Havemann, GML in a Nutshell 1Computer Graphics & Knowledge Visualization

GML in a Nutshell

Sven Havemann

CGV, TU Graz, Austria

Havemann, GML in a Nutshell 2Computer Graphics & Knowledge Visualization

Procedural models deserve aprocedural representation

Generative 3D Models

Man-made shape is parametric shape: Apparent structural similarity in a shape family

Can not be expressed by primitive-based representations: triangles, NURBS, ...

Havemann, GML in a Nutshell 3Computer Graphics & Knowledge Visualization

The GML Language Similar to core of Adobe’s PostScript

Simplicity facilitates automatic code generation The “invisible” programming language printer driver Printer executes program, bitmap formally just side effect

But GML is for 3D (shape) , not for 2D (layout)

Purpose: “Smallest common denominator” for the description of procedural 3D models and data

Compare to role of triangles for description of surfaces Represent the complete construction history,

not just the resulting surface variant design

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Purpose of GML: Easier object creation

Modeling bottleneck: 3D objects are too costly No more separation of viewing from modeling

Viewer with built-in just-in-time modeler Interactive variant modeling in 3D (sliders..)

Shape configurator using high-level parameters Online 3D product configuration, e.g., for fabbing

Unified shape representation: combined B-rep polygonal meshes + subdivision surfs catmull-clark Adaptive multi-resolution tesselation on-the-fly

Havemann, GML in a Nutshell 5Computer Graphics & Knowledge Visualization

GML over the internet

Models usually lean cathedral.zip : 20 KB

Plugin Architecture IE 6, Mozilla Acrobat ActiveGML

Lean interface for JavaScript + MS VB

load(), call()

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Examples

See www.generative-modeling.org Wikipedia: Generative_Modeling_Language

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Go!

DesignMode

ActiveGML Demo Run-time

modeler Send back

only high-level params

Extensibility: Custom operator libraries