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ShapeForge: By-Example Synthesis for Fabrication

Final Report Summary - SHAPEFORGE (ShapeForge: By-Example Synthesis for Fabrication)

The ShapeForge project considers the by-example synthesis of shapes under fabrication, functional and appearance constraints in the context of additive manufacturing. We specialize in assisting users with the creation of virtual objects that are meant to be fabricated.

A major achievement of the project are methods to automatically generate structures resembling an example pattern given as input. For instance, our methods are able to generate a structure flowing along a guiding surface shell while ensuring the final result remains structurally viable: it can be manufactured and it will not break nor collapse. The main applications are in design, art and architecture -- for the intuitive creation of thin, intricate structures that enforce structural constraints -- but also in biology and geology where there is a need for generating complex structures resembling those observed in nature.
A variant of the same methodology allows us to fill large objects with stochastic microstructures resembling foams. These microstructures change the mechanical properties of the final objects, making them lighter and porous, while preserving their rigidity, or making them flexible where needed. The mechanical parameters can be freely graded in space, for instance producing a denser foam, oriented to resist a directional stress.

These methods require a deep understanding of the interactions between appearance (the local shape of the structure, specified as an example pattern) and structural properties (rigidity, balance). We contributed a number of algorithms similarly simplifying the design process, by automatically generating a 3D model enforcing structural properties (e.g. balance) or functionality (e.g. mechanical motions) given a simple example input design. Applications are in product customization, robotics and mechanical engineering.

As we explore the generation of complex objects, we need tools and algorithms able to process these shapes and drive the 3D printers during fabrication. Another achievement of the project is our software for modeling and fabrication --- IceSL --- publicly available. This software allows the modeling of complex shapes as the combination (union, difference, intersection) of many other shapes, which can be defined as meshes, volumes or implicits (equations). It displays results in real time and directly generates instructions for the manufacturing device. It integrates several cutting edge technologies that we developed: The generation of support structures resembling construction scaffoldings, offsetting (erosion/dilation) of complex geometries, optimal slicing using variable layer thickness, color printing by micro-layering and specialized toolpath generation for multi-material deposition systems.