Digital elevation models (DEM) are an essential component of many geographic information systems (GIS), especially in natural resources applications. Recently, a number of prototype geographic information systems based on quadtrees have been developed. Digital elevation data create special problems for quadtree systems, since neighboring grid cells seldom have identical values. In this paper, w...

This paper presents a motion estimation algorithm based on a new multiresolution representation, the quadtree spline. This representation describes the motion field as a collection of smoothly connected patches of varying size, where the patch size is automatically adapted to the complexity of the underlying motion. The topology of the patches is determined by a quadtree data structure, and bot...

The quadtree data structure is widely used in digital image processing and computer graphics for modeling spatial segmentation of images and surfaces. A quadtree is a tree in which each node has four descendants. Since most algorithms based on quadtrees require complex navigation between nodes, efficient traversal methods as well as efficient storage techniques are of great interest. In this pa...

Ang, C.-H. and H. Samet, A fast quadtree normalization algorithm, Pattern Recognition Letters 15 (1994) 57 63. A region quadtree representation of an image can be normalized thereby yielding a quadtree that contains the least number of nodes in O(s 2 log2 s) time where s is the length of the grid. A new algorithm is proposed whose asymptotic time bound is the same but whose first part only take...

A hybrid of wavelet and quadtree image coding is introduced. It uses a recently developed quadtree predictive coding technique, having good rate/fidelity performance and very low complexity, to encode the baseband wavelet coefficients. The resulting quadtree decomposition of the baseband is then used to guide the encoding of higher frequency subbands, by indicating which of their coefficients r...

This paper presents a motion estimation algorithm based on a new multiresolution representation, the quadtree spline. This representation describes the motion field as a collection of smoothly connected patches of varying size, where the patch size is automatically adapted to the complexity of the underlying motion. The topology of the patches is determined by a quadtree data structure, and bot...

This paper presents the hardware architecture for fractal image compression (FIC) with quadtree partitioning. Fractal image coding with quadtree partitioning allows one to produce higher quality of image. Processing image areas of different complexity with image blocks of varying size enables proper exploration of image details. Additionally, exploiting parallelism present within the algorithm ...

This paper presents a Rate-Distortion analysis for a simple horizon edge image model. A quadtree with anisotropy and rotation is performed on this kind of image, giving a toy model for a non-linear adaptive coding technique, and its Rate-Distortion behavior is studied. The effect of refining the quadtree decomposition is also analyzed.

We present an efficient algorithm called the Quadtree Heuristic for identifying a list of similar terms for each unique term in a large document collection. Term similarity is defined using the Expected Mutual Information Measure (EMIM). Since our aim for defining the similarity lists is to improve information retrieval (IR), we present the outcome of an experiment comparing the performance of ...