TUNNEL MODELING USING MOBILE MAPPING LIDAR POINTS

Abstract. In this paper, a method to model a tunnel using lidar points is presented. The data used was collected using Leica Pegasus Two Ultimate with a Z+F 9012 Profiler mounted on a mobile platform. The tunnel was approximately 151 m long. Visual inspection of a cross-section of the tunnel showed two rail tracks supported on ballast and sidewalks along both sidewalls of the tunnel. The walls and the ceiling of the tunnel were made of five planar surfaces. The tunnel alignment was straight, without any horizontal or vertical curves. The bearing of the central axis of the tunnel was N12.2oW. The following methodology was developed to model just the planar surfaces of the tunnel by excluding the rails, ballast, sidewalks, powerlines, and other accessories. The entire methodology was divided into three broad parts. In the first part, a model cross-section was created. Since the design plans of the tunnel were not available, the model cross-section polyline was created using mean tunnel dimensions from random cross-section points. The model cross-section consisted of the walls and the ceiling of the tunnel. Points were placed at every 1 cm along the model polyline. Six of the model points that represented the shape of the tunnel were selected as salient points. The lower-left salient point was considered as the seed point. In the second part, to define a reference axis of the tunnel, an approximate centerline was manually defined by selecting points at its start and end. Lidar points within 1 m at the start and the end of the tunnel were modeled using the model points to determine the centroids. The reference axis was determined by connecting the centroids at the start and the end of the tunnel. In the third part, the tunnel points were sliced along the reference axis at 5 cm intervals. The model cross-section was matched to points within each tunnel slice using a three-stage approach. In the first stage, the pattern of salient points was matched to the tunnel points by placing the seed point at every tunnel point location. The distances between salient points and their nearest tunnel points were calculated. Ten sets of tunnel points with the least differences to the salient points were shortlisted. In the second stage, a dense point-to-point matching was performed between the model and sliced tunnel data at the shortlisted points. The shortlisted point location with the least difference between the tunnel and the model points was considered as a match. At this point, the model points were hinged to the tunnel points at the seed point location. Hence, in the last stage, a six-parameter affine transformation was performed to match the model points to the tunnel data. The transformed model points at every 5 cm of the length of the tunnel were considered as current shape of the tunnel.

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Building a Standard 3D Face Database Based on Planar Templates

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.48-49.280 ◽

2011 ◽

Vol 48-49 ◽

pp. 280-283

Author(s):

Xin Xin Li ◽

Xun Gong

Keyword(s):

3D Models ◽

Face Database ◽

Matching Method ◽

Matching Accuracy ◽

Point Matching ◽

Dense Point ◽

The Mean ◽

Point To Point ◽

3D Face Database ◽

2D Space

This paper presents a new point matching method to solve the dense point-to-point alignment of scanned 3D faces. Texture maps of 3D models are generated at first by unwrapping 3D faces to 2D space. Then, we build planar templates based on the mean shape computed by a group of annotated texture map. 34 landmarks on the unwrapped texture images are located by AAM and the final correspondence is built according to the templates. Comparing to the traditional algorithms, the presented point matching method can achieve good matching accuracy and stability.

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MAPPING FAULTS BY THE REFLECTION METHOD

Geophysics ◽

10.1190/1.1438102 ◽

1937 ◽

Vol 2 (4) ◽

pp. 342-356 ◽

Cited By ~ 1

Author(s):

Henry Salvatori

Keyword(s):

Cross Section ◽

Correlation Method ◽

Reflection Method ◽

Point To Point

In regions where reflections can be correlated from point to point the mapping of faults presents little difficulty, and the hade as well as the throw of a fault can be generally determined. Two records secured across a fault are reproduced and a cross section derived from these records is shown. A description is given of a method of profiling which permits correlation of records in areas where the ordinary correlation method cannot be successfully applied. The application of this method in the determination of faults is outlined.

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Dense point-to-point correspondences between 3D faces using parametric remeshing for constructing 3D Morphable Models

2011 IEEE Workshop on Applications of Computer Vision (WACV) ◽

10.1109/wacv.2011.5711481 ◽

2011 ◽

Cited By ~ 1

Author(s):

Moritz Kaiser ◽

Gernot Heym ◽

Nicolas Lehment ◽

Dejan Arsic ◽

Gerhard Rigoll

Keyword(s):

Dense Point ◽

Point To Point ◽

Morphable Models

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Analysis of the Scattering from a Two Stacked Thin Resistive Disks Resonator by Means of the Helmholtz–Galerkin Regularizing Technique

Applied Sciences ◽

10.3390/app11178173 ◽

2021 ◽

Vol 11 (17) ◽

pp. 8173

Author(s):

Mario Lucido

Keyword(s):

