Query optimizers in object-relational database management systems require users to provide the execution cost models of user-defined functions(UDFs). Despite this need, however, there has been little work done to provide such a model. Furthermore, none of the existing work is self-tuning and, therefore, cannot adapt to changing UDF execution patterns. This paper addresses this problem by introd...

The (region) quadtree, shown in Fig. 1, is a widely studied data structure for representing digitized images. An extensive survey of quadtrees and their use in image processing and graphics appears in Samet [ 1,2]. Unfortunately, the two-dimensional nature of the information they store makes quadtree usage more subtle than, say, binary search tree usage, and efficient algorithms often demand sp...

Quadtree decomposition is a simple technique used to obtain an image representation at different resolution levels. This representation can be useful for a variety of image processing and image compression algorithms. This paper presents a simple way to get better compression performances (in MSE sense) via quadtree decomposition, by using near to optimal choice of the threshold for quadtree de...

A New Quadtree-based Image Compression Technique using Pattern Matching Algorithm F. Keissarian1 Summary In this paper, a new image compression technique is proposed in which variable block size technique is adopted, using quadtree decomposition, for coding images at low bit rates. The proposed algorithm decomposes the host image into blocks of variable sizes according to histogram analysis of ...

The performance of data-parallel algorithms for spatial operations using data-parallel variants of the bucket PMR quadtree, R-tree, and R-tree spatial data structures is compared. The studied operations are data structure build, polygonization, and spatial join in an application domain consisting of planar line segment data (i.e., Bureau of the Census TIGER/Line les). The algorithms are impleme...

We present an all-quad meshing algorithm for general domains. We start with a strongly balanced quadtree. In contrast to snapping the quadtree corners onto the geometric domain boundaries, we move them away from the geometry. Then we intersect the moved grid with the geometry. The resulting polygons are converted into quads with midpoint subdivision. Moving away avoids creating any flat angles,...

Engineering analysis often involves the accurate numerical solution of boundary value problems in discrete form. Hierarchical quadtree (or octree) grid generation offers an efficient method for the spatial discretisation of arbitrary-shaped two- (or three-) dimensional domains. It consists of recursive algebraic splitting of sub-domains into quadrants (or cubes), leading to an ordered hierarchi...

A technique for supporting quadtree matrices in a lazy functional langauge is presented that ameliorates tensions between performance and purity. In large matrix computations the facility to update in-place is a requisite for high performance. Thus, techniques for applying safe side effects to quadtree matrices are presented. Performance enhancements come via intrinsic properties of quadtree ma...

This paper presents a new hybrid scheme for image data compression using quadtree decomposition and parametric line fitting. In the first phase of encoding, the input image is partitioned into quadrants using quadtree decomposition. To prevent from very small quadrants, a constraint of minimal block size is imposed during quadtree decomposition. Homogeneous quadrants are separated from non-homo...