Results 1  10
of
18
Spatial Data Structures
, 1995
"... An overview is presented of the use of spatial data structures in spatial databases. The focus is on hierarchical data structures, including a number of variants of quadtrees, which sort the data with respect to the space occupied by it. Suchtechniques are known as spatial indexing methods. Hierarch ..."
Abstract

Cited by 287 (13 self)
 Add to MetaCart
An overview is presented of the use of spatial data structures in spatial databases. The focus is on hierarchical data structures, including a number of variants of quadtrees, which sort the data with respect to the space occupied by it. Suchtechniques are known as spatial indexing methods. Hierarchical data structures are based on the principle of recursive decomposition. They are attractive because they are compact and depending on the nature of the data they save space as well as time and also facilitate operations such as search. Examples are given of the use of these data structures in the representation of different data types such as regions, points, rectangles, lines, and volumes.
An Overview of Quadtrees, Octrees, and Related Hierarchical Data Structures
 NATO ASI Series
, 1988
"... An overview of hierarchical data structures for representing images, such as the quadtree and octree, is presented. They are based on the principle of recursive decomposition. The emphasis is on the representation of data used in applications in computer graphics, computeraided design, robotics, co ..."
Abstract

Cited by 19 (2 self)
 Add to MetaCart
An overview of hierarchical data structures for representing images, such as the quadtree and octree, is presented. They are based on the principle of recursive decomposition. The emphasis is on the representation of data used in applications in computer graphics, computeraided design, robotics, computer vision, and cartography. There is a greater emphasis on region data (i.e., 2dimensional shapes) and to a lesser extent on point, lin.e, and 3dimensional data.
Implementing ray tracing with octrees and neighbor finding
 Computers And Graphics
, 1989
"... AbstractA ray tracing implementation is described that is based on an octree representation of a scene. Rays are traced through the scene by calculating the blocks through which they pass. This calculation is performed in a bottomup manner through the use of neighbor finding. The octrees are assu ..."
Abstract

Cited by 18 (4 self)
 Add to MetaCart
AbstractA ray tracing implementation is described that is based on an octree representation of a scene. Rays are traced through the scene by calculating the blocks through which they pass. This calculation is performed in a bottomup manner through the use of neighbor finding. The octrees are assumed to be implemented by a pointer representation. The most basic operation in computer graphics is the conversion of an internal model of a threedimensional scene into a twodimensional scene that lies on the viewplane. The purpose is to generate an image of the
Efficient Algorithms for TwoPhase Collision Detection
, 1997
"... This article describes practical collision detection algorithms for robot motion planning. Attention is restricted to algorithms that handle rigid, polyhedral geometries. ..."
Abstract

Cited by 18 (0 self)
 Add to MetaCart
This article describes practical collision detection algorithms for robot motion planning. Attention is restricted to algorithms that handle rigid, polyhedral geometries.
An Improved ZBuffer CSG Rendering Algorithm
 In HWWS ’98: Proceedings of the ACM SIGGRAPH/EUROGRAPHICS workshop on Graphics hardware
, 1998
"... We present an improved zbuffer based CSG rendering algorithm, based on previous techniques using zbuffer parity based surface clipping. We show that while this type of algorithm has been reported as requiring O(n^2)), (where n is the number of primitives), an O(kn) (where k is depth complexity) a ..."
Abstract

Cited by 13 (0 self)
 Add to MetaCart
We present an improved zbuffer based CSG rendering algorithm, based on previous techniques using zbuffer parity based surface clipping. We show that while this type of algorithm has been reported as requiring O(n^2)), (where n is the number of primitives), an O(kn) (where k is depth complexity) algorithm may be substituted. For cases where k is less than n this translates into a significant performance gain.
BOTTOMUP CONSTRUCTION AND 2:1 BALANCE REFINEMENT OF LINEAR OCTREES IN PARALLEL ∗
"... Abstract. In this article, we propose new parallel algorithms for the construction and 2:1 balance refinement of large linear octrees on distributed memory machines. Such octrees are used in many problems in computational science and engineering, e.g., object representation, image analysis, unstruct ..."
Abstract

