scholarly journals Research on Dem Construction Methods With Effective Integration of Topographic Feature Lines

2021 ◽  
Author(s):  
Jing Wang ◽  
Mingwei Zhao
Keyword(s):  
Morphological Characteristics ◽  
Step Length ◽  
Topographic Feature ◽  
Construction Methods ◽  
Contour Lines ◽  
Feature Lines ◽  
Line Parallel ◽  
Feature Line ◽  
Nanjing City ◽  
Parallel Feature

Abstract In cities and other human activity areas, the implementation of various ground projects has resulted in significant changes in natural surface morphology, a prominent feature of which is the formation of a variety of discontinuous terrains, such as roads and building basements. In the process of DEM modeling of these landforms, traditional modeling methods produce obvious topographic distortions at topographic prominences, which limits the application depth of DEMs in these areas. To solve these problems, this paper proposes a DEM modeling method to enhance the expression of discontinuous terrain from the perspective of simplicity and convenience for application. The method is based on terrain data such as topographic feature lines, altimetric points, and contour lines. First, parallel feature lines are generated according to a certain distance. Then, vertices are inserted into the topographic feature line and the parallel feature line according to the specified step length, and the known altimetric points are selected from both sides of the original topographic feature line to estimate the height value of the vertices. Finally, by combining the topographic feature line, parallel feature line and other available topographic data for TIN construction, the result can effectively express the special topography of discontinuous terrain. In this study, a region in Nanjing City, Jiangsu Province, China, was selected as the study area to conduct a DEM construction experiment. The experimental results showed that the DEM constructed by this method could well express the morphological characteristics of discontinuous terrain, and the height accuracy of the construction results was also significantly improved compared with that of the conventional method.

scholarly journals FEATURE LINE BASED BUILDING DETECTION AND RECONSTRUCTION FROM OBLIQUE AIRBORNE IMAGERY

2015 ◽  
Vol XL-4/W5 ◽  
pp. 199-204 ◽  
Author(s):  
Q. Zhu ◽  
W. Jiang ◽  
J. Zhang
Keyword(s):  
Image Matching ◽  
Mesh Segmentation ◽  
Building Detection ◽  
Quality Model ◽  
Test Dataset ◽  
Building Models ◽  
Contour Lines ◽  
Feature Lines ◽  
Feature Line ◽  
Density Image

In this paper, a feature line based method for building detection and reconstruction from oblique airborne imagery is presented. With the development of Multi-View Stereo technology, increasing photogrammetric softwares are provided to generate textured meshes from oblique airborne imagery. However, errors in image matching and mesh segmentation lead to the low geometrical accuracy of building models, especially at building boundaries. To simplify massive meshes and construct accurate 3D building models, we integrate multi-view images and meshes by using feature lines, in which contour lines are used for building detection and straight skeleton for building reconstruction. Firstly, through the contour clustering method, buildings can be quickly and robustly detected from meshes. Then, a feature preserving mesh segmentation method is applied to accurately extract 3D straight skeleton from meshes. Finally, straight feature lines derived from multi-view images are used to rectify inaccurate parts of 3D straight skeleton of buildings. Therefore, low quality model can be refined by the accuracy improvement of mesh feature lines and rectification with feature lines of multi-view images. The test dataset in Zürich is provided by ISPRS/EuroSDR initiative Benchmark on High Density Image Matching for DSM Computation. The experiments reveal that the proposed method can obtain convincing and high quality 3D building models from oblique airborne imagery.

Automated extraction of 3D vector topographic feature line from terrain point cloud

2017 ◽  
Vol 33 (10) ◽  
pp. 1036-1047 ◽  
Author(s):  
Wei Zhou ◽  
Rencan Peng ◽  
Jian Dong ◽  
Tao Wang
Keyword(s):  
Point Cloud ◽  
Automated Extraction ◽  
Topographic Feature ◽  
Feature Line

A Feature-Preserving Hole Filling Algorithm in Reverse Engineering

2012 ◽  
Vol 263-266 ◽  
pp. 2049-2053
Author(s):  
Ying Gao ◽  
Rui Zhao Wang ◽  
Ping Xin Ji
Keyword(s):  
Reverse Engineering ◽  
Experimental Results ◽  
Hole Filling ◽  
Line Extraction ◽  
Mesh Model ◽  
Feature Lines ◽  
Feature Line ◽  
Triangular Mesh Model ◽  
Feature Preserving ◽  
New Feature

To get complete and accurate triangular mesh model in reverse engineering, the hole-filling operation is indispensable. This paper presents a new feature preserving hole-filling algorithm based on the feature line extraction. Firstly, the hole and its neighborhood were obtained. Then, the feature lines in the hole region were extracted which were used to divided the hole to several single surface holes. To each hole, triangulation and subdivision were performed. Finally, the new added vertices in the hole were moved to the underlying surface which was approximated by the hole neighborhood. The experimental results demonstrate that our mesh hole-filling algorithm can effectively recover the original shape of the hole.

