Polygonal Reconstruction Research Articles

Automated filtering and polygonal reconstruction of virtual skull model based on computed tomography

A method of automated filtering and polygonal reconstruction of the skull virtual model using the methods of “Marching cubes” and “Connected component labeling” is considered. An algorithm for effective software implementation is described. A computational experiment on computed tomography data consisting of 244 DICOM images is presented. The experimental results confirm the correctness and computational efficiency of the algorithm.

지향점 데이터로부터 폴리곤 곡면 재건 방법

지향점 데이터로부터 폴리곤 곡면 재건 방법

Polygonal damage shape reconstruction in plates using guided Lamb wave

Tomographic reconstruction of the damaged region using guided Lamb waves provides important information about the health condition of structures. Two general types of shape reconstruction techniques are discussed before: transform based methods and algebraic iterative methods. There are some limitations associated with each method such as high sensitivity to noise and incomplete data sets, limitations for damage size and contrast, bulky setup for scanning the damaged region, or low speed of reconstruction. In this paper, the concepts of a novel method for reconstructing the contour of damage based on the Polygon Reconstruction Technique are introduced. First, the projections (Radon transform) of the damaged region are generated from a small number of angles with the aid of beamforming method. Then, the damaged region is modeled by a polygon, which its optimal number of vertices is estimated using the minimum description length (MDL) principle. Finally, using the polygon reconstruction technique, the coordinates of the vertices are determined. As the proposed method is at its preliminary stage, two finite element models of an aluminum plate with two different holes as the damage are designed in ABAQUS to examine the feasibility and performance of the method. Results show that the introduced technique based on polygonal damage shape reconstruction is fast and accurate. Copyright © 2016 John Wiley & Sons, Ltd.

An Extended Evaluation of Open Source Surface Reconstruction Software for Robotic Applications

Polygonal surface reconstruction is a growing field of interest in mobile robotics. Recently, several open source surface reconstruction software packages have become publicly available. This paper...

O-snap

In this article, we introduce a novel reconstruction and modeling pipeline to create polygonal models from unstructured point clouds. We propose an automatic polygonal reconstruction that can then be interactively refined by the user. An initial model is automatically created by extracting a set of RANSAC-based locally fitted planar primitives along with their boundary polygons, and then searching for local adjacency relations among parts of the polygons. The extracted set of adjacency relations is enforced to snap polygon elements together, while simultaneously fitting to the input point cloud and ensuring the planarity of the polygons. This optimization-based snapping algorithm may also be interleaved with user interaction. This allows the user to sketch modifications with coarse and loose 2D strokes, as the exact alignment of the polygons is automatically performed by the snapping. The generated models are coarse, offer simple editing possibilities by design, and are suitable for interactive 3D applications like games, virtual environments, etc. The main innovation in our approach lies in the tight coupling between interactive input and automatic optimization, as well as in an algorithm that robustly discovers the set of adjacency relations.

RECONSTRUCTION OF 3D VECTOR MODELS OF BUILDINGS BY COMBINATION OF ALS, TLS AND VLS DATA

Abstract. Airborne Laser Scanning (ALS), Terrestrial Laser Scanning (TLS) and Vehicle based Laser Scanning (VLS) are widely used as data acquisition methods for 3D building modelling. ALS data is often used to generate, among others, roof models. TLS data has proven its effectiveness in the geometric reconstruction of building façades. Although the operating algorithms used in the processing chain of these two kinds of data are quite similar, their combination should be more investigated. This study explores the possibility of combining ALS and TLS data for simultaneously producing 3D building models from bird point of view and pedestrian point of view. The geometric accuracy of roofs and façades models is different due to the acquisition techniques. In order to take these differences into account, the surfaces composing roofs and façades are extracted with the same algorithm of segmentation. Nevertheless the segmentation algorithm must be adapted to the properties of the different point clouds. It is based on the RANSAC algorithm, but has been applied in a sequential way in order to extract all potential planar clusters from airborne and terrestrial datasets. Surfaces are fitted to planar clusters, allowing edge detection and reconstruction of vector polygons. Models resulting from TLS data are obviously more accurate than those generated from ALS data. Therefore, the geometry of the roofs is corrected and adapted according to the geometry of the corresponding façades. Finally, the effects of the differences between raw ALS and TLS data on the results of the modeling process are analyzed. It is shown that such combination could be used to produce reliable 3D building models.

