Adjacency list

About: Adjacency list is a research topic. Over the lifetime, 4419 publications have been published within this topic receiving 78449 citations.

Integration of synthetic aperture radar image segmentation method using Markov random field on region adjacency graph

Abstract: A novel approach to obtain precise segmentation of synthetic aperture radar (SAR) images using Markov random field model on region adjacency graph (MRF-RAG) is presented. First, to form a RAG, the watershed algorithm is employed to obtain an initially over-segmented image. Then, a novel MRF is defined over the RAG instead of pixels so that the erroneous segmentation caused by speckle in SAR images can be avoided and the number of configurations for the combinatorial optimisation can be reduced. Finally, a modification method based on Gibbs sampler is proposed to correct edge errors, brought by the over-segmented algorithm, in the segmentations obtained by MRF-RAG. The experimental results both on simulated and real SAR images show that the proposed method can reduce the computational complexity greatly as well as increase the segmentation precision.

Graph product structure for non-minor-closed classes

Abstract: Dujmovic et al. (FOCS 2019) recently proved that every planar graph is a subgraph of the strong product of a graph of bounded treewidth and a path. Analogous results were obtained for graphs of bounded Euler genus or apex-minor-free graphs. These tools have been used to solve longstanding problems on queue layouts, non-repetitive colouring, $p$-centered colouring, and adjacency labelling. This paper proves analogous product structure theorems for various non-minor-closed classes. One noteable example is $k$-planar graphs (those with a drawing in the plane in which each edge is involved in at most $k$ crossings). We prove that every $k$-planar graph is a subgraph of the strong product of a graph of treewidth $O(k^5)$ and a path. This is the first result of this type for a non-minor-closed class of graphs. It implies, amongst other results, that $k$-planar graphs have non-repetitive chromatic number upper-bounded by a function of $k$. All these results generalise for drawings of graphs on arbitrary surfaces. In fact, we work in a much more general setting based on so-called shortcut systems that are of independent interest. This leads to analogous results for map graphs, string graphs, graph powers, and nearest neighbour graphs.

Characterization and identification of forming features for 3-D sheet metal components

Abstract: This paper presents a new classification system for forming operations, and concepts for extracting and recognizing forming feature from the 3-D sheet metal component created in a wireframe model. A set of principles is developed for characterizing forming features geometrically and topologically. Forming features are extracted by identifying 3-D component graph and subgraphs by vector normal method and vertex fusion methodology. Further, various planes and their type in the component graph are identified, and adjacency plane relationship between them is determined. Cross bend features are extracted by identifying common edges. Pattern recognition is then done using isomorphism principle and a set of characterization principles developed for forming features. A flat pattern is developed for the 3-D component and shearing features are identified. Recognized pressworking features help in the integration of Computer Aided Process Planning (CAPP), codification system, mapping of tools, inspection of tools, etc. The system has been tested for live components.

Simplicity surfaces: a new definition of surfaces in Z3

Abstract: In this paper, we introduce a new motion of surfaces in Z3, called simplicity surfaces. In the continuous space, a surface is characterized by the fast that the neighborhood of each point of the surface is homomorphic to an Euclidean disc. The chosen approach consists in characterizing a surface in Z3 by the condition that the neighborhood of any point constitutes a simple closed curve. The major problem is than, if we consider only the usual adjacency relations, this condition is not satisfied even for the simplest surfaces, e.g. digital planes. We thus have to consider another relation. We use a relation for points in Z3 which is based on the notion of homotopy. This allows to define a surface as a connected set of points in which the neighborhood of each point constitutes a simples closed curve for this relation; such a surface is called a simplicity surface. We give two different local characterizations of simplicity surfaces. We then show that a simplicity surface may also be seen as a combinatorial manifold, that is, a set of faces which are linked by an adjacency relation. Furthermore, we show that the main existing notions of surfaces, for the 6- and the 26- adjacency, are also simplicity surfaces.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.