A Fast Voxel Traversal Algorithm for Ray Tracing

This paper presents a method to alleviate performance degradation issues of Haptic Collision Detection when the Bounding Volumes or Bounding Volume Hierarchies of multiple disjoint objects are overlapping or inclusive and force the Haptic Collision Detection methods into narrow phase collision detection with all involved objects. The proposed method aims to generate tighter, mutually exclusive Bounding Volumes at the pre-processing stage, and to quickly cull irrelevant nearby objects at the broad phase to ensure that the Haptic Collision Detection methods will not be overloaded with unnecessary narrow phase collision detection. The proposed method is based on a hybrid representation of Bounding Volume and Space Partitioning and is implemented as an algorithm that automatically generates these new Bounding Volumes for disjoint objects, with details and corner cases discussed. A series of experiments based on real-life Haptic Collision Detection applications has been conducted. The results are analyzed and compared with those from an existing Haptic Collision Detection algorithm. The outcome demonstrates the capability of the proposed method in maintaining a stable Haptic Collision Detection performance under various challenging situations.

In order to improve the real-time and accuracy in the collision detection technology, a collision detection algorithm based on spatial partitioning and bounding volume was proposed . This algorithm adopted different spatial division strategies for different locations of the spaces according to the details in the scenes to exclude objects which can not intersect.Thus defined the potential intersection areas. Then we used a dynamic S-AABB hierarchy bounding boxes to test whether the intersection happened between the objects in the same grids. We used the sphere boxes to rule out the disjoint objects quickly. Then constructed the dynamic AABB bounding boxes trees for the rest of objects for further intersection test. At last, we improved the traditional overlapping test between the primitives for accurate collision detection . Compared to the traditional collision detection algorithm based on spatial partitioning and AABB bounding volume. This algorithm effectively improves the real-time of the collision detection without affecting the accuracy of original collision detection.

Reversible data hiding for encrypted media not only preserves the privacy of the media content but also can convey additional information during message transmission. Some studies advocate separability, that is, the message can be correctly extracted irrespective of whether the encrypted media has been decrypted. However, current research has focused on encrypted images. Urgent research is required on encrypted three-dimensional (3D) models. This paper proposes a separable reversible data hiding method based on spatial subdivision and space encoding for encrypted 3D models. A bounding volume is first constructed using the vertices with boundary values in the processing model. Each vertex coordinate value is then converted into a ratio (between 0 and 1) of the distance between the vertex and minimum boundary point to the side length of the bounding volume. The owner of the 3D model then uses a secret key to encrypt all ratios except those of the boundary vertices to obtain an encrypted 3D model of the same size as the original model. The spatial subdivision technique and a subdivision threshold are subsequently used to divide the bounding volume into a series of blocks and simultaneously control the vertex distortion. The secret message is embedded in the encrypted vertex by using the space encoding method with an embedding threshold. Experimental results indicate that the proposed algorithm enables high privacy, performs separable reversible data hiding, and has low computational complexity, high embedding capacity, and controllable distortion.

We present an algorithm for collision detection between multiple deformable objects translating in a large environment. We use Spatial Partitioning to subdivide the scene and a Bounding Volume Hierarchy to decompose the objects, using octrees in both cases. The algorithm is divided in two parts, the Broad and Narrow Phases, with objects that can be rigid or deformable. In the Broad Phase, an octree is used to partition the scene and cull away the object's Bounding Volumes that are distant. In the Narrow Phase, a hierarchical decomposition of Axis Aligned Bounding Boxes or spheres is employed to reduce the number of primitives in the pairwise comparisons. In summary this work is a general-purpose collision detection technique for performing real time collision detection of deformable bodies in interactive 3D applications.

This paper puts forward a kind of hybrid algorithm-combining the hierarchical bounding volume method and the bounding volume coordinate chain method in the virtual environment. This algorithm can improve the efficiency of collision detection, rigid body and the software both can be applied to with the collision detection. Then we built the task trees by traversing the mixed hierarchical bounding volumes and speeded up the collision detection algorithm by applying a parallel computing and introduce a space-time correlations concept to accelerate the speed of updating of the bounding box at the same time. Objects that intersect precisely in the testing process, combined with hierarchical bounding box tree compression and storage, storage space by reducing the algorithm to improve the detection algorithm speed. Experimental results show that the method compared with the single bounding method level, it advantages, and objects in the detection of more cases can reduce the execution time required for the algorithm.

Reduced precision bounding volume hierarchies and ray traversal can significantly improve the efficiency of ray tracing through low-cost dedicated hardware. A key approach to enabling reduced precision computations during traversal is to translate the ray origin closer to the bounding volume hierarchy node after each traversal step. However, this approach precludes sharing of intersection computations between a parent node and its two children, which is an important optimization. In this paper, we introduce a novel traversal algorithm that addresses this limitation and achieves a significant reduction in the computational complexity of traversal compared to previous approaches. We also include an analysis that shows how our algorithm guarantees watertight intersections which is a key requirement for robust image quality, especially with reduced precision traversal where numerical errors can be large.

