Now showing 1 - 5 of 5
- PublicationStorage, manipulation, and visualization of LiDAR dataIn recent years, three-dimensional (3D) data has become increasingly available, in part as a result of significant technological progresses in Light Detection and Ranging (LiDAR). LiDAR provides longitude and latitude information delivered in conjunction with a GPS device, and elevation information generated by a pulse or phase laser scanner, which together provide an effective way of acquiring accurate 3D information of a terrestrial or manmade feature. The main advantages of LiDAR over conventional surveying methods lie in the high accuracy of the data and the relatively little time needed to scan large geographical areas. LiDAR scans provide a vast amount of data points that result in especially rich, complex point clouds. Spatial Information Systems (SISs)are critical to the hosting, querying, and analyzing of such spatial data sets. Feature-rich SISs have been well-documented. However, the implementation of support for 3D capabilities in such systems is only now being addressed. This paper analyzes shortcomings of current technology and discusses research efforts to provide support for the querying of 3D data records in SISs.
- PublicationThree-dimensional spatial information systems : state of the art reviewA spatial information system (SIS) is critical to the hosting, querying, and analyzing of spatial data sets. The increasing availability of three-dimensional (3D) data (e.g. from aerial and terrestrial laser scanning) and the desire to use such data in large geo-spatial platforms have been dual drivers in the evolution of integrated SISs. Within this context, recent patents demonstrate efforts to handle large data sets, especially complex point clouds. While the development of feature-rich geo-systems has been well documented, the implementation of support for 3D capabilities is only now being addressed. This paper documents the underlying technologies implemented for the support for 3D features in SISs. Examples include ESRI’s ArcGIS geo-database with its support for two-and-a-half dimensions (2.5D) in its Digital Elevation Model (DEM) and Triangular Irregular Network (TIN), the more recent development of the Terrain feature class, and support for 3D objects and buildings with its multi-patch feature class. Recent patents and research advances aim to extract DEMs and TINs automatically from point cloud data. In this context, various data structuring innovations are presented including both commercial and open source alternatives.
- PublicationLateral image degradation in terrestrial laser scanningThe use of aerial laser scanning to detect change in infrastructure and buildings after major disasters has become increasingly common in recent years to help prioritize interventions. More recent efforts are being invested to apply laser scanning in the assessment and structural health monitoring of buildings to simplify and quicken building damage surveys by the automatic detection of defects and deformations. Technology application must, however, be done in cognizance of equipment constraints regarding scan angle, sampling size, and beam width. This article reports a series of laboratory and field experiments designed to begin to quantify and minimise the possible errors for effective defect detection via terrestrial laser scanning during surveying. Varying geometric positions that cause either over- or under-prediction of crack thickness and length as a function of both standoff distance and angle of obliquity between the scanner and the defect are presented. These may over-predict horizontal crack thickness by 15 mm and failing to detect others. To help minimise such errors, a standoff distance of 12–15 m with a maximum obliquity of 45˚ between the scanner and target object are recommended.
880Scopus© Citations 23
- PublicationWeb-Enabling of Architectural Heritage InventoriesSurveys and inventories of the built environment have improved the understanding of the state of existing heritage structures and historic districts and assisted in their preservation by thorough and consistent documentation. Unfortunately, full exploitation of these resources has been impeded by their static, non-interactive nature as printed documents (ie, reports or maps). This article presents recent attempts to improve access of such resources through their web-enablement. Specifically, issues of usability, relevance, contemporaneousness, and spatial integration are evaluated. These requirements are considered with respect to a new resource, Historic Ireland's Built Environment and Road Network Inventories Access (HIBERNIA). This integrated, extendable database and geographic information system (GIS) is featured as an example of how access to these surveys and inventories can be improved to form the basis for future developments to provide a more complete picture of heritage resources and enable innovative resource management strategies.
817Scopus© Citations 7
- PublicationOpportunities and impediments to the use of 3D laser scanning for adjacent excavationsAlthough three-dimensional laser (3DLS) scanning has been used to document and monitor individual excavation walls and structures on a limited basis, impediments remain to its use for major infrastructure projects. This paper outlines current technological opportunities and obstacles for using 3DLS to predict excavation-induced, damage prediction. Specifics are provided as to limitations regarding cost, optical resolution, processing time requirements, data set convergence, data conversion, and data mining. Specific solutions are proposed to advance the state-of-the-art.