5.2 Architectural Design



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Next: 5.3 Data Structures Up: 5 Visualization Previous: 5.1 Introduction

5.2 Architectural Design

The architecture chosen for the visualization is that of a set of orthogonal operations which can be applied to a common data set. A desired visualization result is then achieved by combining these elementary visualization operations in a sequence which is given by the data flow and by providing them with additional parameters if required.

Typical operations include, e.g., Projection, Cutting with a set of parallel planes, Transformation, Surface extraction or Subset and Merge operations. All these operations are vastly independent of the spatial dimension of the data on which they are performed. They can be characterized by the dimensionality relations of their input and output data. But before this can be done, a formalism to describe the type and properties of the visualizable data is needed.

The motivation for this rigorous orthogonal-modules concept is of course that the implementation of future visualization functionality is facilitated by bringing the implementation closer to the formal definition and decomposition of the visualization problem.

For example, a two-dimensional contour plot of a quasi three-dimensional surface can be decomposed (informally) into the following subproblems:

  1. Get the input quasi-three-dimensional surface from somewhere.
  2. Cut the quasi-three-dimensional surface () with a set of planes (all parallel to ).
  3. Project the resulting countour lines in three-dimensional space into the ground plane so they become lines in two-dimensional space.
  4. Plot them on some output device.
By combining generic (that is dimension-independent and parameterized) elementary operations in the above sequence one readily obtains the desired implementation. So an implementation can be more or less directly derived from the formulation of the intended visualization result in terms of elementary operations.

This rather intuitive concept implies a sufficient level of abstraction to be used for the simulation data. No semantics implicitly or explicitly associated with the otherwise purely geometrical information of the data should limit the scope, applicability, and interoperability of the operations that can be combined.

Once a minimum-requirement set of data structures is defined, output and interface modules for driving custom visualization systems may be added, similarily to the actual visualization modules at any level of abstraction and for whatever dimension of visualizable data is required.



next up previous contents index
Next: 5.3 Data Structures Up: 5 Visualization Previous: 5.1 Introduction



Martin Stiftinger
Thu Oct 13 13:51:43 MET 1994