Generative 3D Modeling
paper: http://www.scribd.com/doc/279861/Generative-3D-Models
Wikipedia entry of Generative Modeling Language: http://en.wikipedia.org/wiki/Generative_Modelling_Language
Usual 3D file formats describe a virtual world in terms of geometric primitives. These may be cubes and spheres in a CSG tree, NURBS patches, a set of implicit functions, a consommé of triangles, or just a cloud of points. The term “generative 3D modelling” describes a different paradigm for describing shape. The main idea is to replace 3D objects by object-generating operations: A shape is described by a sequence of processing steps, rather than the triangles which are the end result of applying these operations. Shape design becomes rule design. The approach can be generally applied to any shape representation that provides a basic set of generating functions, called in this context ‘elementary shape operators’. Its effectiveness has been demonstrated, e.g., in the field of procedural mesh generation, with Euler operators as complete and closed set of invertible shape generating functions for meshes, operating on the half-edge level.
Generative modelling gains efficiency through the possibility of creating high-level shape operators from low-level shape operators. Any sequence of processing steps can be grouped together to create a new combined operator. It may use elementary operators as well as other combined operators. Concrete values can easily be replaced by parameters, which makes it possible to separate data from operations: The same processing sequence can be applied to different input data sets. The same data can be used to produce different shapes by applying different combined operators from, e.g., a library of domain-dependent modelling operators. This makes it possible to create very complex objects from only a few high-level input parameters, such as for instance a style library.
With procedural models, the model complexity is no longer directly (i.e., linearly) related with the file size. The Procedural Cathedral, a basic model of the Cologne Cathedral, contains 70 tracery windows, and a single window in highest resolution contains about 7 million triangles. These are “unfolded” from only 126 KB of GML code (18 KB zipped).
Application: Grasshopper for Rhino
working env video: http://www.youtube.com/watch?v=FBrZoQm_Ln8
showcase: http://vimeo.com/6519204
Freehand Drawing 3D Modeling: Rhonda
project website: http://rhondaforever.com/
Apparently this is still a project just released its private beta, and given the fact that I’m not really crazy about 3D, the best thing I like about it is the freehand feel it can achieve in the process of creation, almost a direct opposite to the generative modeling technique (maybe not always).
(cross posted at: http://itp.nyu.edu/RepresentingEarth/?p=717)
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