Kouichi Konno

Feature line extraction from unorganized noisy point clouds using truncated Fourier series

The detection of feature lines is important for representing and understanding geometric features of 3D models. In this paper, we introduce a new and robust method for extracting feature lines from unorganized point clouds. We use a one-dimensional truncated Fourier series for detecting feature points. Each point and its neighbors are approximated along the principal directions by using the truncated Fourier series, and the curvature of the point is computed from the approximated curves. The Fourier coefficients are computed by Fast Fourier Transform (FFT). We apply low-pass filtering to remove noise and to compute the curvature of the point robustly. For extracting feature points from the detected potential feature points, the potential feature points are thinned using a curvature weighted Laplacian-like smoothing method. The feature lines are constructed through growing extracted points and then projected onto the original point cloud. The efficiency and robustness of our approach is illustrated by several experimental results.

Pairwise matching of 3D fragments using fast fourier transform

In this paper, we introduce a new method for pairwise matching of broken fragments from unorganized point clouds. We use a new descriptor that contains not only the cluster of feature points but also curves along the principal directions of the cluster. In our method, feature points are extracted by using the curvature values of points. Curves of the descriptor are approximated using Fourier series. The main idea is motivated by comparing descriptor curves between each cluster of matching faces. For comparing curves, the Fourier coefficients of each curve are computed by using Fast Fourier Transform and total energies of curves are compared.

3D terrain reconstruction based on contours

In 3D terrain reconstruction, the differences of shape and topology among contours in adjacent sections cause a difficulty as the tiling problem of branching terrain. In this paper, we present a brief and pure geometrical algorithm to reconstruct 3D terrain based on contours. The merit of our method is that the tiling rules guarantee arbitrary branching terrain can be divided into correct topology.

Reconstruction Method of Trimmed Surfaces Maintaining G1-Continuity with Adjacent Surfaces

In 3D CAD systems, reconstruction of trimmed surfaces is one of the important research topics. When 3D CAD data is exchanged between different CAD systems, it does not deliver the specifications of CAD systems completely. Therefore, we have to correct the CAD data, such as moving the point in order to fill gaps. Generally, CAD data is expressed by set of trimmed surfaces. Then, we need to modify the trimmed surfaces. It is necessary, however, to modify the trimmed surface shape so as to maintain geometrical consistency of the boundary edges and surfaces in direct modeling, and this is a big restriction. It is effective to apply a new free-form surface to a closed region enclosed with the modified edges because the consistency of a trimmed surface can be maintained. Many shapes with holes or concave shapes are included in CAD data. Moreover, it is necessary to consider maintaining G1-continuity with adjacent surfaces, but it is difficult to reconstruct the trimmed surface by the conventional surface fittin...

Complex hole-filling algorithm for 3D models

In this paper, we propose a new and simple method for filling complex holes in surfaces. To fill a hole, locally uniform points are added to the hole by creating contour curves inside the boundary edges of the hole. A set of contour curves is created by shortening the flow of the boundary edges of the hole. The Delaunay triangulation method in a local area is applied for creating new meshes. The direction of the shortening flow is changed to satisfy the convergence of the curve shortening flow. It enables the filling of a complex hole, such as a hole with an island and a hole with highly curved boundary edges. In addition, the method can be used to fill a hole by preserving the sharp features of the model.

Evaluation of 3D Data Compression and Retrieval Method Based on Curve Mesh Filling

ABSTRACTDigital mock-up (DMU) and/or compound document with 3D data are one of the most important methods to represent a product model. Since the data size of 3D models becomes greater year by year, 3D data compression and retrieval algorithm is required to easily exchange such information through the Internet. Because broadband is still not popular in some regions in the world, it is necessary to send huge data in a small size as much as possible. Therefore, in this paper we developed an application system that transfers 3D surface models and then the performance of the 3D surface compression and retrieval algorithm is evaluated.

Rigid registration of noisy point clouds based on higher-dimensional error metrics

Methods based on distance error metrics, such as the iterative closest point (ICP) algorithm and its variants, do not efficiently register noisy point clouds. In this paper, we propose a novel method for registering noisy point clouds by extending the ICP algorithm. The proposed method, which is based on higher-dimensional error metrics minimization, has two variants: One variant is based on area error metric, and the other is based on volume error metric. For the registration of point clouds, triangles or tetrahedrons are constructed between the point clouds by using an optimal vertices selection algorithm. To reduce computational complexity, the method is linearized by assuming that the rotation angle is small. The main advantage of the proposed method is its robustness for the registration of noisy point clouds. In particular, the volume minimization-based registration variant exhibits good robustness in the presence of strong noise. The proposed method was compared with the variants of ICP algorithm in experiments conducted on many types of point clouds, such as noisy point clouds with different noise levels. The experimental results obtained show that the robustness of the registration is increased by using higher-dimensional error metrics.

Interactive visualization of assembly instruction for stone tools restoration

3D exploded views have been widely used for assembly instructions in many fields but have seldom been used in archaeology. For studying stone tools, relics are repeatedly assembled using indistinct traditional illustrations. We apply this powerful presentation technique on the stone tool models, and study algorithms for point cloud data. In addition to presenting principles for the restoration of stone tools, we designed our system based on archaeological rules. In this paper, we propose an interactive visualization method of assembly instruction using 3D visualization technology to assist in the efficient restoration of stone tools.

Generating a reference model of the surface with a hole for downstream process

ABSTRACTThe value of 3D CAD models is continuously increasing in downstream processes. The more extensive use of a 3D model outside traditional design and manufacturing is trending now. To distribute 3D data quickly to downstream departments is significant boosts to product quality, production costs, and delivery to markets. Unfortunately, interoperability causes poor communication since downstream applications rely on the reusability and interoperability of CAD models. However, 3D CAD data size for expressing precise forms tends to be big and time-consuming for computation, which may interfere in the communication. In addition, downstream processes emphasize surface smoothness more than precision. Therefore, this paper describes the reconstruction method of a smooth surface by integrating the advantages of Gregory and B-spline surfaces. In this paper, a new surface representation is proposed. Two surfaces are connected with G1-continuity by using the control points at the common boundary obtained from jo...

High-quality Approximation Technique for Two G1-continuous Offset Surfaces

This paper proposes a technique for approximating two G1-continuous offset surfaces. Since offset surfaces are in general not rational representation, spline approximations of offset surfaces are widely used. However, when two G1-continuous offset surfaces are approximated using existing methods, the shape data quality is reduced because gaps or creases arise between two approximated surfaces. Our technique generates two G1-continuous approximated surfaces represented by C1-continuous bicubic B-spline surfaces. The approximated surfaces are higher quality than those generated using existing methods, because no gaps or creases arise between those surfaces.