scholarly journals Grid Partition Variable Step Alpha Shapes Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zhenxiu Liao ◽  
Jun Liu ◽  
Guodong Shi ◽  
Junxia Meng
Keyword(s):  
Average Distance ◽  
Discrete Point ◽  
Boundary Extraction ◽  
Grid Partition ◽  
Alpha Shapes ◽  
Extraction Algorithm ◽  
Variable Step ◽  
Point Set ◽  
Index Table ◽  
Previous Step

On the basis of Alpha Shapes boundary extraction algorithm for discrete point set, a grid partition variable step Alpha Shapes algorithm is proposed to deal with the shortcomings of the original Alpha Shapes algorithm in the processing of nonuniform distributed point set and multiconcave point set. Firstly, the grid partition and row-column index table are established for the point set, and the point set of boundary grid partition is quickly extracted. Then, the average distance of the k -nearest neighbors of the point is calculated as the value of α . For the point set of boundary grid partition extracted in the previous step, Alpha Shapes algorithm is used to quickly construct the point set boundary. The proposed algorithm is verified by experiments of simulated point set and measured point set, and it has high execution efficiency. Compared with similar algorithms, the larger the number of point sets is, the more obvious the execution efficiency is.

An Efficient Improved Algorithm of Convex Hull

2014 ◽  
Vol 602-605 ◽  
pp. 3104-3106
Author(s):  
Shao Hua Liu ◽  
Jia Hua Zhang
Keyword(s):  
Convex Hull ◽  
Line Segment ◽  
Main Idea ◽  
Discrete Point ◽  
Directed Line ◽  
Generation Algorithm ◽  
Simple Program ◽  
Point Set ◽  
High Computational Efficiency ◽  
Improved Algorithm

This paper introduced points and directed line segment relation judgment method, the characteristics of generation and Graham method using the original convex hull generation algorithm of convex hull discrete points of the convex hull, an improved algorithm for planar discrete point set is proposed. The main idea is to use quadrilateral to divide planar discrete point set into five blocks, and then by judgment in addition to the four district quadrilateral internally within the point is in a convex edge. The result shows that the method is relatively simple program, high computational efficiency.

scholarly journals Extended Function Analysis of Urban Planning and Design Based on Automatic Extraction Algorithm of Closed Area Boundary

2022 ◽  
Vol 2022 ◽  
pp. 1-8
Author(s):  
Xifeng Mi
Keyword(s):  
Functional Analysis ◽  
Urban Planning ◽  
Function Analysis ◽  
Social Economy ◽  
Automatic Extraction ◽  
Boundary Extraction ◽  
Closed Area ◽  
Planning And Design ◽  
Extraction Algorithm ◽  
Urban Planning And Design

With the continuous development of social economy, the expansion of cities often leads to the disorderly utilization of land resources and even waste. In view of these limitations and requirements, this paper introduces the automatic extraction algorithm of closed area boundary, combs the requirements of urban boundary extraction involved in urban planning and design, and uses the technology of geospatial analysis to carry out spatial analysis practice from three angles, so as to realize the expansion of functional analysis of urban planning and design and improve the efficiency and rationality of urban planning. The simulation results show that the automatic extraction algorithm of closed area boundary is effective and can support the functional analysis of urban planning and design expansion.

4H-SiC Epi-Ready Substrate Qualification by Using Mirror Electron Microscope Inspection System

2020 ◽  
Vol 1004 ◽  
pp. 369-375
Author(s):  
Masaki Hasegawa ◽  
Kentaro Ohira ◽  
Noriyuki Kaneoka ◽  
Tomohiko Ogata ◽  
Katsunori Onuki ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Mechanical Polishing ◽  
Inspection System ◽  
Layer Surface ◽  
Discrete Point ◽  
Surface Polishing ◽  
Point Set ◽  
Crystal Damage

Crystal damage beneath the surface remaining after chemo-mechanical polishing (CMP) and basal plane dislocations (BPDs) of 4H-SiC epi-ready substrates have been inspected by using a mirror electron microscope inspection system non-destructively. Distributions of crystal damage and BPDs as well as their average densities are estimated by acquiring 80-μm square mirror electron images at positions distributed with an equal pitch over a substrate (“Discrete point set inspection”). Although the total inspected area is less than 1% of the entire substrate area, the inspection results for nine commercially available wafers reveal that there are large differences in surface polishing quality and BPD density between them. Evaluation on an epitaxial layer with a thickness of 10 μm grown on one of the inspected substrates indicated that correlation between distribution of the crystal damages on the substrate and that of bunched steps on the epitaxial layer surface.