Cited by 11 (7 self)
 Add to MetaCart
Abstract. In this article, we propose new parallel algorithms for the construction and 2:1 balance refinement of large linear octrees on distributed memory machines. Such octrees are used in many problems in computational science and engineering, e.g., object representation, image analysis, unstructured meshing, finite elements, adaptive mesh refinement and Nbody simulations. Fixedsize scalability and isogranular analysis of the algorithms, using an MPIbased parallel implementation, was performed on a variety of input data and demonstrated good scalability for different processor counts (1 to 1024 processors) at the Pittsburgh Supercomputing Center’s TCS1 AlphaServer. The results are consistent for different data distributions. Octrees with over a billion octants were constructed and balanced in less than a minute on 1024 processors. Like other existing algorithms for constructing and balancing octrees, our algorithms have O(n log n) work and O(n) storage complexity. Under reasonable assumptions on the distribution of octants and the work per octant, the parallel time complexity is O(n/np log(n/np) + np log np), were n is the final number of leaves and np is the number of processors. Key words. Linear octrees, Balance refinement, Morton encoding, large scale parallel computing, space filling curves AMS subject classifications. 65N50, 65Y05, 68W10, 68W15 1. Introduction. Spatial
Mobile Robot Navigation Exploration Algorithm
, 1992
"... This paper will present an algorithm for path planning to a goal with a mobile robot in an unknown environment. The robot maps the environment only to the extent that is necessary to achieve the goal. Mapping is achieved using tactile sensing while the robot is executing a path to the specified goal ..."
Abstract

Cited by 7 (0 self)
 Add to MetaCart
This paper will present an algorithm for path planning to a goal with a mobile robot in an unknown environment. The robot maps the environment only to the extent that is necessary to achieve the goal. Mapping is achieved using tactile sensing while the robot is executing a path to the specified goal. Paths are generated by treating unknown regions in the environment as free space. As obstacles are encountered en route to a goal, the model of the environment is updated and a new path to the goal is planned and executed. Initially the paths to the goal generated by this algorithm will be negotiable paths. However as the robot acquires more knowledge about the environment, the length of the planned paths will be optimised. The optimisation criteria can be modified to favour or avoid unexplored regions in the environment. The algorithm presented in this paper makes use of the quadtree data structure to model the environment and uses the distance transform methodology to generate paths for ...
Efficient Collision Detection Among Objects in Arbitrary Motion Using Multiple Shape Representations
 Proceedings 12th IARP Inter. Conference on Pattern Recognition. pp
, 1994
"... We propose an eficient method for detecting potential collisions among multiple objects with arbitrary motion (translation and rotation) in threedimensional (30) space. The method is useful for online monitoring and path planning in a 30 environment in which there are multiple independentlymov ..."
Abstract

Cited by 4 (1 self)
 Add to MetaCart
We propose an eficient method for detecting potential collisions among multiple objects with arbitrary motion (translation and rotation) in threedimensional (30) space. The method is useful for online monitoring and path planning in a 30 environment in which there are multiple independentlymoving objects. The method consists of two main stages. In the first, coarse stage, an approximate test is performed to identify interfering objects in thd entire workspace using octree representation of object shapes. In the second, fine stage, polyhedral representation of object shapes is used to more accurately identijy any object parts that might cause interference and collisions. For this purpose, specific pairs of faces belonging to any of the interfering objects found in the first stage are tested, thus performing detailed computation on a reduced amount of data. Experimental results, which demonstrate the eficiency of the proposed collision detection method, are given. 1
A Survey on Collision Detection Techniques for Virtual Environment
 Proceedings of 5 th Symposium on Virtual Reality
, 2002
"... Abstract. Collision detection is an important component of many applications in computer graphics applications. In particular, it is a critical question for virtual environments applications, where real time performance is required to provide the feeling of being immerse in a environment that looks ..."
Abstract

Cited by 4 (3 self)
 Add to MetaCart
Abstract. Collision detection is an important component of many applications in computer graphics applications. In particular, it is a critical question for virtual environments applications, where real time performance is required to provide the feeling of being immerse in a environment that looks and is interactive like a real one. In this paper, we look into current approaches for collision detection that can be used for real time interactive virtual environments where the trajectories of moving objects are not predefined. We also present a taxonomy for classifying different collision detection algorithms. In the end, using collision detection toolkits publicly available, we have performed a set of experiments in order to compare the performance between collision detection algorithms based on axisaligned, discrete orientation polytopes and oriented bounding boxes. 1.