The Influence of Added Mass on Optimal Step Length in Running

2016 ◽  
Vol 11 (7) ◽  
pp. 920-926 ◽  
Author(s):  
Jasper Reenalda ◽  
Maurice T.F. Maas ◽  
Jos J. de Koning
Keyword(s):  
Oxygen Uptake ◽  
Mass Distribution ◽  
Morphological Characteristics ◽  
Step Length ◽  
Added Mass ◽  
Leg Length ◽  
Experienced Male ◽  
The Individual ◽  
Induced Changes ◽  
Insight Into

Purpose:To examine the influence of induced changes in the morphology of the leg by adding mass on the optimal step length (OSL) in experienced runners to get more insight into parameters that influence preferred step length (PSL) and OSL.Methods:Thirteen experienced male runners (mean age 26.9 ± 6.1 y, height 183.7 ± 7.1 cm, mass 71.8 ± 5.9 kg) ran on a treadmill in 3 different conditions: unloaded (UL), loaded with 2 kg mass at the ankles (MA), and loaded with 2 kg mass at the hips (MH) at 7 different step lengths (SLs). SL deviations were expressed as deviations in relative leg length (%LL) from the individual PSL: 0%LL, ±5%LL, ±10%LL, and ±15%LL. Trials lasted 8 min, and 8 min of rest was given between trials. Oxygen uptake (V̇O2) was expressed as a fraction of V̇O2 at PSL + 0%LL in the unloaded condition (%V̇O2). The %SL with the lowest value of %V̇O2 was considered the OSL for this group of participants.Results:OSL at the UL condition was 6% shorter than PSL. The MA condition resulted in a 7%LL larger OSL than at UL and MH (P < .05).Conclusions:The mass distribution of the leg is a determinant of the OSL. As a consequence of the added mass to the ankles, OSL was 7%LL longer. Morphological characteristics of the leg might therefore play an important role in determining the runner’s individual optimal SL.

scholarly journals A Kinematics Analysis Of Three Best 100 M Performances Ever

2013 ◽  
Vol 36 (1) ◽  
pp. 149-160 ◽  
Author(s):  
Maćkała Krzysztof ◽  
Antti Mero
Keyword(s):  
Body Height ◽  
Morphological Characteristics ◽  
Step Length ◽  
Stride Frequency ◽  
Leg Length ◽  
Step Frequency ◽  
Running Speed ◽  
Main Hypothesis ◽  
Video Footage ◽  
Main Factor

The purpose of this investigation was to compare and determine the relevance of the morphological characteristics and variability of running speed parameters (stride length and stride frequency) between Usain Bolt’s three best 100 m performances. Based on this, an attempt was made to define which factors determine the performance of Usain Bolt's sprint and, therefore, distinguish him from other sprinters. We analyzed the previous world record of 9.69 s set in the 2008 Beijing Olympics, the current record of 9.58 s set in the 2009 Berlin World Championships in Athletics and the O lympic record of 9.63 s set in 2012 London Olympics Games by Usain Bolt. The application of VirtualDub Programme allowed the acquisition of basic kinematical variables such as step length and step frequency parameters of 100 m sprint from video footage provided by NBC TV station, BBC TV station. This data was compared with other data available on the web and data published by the Scientific Research Project Office responsible on behalf of IAAF and the German Athletics Association (DVL). The main hypothesis was that the step length is the main factor that determines running speed in the 10 and 20 m sections of the entire 100 m distance. Bolt’s anthropometric advantage (body height, leg length and liner body) is not questionable and it is one of the factors that makes him faster than the rest of the finalists from each three competitions. Additionally, Bolt’s 20 cm longer stride shows benefit in the latter part of the race. Despite these factors, he is probably able to strike the ground more forcefully than rest of sprinters, relative to their body mass, therefore, he might maximize his time on the ground and to exert the same force over this period of time. This ability, combined with longer stride allows him to create very high running speed - over 12 m/s (12.05 -12.34 m/s) in some 10 m sections of his three 100 m performances. These assumption confirmed the application of Ballerieich's formula for speed development. In most 10 m sections of the 100 m sprint, the step length was the parameter that significantly determined the increase of maximal running speed, therefore, distinguishing Bolt from the other finalists.

FEATURE LINE EXTRACTION ON MESHES THROUGH VERTEX MARKING AND 2D TOPOLOGICAL OPERATORS

2011 ◽  
Vol 11 (04) ◽  
pp. 531-548 ◽  
Author(s):  
DIMITRI KUDELSKI ◽  
SOPHIE VISEUR ◽  
GIOVANNI SCROFANI ◽  
JEAN-LUC MARI
Keyword(s):  
Regular Representation ◽  
Candidate Region ◽  
Line Detection ◽  
3D Mesh ◽  
Line Extraction ◽  
Feature Lines ◽  
Feature Line ◽  
High Connectivity ◽  
Candidate Regions ◽  
Traditional Approaches

Classical approaches of feature line detection rely on curvature derivatives. They generally suffer from a common problem: the connectivity is hard to obtain and it is impossible to generate intersections between feature lines. This article presents a method to extract feature lines on 3D meshes. In order to sort out the recurrent issues of traditional approaches, we propose a novel algorithm based on two ideas. First, all the mesh vertices are marked according to the curvature values: a binary map with candidate regions is then constructed. The second idea is to isolate each candidate region and transform it into a line. To achieve this, we parameterize the region into its 2D regular representation. We then perform a skeletonization to obtain lines with high connectivity. By applying the inverse parameterization, the feature lines are mapped back onto the 3D mesh. In the end, we extract perceptual salient parts and above all connected feature lines. In order to evaluate and validate our algorithm, we compare our method to classical ones and apply our technique to a geological context.

