A Fluid Based soft Object Model

Daniel A. Nixon, MSc thesis 1998


Abstract

Soft objects are those everyday objects that deform significantly in response to their normal environment. Examples include cushions, plasticine and balloons filled with treacle. We present a new physically based model for animating soft objects. The model consists of two components: an elastic surface and a compressible fluid. The surface envelops the fluid, and is represented as a mass spring system. The fluid is modelled using finite difference approximations to the Navier-Stokes equations of fluid flow. Where the fluid and surface are in contact, their behaviour is defined by the no-slip condition. Unlike models that use implicit surfaces, surface tension is a natural feature of the model. Furthermore, the volume of the object is maintained depending on the properties of the fluid, and no explicit volume adjustment is necessary. We develop the model in one, two and three dimensions. We illustrate the behaviour of the soft object in environments with gravity and collisions with planes.


Thesis

Zipped postscript
Adobe acrobat (pdf)

Images

Soft object falling Miscellaneous soft object images

Animations

Animations are in the MPEG-1 format:
Falling onto a flat surface fall3D_Elas120.mpg 435KB
Squidging through a funnel funnel.mpg 395KB
Rolling down a spiral slide spiralSlide.mpg 757KB
Falling onto a small pyramid tent.mpg 865KB