abstract

Imbalance suggests a feeling of dynamism and movement in static objects. It is therefore not surprising that many 3D models stand in impossibly balanced configurations. As long as the models remain in a computer this is of no consequence: the laws of physics do not apply. However, fabrication through 3D printing breaks the illusion: printed models topple instead of standing as initially intended. We propose to assist users in producing novel, properly balanced designs by interactively deforming an existing model. We formulate balance optimization as an energy minimization, improving stability by modifying the volume of the object, while preserving its surface details. This takes place during interactive editing: the user cooperates with our optimizer towards the end result. We demonstrate our method on a variety of models. With our technique, users can produce fabricated objects that stand in one or more surprising poses without requiring glue or heavy pedestals.

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acknowledgments

We thank Daniele Panozzo and Philippe Block for insightful discussions; Ladislav Kavan for providing source code for bounded biharmonic weights; Amit Bermano, Bernd Bickel and Markus Buehler for their help with producing the 3D models; and Gioacchino Noris, Ronnie Gänsli and Steven Poulakos for their help in painting and photographing the printed 3D models. We thank Alec Jacobson and Ladislav Kavan for the Dancing Armadillo models. Other models are from turbosquid.com: T-Rex (by csirkeFrs), Gargoyle (by csirkeFrs), Mr Humpty (by ArtbySmity); and archive3d.net: Horse (by Gian Lorenzo) and Christmas ornament (by Labrouste Henri). The Teddy Bear model is provided courtesy of the AIM@SHAPE Shape Repository. This work was supported in part by an SNF award 200021_137879, ERC grant ShapeForge (StG-2012-307877), ERC grant iModel (StG-2012-306877) and a gift from Adobe Research. Emily Whiting is supported by the ETH Zurich Postdoctoral Fellowship.