We present an exact and interactive collision detection system, I-COLLIDE, for large-scale environments. Such environments are characterized by the number of objects undergoing rigid motion and the complexity of the mod-els. The algorithm does not assume the objects ’ motions can be expressed as a closed form function of time. The collision detection system is general and can be easily in-terfaced with a variety of applications. The algorithm uses a two-level approach based on pruning multiple-object pairs using bounding boxes and performing exact collision detection between selected pairs of polyhedral models. We demonstrate the performance of the system in walkthrough and simulation environments consisting of a large number of moving objects. In particular, the system takes less than l/20 of a second to determine all the collisions and contacts in an environment consisting of more than a 1000 moving polytopes, each consisting of more than 50 faces on an HP-9000/750. 1

The need to perform fast and accurate proximity queries arises frequently in physically-based modeling, simulation, animation, real-time interaction within a virtual environment, and game dynamics. The set of proximity queries include intersection detection, tolerance verification, exact and approximate minimum distance computation, and (disjoint) contact determination. Specialized data structures and algorithms have often been designed to perform each type of query separately. We present a unified approach to perform any of these queries seamlessly for general, rigid polyhedral objects with boundary representations which are orientable 2-manifolds. The proposed method involves a hierarchical data structure built upon a surface decomposition of the models. Furthermore, the incremental query algorithm takes advantage of coherence between successive frames. It has been applied to complex benchmarks and compares very favorably with earlier algorithms and systems.

solid models

In a geometric context, a collision or proximity query reports information about the relative configuration or placement of two objects. Some of the common examples of such queries include checking whether two objects overlap in space, or whether their boundaries intersect, or computing the minimum Euclidean separation distance between their boundaries. Hundreds of papers have been published on di#erent aspects of these queries in computational geometry and related areas such as robotics, computer graphics, virtual environments, and computer-aided design. These queries arise in di#erent applications including robot motion planning, dynamic simulation, haptic rendering, virtual prototyping, interactive walkthroughs, computer gaming, and molecular modeling. For example, a large-scale virtual environment, e.g., a walkthrough, creates a model of the environment with virtual objects. Such an environment is used to give the user a sense of presence in a synthetic world and it s

this paper, we address the first two elements by presenting general a purpose collision detection and contact area determination algorithm for simulations. The collision response is application dependent. The algorithm reports the contact area and thus enables the application to compute an appropriate response. Our algorithm not only addresses interaction between a pair of general polygonal objects, but also large environments consisting of hundreds of moving parts, such as those encountered in the manufacturing plants. Furthermore, we do not assume the motions of the objects to be expressed as a closed form function of time. Our collision detection scheme is efficient and accurate (to the resolution of the models). Given the geometric models, the algorithm precomputes the convex hull and a hierarchical representation of each model in terms of oriented bounding boxes. At runtime, it uses tight fitting axis-aligned bounding boxes to pair down the number of object pair interactions to only those pairs within close proximity [12]. For each pair of objects whose bounding boxes overlap, the algorithm checks whether their convex hulls are intersecting based on the closest feature pairs [22]. Finally for each object pair whose convex hulls overlap, it makes use of oriented bounding box hierarchy (OBBTree) to check for actual contact [18]. Organization: The rest of the paper is organized as follows: Section 2 reviews some of the previous work in collision detection. Section 3 outlines the algorithm for pruning the number of object pairs. We briefly describe the closest feature and contact determination algorithms in Section 4. Finally, we describe the imple- leftmark

We present a novel and fast algorithm to compute penetration depth (PD) between two polyhedral models for physically-based animation. Given two overlapping polyhedra, it computes the minimal translation distance to separate them using a combination of object-space and image-space techniques. The algorithm computes pairwise Minkowski sums of decomposed convex pieces and performs a closest point query using rasterization hardware. It uses bounding volume hierarchies, object-space and image-space culling algorithms to further accelerate the computation and refines the estimated PD in a hierarchical manner. We demonstrate its application to contact response computation and a time-stepping method for dynamic simulation.

We present a novel algorithm for accurately detecting all contacts, including self-collisions, between deformable models. We precompute a chromatic decomposition of a mesh into non-adjacent primitives using graph coloring algorithms. The chromatic decomposition enables us to check for collisions between non-adjacent primitives using a linear-time culling algorithm. As a result, we achieve higher culling efficiency and significantly reduce the number of false positives. We use our algorithm to check for collisions among complex deformable models consisting of tens of thousands of triangles for cloth modeling and medical simulation. Our algorithm accurately computes all contacts at interactive rates. We observed up to an order of magnitude speedup over prior methods.

We present a novel and fast algorithm to compute penetration depth (PD) between two polyhedral models. Given two overlapping polyhedra, it computes the minimal translation distance to separate them using a combination of object-space and image-space techniques. The algorithm computes pairwise Minkowski sums of decomposed convex pieces, performs closest-point query using rasterization hardware and refines the estimated PD by object-space walking. It uses bounding volume hierarchies, model simplification, object-space and image-space culling algorithms to further accelerate the computation and refines the estimated PD in a hierarchical manner. We highlight its performance on complex models and demonstrate its application to dynamic simulation and tolerance verification.

Keywords: Video-based graphics, animation and rendering; collision detection; rigid body simulation; visual hull; Abstract: We present a novel way of interacting with a virtual 3D scene in the context of free-viewpoint video. Using a multi-camera setup, our technique detects collisions between virtual objects and real objects, including people. We perform collision computations directly on the image data, as opposed to reconstructing the full geometry of the subject. This reduces implementation complexity, and moreover, yields interactive performance. We demonstrate the effectiveness of our technique by incorporating it in a rigid body simulation. The subject can interact with virtual objects and observe his or her actions while being able to adjust the viewpoint, all in real-time. Figure 1: A person, captured by multiple calibrated digital video cameras, interacts with a rigid body simulation at interactive speeds. 1

This paper surveys the techniques used to perform collision detection operations on 3D models. Virtual prototyping, robotics path-planning, and animation applications demand compute intensive interference testing. As hardware becomes faster and algorithmic techniques improve, collision detection is becoming more widely used in commercial systems and applied to large models. The purpose of this paper is to bring together the techniques used to perform collision detection operations. Most of the techniques employ various divide-and-conquer approaches, such as adaptive subdivision, bounding volume hierarchies (BVHs), or hierarchical spatial subdivisions (HSSs). A few techniques resemble sweep-and-prune approaches, and a few others are difficult to categorize. The different types of model representations generally have their own followers and techniques developed for them. For instance, the paramtric surfaces are almost exclusively the domain of the computer aided geometric design community, which has little overlap with the computational geoemtry community, for example. But the operations are very similar: reporting intersections among a set of mathematical objects is a classic computational geoemetry problem. Computing the space curve which is the intersection of two parametric cubic surfaces is a classic problem in computor-aided geometric design. They are both intersection problems. We will begin our survey first with a review of the types of representations available for 3D models. Next we review the variations on collision detection problem. Then we look briefly at four fields rom which the solutions to these problems are being drawn. Then the bulk of the paper is devoted to reviewing the techniques employed by researchers and practitioners to solve the variations of ...