Extraction of Mountain Feature Line Based on 3D Laser Scanning

2012 ◽  
Vol 182-183 ◽  
pp. 1821-1825 ◽  
Author(s):  
Cheng Hui Wan ◽  
Xiao Jun Cheng
Keyword(s):  
Point Cloud ◽  
Laser Scanning ◽  
Point Cloud Data ◽  
Feature Points ◽  
3D Laser Scanning ◽  
Cloud Data ◽  
3D Space ◽  
Contour Lines ◽  
Feature Line ◽  
Cut Surface

This paper applies a Cut-and-Sew algorithm extracting feature line of the mountain based on laser 3D scanning. The mountain is cut at the direction of contour lines. Point cloud data of the cut surface fits curve that project the same plane. Feature points find the curve corresponding to match. Through the connection of feature points, then returning the 3D space to achieve feature line, and the establishment of the formation of the triangular feature line is reconstructed on the mountain.

Selection of Construction Parameters in Heading Pre-Reinforcement Working Method for Liuyang River Tunnel on Wuhan-Guangzhou High-Speed Railway

2011 ◽  
Vol 361-363 ◽  
pp. 1730-1739
Author(s):  
Zhi Min Xiang ◽  
Ren Ai Yuan ◽  
Tai Yue Qi
Keyword(s):  
High Speed ◽  
Step Length ◽  
Wall Rock ◽  
Geological Condition ◽  
Reinforcement Density ◽  
High Speed Railway ◽  
Construction Methods ◽  
Core Soil ◽  
Working Method ◽  
Selection Of

The Liuyang River Tunnel on Wuhan-Guangzhou High-Speed Railway goes through the bottom of Liuyang River, the geological condition of which wall rock is not suitable for the construction. The paper proposes the heading pre-reinforcement method, namely pre-reinforcing core soil ahead of heading with fiberglass rockbolt in construction in order to optimize the construction methods and avoid both the deformation inside the tunnel and surface subsidence, and to ensure safety of tunnel construction. In order to determine the reasonable construction parameters, the paper obtains reinforcement density and length of fiberglass rockbolt, pre-reinforcement method on outline of heading, excavation step length and other construction parameters, by the numerical simulation, the indoor model tests and other methods, and analyzes its sensitivity. It is shown by the practices in construction that the selected parameters are reasonable and significantly effective, thus providing valuable experience for promotion and application of heading pre-reinforcement method.

Influence Surfaces for Stresses in Slabs

1941 ◽  
Vol 8 (1) ◽  
pp. A3-A13
Author(s):  
Francis M. Baron
Keyword(s):  
Stress Function ◽  
Middle Surface ◽  
Correction Function ◽  
Edge Condition ◽  
Influence Diagrams ◽  
Basic Solution ◽  
Bending Moments ◽  
Contour Lines ◽  
Line Parallel ◽  
Rectangular Slab

Abstract The investigation reported herein presents a formal analytical solution of some problems involving influence surfaces for stresses in slabs. It deals primarily with the determination of influence diagrams for stresses in homogeneous elastic slabs and is based upon the extension of Müller-Breslau’s principle established in structural mechanics. The analysis is based upon the classical procedure of obtaining a solution of Lagrange’s differential equation of the deflected middle surface of the slab, satisfying at the same time, all of the boundary conditions at the various edges. Systematic use of a stress function, introduced by Nádai in the theory of slabs, is made in forming the expressions for bending moments, twisting moments, and shears at any point of a semi-infinite slab cantilevered from a single fixed edge. The problem is meant only as an illustration in the use of Nádai’s stress function when a fixed edge condition is desired. The influence surface for a bending moment at a point on the fixed edge of an infinitely long rectangular slab, with a fixed edge transverse to two parallel simply supported edges, is defined by a function in finite form. Contour lines of the influence surfaces for the bending moments at the quarter points and at the mid-point of the fixed edge are given. The solution for the infinitely long rectangular slab is considered as a basic solution to which a correction function is added to obtain any desired condition along a line parallel to the fixed edge. The correction functions required to obtain either a simple or fixed support along a line parallel to the given fixed edge are stated in the form of an infinite series. A few illustrative figures of the resultant diagrams are given. Approximate formulas for the correction functions are also stated. Influence functions are stated for the moments at the mid-point and at a point on the fixed edge of a circular slab with a fixed edge. Contour lines of the influence surfaces are given. Each solution defining an influence surface for a stress at a given point of a homogeneous elastic slab may also be used to solve the related two-dimensional problem of stresses in a slice. A slab is converted into a slice when the loads applied transverse to the slab are replaced by forces that are parallel to the middle plane of the slice and produce no bending or transverse shears.

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