Polygonal shape reconstruction in the plane

In this study a robust shape reconstruction algorithm is proposed which guarantees a simple polygon as output and works well on both types of input, dot patterns and boundary samples, in the plane. Guaranteed polygonal output makes it favourable for many applications because of its ease of manipulation and use. The proposed algorithm, called simple-shape, starts reconstruction from the convex hull and makes it concave step by step based on a new hybrid selection criterion which is built on human beings visual perception. Also at the end, a simple-shape algorithm is tested in several cases and the results are compared with the latest shape reconstruction algorithm in the literature.

Orthogonal polygon reconstruction from stabbing information

Reconstruction of polygons from visibility information is known to be a difficult problem in general. In this paper, we consider a special case: reconstruction of orthogonal polygons from horizontal and vertical visibility information and show that this reconstruction can be performed in O( nlog n) time.

Curve reconstruction: Connecting dots with good reason

Curve reconstruction algorithms are supposed to reconstruct curves from point samples. Recent papers present algorithms that come with a guarantee: Given a sufficiently dense sample of a closed smooth curve, the algorithms construct the correct polygonal reconstruction. Nothing is claimed about the output of the algorithms, if the input is not a dense sample of a closed smooth curve, e.g., a sample of a curve with endpoints. We present an algorithm that comes with a guarantee for any set P of input points. The algorithm constructs a polygonal reconstruction G and a smooth curve Γ that justifies G as the reconstruction from P.

Tomographic Reconstruction of Polygons from Knot Location and Chord Length Measurements

In this work, we develop statistically based algorithms to reconstruct binary polygonal objects from sparse and noisy tomographic-based observation data. Traditional approaches to the reconstruction of geometric objects from projection data often lead to highly nonlinear estimation problems. To avoid the difficulties associated with such nonlinear problems, we first examine the problem of reconstruction of an object based on knot location measurements, i.e., measurements of the locations of abrupt change in the projections. The ties between this problem and that of multitarget radar tracking enable us to develop a sequential hypothesis-testing algorithm requiring only the solution of a series of linear estimation problems. In particular, data association hypotheses are generated, under each of which the inversion is linear. The complexity of the association possibilities are kept in check through the use of constraints on the reconstruction imposed by the tomography problem. The solution of this first problem is then used as an initialization to a more complete reconstruction which, while utilizing all the projection data, is nonlinear. We demonstrate that the estimates provided by the first, efficient algorithm are of good quality on their own, and, when combined with a fully nonlinear inversion, produce excellent object estimates.

Representation and reconstruction of polygons and polyhedra using Hierarchical Extended Gaussian Images

In this paper, two new representation schemes called the Branched Gaussian Image (BGI) and the Hierarchical Extended Gaussian Image (HEGI) are proposed. They can be used for uniquely representing both concave and convex, two-dimensional figures and three-dimensional objects. The representation by the Branched Gaussian Image involves several Gaussian spheres connected by branches where the traversing directions might be different. Examples showing how the use of the BGI enables us to achieve the mapping and inverse mapping of concave polygons and polyhedra uniquely are presented. The Gaussian spheres in the BGI can be organized into a tree-like hierarchical structure known as the Hierarchical Extended Gaussian Image. A general procedure for mapping a polygon or polyhedron to its HEGI representation is described. An approach for reconstructing concave polygons from Branched Gaussian Images is presented. The reconstruction of a concave polyhedron from its Hierarchical Extended Gaussian Images by using an iterative method or a closed-form method for each convex component is also described.

Reconstruction of polygons from projections

The projection probe and the line probe are abstractions of two types of crude robotic sensory devices for indentifying and locating objects. A projection probe is a mathematical projection of a planar object onto a line; a line probe is a line sliding over the plane until it intersects an object. This paper determines the number of projection probes necessary and sufficient for the reconstruction of a convex polygon and the number of line probes necessary and sufficient for the same purpose.

Reconstruction of Polygons by Digitized Line Segments for a GIS

Reconstruction of Polygons by Digitized Line Segments for a GIS