Knowledge-based Graphics Generation

 Computer graphics concerns the pictorial synthesis of real or imaginary objects from their computer-internal models. The advanced methods and tools available today enable the production of an immense variety of static 2D and 3D computer graphics as well as animations. Computer graphics systems, however, typically rely on human intervention for the design of the resulting pictures. The traditional input that specifies a computer-generated picture or animation sequence consists not only of the underlying models which describe the geometry and dynamics of all the objects to be depicted. In addition, a large set of rendering options needs to be specified to affect aspects like resolution, viewing perspective, lighting conditions, etc. The values assigned to these parameters affect the outcome of the pictures, and thus their semantic and pragmatic value. Knowledge-based graphics systems differ from conventional ones in that they deploy Artificial Intelligence techniques to automatically generate some or all of this otherwise hand-made input for a graphics system.

The explicit representation and exploitation of knowledge can be advantageous for automatic decision making during all stages of the graphics generation process. In particular, knowledge-based approaches have been devised to address the following important tasks of graphics design and realization:

• determination of the objects to be included in the presentation;
• selection of object properties and attributes to depict;
• object positioning;
• selection and application of illustration strategies (e.g. annotations, cutaways, etc.);
• stylistic choices;
• construction of animation sequences;
• temporal coordination of animations.

Given the diversity of computer graphics application contexts, it is not surprising that knowledge-based graphics systems differ greatly not only in the types of graphics produced, but also in the types of knowledge and decision making used. As yet, research prototypes have been implemented for various classes of applications, including for example:

• presentation of relational information by means of business graphics;
• automatic generation of cartographic displays;
• automated layout and graphical display of networks;
• illustration of objects and action sequences;
• visualization of natural language descriptions;
• automatic synthesis of animations;
• interactive graphics design.

Selected References:

  

• N. I. Badler, C. B. Phillips, B. L. Webber: Simulating Humans: Computer Graphics Animation and Control. New York, Oxford: Oxford University Press, 1993.
• S. Feiner, B. MacIntyre, D. Seligmann: Knowledge-based Augmented Reality. In: Communications of the ACM, 36(7), pp. 52-62, 1993.
• J. D. Mackinlay: Automating the Design of Graphical Presentations of Relational Information. In: ACM Transactions on Graphics, 5(2), pp. 110-141, 1986.
• T. Rist, E. André: From Presentation Tasks to Pictures: Towards a Computational Approach to Graphics Design. In: Proc. of the 10th ECAI, Vienna, Austria, pp. 764-768, 1992.
• S. F. Roth, J. Kolojejchick, J. Mattis, J. Goldstein: Interactive Graphic Design Using Automatic Presentation Knowledge. In: Proc. of CHI'94: Conf. on Human Factors in Computing Systems, Boston, MA, pp. 112-117, Association for Computing Machinery, 1994.