Spatial knowledge implications by using a Virtual

Spatial knowledge implications by using a Virtual Environment during design review DIRK DONATH Bauhaus Universität Weimar ERNST KRUIJFF Bauhaus Universität Weimar HOLGER REGENBRECHT Bauhaus Universität Weimar / Daimler Chrysler AG Germany Abstract In this abstract we aim to describe the underlying foundation and strength of using a Virtual Environment for review in the architectural design process. We built upon the assumption that during review, the combination of both egocentric (first person view) and exocentric (bird's view) perspectives is ideal to judge spatial qualities of a design. According to Howard (Howard91), the task of creating a representation which matches a human, non-exocentric perspective is known as an egocentric task. In an egocentric task, position, orientation and motion of objects is judged according to the egocentric reference frame. With the egocentric reference frame, we can make a distinction between the station-point frame, retinocentric frame, headcentric frame, bodycentric frame and proprioceptive frame. In these sub-frames, the position and orientation of the basic element defining the frame is used to make spatial judgements. On the other hand, Howard describes that during an exocentric task, position, orientation and movement of objects are judged according to coordinates external to the body, namely defined by object shape, orientation and motion. During both egocentric and exocentric tasks, a human being builds up a mental model of the design. According to Darken et al (Darken et al 97), one can distinguish three kinds of spatial knowledge building up the mental model, namely configurational knowledge (geocentric information on object locations and inter-object relations), procedural knowledge (depiction of sequences of actions) and landmark knowledge (visual details). We claim that the quality of a design medium with respect to spatial knowledge acquisition and usage can be rated, by comparing different design media on the factors described above, added with some specific, related factors. Manual drawings and through-the window CAD tools are mainly focused on providing the user with exocentric, abstracted views on the design. CAD tools allow the user to obtain multiple scaled, semi-egocentric viewpoints with a limited field-of-view, which are, however, hard to combine to a consistent mental representation. Large projection walls introduces the presence (adoption of an egocentric reference frame (Regenbrecht, Schubert97)) factor into spatial knowledge acquisition. High resolution, an abundance of visual stimuli and the large field-of-view normally induces the effect of vection (Ware96), which makes the user feel that he or she moves through the viewed space, but can cause intersensory conflicts reducing the subject's perceptual experience (Harris et al 99). Projection screens, manual drawings and CAD tools are only supplying configurational and limited landmark knowledge. Immersive media (stereoprojection systems and head-mounted displays) like a Virtual Reality Aided Design system (Donath, Regenbrecht95) allow both egocentric and exocentric views on designs by viewpoint motion control. By tracking the physical motion (egomotion) via a tracking device, the match between egomotion and viewpoint motion in the virtual world can deliver full support of egocentric reference frame cues and provides a strong basis for procedural knowledge, next to support for configurational and landmark knowledge aquisition. Furthermore, the sense of directly controlling a design, in case VRAD tool is extended with editing functions, can greatly advance the spatial understanding of a design.

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