*Volkmar Hovestadt and **Oliver Gramberg and **Oliver Deussen
* Institut fuer Industrielle Bauproduktion,
**Institut fuer Betriebs- und Dialogsysteme
University of Karlsruhe
76128 Karlsruhe, Germany
phone: ++49/721/608-2167
volkmar@ifib1.ifib.uni-karlsruhe.de
An architect's work involves mostly visually represented data. Problems are often
outlined and dealt within a graphical manner. Only this form of expression serves as
a basis for work and discussion.
Therefore the designer should have maximum visual control over the processes
taking place within the design continuum. Further questions arise about navigation,
associative information access, programming and communication within very large
data sets.
FIGURE 1 :scenario of the proposed user interface
First we look for a mapping of the design continuum onto a limited working area, e.
g. a computer screen. We seek to maximize the amount of information visible to and
manageable by the user. In addition to known methods like the use of scrollbars or
overall views the literature contains diverse proposals of display techniques [1][2][4].
We are concerned not only in the transformation of possibly unconstrained data in
order to achieve better navigation and control, but also in the full integration of a
working area into the transformed data display and thereby a continuous transition
from design to navigation.
FIGURE 2: transformation process
Transformation of the data in the object plane is accomplished by central projection
onto a so-called base corpus and, in a second step, by parallel
projection back onto the object plane.
FIGURE 3: (a) spherical projection
FIGURE 4: (b) projection with untransformed area
FIGURE 5: (c) coordinate-wise transformation
Hyperboloides, cones, and spheres have been considered for base corpuses. In
addition to the bivariate transformation also a coordinate-wise transformation has
been implemented which preserves straight lines parallel to the axes (see Fig.3, 4, 5)
The transformation is termed hyperbolic because the size of objects
converges to zero with growing distance from the point of view. This allows possibly
infinite data planes to be transformed into a finite display.
In the case of a spherical base corpus the mapping function of the x-coordinate is
FIGURE 6: equation
where x is the distance of the point in the object plane to be transformed from the
perpendicular of the center of the sphere onto the plane, r is the radius of the
sphere, z is the distance between the projection center and the object plane, and o is
the distance between the center of the sphere and the object plane (see Fig.2).
All transformations divide the interface into two parts. The center shows an
undistorted portion of the data where objects are displayed at full size and
complexity and can be manipulated with tools commonly available in CAD
applications. This working area is framed
by a transformed display of the other data (see Fig. 3, 4, 5)
The division for a spherical base corpus is obtained by the following case distinction:
FIGURE 7: equation
We regard the combination of the working area and the overview/navigation
instrument as an advantage over existing navigation aids, because it permits the
visually-working architect to switch smoothly between object editing and navigation.
Efforts like lenses [3] have been considered, but
they do not provide this kind of transition between the planar and the transformed
parts of the data as desired by the application.
Navigation within the partially extremely distorted display is possible because the
graphical data generated by architectural design processes commonly show
predominant structures which allow recognition even under extreme deformation.
All transformations can be parameterized in order to alter the display of the data from
a large working area with a thin and highly distorted border to a small working area
with a broad and less distorted border. Combination with zooming effects is possible.
A compressed overall view is just a special case of our transformation.
The work on the different transformation methods has been accompanied by the
development of techniques for reduction of the visual data. The representation of the
data outside the working area is possibly modified by two methods. Complex objects
like text fragments, pictures, or free-hand drawings are being replaced by their
bounding box. Different kinds of objects are discernible by different colors. Objects
with transformed sizes below a given threshold are being drawn as dots. The
interface was realized so far under NeXTStep with Postscript, ObjectiveC and C.
The efficiency of the implemented methods with respect to user requirements has
been verified by a series of tests involving simulation of the behavior of an architect
using the design environment.
Abstract
We present basic ideas and a prototypical implementation of a graphical user
interface intended for the architectural design process. The interface integrates CAD-
like object manipulation and navigation through large data sets. Navigation and
working area are not separated as done in prior work. Geometric transformations
produce a deformed but controllable display of the data in the border area of the
working window while normal working is possible in the untransformed center. The
arrangement allows the user to shift
directly from construction tasks to navigation tasks. Data reduction techniques have
been implemented in order to reduce the cost of transformation and display.
Keywords
Computer Aided Architectural Design (CAAD), Information Visualization, Fisheye
Technique, Focus+Context Technique, Interaction
Introduction
Architectural design processes tend to integrate models isolated so far. Many
different kinds of expert knowledge, tools, visualization techniques, and media are to
be combined. The design process covers the complete life cycle of the building, i. e.
construction as well as operation, reorganization, and destruction. Considering the
shared use of digital design tools and the exchange of information and knowledge
between designers and across different projects, we speak of a design continuum.
