The Virtual Botanical Laboratory (VBL) is a software system that models plant systems. (Known as the L-systems) For introduction read the excellent book by P. Prusinkiewicz and A. Lindenmayer (from the latter the system got its name) 'The Algorithmic Beauty of Plants', 1990, Springer-Verlag Inc.
What we did is to integrate the known technology into a coherent system: 1. A front-end compiler that takes L-specifications and generates L-strings; (intermediate code) 2. A graphics interpreter that translates L-strings into graphics commands (code generator) in the Turtle graphics style; 3. A rendering system that renders the results to the monitor; (code execution) 4. A GUI interface that binds the three parts together.
We appreciate the team members that have devoted time and energy into this endevor: S. Brower, N. Price, S. Sharma, C. Wright, V. Yalamanchili. (In alphabetical order) The team presented the system at the ACM Conference in 1993 at Indianapolis, Indiana, and won the first place award in the Poster Competition of the Graduate Division.
What follows are some representative displays of some of the output from the system.
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The basic components are planar polygons which may be made refined or coarse - depending on how far is the viewer, how much detail one desires, and how much computing time one wishes to spend. The one above is a close-up and the individual polygons are clearly apparent. The one below is a distant view and the polygons are not so apparent.
Presented here is a hanging plant. Notice that one can choose to control the shades of the leaves - the young ones are in a bright green shade and the mature ones are darker. One may choose different color for the leaves - some are yellow and some are green.
There is no such plants in the real world. In the simulated virtual world of the L-system, any composition is possible. One may choose to transplant some objects to be with some other objects. If so desired one may choose to interchange the positions of flowers and leaves. They are all just L-system library objects.
The above plant is without flowers and the one below does.
The growth factor of a plant can be controlled. During the generation of a plant, one must specify how many stages one wishes the plant to grow. A low number yielded the plant above and a high number the one below. If one examines closely, one may recognize that the system is recursing on itself. (Notice the sub-patterns are the same as the global pattern.) Under-gowth produces a sparse plant and over-growth can yield a plant that is too dense. A good growth value can be obtained only through time consuming trial-and-error. It would be interesting to see growth inhibitor factor build into the system - let plant density inhibit plant growth.
This project took three years of work by five dedicated students. None of them is supported by any grant or industrial resources. We appreciate their dedication to higher learning. The system was implemented on Sun Sparc I+. Rendering support was provided by the RenderMan software. It was written in straight C code.
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soong@monet.vill.edu Sept 25, 1995.