A beam tracing method with precise antialiasing for polyhedral scenes

To improve the efficiency of collision detection between rigid bodies in complex scenes, this paper proposes a method based on hybrid bounding volume hierarchies for collision detection. In order to improve the simulation performance, the method is based on weighted oriented bounding box and makes dense sampling on the convex hulls of the geometric models. The hierarchical bounding volume tree is composed of many layers. The uppermost layer adopts a cubic bounding box, while lower layers employ weighted oriented bounding box. In the meantime, the data of weighted oriented bounding box is reused for triangle intersection check. We test the method using two scenes. The first scene contains two Buddha models with totally 361,690 triangle facets. The second scene is composed of 200 models with totally 115, 200 triangle facets. The experiments verify the effectiveness of the proposed method.

Collision detection is a critical module in many applications such as computer graphics, robot motion planning, physical simulation, CAD/CAM, and molecular modeling. Many efficient algorithms have been proposed to solve the collision-detection problem, and most of them use some sort of hierarchical bounding volume to speed up the time-consuming process. In this research, we focus on a special situation for applications such as interactive virtual environment, where accuracy may not be crucial but the available time for performing the check is limited. We describe our findings on the inherencies of bounding volume traverse trees (BVTT). Based on this observation, we propose a time-budgeted collision detection method that can traverse the critical regions of BVTT earlier if the time budget is limited. Preliminary experimental results are also reported, and a new strategy is suggested based on the concept of confidence value

Ray Tracing is already established as a powerful and elegant technique for image synthesis, but is too inconvenient because of its high computational cost, especially in complex scenes. Because of this, the effort to accelerate Ray Tracing has been important. The utilization of hierarchical bounding volumes produces important time reductions, increasing the memory consumption. Parallelisation in general purpose computers is another way of reducing time. We present an algorithm that permits visualizing by Ray Tracing very complex natural scenes generated by procedural models in distributed memory multiprocessors with any memory size. In this approach, the primitive database is not generated; each processor contains the initial specification of the scene and realizes the visualization, working hierarchically, directly from the specification and a partial generation of the model. The rest of the available memory is used to store some levels of the hierarchical bounding volume, computing in tracing time bounding volumes and primitives not stored. In this way, there are no communications during the tracing phase. The algorithm is also valid for shared memory multiprocessors.KeywordsNatural SceneMemory ConsumptionVirtual MemoryInitial SpecificationImage SynthesisThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

An orthogonal BSP (binary space partitioning) tree is a commonly used spatial subdivision data structure for ray-tracing acceleration. While the construction of a BSP tree takes a relatively short time, the efficiency of a traversal algorithm significantly influences the overall rendering time. We propose a new fast traversal algorithm based on statistical evaluation of all possible cases occuring during the traversal of a BSP tree. More frequent cases are handled simply, while less frequent ones are more computationally expensive. The proposed traversal algorithm handles all singularities correctly, and saves between 30% and 50% of traversal time compared with the commonly-known Sung and Arvo algorithms.

This paper introduces a new spatial index structure, called Bounded KD tree (B-KD tree), for realtime ray tracing of dynamic scenes. By presenting hardware units of all time critical B-KD tree algorithms in the context of a custom realtime ray tracing chip we show that this spatial index structure is well suited for hardware implementation. B-KD trees are a hybrid spatial index structure that combine the advantages of KD trees and Bounding Volume Hierarchies into a single, simple to handle spatial index structure. Similar to KD trees, B-KD trees are binary trees where each node considers only a single spatial dimension. However, instead of a single splitting plane that divides space into two disjoint sub-spaces, each node in B-KD trees contains two pairs of axis aligned planes that bound the geometry of its two child nodes. As a bounding volume approach B-KD trees allow for simple and efficient updates when changing geometry while maintaining the fast traversal operations and simple hardware implementation known from KD trees. This enables the support for dynamic scenes with constant mesh topology and coherent dynamic changes, like typical skinned meshes.

Implementation of the shooting and bouncing rays (SBR) method for radar cross section or scattering center prediction of complex electrically large objects is studied with a focus on the computational efficiency. A triangulated CAD model is assumed and SBR is processed by a ray‐triangle intersection algorithm. An octree space partitioning, which might be based on either rectangular boxes or spheres as bounding volumes, is used to speedup the intersection decision. The effect of proper implementation and choice of the bounding volume to reduce “the constant in front” of the leading order complexity is demonstrated. It is shown that the required computer resources can be reduced drastically using the techniques outlined in this article. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2409–2413, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25492

A novel data hiding scheme for color images using a BSP tree

This paper constructs the signal light model of intersection considering dynamic traffic flow, and proposes an ecological cruise control strategy using the pseudo-spectral method to optimize the energy consumption of electric connected and automated vehicles when passing through multiple intersections. Firstly, a method for a dynamic effective red light duration model considering the average queue effect and the real-time flow fluctuation effect is proposed. Secondly, a recursive and traversal search algorithm is used to identify different combinations of traffic schemes to reduce the complexity of a solving global optimization problems. Finally, considering the constraints of dynamic effective red light duration, the pseudo-spectral method is proposed which can be used in the traffic energy-saving planning of single intersection and multiple intersections. Simulation results demonstrate that compared with dynamic programming benchmark algorithm, the energy-saving effect of this control strategy is much close to the global optimum, and the calculation efficiency is far better. Besides, compared with the intelligent driver model which used as the energy consumption benchmark, this control strategy can produce a better energy-saving speed reference trajectory.