Modeling And Simulation Of Soft Bodies

As graphics and simulations become more realistic, techniques for approximating soft body objects, that is, non-solid objects such as liquids, gases, and cloth, are becoming increasingly common. The proposed generalized soft body method encompasses some specific cases of other existing models enabling simulation of a variety of soft body materials by parameter adjustment. This research presents a general method of soft body model and simulation in which parameters for body control, surface deformation, volume control, and gravitation, can be adjusted to simulate different types of soft bodies. In this method, the soft body mesh structure maintains configuration among surface points while fluid modeling deforms the details of the surface. To maintain volume, an internal pressure is approximated by simulated molecules within the soft body. Free fall motion of soft body is generated by gravitational field. Additionally, a constraint is specified based on the property of the soft body being modeled. There are several standard methods to control soft body volume. This work illustrates the simplicity of simulation by selecting a mass-spring system for the deformation of the connected points of a three-dimensional mesh, while an internal pressure force acts upon the surface triangles. To incorporate fluidity, smooth particles hydrodynamics (SPH) is applied where surface points are considered as free moving particles interacting with neighboring surface points within a SPH radius. Because SPH is computationally expensive, it requires an efficient method to determine neighboring surface points. Collision detection with soft bodies and other rigid body objects also requires such fast neighbor detection. To determine the neighboring surface point, Axis Aligned Bounding Box (AABB), Octree, and a partitioning and hashing schemes iv have been investigated and the result shows that the partitioning and hashing scheme provides the best frame rate. Thus a fast partitioning and hashing scheme is used in this research to reduce both computational time and the memory requirements. The proposed soft body model aims to be applied in several types of soft body application depending on the specific types of soft body deformation. The work presented in this dissertation details experiments with a variety of visually appealing fluid-like surfaces and organic materials animated at interactive speeds. The algorithm is also used to implement animated space-blob creatures in the Galactic Arms Race video game and a human lung simulation, demonstrating the effectiveness of the algorithm in both an actual video game engine and a medical application. The simulation results show that the general model of the soft body can be applied to several applications by adjusting the soft body parameters according to the appearance results

Simulation of Soft Bodies with Pressure Force and the Implicit Method

The implicit approach can be used to efficiently model realistically deformable objects for large constraints such as stiffness or time. In soft bodies with pressure forces, models are composed of mesh points connected by springs and applied with pressure forces. System parameters such as spring constant, damping constant, etc. are defined to describe the behaviors of the deformable objects. Since the simulation of soft bodies with pressure force fails when the constraints are large, this paper proposes the method to solve this problem by using the implicit integration method for soft bodies with particular force. The results show that our method can realistically simulate the soft bodies when large constraints are applied

Line-Triangle Test For Collision Detection And Response In Soft Bodies

Soft-body models are common in games to simulate cloth or elastic objects. To realistically simulate soft-body objects, collision detection and response is required. In addition, soft-body models must re-arrange their internal structure to react to the collision. This paper presents a new collision detection and response algorithm which can simulate a variety of soft-body material behaviors ranging from stiff to elastic. In this approach, a line-triangle intersection test is used for collision detection and force propagation is used for collision response. Implementation and experiments using the algorithm show that complex deformable objects composed of thousands vertices can be animated at interactive speeds

Experimenting With Real Time Simulation Parameters For Fluid Model Of Soft Bodies

In soft body simulation with fluid modeling, smooth particle hydrodynamics (SPH) is one of the most efficient methods to simulate the soft body for real time applications. In this paper, we introduce a general model of soft bodies with SPH fluid modeling as one of the components for interaction among particles. The fluid force in SPH depends on the density of neighboring fluid particles in the kernel of the considered particle. The fluid force is related to fluid attributes such as fluid density, fluid pressure, and fluid viscosity. Computation becomes faster if the neighboring fluid particles are known during the computations of the fluid attributes. In our simulation of soft body model, the kernels of the fluid attributes are identical, and hence we use the same neighboring fluid particles to evaluate the fluid attributes. In this paper we introduce partitioning and hashing schemes to identify the neighboring fluid particles for SPH to compute the fluid force in the soft body simulation. The suitable parameters for the partitioning and hashing schemes are presented for the modeling. Experimental results show that the grid based scheme can reduce time computation in SPH for fluid modeling in real time applications. We also present a result of a soft body in which the model includes all forces. © 2010 SCS

