3D Modelling of Buildings and Environments using Laser Scanning and Surface Reconstruction

ABSTRACT: 3D models of environments and buildings are widely used in Geographical Information Systems (GIS), building information models, constructional management, environmental planning, city guides, path finding and Robotic applications, where the accuracy of data collection and resolution of the 3D model have been the main concern. 3D models of buildings and other objects can be constructed by following three main steps, namely, data acquisition, alignment and surface reconstruction. This project aims at introducing the process of forming a 3-D model from 3-D scan data and describing the data acquisition, alignment and surface reconstruction sequences in detail. Hardware and software design and implementation has been made for each stage of the 3D modelling process and a full grasp of the system is achieved. However, due to the complexity of the system, and also due to time limitation, it was not possible to achieve sufficient performance from the designed system. Instead, a commercial 3D laser scanner was used for the sake of completing the requirements of the 3D Modelling process with a reasonable performance. Current data acquisition systems have been reviewed and compared to discuss their advantages and drawbacks, as a result of which, 3D laser scanner has been chosen to be the most accurate and fast data acquisition system appropriate for scanning indoor and outdoor environments. Due to some limitations of the available 3D laser scanners, a commercial 1D-laser scanner has been converted into a 3D laser scanner, by designing and constructing a pan-tilt mechanism for the 3 axis control of the 1D laser scanner. The new 3D laser scanner is a simple and light in weight, which is easily adopted to a remote operating and monitoring Vehicle (ROMV) which has been designed in this project to add an indoor and outdoor mobility feature to the device. Although the new 3D Laser scanner operates properly, the accuracy and resolution of the scan results are not as expected yet. In order to complete the 3D modelling process with a reasonable accuracy and resolution, data acquisition is achieved by using the 3D laser scanner provided form the Stevens Institute of technology (CAD eye Scanner). This system is not only able to scan indoor and outdoor environments with acceptable resolution, but also it is able to collect RGB data corresponding to each scanned point in the scanned environment. For the Alignment or Registration of the acquired coordinate data obtained by the 3D Laser scanner, this research has used the semi- automatic method produced by an academic software tool called Mesh-lab. Point cloud model of the Techno park building was obtained by using professional software called Pointools. Surface reconstruction methods are investigated to obtain models with seamless and smooth surfaces from the point cloud model. It is realized that the existing methods fail to produce realistic surfaces under noisy data and a new method based on implicit surface reconstruction using isotropic basis functions has been developed to represent the sharp features more close to their real appearance. Some initial simple results of this method are presented in the thesis. A further work is needed to apply this method to reconstruct the surfaces of a complete 3D building model. Keywords: 3D Laser scanner, surface reconstruction, registration, radial basis functions, generalization..........