josef@nixdorf.de (Moellers) (11/05/90)
Hi, In "Circuit Cellar INK" there was an article on Fractals which referred to L-systems (L stands for Lindenmayer). In this system, (veeeery) long character strings are generated using a so-called "axiom" (e.g. "G") and one or more production rules (e.g. "G" -> "GFX(+G)(-G)" -and- "X" -> "X(-FFF)(+FFF)FX"). If You apply these rules one or more times, and interpret the generated string properly, You can generated quite natural looking plants. My question is on the "properly". The article says: "Here, F represents a graphically drawn line and each + or - is used to specify a change in the orientation for the drawing of the next line segment" But ... how do I interpret the "G"s and "X"s? Or are they just "nonterminals" that must be ignored when interpreting the result? What about the parentheses? -- | Josef Moellers | c/o Siemens Nixdorf Informatonssysteme AG | | USA: mollers.pad@nixdorf.com | Abt. PXD-S14 | | !USA: mollers.pad@nixdorf.de | Heinz-Nixdorf-Ring | | Phone: (+49) 5251 104662 | D-4790 Paderborn |
thomson@cs.utah.edu (Rich Thomson) (11/06/90)
I think the defacto reference on L-systems will become:
_The Algorithmic Beauty of Plants_,
Premizlaw Prusinkeveic (probably spelled wrong, sorry PP! ;-)
This was just published this year by Springer-Verlag and is written by
one of the most authoritative researchers into L-systems (IMHO) since
Lindenmayer.
-- Rich
Rich Thomson thomson@cs.utah.edu {bellcore,hplabs,uunet}!utah-cs!thomson
``If everybody is thinking the same thing, is anybody thinking?'' --Bob Johnsonelf@dgp.toronto.edu (Eugene Fiume) (11/06/90)
In article <1990Nov5.182451.3591@hellgate.utah.edu> thomson@cs.utah.edu (Rich Thomson) writes: >I think the defacto reference on L-systems will become: > > _The Algorithmic Beauty of Plants_, > Premizlaw Prusinkeveic (probably spelled wrong, sorry PP! ;-) Przemyslaw Prusinkiewicz (I believe) > >This was just published this year by Springer-Verlag and is written by >one of the most authoritative researchers into L-systems (IMHO) since >Lindenmayer. If by "defacto reference" you mean the application of L-systems to the visual modelling of plants, you're probably right (no disrespect intended). Don't overlook the fact that L-systems have a well-established theory with applications to many areas. For the basic theory, see the badly-titled book: Arto Salomaa, _Jewels of Formal Language Theory_, Computer Science Press, Rockville, Maryland, 1981. The cast of characters who have worked on the theoretical structure of L-systems is large and formidable. -- Eugene Fiume, Dynamic Graphics Project Department of Computer Science, University of Toronto elf@dgp.toronto.edu, (416) 978-5472
jones@skorpio.Usask.ca (W. Jones) (11/14/90)
In article <1990Nov6.105225.22702@jarvis.csri.toronto.edu> elf@dgp.toronto.edu (Eugene Fiume) writes: >In article <1990Nov5.182451.3591@hellgate.utah.edu> thomson@cs.utah.edu (Rich Thomson) writes: >>I think the defacto reference on L-systems will become: >> _The Algorithmic Beauty of Plants_, >> Przemyslaw Prusinkiewicz >>This was just published this year by Springer-Verlag and is written by >>one of the most authoritative researchers into L-systems (IMHO) since >>Lindenmayer. > >If by "defacto reference" you mean the application of L-systems to the visual >modelling of plants, you're probably right (no disrespect intended). Don't >overlook the fact that L-systems have a well-established theory with >applications to many areas. For the basic theory, see the badly-titled book: > >Arto Salomaa, _Jewels of Formal Language Theory_, Computer Science Press, >Rockville, Maryland, 1981. Prusinkiewicz isn't connected to Usenet and asked that I mention a few things. It should be remembered that the late Aristid Lindenmayer is a co-author of the plant book. (ISBN 0-387-97297-8, BTW). Salomaa's book covers L-systems to some extent but there are also two monographs devoted solely to the topic: - G. Herman and G. Rozenberg. Developmental systems and languages, North- Holland, Amsterdam 1975. - G. Rozenberg and A. Salomaa. The mathematical theory of L-systems, Academic Press, New York 1980, ISBN 0-125-97140-0. There is also a collection of papers, published on the occasion of Lindenmayer's 60th birthday, which survey the current status of the field: - G. Rozenberg and A. Salomaa, eds. The book of L, Springer-Verlag, New York 1985, ISBN 0-387-16022-1.