Proceedings of the 21st International Cartographic Conference (ICC) Durban, South Africa, 10 � 16 August 2003�Cartographic Renaissance� Hosted by The International Cartographic Association (ICA)ISBN: 0-958-46093-0 Produced by: Document Transformation Technologies

COMBINING REAL AND VIRTUAL COMPONENTSFOR VISUALIZING ECOLOGICAL BARRIERS

Krisp, J. and Ahonen-Rainio, P.

Helsinki University of Technology (HUT), Department of Surveying,Institute of Cartography and Geoinformatics, P.O.Box 1200, FIN 02015 Helsinki, Finland.

Tel: +358 9 451 5832. E-mail: jukka.krisp@hut.fi and paula.ahonen@hut.fiWebsite: http://www.hut.fi/Units/Cartography

ABSTRACT

In this paper we organize the level of abstraction for reality using a model classification for displays on the Reality -Virtuality continuum. We illustrate our organization by a case study on three-dimensional models that representecological barriers to animal movement in the city of Järvenpää, Finland. Visualizing ecological barriers as acombination of real and virtual representations contributes to the research how these maps can be used as visualizationtools for exploring digital geographic information. In addition to exploring they can be a valuable support in makingdecisions and solving spatial problems. As user groups for this kind of visualizations we identified the general public,the decision makers in land use planning, and the land use planners. We preliminary identify their specific preferenceson spatial representations according to our classification.

1. INTRODUCTION

The combination of modern computing technology and the exhaustive digital coverage of the earth at multiple scales isa particular form of cyberspace, blurring the distinction between reality and a representation of it (Peuquet, Kraak2002). In the past few years Mixed Reality and Augmented Reality have received increasing attention, as indicated by aseries of events devoted to these areas, including international workshops and symposia on Augmented Reality in theUSA and Europe as well as the International Symposia on Mixed Reality in Japan (ISMAR 2003). By its very nature,Mixed Reality and Augmented Reality are highly interdisciplinary fields involving signal processing, computer vision,computer graphics, user interfaces, human factors, wearable computing, mobile computing, computer networks,distributed computing, information access, information visualization, and hardware design for new displays and sensors.Mixed Reality and Augmented Reality concepts are applicable to a wide range of applications. In our case we will focuson their application in visualization of information about spatial phenomena.

The boundary between direct and indirect experience of the environment is becoming so fuzzy that it turns out to bedifficult in a cyber-world to distinguish between the real and the created. Is that ever going to replace textual andgraphic representations of geographic space? According to Peuquet and Kraak (2002) the answer is clearly no, becausemaps by definition are symbolized abstractions of reality. Our special interest is the question of how can abstract databe combined with a �realistic� representation of reality. Part of the power of maps lies in their ability to abstract andprovide selections from reality that facilitate an understanding of the selected features. On the other hand, themotivation of the development of virtual reality relating to geography (Unwin, Fisher 2001) has been in providing asrealistic views as possible. The combination of realistic and virtual components in one visualization can assist theunderstanding of the phenomenon. In this case what is the optimal level of realism to make a three-dimensional mapeffective? The challenge with maps is how to utilize this common form of spatial display in new ways that encouragesexploration and the subsequent discovery of novel insights in geographic databases (Peuquet, Kraak 2002).

As Peuquet and Kraak (2002) state maps need to change, as mapping has already changed, and we need research intohow maps can be best used as visualization tools for exploring digital geographic databases and as interactive aids inexperiencing the world, deriving decisions and solving spatial problems. There is a need for development of strategiesfor appropriately using maps and related displays as tools in the hands of the user for exploring virtual worlds. In thispaper, we do not consider the actual exploratory process and interaction between the user and the visualization butconcentrate on the visual components. We apply a four-category organization of the levels of abstraction for reality to acase study of visualization of ecological barriers where spatial datasets are combined and visualized in a three-dimensional environment.

2. CASE STUDY � REPRESENTING ECOLOGICAL BARRIERS

Ecological barriers represent the restricting influence of certain landcover (like infrastructure and urban areas) onanimal movement. These landcovers can cause a splitting of natural ecosystems into smaller and more isolated patches.As this fragmentation increases, moose and other wildlife need suitable areas to be preserved in their natural condition.In addition, they need ecological corridors, which connect isolated patches of different animal habitats and enablediverse populations to interact with each other (Krisp 2002). Within the project �Ecological Network Planning � Three-Dimensional Visualizations of ecological barriers� (Väre, Krisp 2003) we studied the visualizing of ecological barriersfor selected cities in Finland. We succeeded in defining the ecological barriers and visualizing them in maps by usingthe third dimension. In this case the theoretical concept of an �ecological barrier� demands further explanation. Howcan we better illustrate what is an ecological barrier and where they show in the landscape? To demonstrate the conceptwe find it very useful to combine visualizations of our model with different kind information. We are now able tocombine these three-dimensional maps with other data from different data sources including various satellite images,aerial photographs and photographs of landscapes.

3. REPRESENTATION CATEGORIES

Maps are now being replaced with what might be described as imitation of experience through exhaustive coverages incyberspace, complete with realistic images and imagery (Peuquet, Kraak 2002). To describe the level of abstraction forreality we have identified four different categories for our combined data representations. We defined them as �Realisticrepresentations�, �Extended realistic representations�, �Extended virtual representations� and �VirtualRepresentations�. According to Milgram and Kishino (1994) �Extended realistic representations� can be also describedas �Augmented Reality� (AR) and �Extended virtual representations� as �Augmented Virtuality� (AV). They describe ataxonomy that identifies how augmented reality and virtual reality work are related. They define the Reality-Virtuality(RV) continuum shown in Figure 1.

