Terrestrial laser scanning (TLS) provides a rapid, remote sensing technique to model 3D objects. Previous work applying TLS to structural analysis has demonstrated its effectiveness in capturing simple beam deflections and modeling existing structures. This paper extends TLS to the application of damage detection and volumetric change analysis for a full-scale structural test specimen. Importantly, it provides a framework necessary for such applications, in combination with an analysis approach that does not require tedious development of complex surfaces. Intuitive slicing analysis methods are presented, which can be automated for rapid generation of results. In comparison with conventional photographic and surface analysis methods, the proposed approach proved consistent. Furthermore, the TLS data provided additional insight into geometric change not apparent using conventional methods. As with any digital record, a key benefit to the proposed approach is the resulting virtual test specimen, which is av...

Substantial erosion of the unstable seacliffs along the economically important coastline of San Diego County, California, threatens existing developments and public safety. Time-series mapping of the seacliffs and beaches provides valuable information about seasonal and rapid-event erosion. With high resolution terrestrial laser scanning (TLS) georeferenced using real-time-kinematic global positioning systems, it is possible to establish reliable comparisons of time-series surveys for quantitative change analysis of seacliff morphology. This paper introduces new field survey methods for georeferencing TLS surveys collected in dynamic environments where conventional control methods cannot be effectively implemented for large-scale mapping. Specifically, the quality control of scan alignment and the identification of optimal surveying parameters of point separation/density, distance from target, setup spacing, and efficiency are discussed for long cliff sections. These TLS surveys, performed several times a...

This paper presents new techniques with corresponding algorithms to automate three-dimensional point-cloud georeferencing for large-scale data sets collected in dynamic environments where typical controls cannot be efficiently employed. Beam distortion occurs at the scan window edges of long-range scans on near-linear surfaces from oblique laser reflections. Coregistration of adjacent scans relies on these overlapping edges, so alignment errors quickly propagate through the data set unless constraints (origin and leveling information) are incorporated throughout the alignment process. This new methodology implements these constraints with a multineighbor least-squares approach to simultaneously improve alignment accuracy between adjacent scans in a survey and between time-series surveys, which need to be aligned separately for quantitative change analysis. A 1.4-km test survey was aligned without the aforementioned constraints using global alignment techniques, and the modified scan origins showed poor ag...

Complicated menu-based, command line, or scriptable interfaces used in most simulation tools create an unnatural working environment for model development and analysis. Even engineers and scientists familiar with such systems spend significant time converting hand-drawn designs into digital models for simulation. Subsequently, they convert these results into other formats for visualization. These detailed steps lead to many hours of transcribing, rather than interpreting results. To address this problem, we present a unified two-dimensional sketch-based finite-element system, termed 2DSketchFEA, which integrates drawing and recognition of common engineering symbols with geometric meshing, finite-element analysis, and visualization, all within a unified “sketchpad.” The novelty of this work is provided by the sketching pad interface, an upgraded geometric quad meshing algorithm, and the integration of these tools with a FEA solver into a single platform. The result is a system that is easy and rapidly used by the analyst to study model behavioral phenomena. In this paper, we present example model construction and simulation results, each conducted in less than five minutes, and each interpreted by the system using primitive sketching commands. The emphasis of this work is on models within a two-dimensional space constructed of conventional one- and two-dimensional finite elements.

Seacliff erosion plagues the coastline of northern San Diego County, California through both marine and subaerial processes. Heavy development on seacliffs and the economic value of beaches in San Diego County, California place a heavy emphasis on maintaining a healthy and safe beach. This paper illustrates the development of a rapid response program to study and document seacliff erosional processes utilizing a terrestrial LIght Detection And Ranging (LIDAR) system in combination with interactive visualization techniques to publically present this research. One of the cliff failures currently being studied as part of this rapid response program is described in this paper to demonstrate the insights that can be gained by observing the temporal change of a failure mass using frequent site monitoring.