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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
Real 3D presentations use all available bi- and monocular
physiological and psychological depth cues. Within these
images of space, continuous effects of parallax occur in all
directions. The main technologies for production of these
images are volumetric imaging, light emitting volume, rotating
helix mirror and processes of holography. [Bollmann et al
2002]
Basically these three different kinds of visual presentation are
dominated by the theory of spatial perception, the physical
parameters of the display and the graphical semiotic. The
parameters for the visual perception of depth are classified in
physiological and psychological terms. The physiological
parameters describe the technique of the human visual system
and include retinal parallax, accommodation, convergence and
the parallax of movement. The psychological class 1s
independent from the technical condition, supporting relations
between the real and percepted world and strengthens the
spatial impression. It consists of the size of the retinal picture,
linear-perspective, air-perspective, overlay and hiding, shading
and gradients of texture. [Albertz 1997]
Due to the fact that multimedia 3D cartography not only
consists of visual presentation, but which forms a substantial
focusing point, a more common classification may be added.
Based upon the work of Heim [1998] four "I" factors are
important for creating a multimedia 3D cartographic application
_ immersion, interactivity, information intensity and
intelligence of objects [MacEachren et al 1999].
The intelligence of objects specifies the possibilities for
supporting users in interpreting a cartographic environment, the
information intensity is a formalisation for the “level of detail”
— in this sense the amount of information presented — ,
interactivity assist users in orientation finding and information
extraction. Immersion names the submersion of a user in the
virtual cartographic environment.
The factor of immersion is strongly connected to the parameters
of visual perception. The definition ^..a psychological state
characterised by perceiving oneself to be enveloped by,
included in, and interacting with an environment..." [Witmer
and Singer 1998, p.227] assumes the existence of psychological
and physiological parameters for spatial perception. The more
parameters — depth cues — used by a visual user interface, the
more an user will be immersed into the virtual environment.
32 Knowledge acquisition
The assimilation of information within a multimedia 3D
environment does not only depend on depth cues but also on
processes of memorising and learning. Therefore a 3D
environment may be a helpful tool when thinking about active
knowledge acquisition.
Following. the principle of Zimbardo [1995], knowledge
acquisition is supported by the grouping of information and the
usage of individual rules of organisation and order. In
cartographic tasks this means that criteria for similarities of
body structure and temporal behaviors, common meaning and
organisational structures according to semantical classification
and hierarchical structuring are being made [Buziek 2000].
In addition the learning theory of Bandura reverts to a dual
coding. It says that the establishing of knowledge is based upon
learning of direct experience and representative experience.
Therefore imitating and evaluating sequences of imitation
[Bandura 1987].
639
The construction of patterns and the adoption of categorical
behaviors is activated by processes of enhancement and
motivation, which may be evoked by the usage of different
modalities of the same information — e.g. changing of color and
sound to express one information [Dransch 1997]. With the
help of individual memory-structures, changing knowledge of
an environment is a process of building, storing and realisation
(essentially as patterns). New experiences, interactions and
situational activities change stored knowledge and reshape it.
Perception and knowledge acquisition is a continuous activity
that may be depicted as cycle of perception [Neisser 1979].
Spatial perception and knowledge acquisition are the two main
aspects in the transmission of spatially related information. Both
may be combined as the notion communication. At a very
common approach communication consists of a sender-acceptor
model, which describes the coding- decoding and interpretation
of information. During the interpretation part errors may occur
depending on the user's experiences.
This observation supports the system's theoretical description of
communication. It says that each individual builds-up their own
island — truth or understanding — of the real world depending on
their experiences and knowledge. Communication can only
exist, if these islands of understanding overlap. In the end
“truth” will be what the acceptor understood and interpreted,
but not what the sender said (system theoretical description —
Birkenbiehl).
The knowledge transfer within a 3D multimedia presentation
underlies these theories and observations. It consists of three
islands — reality, the mapmaker and the user — where the number
of user islands is infinite. Overlapping within the user groups
takes place according to similarities of knowledge and
experience. For the author the hypothesis that the elaborated
usage of 3D presentation and metaphors may support the
cartographic communication process exists. It is based on
keeping up habits of perception and a familiar environment and
thus combining and overlapping the individual islands.
4. IMPLEMENTATION FOR A 3D MULTIMEDIA
PRESENTATION
The aim of a multimedia 3D cartographic application for
cultural heritage would be a reasonable and sustainable product
for experts and equally for educational purposes for the public.
Therefore the aspects of communication — psychological and
physiological parameters of spatial perception and knowledge
acquisition — as well as technical requirements — concerning
data quality, data description, data formats, programming
techniques and semiotic issues — have to be considered. In
addition the lifetime and durability of digital media and long-
term archival concepts must not be disregarded.
Results of photogrammetricly recorded objects, remote sensing
and GIS should be combined in this cartographic application.
Before, a common description of data and formats are needed.
Of course the rules of cartographic generalisation and
symbolisation also have to be borne in mind and applied
dependent on the scale or “level of detail” required.
4.1 Graphical elements in a cartographic 3D application
A 3D multimedia presentation combines visual, aural and,
depending on the user interface, tactile components with the
characteristics of “multimedia”, computer-based, multi-modal,
interactivity, multi-coding.
The most used interface for computer based applications is the