An improved building boundary extraction algorithm based on fusion of optical imagery and LIDAR data

Optik ◽  
2013 ◽  
Vol 124 (22) ◽  
pp. 5357-5362 ◽  
Author(s):  
Yong Li ◽  
Huayi Wu ◽  
Ru An ◽  
Hanwei Xu ◽  
Qisheng He ◽  
...  
Keyword(s):  
Lidar Data ◽  
Boundary Extraction ◽  
Extraction Algorithm ◽  
Optical Imagery

Automatic boundary extraction from magnetic field data using triangular meshes

Geophysics ◽  
2016 ◽  
Vol 81 (3) ◽  
pp. J47-J60 ◽  
Author(s):  
Nathan Leon Foks ◽  
Yaoguo Li
Keyword(s):  
Magnetic Field ◽  
Synthetic Data ◽  
Magnetic Data ◽  
Lake Area ◽  
Boundary Extraction ◽  
Data Set ◽  
Magnetic Field Data ◽  
Line Segments ◽  
Extraction Algorithm ◽  
The Magnetic Field

Boundary extraction is a collective term that we use for the process of extracting the locations of faults, lineaments, and lateral boundaries between geologic units using geophysical observations, such as measurements of the magnetic field. The process typically begins with a preprocessing stage, where the data are transformed to enhance the visual clarity of pertinent features and hence improve the interpretability of the data. The majority of the existing methods are based on raster grid enhancement techniques, and the boundaries are extracted as a series of points or line segments. In contrast, we set out a methodology for boundary extraction from magnetic data, in which we represent the transformed data as a surface in 3D using a mesh of triangular facets. After initializing the mesh, we modify the node locations, such that the mesh smoothly represents the transformed data and that facet edges are aligned with features in the data that approximate the horizontal locations of subsurface boundaries. To illustrate our boundary extraction algorithm, we first apply it to a synthetic data set. We then apply it to identify boundaries in a magnetic data set from the McFaulds Lake area in Ontario, Canada. The extracted boundaries are in agreement with known boundaries and several of the regions that are completely enclosed by extracted boundaries coincide with regions of known mineralization.

Robust Iris Recognition Process Using Boundary Extraction Algorithm

2014 ◽  
Vol 15 (1) ◽  
pp. 7-11
Author(s):  
Chimata Nagababu ◽  
◽  
P Kranthi Chaithnya ◽  
T.V.S prasad guptha
Keyword(s):  
Iris Recognition ◽  
Boundary Extraction ◽  
Recognition Process ◽  
Extraction Algorithm

scholarly journals Expected sizes of Poisson–Delaunay mosaics and their discrete Morse functions

2017 ◽  
Vol 49 (3) ◽  
pp. 745-767 ◽  
Author(s):  
Herbert Edelsbrunner ◽  
Anton Nikitenko ◽  
Matthias Reitzner
Keyword(s):  
Point Process ◽  
Poisson Point Process ◽  
Probabilistic Models ◽  
Morse Function ◽  
Discrete Point ◽  
Expected Number ◽  
Low Dimensions ◽  
Morse Functions ◽  
Point Set ◽  
Discrete Morse Function

AbstractMapping every simplex in the Delaunay mosaic of a discrete point set to the radius of the smallest empty circumsphere gives a generalized discrete Morse function. Choosing the points from a Poisson point process in ℝn, we study the expected number of simplices in the Delaunay mosaic as well as the expected number of critical simplices and nonsingular intervals in the corresponding generalized discrete gradient. Observing connections with other probabilistic models, we obtain precise expressions for the expected numbers in low dimensions. In particular, we obtain the expected numbers of simplices in the Poisson–Delaunay mosaic in dimensionsn≤ 4.

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