Soft Body Simulation With Leaking Effect

Though there is much research on physically-based animation of soft bodies, simulating soft body objects in real-time remains challenging problem. This paper presents an algorithm for simulating leaking effects in real-time soft body simulations where fast calculation is priority. To simulate leaking effects in a soft body, geometrical cases of broken springs are defined and an algorithm rearranges the topology of neighbors in which the broken springs are connected. Then, internal forces are applied to surface points to model the leaking effect and deform the soft body. Experiments show that the soft body objects with leaking effects can be realistically simulated at interactive speeds on common hardware. © 2008 IEEE

KEYWORDS Line-Triangle Test for Collision Detection and Response in Soft Bodies

soft body collision, animation, spatial subdivision, spatial hashing Soft-body models are common in games to simulate cloth or elastic objects. To realistically simulate soft-body objects, collision detection and response is required. In addition, soft-body models must re-arrange their internal structure to react to the collision. This paper presents a new collision detection and response algorithm which can simulate a variety of soft-body material behaviors ranging from stiff to elastic. In this approach, a line-triangle intersection test is used for collision detection and force propagation is used for collision response. Implementation and experiments using the algorithm show that complex deformable objects composed of thousands vertices can be animated at interactive speeds. 1

A General Model For Soft Body Simulation In Motion

Soft bodies are the models in which the bodies deform during animated frames depending on the interaction between themselves and environment. This paper presents a parametric general model for soft body simulation in which structure, deformation, and volume controls generate animated deformations restricted by a set of constraints within or without an environment of gravitation. In this model, the soft body shape is controlled by structure control and anamorphosis of the soft body is created by deformation control, while the mass is approximated by volume control. A set of constraints for these controls further restrict the types of deformation of the soft body. By selecting specific methods for structure, deformation, and volume controls with a set of constraints, we demonstrate a variety of appealing fluid-like surfaces and respiration of lungs for validating the usefulness of the general model. © 2011 IEEE

3D Soft Body Simulation Using Mass-spring System with Internal Pressure Force and Simplified Implicit Integration

Abstract — In this paper, we propose a method to simulate soft bodies by using gravitational force, spring and damping forces between surface points, and internal molecular pressure forces. We consider a 3D soft body model composed of mesh points that define the body’s surface such that the points are connected by springs and influenced by internal molecular pressure forces. These pressure forces have been modeled on gaseous molecular interactions. Simulation of soft body with internal pressure forces is known to become unstable when high constants are used and is averted using an implicit integration method. We propose an approximation to this implicit integration method that considerably reduces the number of computations in the algorithm. Our results show that the proposed method realistically simulates soft bodies and improves performance of the implicit integration method. Index Terms — Soft body simulation, implicit integration method, internal pressure force, mass-spring system I

Avoiding Greediness In Cooperative Peer-To-Peer Networks

In peer-to-peer networks, peers simultaneously play the role of client and server. Since the introduction of the first file-sharing protocols, peer-to-peer networking currently causes more than 35% of all internet network traffic-with an ever increasing tendency. A common file-sharing protocol that occupies most of the peer-to-peer traffic is the BitTorrent protocol. Although based on cooperative principles, in practice it is doomed to fail if peers behave greedily. In this work-in-progress paper, we model the protocol by introducing the game named Tit-for-Tat Network Termination (T4TNT) that gives an interesting access to the greediness problem of the BitTorrent protocol. Simulations conducted under this model indicate that greediness can be reduced by solely manipulating the underlying peer-to-peer topology.. © 2009 ICST Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering