Topic
Quadtree
About: Quadtree is a research topic. Over the lifetime, 3053 publications have been published within this topic receiving 44622 citations.
Papers published on a yearly basis
Papers
TL;DR: An optimized tree is defined and an algorithm to accomplish optimization in n log n time is presented, guaranteeing that Searching is guaranteed to be fast in optimized trees.
Abstract: The quad tree is a data structure appropriate for storing information to be retrieved on composite keys. We discuss the specific case of two-dimensional retrieval, although the structure is easily generalised to arbitrary dimensions. Algorithms are given both for staightforward insertion and for a type of balanced insertion into quad trees. Empirical analyses show that the average time for insertion is logarithmic with the tree size. An algorithm for retrieval within regions is presented along with data from empirical studies which imply that searching is reasonably efficient. We define an optimized tree and present an algorithm to accomplish optimization in n log n time. Searching is guaranteed to be fast in optimized trees. Remaining problems include those of deletion from quad trees and merging of quad trees, which seem to be inherently difficult operations.
2,294 citations
TL;DR: A method that combines region growing and edge detection for image segmentation is presented and is thought that the success in the tool images is because the objects shown occupy areas of many pixels, making it is easy to select parameters to separate signal information from noise.
Abstract: A method that combines region growing and edge detection for image segmentation is presented. The authors start with a split-and merge algorithm wherein the parameters have been set up so that an over-segmented image results. Region boundaries are then eliminated or modified on the basis of criteria that integrate contrast with boundary smoothness, variation of the image gradient along the boundary, and a criterion that penalizes for the presence of artifacts reflecting the data structure used during segmentation (quadtree in this case). The algorithms were implemented in the C language on a Sun 3/160 workstation running under the Unix operating system. Simple tool images and aerial photographs were used to test the algorithms. The impression of human observers is that the method is very successful on the tool images and less so on the aerial photograph images. It is thought that the success in the tool images is because the objects shown occupy areas of many pixels, making it is easy to select parameters to separate signal information from noise. >
590 citations
1 Sep 1986
TL;DR: Hierarchical path-searching methods are introduced, which make use of this multiresolution representation, to speed up the path planning process considerably.
Abstract: The problem of automatic collision-free path planning is central to mobile robot applications. An approach to automatic path planning based on a quadtree representation is presented. Hierarchical path-searching methods are introduced, which make use of this multiresolution representation, to speed up the path planning process considerably. The applicability of this approach to mobile robot path planning is discussed.
506 citations
TL;DR: Technical details of the block partitioning structure of HEVC are introduced with an emphasis on the method of designing a consistent framework by combining the three different units together and experimental results are provided to justify the role of each component.
Abstract: High Efficiency Video Coding (HEVC) is the latest joint standardization effort of ITU-T WP 3/16 and ISO/IEC JTC 1/SC 29/WG 11. The resultant standard will be published as twin text by ITU-T and ISO/IEC; in the latter case, it will also be known as MPEG-H Part 2. This paper describes the block partitioning structure of the draft HEVC standard and presents the results of an analysis of coding efficiency and complexity. Of the many new technical aspects of HEVC, the block partitioning structure has been identified as representing one of the most significant changes relative to previous video coding standards. In contrast to the fixed size 16 × 16 macroblock structure of H.264/AVC, HEVC defines three different units according to their functionalities. The coding unit defines a region sharing the same prediction mode, e.g., intra and inter, and it is represented by the leaf node of a quadtree structure. The prediction unit defines a region sharing the same prediction information. The transform unit, specified by another quadtree, defines a region sharing the same transformation. This paper introduces technical details of the block partitioning structure of HEVC with an emphasis on the method of designing a consistent framework by combining the three different units together. Experimental results are provided to justify the role of each component of the block partitioning structure and a comparison with the H.264/AVC design is performed.
489 citations
TL;DR: By allowing the use of quadrants with cut corners, this modeling technique overcomes some of the drawbacks of standard quadtree encoding for finite element mesh generation.
Abstract: By allowing the use of quadrants with cut corners, this modeling technique overcomes some of the drawbacks of standard quadtree encoding for finite element mesh generation.
362 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2026 | 1 |
| 2025 | 14 |
| 2024 | 39 |
| 2023 | 61 |
| 2022 | 115 |
| 2021 | 77 |