, I wish to thank my mother and Barbara for their support and understanding, especially in the final phases of this work.

[Contents]--[Abstract]--[1]--[2]--[3]--[4]--[5]--[6]--[7]--[8]--[References]

last modified on 7/2000
Andreas Dieberger
andreas.dieberger@acm.org