1,210 research outputs found
Fast Simulation of Skin Sliding
Skin sliding is the phenomenon of the skin moving over underlying layers of fat, muscle and bone. Due to the complex interconnections between these separate layers and their differing elasticity properties, it is difficult to model and expensive to compute. We present a novel method to simulate this phenomenon at real--time by remeshing the surface based on a parameter space resampling. In order to evaluate the surface parametrization, we borrow a technique from structural engineering known as the force density method which solves for an energy minimizing form with a sparse linear system. Our method creates a realistic approximation of skin sliding in real--time, reducing texture distortions in the region of the deformation. In addition it is flexible, simple to use, and can be incorporated into any animation pipeline
The application of three-dimensional mass-spring structures in the real-time simulation of sheet materials for computer generated imagery
Despite the resources devoted to computer graphics technology over the last 40 years,
there is still a need to increase the realism with which flexible materials are simulated.
However, to date reported methods are restricted in their application by their use of
two-dimensional structures and implicit integration methods that lend themselves to
modelling cloth-like sheets but not stiffer, thicker materials in which bending moments
play a significant role.
This thesis presents a real-time, computationally efficient environment for simulations
of sheet materials. The approach described differs from other techniques principally
through its novel use of multilayer sheet structures. In addition to more accurately
modelling bending moment effects, it also allows the effects of increased temperature
within the environment to be simulated. Limitations of this approach include the
increased difficulties of calibrating a realistic and stable simulation compared to
implicit based methods.
A series of experiments are conducted to establish the effectiveness of the technique,
evaluating the suitability of different integration methods, sheet structures, and
simulation parameters, before conducting a Human Computer Interaction (HCI) based
evaluation to establish the effectiveness with which the technique can produce credible
simulations. These results are also compared against a system that utilises an
established method for sheet simulation and a hybrid solution that combines the use of
3D (i.e. multilayer) lattice structures with the recognised sheet simulation approach.
The results suggest that the use of a three-dimensional structure does provide a level of
enhanced realism when simulating stiff laminar materials although the best overall
results were achieved through the use of the hybrid model
Vector offset operators for deformable organic objects.
Many natural materials and most of living tissues exhibit complex deformable behaviours that may be characteriseda s organic. In computer animation, deformable organic material behaviour is needed for the development of characters and scenes based on living creatures and natural phenomena. This study addresses the problem of deformable organic material behaviour in computer animated objects. The focus of this study is concentrated on problems inherent in
geometry based deformation techniques, such as non-intuitive interaction and difficulty in achieving realism. Further, the focus is concentrated on problems inherent in physically based deformation techniques, such as inefficiency and difficulty in enforcing spatial and temporal constraints. The main objective in this study is to find a general and efficient solution to interaction and animation of deformable 3D objects with natural organic material properties and constrainable behaviour. The solution must provide an interaction and animation framework
suitable for the creation of animated deformable characters. An implementation of physical organic material properties such as plasticity, elasticity and iscoelasticity can provide the basis for an organic deformation model. An efficient approach to stress and strain control is introduced with a deformation tool named Vector Offset Operator. Stress / strain graphs control
the elastoplastic behaviour of the model. Strain creep, stress relaxation and hysteresis graphs control the viscoelastic behaviour of the model. External forces may be applied using motion paths equipped with momentum / time graphs. Finally, spatial and temporal constraints are
applied directly on vector operators. The suggested generic deformation tool introduces an intermediate layer between user interaction, deformation, elastoplastic and viscoelastic material behaviour and spatial and temporal constraints. This results in an efficient approach to
deformation, frees object representation from deformation, facilitates the application of constraints and enables further development
Non-smooth developable geometry for interactively animating paper crumpling
International audienceWe present the first method to animate sheets of paper at interactive rates, while automatically generating a plausible set of sharp features when the sheet is crumpled. The key idea is to interleave standard physically-based simulation steps with procedural generation of a piecewise continuous developable surface. The resulting hybrid surface model captures new singular points dynamically appearing during the crumpling process, mimicking the effect of paper fiber fracture. Although the model evolves over time to take these irreversible damages into account, the mesh used for simulation is kept coarse throughout the animation, leading to efficient computations. Meanwhile, the geometric layer ensures that the surface stays almost isometric to its original 2D pattern. We validate our model through measurements and visual comparison with real paper manipulation, and show results on a variety of crumpled paper configurations
Three dimensional simulation of cloth drape
Research has been carried out in the study of cloth modelling over many decades.
The more recent arrival of computers however has meant that the necessary
complex calculations can be performed quicker and that visual display of the
results is more realistic than for the earlier models.
Today's textile and garment designers are happy to use the latest two dimensional
design and display technology to create designs and experiment with patterns and
colours. The computer is seen as an additional tool that performs some of the
more tedious jobs such as re-drawing, re-colouring and pattern sizing.
Designers have the ability and experience to visualise their ideas without the need
for photo reality. However the real garment must be created when promoting
these ideas to potential customers. Three dimensional computer visualisation of a
garment can remove the need to create the garment until after the customer has
placed an order.
As well as reducing costs in the fashion industry, realistic three dimensional cloth
animation has benefits for the computer games and film industries.
This thesis describes the development of a realistic cloth drape model. The
system uses the Finite Element Method for the draping equations and graphics
routines to enhance the visual display. During the research the problem of
collision detection and response involving dynamic models has been tackled and a
unique collision detection method has been developed. This method has proved
very accurate in the simulation of cloth drape over a body model and is also
described in the thesis.
Three dimensional design and display are seen as the next logical steps to current
two dimensional practices in the textiles industry. This thesis outlines current and
previous cloth modelling studies carried out by other research groups. It goes on
to provide a full description of the drape method that has been developed during
this research period
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