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Raphael Diziol, Daniel Bayer and Jan Bender, Simulating Almost Incompressible Deformable Objects, Virtual Reality Interactions and Physical Simulations (VRIPhys), Karlsruhe, November 5-6, 2009 PDF BibTexAbstractWe present a new method for simulating almost incompressible deformable objects. A tetrahedral model is used to represent and restore the volume during the simulation. The new constraint computes impulses in the onering of each vertex of the tetrahedral model, in order to conserve the initial volume. With different parameters, the presented method can handle a large variety of different deformation behaviors, ranging from stiff to large deformations and even plastic deformations. The algorithm is easy to implement and reduces the volume error to less than 1% in most situations, even when large deformations are applied.
Raphael Diziol, Jan Bender and Daniel Bayer, Volume Conserving Simulation of Deformable Bodies, Short Paper Proceedings of Eurographics, Munich, March 2009 PDF BibTexAbstractWe present a new method for simulating volume conserving deformable bodies using an impulse-based approach. In order to simulate a deformable body a tetrahedral model is generated from an arbitrary triangle mesh. All resulting tetrahedrons are assigned to volume constraints which ensure the conservation of the total volume. For the simulation of such a constraint impulses are computed and applied to the particles of the assigned tetrahedrons. The algorithm is easy to implement and ensures exact volume conservation in each simulation step.
Jan Bender and Daniel Bayer, "Parallel simulation of inextensible cloth", Virtual Reality Interactions and Physical Simulations (VRIPhys), Grenoble, November 13-14, 2008 PDF BibTexAbstractThis paper presents an efficient simulation method for parallel cloth simulation. The presented method uses an impulse-based approach for the simulation. Cloth simulation has many application areas like computer animation, computer games or virtual reality. Simulation methods often make the assumption that cloth is an elastic material. In this way the simulation can be performed very efficiently by using spring forces. These methods disregard the fact that many textiles cannot be stretched significantly. The simulation of inextensible textiles with methods based on spring forces leads to stiff differential equations which cause a loss of performance. In contrast to that, in this paper a method is presented that simulates cloth by using impulses. The mesh of a cloth model is subdivided into strips of constraints. The impulses for each strip can be computed in linear time. The strips that have no common particle are independent from each other and can be solved in parallel. The impulse-based method allows the realistic simulation of inextensible textiles in real-time. Jan Bender, "Impulse-based simulation of inextensible cloth", Computer Graphics and Visualization (CGV 2008) - IADIS Multi Conference on Computer Science and Information Systems, Amsterdam 2008 PDF BibTexAbstractIn this paper an impulse-based method for cloth simulation is presented. The simulation of cloth is required in different application areas like computer animation, virtual reality or computer games. Simulation methods often assume that cloth is an elastic material. With this assumption the simulation can be performed very efficiently using spring forces. The problem is that many textiles cannot be stretched significantly. A realistic simulation of these textiles with spring forces leads to stiff differential equations which cause a deterioration of performance. The impulse-based method described in this paper solves this problem and allows the realistic simulation of inelastic textiles. Dieter Finkenzeller and Jan Bender, Semantic representation of complex building structures, Computer Graphics and Visualization (CGV 2008) - IADIS Multi Conference on Computer Science and Information Systems, 2008 PDF BibTexAbstractIn this paper we present an abstract semantic representation that is suitable for complex buildings. Facades with high-level detail are required in several domains, e.g. visualization of architectural settings and archaeological sites as well as computer animations. In order to support the user’s modeling task, besides geometrical data structural information like spatial relations is required. This supplementary information represents the semantics of the model. Therefore the model description must incorporate the geometry and the semantics. Such a description allows a partial automation of the modeling process, e.g. adjacent and nested elements are adjusted automatically. An abstract model representation with integrated semantics is presented in this paper and it is shown that it facilitates the modeling task significantly. Images
Jan Bender, Impulse-based dynamic simulation in linear time, In Journal of Computer Animation and Virtual Worlds, John Wiley & Sons Ltd, 2007 PDF BibTex Abstract:This paper describes an impulse-based dynamic simulation method for articulated bodies which has a linear time complexity. Existing linear-time methods are either based on a reduced-coordinate formulation or on Lagrange multipliers. The impulse-based simulation has advantages over these well-known methods. Unlike reduced-coordinate methods, it handles nonholonomic constraints like velocity-dependent ones and is very easy to implement. In contrast to Lagrange multiplier methods the impulse-based approach has no drift problem and an additional stabilisation is not necessary. The presented method computes a simulation step in O(n) time for acyclic multi-body systems containing equality constraints. Closed kinematic chains can be handled by dividing the model into different acyclic parts. Each of these parts is solved independently from each other. The dependencies between the single parts are solved by an iterative method. In the same way inequality constraints can be integrated in the simulation process in order to handle collisions and permanent contacts with dynamic and static friction. Additional information:The paper describes an algorithm to compute the required impulses in linear time and linear space. Jan Bender and Alfred Schmitt, Fast Dynamic Simulation of Multi-Body Systems Using Impulses, Virtual Reality Interactions and Physical Simulations (VRIPhys), 2006  PDF BibTex Abstract:
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Jan Bender and Alfred Schmitt, Constraint-based collision and contact handling using impulses, In Proceedings of the 19th international conference on computer animation & social agents, 2006 PDF BibTex Abstract:
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Dieter Finkenzeller, Jan Bender and Alfred Schmitt, Feature-based decomposition of façades, In Proceedings of Virtual Concept, 2005 PDF BibTexAbstractDue to advances in computer hardware, virtual environments become significantly larger and more complex. Therefore the modeling of virtual worlds, e.g. for computer animation and games becomes increasingly time and resource consuming. In architectural settings façade features are influenced by the underlying geometrical structure or even by other façade structures, e.g. façade edges made of large stones influence the adjacent walls. To achieve an aesthetic look of the façade adjacent structures must be seamlessly aligned. The modeling of such structures is a tedious work. With our approach only a few basic parameters are needed to create highly detailed façades. This relieves the designer of the burden of difficult modeling tasks and gives him more high level control. In this paper we present a strategy for a floor plan representation that permits arbitrary floor plan outlines. This simplifies the roof generation for different roof types in an easy way to achieve an aesthetic goal. Based on the floor plan representation we describe a hierarchical decomposition of architectural façade features. With an order relation on it we represent the interdependencies between the façade features and introduce a geometry generator for them. With our approach every building in a large VR city will look different but can have a high level on architectural details. Images
Jan Bender, Dieter Finkenzeller and Peter Oel, HW3D: A tool for interactive real-time 3D visualization in GIS supported flood modelling, In Proceedings of the 17th international conference on computer animation & social agents (CASA), 2004  PDF BibTexAbstractLarge numerical calculations are made to get a prediction what damage a possible flood would cause. These results of the simulation are used to prevent further flood catastrophes. The more realistic a visualization of these calculations is the more precaution will be taken by the local authority and the citizens. This paper describes a tool and techniques to get a realistic looking, three-dimensional, easy to use, realtime visualization despite of the huge amount of data given from the flood simulation process. Detailed information about this project can be found here: Real-time 3D visualization in GIS supported flood modelling VideosThe toolThe animations were generated with the programm "HW3D" that I developed during my research. The tool can visualize terrain surfaces with a high resolution in real-time. It also handles large textures. In order to get a realistic visualization, buildings were reconstructed using the original floor plans of cities. Other GIS data like topography points can also be visualized by the tool. Further information can be found here: Real-time 3D visualization in GIS supported flood modelling     |
