Workshop on Shape Synthesis for Modeling and Fabrication


(New) A recording of all the talks presented during the workshop is now available here.


Welcome coffee at 10:00.

Lunch break (lunch not included).

Coffee break.


Joëlle Thollot (Grenoble INP / Inria, France)

Programmable 2D Arrangements for Element Texture Design

We present a programmable method for designing stationary 2D arrangements for element textures, namely textures made of small geometric elements. These textures are ubiquitous in numerous applications of computer-aided illustration. Previous methods, whether they be example-based or layout-based, lack control and can produce a limited range of possible arrangements. Our approach targets technical artists who will design an arrangement by writing a script. These scripts are using three types of operators: partitioning operators for defining the broad-scale organization of the arrangement, mapping operators for controlling the local organization of elements, and merging operators for mixing different arrangements. These operators are designed so as to guarantee a stationary result meaning that the produced arrangements will always be repetitive. We show that this simple set of operators is sufficient to reach a much broader variety of arrangements than previous methods. Editing the script leads to predictable changes in the synthesized arrangement, which allows an easy iterative design of complex structures. Finally, our operator set is extensible and can be adapted to application-dependent needs.


Bernhard Thomaszewski (Disney Research Zurich, Switzerland)

Computational Tools for Personalized Design

One of the most exciting promises of digital fabrication is the immediate and effortless transition from an idea to its tangible realization. But in order for this technology to be useful for a broad range of creatives, we need software tools that can automate the technically difficult parts of the design process. In this talk, I will argue for a new generation of design tools that rely on three key components: simulation models that are able to predict the functional aspects of a given design; optimization algorithms that can invert the simulation model in order to determine design parameters that lead to desired functional aspects; and graphical interfaces that integrate these two components to help users navigate the design space in an intuitive and efficient way. I will highlight a number of challenges that arise in this context and illustrate some key concepts on two examples: personalized robotic creatures that can walk in stable an compelling ways; and 3D-printed deformable controllers that can sense their state of deformation.


Marco Attene (IMATI-GE / CNR, Italy)

Automatic Process Planning Solutions for Additive Manufacturing

A good Process Planning (PP) for Additive Manufacturing makes the difference between a printing success and a failure. Today this still depends on the user experience: the operator ability to predict failures is unmatched by any automatic methodology available. Nonetheless, key ingredients of an optimal PP such as mesh repairing, slicing and support structures are all subjects of a vibrant research within the Geometry Processing community, which is therefore becoming a fundamental source of innovation for the 3D printing world.

Within the EU project CAxMan, competences from Engineering, Computer Graphics and Geometry Processing are put together to automatise the PP and minimise failures. The project is focused on industrial metal manufacturing and considers two use cases: the production of moulds with optimised cooling systems which would be impossible to be produced with subtractive technologies; and the production of the NUGEAR, an innovative gearbox whose fabrication is particularly challenging, and would require a special and expensive 5-axis CNC machining to be produced with a subtractive technique.


Grégoire Allaire (Ecole Polytechnique, France)

The level set method for shape and topology optimization of structures: a brief review of manufacturing constraints.

The level set method for shape and topology optimization of structures has became an efficient and popular numerical algorithm, able to treat various mechanical models and objective functions, with a clear definition of the structure boundary at any iteration (contrary to density-based algorithm like SIMP). Industrial applications often impose some further feasibility constraints, like geometrical constraints or processing constraints on the final design. In this talk we shall present some recent results and ideas on how to handle geometrical constraints like a minimal or maximal thickness of members, respecting a draw direction, avoiding overhangs in additive manufacturing. This is a joint work with Ch. Dapogny, A. Faure, L. Jakabcin, F. Jouve, and G. Michailidis.


Rüdiger Westermann (Technical University Munich, Germany)

Scalable Topology Optimization and Beyond

In my talk I will present our recent work on scalable system designs for generating 3D objects using topology optimization, which allows to efficiently evolve the topology of high-resolution solids towards printable and light-weight-high-resistance structures. Furthermore, I will shed light on the simulation of porous structures such as trabecular bone, as they are widely seen in nature. These structures are lightweight and exhibit strong mechanical properties. I will present a new method to generate bone-like porous structures as lightweight infill for additive manufacturing. The method builds upon and extends voxel-wise topology optimization, yet for the purpose of generating sparse yet stable structures distributed in the interior of a given shape, it introduces upper bounds on the localized material volume in the proximity of each voxel in the design domain. These local per-voxel constraints are then aggregated by their p-norm into an equivalent global constraint, in order to facilitate an efficient optimization process.


Paolo Cignoni (CNR-ISTI, Italy)

FlexMolds: Automatic Design of Flexible Shells for Molding

FlexMolds are a novel computational approach to automatically design flexible, reusable molds that, once 3D printed, allow to physically fabricate, by means of liquid casting, multiple copies of complex shapes with rich surface details and complex topology. The approach to design such flexible molds is based on a greedy bottom-up search of possible cuts over an object, evaluating for each possible cut the feasibility of the resulting mold. We use a dynamic simulation approach to evaluate candidate molds, providing a heuristic to generate forces that are able to open, detach, and remove a complex mold from the object it surrounds. We have tested the approach with a number of objects with nontrivial shapes and topologies.


Marie-Paule Cani (Grenoble INP / Ensimag France)

Expressive modeling of virtual worlds: combining knowledge and control

While they made design for fabrication more generally accessible, the conceptual tools used in expressive modeling – e.g. sketching, sculpting and transfer interfaces – are also extremely promising for the design of virtual worlds. In these applications, the number of features and the consistency constraints they need to maintain – coming from physical laws, but also from geology or botanic – make direct creation extremely tedious and difficult. This talks explores the combination of models embedding a priori knowledge with examples and gesture-based control, to create large, controllable landscapes populated with consistent ecosystems.


Bruno Lévy (Inria-Loria, France)

Voronoy Story: To L-infinity and beyond

I’ll talk about some generalizations of Voronoi diagrams, algorithms to compute them, and some applications in 3D modeling for computer fabrication. I’ll present a general algorithm that computes the intersection between a (generalized) Voronoi diagram and a tetrahedralized mesh. This algorithm can be used by different numerical optimizations where the discretization of space is dynamically optimized, such as Voronoi meshing by Lloyd relaxation and implementing some particular numerical schemes (semi-discrete) for solving some Partial Differential Equations (Monge-Ampere).



Workshop funded by ERC grant ShapeForge (StG-2012-307877).