Figure 1. An organization of displays on the Reality - Virtuality continuum (Adapted from Milgram et.al. 1994).

The �real world� and a �totally virtual environment� are at the two ends of this continuum while the middle region iscalled �Mixed Reality� (MR). Augmented reality, or in our case �Extended realistic representations�, lies near the realworld end of the line with predominate perception being the real world augmented by computer-generated data.�Extended virtual representations� in our case, or �Augmented Virtuality� is a term created by Milgram and Kishino(1994) to identify systems, which are mostly synthetic with some real world imagery added. Pioneering work in thisdomain has been performed by Fournier (1993). Vallino (1998) states that this is a distinction that will fade as thetechnology improves and the virtual elements in the scene become less distinguishable from the real ones. In ourexample this cannot be the case as we are visualizing an artificial concept (ecological barriers) and do not try tocombine real objects (for example houses) that are virtually constructed with real environmental data. In the following,we are using combined data from the city of Järvenpää, Finland to exemplify and illustrate our classification. Thesample figures are produced by using commercial GIS software and graphic software products. The data has beenprovided by the city and the Helsinki University of Technology.

Realistic representations intend to reflect the data or facts as close to reality as possible. In this case videos, photos oraerial photographs can reflect reality. At this level of abstraction, every object within the representation is specific.Every object has its own identity. Figure 2 shows as an example an aerial photograph. It has a five-meter resolution andis provided by the city of Järvenpää.

Figure 2. An aerial photograph as an example of a realistic representation forecological barriers in Järvenpää, Finland.

Extended realistic representations generate a composite view for the user. It is a combination of the real scene viewedby the user and a virtual reality (VR) scene generated by the computer that augments the scene with additionalinformation. These representations abstract reality by combining photos with virtual objects. For example aerialphotographs are used as a background for virtual models. That is illustrated in Figure 3 as the aerial photograph fromJärvenpää is used as a background for the visualization of ecological barrier effects.

Figure 3. An extended realistic representation for ecological barriers in Järvenpää, Finland.

Extended virtual representations are building up in a virtual environment to model and shape reality. They explain theirmodel further by realistic representations like photos or videos. In Figure 4 we illustrate the virtual model of ecologicalbarriers further by actual photographs taken from selected spots that are represented in the model.

Figure 4. An extended virtual representation for ecological barriers in Järvenpää, Finland.

Virtual Representations describe reality only by virtual models. Virtual models use general symbols for more than onespecific object. In our case real objects (like streets, rivers etc.) are classified into several abstract ecological barrierclasses. The model shown in Figure 5 does represent a virtual reality to identify and analyze spatial problems in reality.

Figure 5. A virtual representation for ecological barriers in Järvenpää, Finland.

4. DISCUSSION

The classification of our different representations into the four categories proves to be functional as we can categorizeall our representations accordingly and each category is occupied. In our case, the usefulness of the categorizationwould be verified in the future by guidelines for the use of the different visual components. But before the guidelinescan be drawn use of these visualizations should be studied. The utility and usability (Nielsen 1993) of visualizationheavily depend on the user and the purpose of the visualization. Evaluation of the four categories of representationtherefore requires specification of the use context. We can make some presumptions on the applicability of variouscategories based on user comments and discussions throughout the case project (Anon. 2002, Väre, Krisp 2003), anddesign further testing of visualization on that basis. Based on our previous experience within the project work, weassume that most users will demand maps that combine virtual models with realistic representations as a furtherexplanation of the ecological barrier concept.

The user groups of visualization of ecological barriers would be the general public, the political decision makers in landuse planning, and the land use planners. The land use planners need to have an insight of the ecological environment.They need exploratory geovisualization tools (Kraak 1999) for studying the ecological landscape and alternativeapproaches for land use. Interaction and expertise are key issues for the planners. An interpretation of abstractphenomena, like ecological barriers from a realistic representation, requires expertise that cannot be expected fromeither the general public or decision makers. Concerning the visual component the two extremes, i.e. the realisticrepresentations and the virtual representations, can be seen as the categories best meeting the needs of the land useplanners. In addition to exploring the situation the land use planners produce visualization of ecological barriers for theother two user groups. The decision makers are typically not motivated in exploring the situation but hearing reasoningfor the proposed actions. The land use planners are producing visualization for them in order to convince them on theproper actions. These visualizations may be animations or static images. The choice of framing the visualization, theorientation of the geographic space in relation to the viewer, as well as the selection of the spatial area portrayed, allsimilarly affect the overall message in these cases (Cosgrove 1999). The aim of visualizing ecological barriers togeneral public is to gain their attention and get them interested in the ecological aspects of land use planning. In thisrespect visualization must be attractive and thought provoking; reading of the details of the actual information is notnecessary. The combination of photographs and 3D maps can result in an appealing visualization. Therefore, theextended realistic representations and the extended virtual representations can be seen as the categories bet fitting forthe visualization to political decision makers and the general public. However, the usefulness and usability of thesecombined 3D maps needs to be proven empirically. In addition, use and effect of colors, scaling in both 2D and in the3rd D as well as the output formats have to be still considered in the future studies.

5. CONCLUSION

From a technical point of view, GIS software and graphic tools enable us to freely combine real and virtualrepresentation of reality. This is a great advancement in the technical development, but so far we cannot see many mapsor other cartographic representations making full use of this possibility. Tools for exploratory visualization should aswell be combined in this context. The Reality - Virtuality continuum helps us to organize our visualizations. It assists usin choosing the right visualization for the users specific needs. These needs can include the promotion of a region, thedescription of an area or the analysis of the wildlife network for a certain district. The combination of realistic andvirtual components in one visualization can aid to understand and explore the problem represented in the map.

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City of Helsinki � Department of Environment, (2003)