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APPLICATIONS FOR MIXED REALITY 
Sven Wursthorn, Alexandre Hering Coelho and Guido Staub 
, 
Institute for Photogrammetry and Remote Sensing 
University of Karlsruhe (TH) 
Englerstr. 7, D-76128 Karlsruhe, Germany 
{wursthorn|coelho[staub}@ipf.uni-karlsruhe.de 
KEY WORDS: Augmented Reality, GIS, Mobile, Application, Disaster, Floods. 
ABSTRACT 
Mixed or Augmented Reality (AR) systems align computer generated virtual objects and real world objects with each other 
to enhance the vision of the physical reality with the virtual objects in a manner, that will allow a user to interact with 
spatial data in his natural environment and scale (1:1). Especially when dealing with natural disasters the advantage of a 
user's view augmented with additional supporting data is apparent. Activities like preventive protective measures, effective 
reaction and reconstruction need to be assisted by a technology that improves the operators efficiency and performance. 
This approach deals with a system that serves particular needs regarding earth science and disaster management. We 
will present our work developing an AR-System (ARS) and its components with examples of practical applications. The 
crucial point of this implementation is the use of laser scanning models with adequate accuracy, reliability, actuality 
and completeness. VRML tiles produced from the laser scanning data are displayed in the operator's field of view 
together with additional water surface models or simple features like points and lines. These geometrical objects are 
visualised and controlled using scene graph parent-child relationship of Java3D. In this paper, flood disasters are used 
to illustrate possible applications in a typical four-phased disaster management process. Additionally, several examples 
representing the virtual water surface for flood damage prediction are discussed. Results of virtual water models are used 
by applying digital image processing techniques to laser scanning data in order to provide tactical information for disaster 
management. 
1 INTRODUCTION AND RELATED WORK 
The "Reality-Virtuality Continuum" (Milgram, 1994) (fig. 
1) defines mixed reality as a generic term being in-between 
the real world and complete virtual environments. Mixed 
or augmented reality (AR) extends a user's vision of the 
real world with additional information of computer gen- 
erated objects with the user being in the real world. This 
is in contrast to virtual reality where the physical world is 
totally replaced by computer generated environment. Al- 
though vision is not the only sense that can be augmented, 
it is the strongest one (visual capture) - what we see is 
"true" (Welch, 1978). 
Pina Mixed Reality Te 
real augmented 
environment reality 
augmented virtual 
virtuality reality 
Figure 1: The Reality-Virtuality Continuum 
If augmented objects are derived from spatial data which 
represent real features like buildings or streets, an exact 
overlay of these objects with the real objects is a funda- 
mental requirement. Additionally this overlay has to hap- 
pen in real time (Azuma et al., 2001) to let the user’s vi- 
sion keep the impression of the augmentation during move- 
ments. 
With augmented reality systems, the user can interact with 
spatial data in his own natural scale, 1:1. Spatial features 
and meta data can be queried by position and view direc- 
tion and can be interactively manipulated in the viewed 
scene. In contrast to handheld computers with 2D map dis- 
plays, the user is unburdened from the task of comparing 
1049 
the results of a spatial query shown on the display with the 
environment on site. Another possibility is to show objects 
covered beneath the surface to see underground features 
like tubes (Roberts et al., 2002). 
The MARS Project (Hollerer et al., 1999) experimented 
with AR solutions for pedestrian navigation, both indoors 
and outdoors. (Livingston et al., 2002) provide a mobile 
outdoor system for military operations. The Australian 
"Tinmith" project has developed an indoor and outdoor ca- 
pable system with a solution for interactive data manipu- 
lation e.g. with gloves which are typically utilized in VR 
applications (Piekarski and Thomas, 2001). 
All of these projects have some typical hardware compo- 
nents in common that are needed for an ARS. These con- 
figuration affected our hardware selection which is dis- 
cribed in the following section. 
2 HARDWARE 
The head mounted display (HMD) system, Nomad from 
Microvision, projects an SVGA (800x600) image with a 
semi-transparent mirror directly on the retina, overlaying 
see-through information on the user’s vision. The advan- 
tage of this solution is bright "display" that can be used 
outdoors, the disadvantage is a lack of colors. The mono- 
chrome display supports 32 shades, covering a field of view 
of 23°x 17° which equals a 17” Display at arm's length. 
Furthermore our system is monocular. There is no need for 
a stereo display, because human vision is able to combine 
the three dimensional impression of the real world with the 
augmented objects from the HMD.