Generating Free-Form Grid Truss Structures from 3D Scanned Point Clouds

Hui Ding,Xian Xu,Yaozhi Luo

doi:10.1155/2017/5818627

Abstract

Reconstruction, according to physical shape, is a novel way to generate free-form grid truss structures. 3D scanning is an effective means of acquiring physical form information and it generates dense point clouds on surfaces of objects. However, generating grid truss structures from point clouds is still a challenge. Based on the advancing front technique (AFT) which is widely used in Finite Element Method (FEM), a scheme for generating grid truss structures from 3D scanned point clouds is proposed in this paper. Based on the characteristics of point cloud data, the search box is adopted to reduce the search space in grid generating. A front advancing procedure suit for point clouds is established. Delaunay method and Laplacian method are used to improve the quality of the generated grids, and an adjustment strategy that locates grid nodes at appointed places is proposed. Several examples of generating grid truss structures from 3D scanned point clouds of seashells are carried out to verify the proposed scheme. Physical models of the grid truss structures generated in the examples are manufactured by 3D print, which solidifies the feasibility of the scheme.

Highlights

Grid truss structures are widely used in large span roofs and shelters
The first category is wholly artificial forms, such as curved surfaces sketched by architects or free shapes created by CAD software
The initial shape of the single-layer glass grid shell over the courtyard of the renovated “Palacio de Comunicaciones” in Madrid was derived from an inflated balloon [2]

Summary

Introduction

Grid truss structures are widely used in large span roofs and shelters. Traditional grid truss structures usually have regular geometrical configurations, such as plates, spherical shells, and cylindrical shells. After the shape information is obtained, interpolation and fitting are carried out to generate a curved surface from the point cloud, and the grid design is conducted on the surface [4]. Physical models generally have irregular shapes and the step from point clouds to surfaces. The grids of the single-layer glass grid shell over the courtyard of the renovated “Palacio de Comunicaciones” in Madrid and the grids of the “Sunshine Valley” of World Expo Shanghai 2010 were generated by a mapping procedure [2, 17] These methods can only be applied on surfaces and cannot be directly applied on point clouds. A novel scheme for generating grid truss structures from physical objects is proposed. The 3D scan technology is used to obtain point clouds from the surface of physical objects. The software matched with a Shining 3D scanner is used

Grid Generating

Grid Optimization and Adjustment

Examples

Findings

Conclusions