VIPER -- Volume Invariant Position-based Elastic Rods

Abstract

We extend the formulation of position-based rods to include elastic volumetric deformations. We achieve this by introducing an additional degree of freedom per vertex -- isotropic scale (and its velocity). Including scale enriches the space of possible deformations, allowing the simulation of volumetric effects, such as a reduction in cross-sectional area when a rod is stretched. We rigorously derive the continuous formulation of its elastic energy potentials, and hence its associated position-based dynamics (PBD) updates to realize this model, enabling the simulation of up to 26000 DOFs at 140 Hz in our GPU implementation. We further show how rods can provide a compact alternative to tetrahedral meshes for the representation of complex muscle deformations, as well as providing a convenient representation for collision detection. This is achieved by modeling a muscle as a bundle of rods, for which we also introduce a technique to automatically convert a muscle surface mesh into a rods-bundle. Finally, we show how rods and/or bundles can be skinned to a surface mesh to drive its deformation, resulting in an alternative to cages for real-time volumetric deformation.

License

Except as noted below this project is released under the Apache License, Version 2. See the LICENSE file for the full text.

IMPORTANT NOTICE: The assets data/mesh.bin and data/texture.bin are proprietary and are NOT released under an open-source license. You are NOT permitted to redistribute them or to use them for any purpose other than running this demo.

How to Build

Recommended configuration

NVIDIA GTX1080Ti or better
Ubuntu 18.04
CUDA 10.x

Initialize submodules

Either user `git clone --recursive'' or, after cloning, execute

git submodule init
git submodule update

Install dependencies

sudo apt-get install cmake
sudo apt-get install xorg-dev
sudo apt-get install libboost-all-dev
sudo apt-get install libglew-dev
sudo apt-get install libcgal-dev
sudo apt-get install libtbb-dev

Build & run

Ensure /usr/local/cuda exists!

export LD_LIBRARY_PATH=/usr/local/cuda/lib64
mkdir build
cd build
cmake ..
make
./demo

How to cite this work

@conference{angles2019viper,
  title={VIPER: Volume Invariant Position-based Elastic Rods},
  author={Baptiste Angles, Daniel Rebain, Miles Macklin, Brian Wyvill, Loic Barthe, John Lewis, Javier von der Pahlen, Shahram Izadi, Julien Valentin, Sofien Bouaziz, Andrea Tagliasacchi},
  booktitle={Proceedings of Symposium on Computer Animation},
  year={2019}
}

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