Cross Section ◽

Near Field ◽

Surface Current ◽

Coefficient Matrix ◽

Hankel Transform ◽

General Purpose ◽

Analytical Technique ◽

Planar Surfaces ◽

Natural Modes ◽

Resonance Frequencies

In this paper, the scattering of a plane wave from a lossy Fabry–Perót resonator, realized with two equiaxial thin resistive disks with the same radius, is analyzed by means of the generalization of the Helmholtz–Galerkin regularizing technique recently developed by the author. The disks are modelled as 2-D planar surfaces described in terms of generalized boundary conditions. Taking advantage of the revolution symmetry, the problem is equivalently formulated as a set of independent systems of 1-D equations in the vector Hankel transform domain for the cylindrical harmonics of the effective surface current densities. The Helmholtz decomposition of the unknowns, combined with a suitable choice of the expansion functions in a Galerkin scheme, lead to a fast-converging Fredholm second-kind matrix operator equation. Moreover, an analytical technique specifically devised to efficiently evaluate the integrals of the coefficient matrix is adopted. As shown in the numerical results section, near-field and far-field parameters are accurately and efficiently reconstructed even at the resonance frequencies of the natural modes, which are searched for the peaks of the total scattering cross-section and the absorption cross-section. Moreover, the proposed method drastically outperforms the general-purpose commercial software CST Microwave Studio in terms of both CPU time and memory occupation.

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Ideal Seed Point Location Approximation for GrowCut Interactive Image Segmentation

Bildverarbeitung für die Medizin 2018 - Informatik aktuell ◽

10.1007/978-3-662-56537-7_60 ◽

2018 ◽

pp. 210-215

Author(s):

Mario Amrehn ◽

Maddalena Strumia ◽

Stefan Steidl ◽

Tim Horz ◽

Markus Kowarschik ◽

...

Keyword(s):

Image Segmentation ◽

Point Location ◽

Seed Point ◽

Interactive Image Segmentation

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PLANAR CONSTRAINTS FOR AN IMPROVED UAV-IMAGE-BASED DENSE POINT CLOUD GENERATION

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-1-w4-269-2015 ◽

2015 ◽

Vol XL-1/W4 ◽

pp. 269-274 ◽

Cited By ~ 4

Author(s):

F. He ◽

A. Habib ◽

A. Al-Rawabdeh

Keyword(s):

Point Cloud ◽

Experimental Tests ◽

Point Clouds ◽

Geometric Information ◽

Planar Surfaces ◽

3D Point Clouds ◽

Dense Image ◽

Dense Point ◽

Uav Image

In this paper, we proposed a new refinement procedure for the semi-global dense image matching. In order to remove outliers and improve the disparity image derived from the semi-global algorithm, both the local smoothness constraint and point cloud segments are utilized. Compared with current refinement technique, which usually assumes the correspondences between planar surfaces and 2D image segments, our proposed approach can effectively deal with object with both planar and curved surfaces. Meanwhile, since 3D point clouds contain more precise geometric information regarding to the reconstructed objects, the planar surfaces identified in our approach can be more accurate. In order to illustrate the feasibility of our approach, several experimental tests are conducted on both Middlebury test and real UAV-image datasets. The results demonstrate that our approach has a good performance on improving the quality of the derived dense image-based point cloud.

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Study of the jet stream over India and to its north in winter: Part I

MAUSAM ◽

10.54302/mausam.v22i1.3978 ◽

2021 ◽

Vol 22 (1) ◽

pp. 1-14

Author(s):

SQN. LDR. M. S. SINGH

Keyword(s):

Cross Section ◽

Cross Sections ◽

Polar Front ◽

Maximum Speed ◽

Jet Stream ◽

Jet Streams ◽

Model Cross Section ◽

Average Maximum ◽

The One ◽

Polar Front Jet

Characteristics of the jet streams over India and to its north in winter were studied with the daily vertical cross sections (1200 GMT) along 75°E from 8oN to 60°N for the period I to 15 February 1967, It was observed that there are three separate jet cores present in this latitl1de belt on most of the days, located on an average at 43°N, 31°N and 23°N. of these three, the most stable and persistent one is the second which is located between Delhi and Srinagar, at 200-mb level with an average maximum speed of 140-150 kt. The one to its south is weaker and quite variable in location as well as altitude. The jet at 31°N, therefore, has been called the primary sl1b-tropical jet over India and its characteristics studied. Based on this study, a. model cross-section has been. prepared for this STJ, The descriptions of the STJ at 23°N and also of PFJ (Polar Front Jet) at 43°N are included.

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A Novel Detection Method of Paper Defects Based on Visual Attention Mechanism

International Journal of Advanced Pervasive and Ubiquitous Computing ◽

10.4018/japuc.2011070103 ◽

2011 ◽

Vol 3 (3) ◽

pp. 24-31 ◽

Cited By ~ 1

Author(s):

Ping Jiang ◽

Tao Gao

Keyword(s):

Visual Attention ◽

Detection Method ◽

Saliency Map ◽

Attention Mechanism ◽

Feature Maps ◽

Seed Point ◽

Multi Scale ◽

Comparative Maps ◽

Salient Points ◽

Visual Attention Mechanism

In this paper, an improved paper defects detection method based on visual attention mechanism computation model is presented. First, multi-scale feature maps are extracted by linear filtering. Second, the comparative maps are obtained by carrying out center-surround difference operator. Third, the saliency map is obtained by combining conspicuity maps, which is gained by combining the multi-scale comparative maps. Last, the seed point of watershed segmentation is determined by competition among salient points in the saliency map and the defect regions are segmented from the background. Experimental results show the efficiency of the approach for paper defects detection.

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