Graphical Applications of L-Systems
# Graphical Applications of L-Systems

Przemyslaw Prusinkiewicz

University of Regina
## Abstract

Rewriting systems can be used to generate pictures in two different ways. In the first case,
a rewriting system operates directly on two-dimensional objects, such as arrays [Kirsch 1964,
Dacey 1970], graphs [Rosenfeld and Milgram 1972, Efate 1972], or "shapes'. [Gips 1975, Stiny 1975].
In the second case, a string grammar (in the broad sense of the word, including parallel rewriting
systems) is used to define strings of symbols. A graphic interpretation function subsequently maps
these strings into pictures. This paper is devoted to this second approach. After the idea of applying
string grammars to pictures is put into a historic perspective in Section 2, attention is focused on
L-systems. The necessary definitions related to L-systems are collected in Section 3. Sections 4 and
5 concentrate on pictures generated by OL-systems under two particular interpretations, the chain-code
and the turtle interpretation, respectively. Examples of pictures are given and the classes of pictures
generated under both interpretations are compared. Two approaches for extending the gamut of generated
pictures are discussed in Sections 6 and 7. The first approach relies on extending the generative power
of L-systems beyond that of OL-systems. The second approach employs more sophisticated interpretation
functions. Section 8 presents some open problems.

## Reference

Przemyslaw Prusinkiewicz. Graphical Applications of L-Systems. Technical report. November 1985.
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